The best metabolic conditions for the biodegradation of hydrocarbons by a selected microbial cons... more The best metabolic conditions for the biodegradation of hydrocarbons by a selected microbial consortium from a natural soil were investigated in order to improve the efficiency of bioremediation processes for cleaning of polluted waters and soils. Phenanthrene is one of the most recalcitrant pollutants to microbial decomposition and most difficult to remove. A microbial consortium was selected from a non polluted soil using a selective medium containing phenanthrene as a sole carbon source; DNA was extracted from the purified strains and the 16S rDNA was PCR-amplified and sequenced for the characterization. In order to improve the bioavailability of phenanthrene ¿-, B., y-, cyclodextrin were tested as coadjuvants. The degradation kinetics were carried out in presence of ¿, B, y-, cyclodextrin in an aqueous phase at 28°C and 37°C; in presence of ¿-cyclodextrin in slurry phase at 37°C and in solid phase at room temperature. Phenanthrene concentration was detected by HPLC. The degradat...
Communications in agricultural and applied biological sciences
Biolog methodology was used for the preliminary screening of different cultural conditions in ord... more Biolog methodology was used for the preliminary screening of different cultural conditions in order to detect the best combination/s of factors influencing the metabolic performance of bacterial consortia active in the degradation of hydrocarbons. Two microbial consortia were tested for their activity on 2 hydrocarbons (nonadecane and eicosane) in presence of the following cultural coadjuvants: vegetal oil, beta-cyclodextrine, sodium acetate, mineral solution. Tests were conducted in Biolog MT plates, where only the redox indicator of microbial growth (tetrazolium violet) and no carbon sources are provided. The microwells were filled with various combinations of hydrocarbons, microbial inoculum and coadjuvants. Blanks were prepared with the same combinations but without hydrocarbons. The results obtained show the suitability of the methodology developed to identify the most active consortium and the conditions for its best degradation performance. The efficacy of Biolog methodology ...
the volatile composition of aromatic grape varieties at harvest is a very important criterion in ... more the volatile composition of aromatic grape varieties at harvest is a very important criterion in the choice of vinification technique to yield the optimal quality of the final product. the berry mechanical characteristics are important for assessing resistance to fungal attacks and for the estimation of shattering. In this study the effect of irrigation on the volatile fingerprint and the mechanical properties of the Muscat blanc (Vitis vinifera L.) grapes grown in mountain north-west region of Italy was investigated. three water regimes were compared: standard irrigation, moderate irrigation and drought.
Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2007
In situ bioremediation of polycyclic aromatic hydrocarbons (PAH) polluted soils can be improved b... more In situ bioremediation of polycyclic aromatic hydrocarbons (PAH) polluted soils can be improved by the augmentation of degrading microbial populations and by the increase of hydrocarbon bioavailability. b-cyclodextrin (b-CD) significantly accelerate the induction of hydrocarbon biodegradation, but it is not still clear its effectiveness during final, slower stages of degradation. Moreover, it is yet not known if the PAH uptake from plants is influenced by the presence of CD. A field study was carried out by creating two plots (A and B). Diesel fuel was spread on the surface, and on plot B a commercial microbial consortium and b-CD were spread. Soybean was seeded in both plots. Soil samples were withdrawn every 10 cm layers from 0 to 60 cm depth, before fuel spreading, immediately after seeding and after soya harvesting. Chemical and microbial analyses were carried out throughout the process to characterize the soil and to determine residual PAHs. Soybean seeds were analyzed for PAH content. It was observed that b-CD induced a significant increase of PAH degradation rate. The microbial inoculum did not improve the degradation; biodegradation activity was strong in superficial layers, and some PAH leaching was observed, that was reduced by CD. The analysis of PAH in soyabeans revealed that an uptake of hydrocarbons occurred, and that it was more significant in plot B. This suggests that the b-CDenhanced bioremediation process can further be improved by phytoremediation, that could also allow to simultaneously reach an additional profit from a non-food yield for biofuel production.
To verify a possible correlation between cell lipid composition, expression of key genes in lipid... more To verify a possible correlation between cell lipid composition, expression of key genes in lipid metabolism and fermentative behaviour of Saccharomyces cerevisiae wine strains. Methods and Results: The fermentative abilities of two commercial wine strains of S. cerevisiae were tested under stressful conditions. Cell number, glucose and fructose concentrations, expression of ACS1, ACS2, ACC1, OLE1, ERG9, ERG10, ARE1 and ARE2 and lipid content were evaluated. The strain that failed to complete the fermentation had lower amounts of C16:1 and C16:0 fatty acids at the beginning of fermentation (0 h) and late logarithmic phase (72 h). While the amount of C18:1 in this strain was lower than that in the strain that completed the fermentation at 0 h, same levels were observed for both strains at 72 h. The sterol levels were generally higher in the strain that failed to complete the fermentation. Gene expression generally increased from the beginning of the fermentation to the late logarithmic phase in both strains. Conclusion: A positive correlation between good fermentative ability, elevated fatty acid content and ACC1 gene expression has been identified. Significance and Impact of the Study: The cell lipid content at the time of inoculum and expression of ACC1 gene of starter strains should be carefully considered in order to identify the possible stuck ⁄ sluggish fermentations.
During must fermentation wine strains are exposed to a variety of biotic and abiotic stresses whi... more During must fermentation wine strains are exposed to a variety of biotic and abiotic stresses which, when prevailing over the cellular defence systems, can affect cell viability with negative consequences on the progression of the fermentative process. To investigate the ability of wine strains to survive and adapt to unfavourable conditions of fermentation, the lipid composition, membrane integrity, cell viability and fermentative activity of three strains of Saccharomyces cerevisiae were analysed during hypoxic growth in a sugar-rich medium lacking lipid nutrients. These are stressful conditions, not unusual during must fermentation, which, by affecting lipid biosynthesis may exert a negative effect on yeast viability. The results obtained showed that the three strains were able to modulate cell lipid composition during fermentation. However, only two of them, which showed highest viability and membrane integrity at the end of the fermentation process, reached a fatty acid composition which seemed to be optimal for a successful adaptation. In particular, C16/TFA and UFA/TFA ratios, more than total lipid and ergosterol contents, seem to be involved in yeast adaptation.
ABSTRACT Wet spent coffee grounds (SCG) from espresso capsules, a post- consumer organic solid re... more ABSTRACT Wet spent coffee grounds (SCG) from espresso capsules, a post- consumer organic solid residue produced worldwide, were analysed to determine their chemical and microbiological stability during storage. In particular, the changes in the total phenolic content and antioxidant capacity (based on two free radical scavenging assays and one oxygen radical absorbance assay) were determined on espresso SCG stored in capsules for up to one month at room temperature in a container open to the air. Phenolic compounds were also identified and quantified using high performance liquid chromatography coupled with diode array and mass detectors. Microbiological analysis was performed in parallel on the same stored SCG to determine the total counts and quantify the main microbial groups present during the storage. The total phenolic content, antioxidant capacity and the most important bioactive compounds, such as the total caffeoylquinic acids, were significantly stable during storage for up to one month, while overall microbial stability was observed for up to two weeks of storage. Overall, the recovery of espresso coffee capsules within 15 days could guarantee the maintenance of microbiological stability as well as the content of valuable antioxidant compounds.
To further elucidate the biosynthesis of lipids in flor strains under fermentative conditions, th... more To further elucidate the biosynthesis of lipids in flor strains under fermentative conditions, the transcription levels of the lipid biosynthetic genes ACS1, ACS2, ACC1, OLE1, ERG1, ERG11, ARE1 and ARE2, as well as the lipid composition and cell viability of a flor strain were compared with that of a non-flor strain during hypoxic and aerobic fermentations in the absence of lipid nutrients. While no significant differences in transcription levels or lipid compositions were observed between the two strains when oxygen was not limiting, significant differences were seen during hypoxic fermentation. In this last condition, the flor strain, in spite of higher levels of transcription of hypoxic genes, lost the abilities to desaturate fatty acids and complete ergosterol biosynthesis, and showed a dramatic loss of viability. In contrast, the non-flor strain, which showed lower transcription levels, was able to reach a balanced lipid composition and maintained a higher cell viability. One possible explanation is that the flor strain requires a higher amount of oxygen than the non-flor strain in order to carry out the oxygen-dependent steps of lipid biosynthesis under fermentative conditions.
The discovery of several healthy beneficial effects of the consumption of dairy products fermente... more The discovery of several healthy beneficial effects of the consumption of dairy products fermented with some bacterial strains led to the investigation of the functional properties of these microorganisms. One of the most studied properties is the cholesterol-lowering activity of bacteria with probiotic characteristics, mostly isolated from human gut. In this work, eight Lactobacillus plantarum and five Lactobacillus paracasei strains isolated from cheese were studied in vitro for their cholesterol-lowering action and their acid and bile tolerance. The ability of these strains to remove cholesterol was assessed in de Man, Rogosa and Sharpe (MRS) medium, supplied with cholesterol, and in ultra-high temperature (UHT) whole homogenized milk. Among all tested strains, two L. plantarum and three L. paracasei strains gave rise to a significant reduction of the cholesterol level in MRS broth; in particular, L. plantarum strains lowered the cholesterol content by an average of 19.4%, whereas L. paracasei strains lowered by an average of 6.8%. The two L. plantarum strains possessing the highest cholesterol-lowering activity in MRS broth were also tested in milk. Results showed that L. plantarum strains maintained this activity because after 24 h the cholesterol decrease ranged from about 5.0% to 8.2% without significant variations between the two strains. Results from the binding assay suggested that cholesterol was mainly removed through the adsorption on the cell wall. Data from acid and bile tolerance assays showed that the L. plantarum dairy isolates were able to maintain viability at pH 2 and to grow in a medium with bile salts, and therefore were regarded as probiotics or dairy starters for new probiotic or functional food production.
Biosynthesis of cell membrane lipids is a crucial metabolic pathway for the growth and viability ... more Biosynthesis of cell membrane lipids is a crucial metabolic pathway for the growth and viability of eucaryotic microorganisms. In Saccharomyces cerevisiae, unsaturated fatty acids and ergosterol synthesis needs molecular oxygen. Stuck and sluggish fermentations are related to this aspect of metabolism and constitute a major problem in the wine industry. Anaerobiosis, when lipids are not available in the growth medium, highly stresses cells. They release lipid biosynthesis metabolites and soon cease to multiply. This paper describes an investigation of the nutritional role of exogenous lipids from inactivated yeast cells (IYCs). Fermentations were carried out in a nitrogen-rich synthetic medium similar to grape juice with glucose and fructose as carbon sources, without lipid sources, and in anaerobiosis. The effect of the addition of IYC was assessed. Cell growth, cell lipid composition, glucose and fructose consumption, and acetic acid production were measured during fermentation. Addition of IYC boosted cell growth and sugar consumption, whereas acetic acid production decreased. Biomass yield was influenced by ergosterol availability and increased when IYCs were added. Fatty acid composition of yeast cells was changed by IYC addition.
The best metabolic conditions for the biodegradation of hydrocarbons by a selected microbial cons... more The best metabolic conditions for the biodegradation of hydrocarbons by a selected microbial consortium from a natural soil were investigated in order to improve the efficiency of bioremediation processes for cleaning of polluted waters and soils. Phenanthrene is one of the most recalcitrant pollutants to microbial decomposition and most difficult to remove. A microbial consortium was selected from a non polluted soil using a selective medium containing phenanthrene as a sole carbon source; DNA was extracted from the purified strains and the 16S rDNA was PCR-amplified and sequenced for the characterization. In order to improve the bioavailability of phenanthrene ¿-, B., y-, cyclodextrin were tested as coadjuvants. The degradation kinetics were carried out in presence of ¿, B, y-, cyclodextrin in an aqueous phase at 28°C and 37°C; in presence of ¿-cyclodextrin in slurry phase at 37°C and in solid phase at room temperature. Phenanthrene concentration was detected by HPLC. The degradat...
Minas cheese is a popular dairy product in Brazil that is traditionally produced using raw or pas... more Minas cheese is a popular dairy product in Brazil that is traditionally produced using raw or pasteurized cow milk. This study proposed an alternative production of Minas cheese using raw goat milk added of a nisin producer Lactococcus lactis subsp. lactis GLc05. An in situ investigation was carried on to evaluate the interactions between the L. lactis subsp. lactis GLc05 and the autochthonous microbiota of a Minas cheese during the ripening; production of biogenic amines (BAs) was assessed as a safety aspect. Minas cheese was produced in two treatments (A, by adding L. lactis subsp. lactis GLc05, and B, without adding this strain), in three independent repetitions (R1, R2, and R3). Culture dependent (direct plating) and independent (rep-PCR and PCR-DGGE) methods were employed to characterize the microbiota and to assess the possible interferences caused by L. lactis subsp. lactis GLc05. BA amounts were measured using HPLC. A significant decrease in coagulase-positive cocci was observed in the cheeses produced by adding L. lactis subsp. lactis GLc05 (cheese A). The rep-PCR and PCR-DGGE highlighted the differences in the microbiota of both cheeses, separating them into two different clusters. Lactococcus sp. was found as the main microorganism in both cheeses, and the microbiota of cheese A presented a higher number of species. High concentrations of tyramine were found in both cheeses and, at specific ripening times, the BA amounts in cheese B were significantly higher than in cheese A (p<0.05). The interaction of nisin producer L. lactis subsp. lactis GLc05 was demonstrated in situ, by demonstration of its influence in the complex microbiota naturally present in a raw goat milk cheese and by controlling the growth of coagulase-positive cocci. L. lactis subsp. lactis GLc05 influenced also the production of BA determining that their amounts in the cheeses were maintained at acceptable levels for human consumption.
Communications in agricultural and applied biological sciences
Biolog methodology was used for the preliminary screening of different cultural conditions in ord... more Biolog methodology was used for the preliminary screening of different cultural conditions in order to detect the best combination/s of factors influencing the metabolic performance of bacterial consortia active in the degradation of hydrocarbons. Two microbial consortia were tested for their activity on 2 hydrocarbons (nonadecane and eicosane) in presence of the following cultural coadjuvants: vegetal oil, beta-cyclodextrine, sodium acetate, mineral solution. Tests were conducted in Biolog MT plates, where only the redox indicator of microbial growth (tetrazolium violet) and no carbon sources are provided. The microwells were filled with various combinations of hydrocarbons, microbial inoculum and coadjuvants. Blanks were prepared with the same combinations but without hydrocarbons. The results obtained show the suitability of the methodology developed to identify the most active consortium and the conditions for its best degradation performance. The efficacy of Biolog methodology ...
the volatile composition of aromatic grape varieties at harvest is a very important criterion in ... more the volatile composition of aromatic grape varieties at harvest is a very important criterion in the choice of vinification technique to yield the optimal quality of the final product. the berry mechanical characteristics are important for assessing resistance to fungal attacks and for the estimation of shattering. In this study the effect of irrigation on the volatile fingerprint and the mechanical properties of the Muscat blanc (Vitis vinifera L.) grapes grown in mountain north-west region of Italy was investigated. three water regimes were compared: standard irrigation, moderate irrigation and drought.
Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2007
In situ bioremediation of polycyclic aromatic hydrocarbons (PAH) polluted soils can be improved b... more In situ bioremediation of polycyclic aromatic hydrocarbons (PAH) polluted soils can be improved by the augmentation of degrading microbial populations and by the increase of hydrocarbon bioavailability. b-cyclodextrin (b-CD) significantly accelerate the induction of hydrocarbon biodegradation, but it is not still clear its effectiveness during final, slower stages of degradation. Moreover, it is yet not known if the PAH uptake from plants is influenced by the presence of CD. A field study was carried out by creating two plots (A and B). Diesel fuel was spread on the surface, and on plot B a commercial microbial consortium and b-CD were spread. Soybean was seeded in both plots. Soil samples were withdrawn every 10 cm layers from 0 to 60 cm depth, before fuel spreading, immediately after seeding and after soya harvesting. Chemical and microbial analyses were carried out throughout the process to characterize the soil and to determine residual PAHs. Soybean seeds were analyzed for PAH content. It was observed that b-CD induced a significant increase of PAH degradation rate. The microbial inoculum did not improve the degradation; biodegradation activity was strong in superficial layers, and some PAH leaching was observed, that was reduced by CD. The analysis of PAH in soyabeans revealed that an uptake of hydrocarbons occurred, and that it was more significant in plot B. This suggests that the b-CDenhanced bioremediation process can further be improved by phytoremediation, that could also allow to simultaneously reach an additional profit from a non-food yield for biofuel production.
To verify a possible correlation between cell lipid composition, expression of key genes in lipid... more To verify a possible correlation between cell lipid composition, expression of key genes in lipid metabolism and fermentative behaviour of Saccharomyces cerevisiae wine strains. Methods and Results: The fermentative abilities of two commercial wine strains of S. cerevisiae were tested under stressful conditions. Cell number, glucose and fructose concentrations, expression of ACS1, ACS2, ACC1, OLE1, ERG9, ERG10, ARE1 and ARE2 and lipid content were evaluated. The strain that failed to complete the fermentation had lower amounts of C16:1 and C16:0 fatty acids at the beginning of fermentation (0 h) and late logarithmic phase (72 h). While the amount of C18:1 in this strain was lower than that in the strain that completed the fermentation at 0 h, same levels were observed for both strains at 72 h. The sterol levels were generally higher in the strain that failed to complete the fermentation. Gene expression generally increased from the beginning of the fermentation to the late logarithmic phase in both strains. Conclusion: A positive correlation between good fermentative ability, elevated fatty acid content and ACC1 gene expression has been identified. Significance and Impact of the Study: The cell lipid content at the time of inoculum and expression of ACC1 gene of starter strains should be carefully considered in order to identify the possible stuck ⁄ sluggish fermentations.
The best metabolic conditions for the biodegradation of hydrocarbons by a selected microbial cons... more The best metabolic conditions for the biodegradation of hydrocarbons by a selected microbial consortium from a natural soil were investigated in order to improve the efficiency of bioremediation processes for cleaning of polluted waters and soils. Phenanthrene is one of the most recalcitrant pollutants to microbial decomposition and most difficult to remove. A microbial consortium was selected from a non polluted soil using a selective medium containing phenanthrene as a sole carbon source; DNA was extracted from the purified strains and the 16S rDNA was PCR-amplified and sequenced for the characterization. In order to improve the bioavailability of phenanthrene ¿-, B., y-, cyclodextrin were tested as coadjuvants. The degradation kinetics were carried out in presence of ¿, B, y-, cyclodextrin in an aqueous phase at 28°C and 37°C; in presence of ¿-cyclodextrin in slurry phase at 37°C and in solid phase at room temperature. Phenanthrene concentration was detected by HPLC. The degradat...
Communications in agricultural and applied biological sciences
Biolog methodology was used for the preliminary screening of different cultural conditions in ord... more Biolog methodology was used for the preliminary screening of different cultural conditions in order to detect the best combination/s of factors influencing the metabolic performance of bacterial consortia active in the degradation of hydrocarbons. Two microbial consortia were tested for their activity on 2 hydrocarbons (nonadecane and eicosane) in presence of the following cultural coadjuvants: vegetal oil, beta-cyclodextrine, sodium acetate, mineral solution. Tests were conducted in Biolog MT plates, where only the redox indicator of microbial growth (tetrazolium violet) and no carbon sources are provided. The microwells were filled with various combinations of hydrocarbons, microbial inoculum and coadjuvants. Blanks were prepared with the same combinations but without hydrocarbons. The results obtained show the suitability of the methodology developed to identify the most active consortium and the conditions for its best degradation performance. The efficacy of Biolog methodology ...
the volatile composition of aromatic grape varieties at harvest is a very important criterion in ... more the volatile composition of aromatic grape varieties at harvest is a very important criterion in the choice of vinification technique to yield the optimal quality of the final product. the berry mechanical characteristics are important for assessing resistance to fungal attacks and for the estimation of shattering. In this study the effect of irrigation on the volatile fingerprint and the mechanical properties of the Muscat blanc (Vitis vinifera L.) grapes grown in mountain north-west region of Italy was investigated. three water regimes were compared: standard irrigation, moderate irrigation and drought.
Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2007
In situ bioremediation of polycyclic aromatic hydrocarbons (PAH) polluted soils can be improved b... more In situ bioremediation of polycyclic aromatic hydrocarbons (PAH) polluted soils can be improved by the augmentation of degrading microbial populations and by the increase of hydrocarbon bioavailability. b-cyclodextrin (b-CD) significantly accelerate the induction of hydrocarbon biodegradation, but it is not still clear its effectiveness during final, slower stages of degradation. Moreover, it is yet not known if the PAH uptake from plants is influenced by the presence of CD. A field study was carried out by creating two plots (A and B). Diesel fuel was spread on the surface, and on plot B a commercial microbial consortium and b-CD were spread. Soybean was seeded in both plots. Soil samples were withdrawn every 10 cm layers from 0 to 60 cm depth, before fuel spreading, immediately after seeding and after soya harvesting. Chemical and microbial analyses were carried out throughout the process to characterize the soil and to determine residual PAHs. Soybean seeds were analyzed for PAH content. It was observed that b-CD induced a significant increase of PAH degradation rate. The microbial inoculum did not improve the degradation; biodegradation activity was strong in superficial layers, and some PAH leaching was observed, that was reduced by CD. The analysis of PAH in soyabeans revealed that an uptake of hydrocarbons occurred, and that it was more significant in plot B. This suggests that the b-CDenhanced bioremediation process can further be improved by phytoremediation, that could also allow to simultaneously reach an additional profit from a non-food yield for biofuel production.
To verify a possible correlation between cell lipid composition, expression of key genes in lipid... more To verify a possible correlation between cell lipid composition, expression of key genes in lipid metabolism and fermentative behaviour of Saccharomyces cerevisiae wine strains. Methods and Results: The fermentative abilities of two commercial wine strains of S. cerevisiae were tested under stressful conditions. Cell number, glucose and fructose concentrations, expression of ACS1, ACS2, ACC1, OLE1, ERG9, ERG10, ARE1 and ARE2 and lipid content were evaluated. The strain that failed to complete the fermentation had lower amounts of C16:1 and C16:0 fatty acids at the beginning of fermentation (0 h) and late logarithmic phase (72 h). While the amount of C18:1 in this strain was lower than that in the strain that completed the fermentation at 0 h, same levels were observed for both strains at 72 h. The sterol levels were generally higher in the strain that failed to complete the fermentation. Gene expression generally increased from the beginning of the fermentation to the late logarithmic phase in both strains. Conclusion: A positive correlation between good fermentative ability, elevated fatty acid content and ACC1 gene expression has been identified. Significance and Impact of the Study: The cell lipid content at the time of inoculum and expression of ACC1 gene of starter strains should be carefully considered in order to identify the possible stuck ⁄ sluggish fermentations.
During must fermentation wine strains are exposed to a variety of biotic and abiotic stresses whi... more During must fermentation wine strains are exposed to a variety of biotic and abiotic stresses which, when prevailing over the cellular defence systems, can affect cell viability with negative consequences on the progression of the fermentative process. To investigate the ability of wine strains to survive and adapt to unfavourable conditions of fermentation, the lipid composition, membrane integrity, cell viability and fermentative activity of three strains of Saccharomyces cerevisiae were analysed during hypoxic growth in a sugar-rich medium lacking lipid nutrients. These are stressful conditions, not unusual during must fermentation, which, by affecting lipid biosynthesis may exert a negative effect on yeast viability. The results obtained showed that the three strains were able to modulate cell lipid composition during fermentation. However, only two of them, which showed highest viability and membrane integrity at the end of the fermentation process, reached a fatty acid composition which seemed to be optimal for a successful adaptation. In particular, C16/TFA and UFA/TFA ratios, more than total lipid and ergosterol contents, seem to be involved in yeast adaptation.
ABSTRACT Wet spent coffee grounds (SCG) from espresso capsules, a post- consumer organic solid re... more ABSTRACT Wet spent coffee grounds (SCG) from espresso capsules, a post- consumer organic solid residue produced worldwide, were analysed to determine their chemical and microbiological stability during storage. In particular, the changes in the total phenolic content and antioxidant capacity (based on two free radical scavenging assays and one oxygen radical absorbance assay) were determined on espresso SCG stored in capsules for up to one month at room temperature in a container open to the air. Phenolic compounds were also identified and quantified using high performance liquid chromatography coupled with diode array and mass detectors. Microbiological analysis was performed in parallel on the same stored SCG to determine the total counts and quantify the main microbial groups present during the storage. The total phenolic content, antioxidant capacity and the most important bioactive compounds, such as the total caffeoylquinic acids, were significantly stable during storage for up to one month, while overall microbial stability was observed for up to two weeks of storage. Overall, the recovery of espresso coffee capsules within 15 days could guarantee the maintenance of microbiological stability as well as the content of valuable antioxidant compounds.
To further elucidate the biosynthesis of lipids in flor strains under fermentative conditions, th... more To further elucidate the biosynthesis of lipids in flor strains under fermentative conditions, the transcription levels of the lipid biosynthetic genes ACS1, ACS2, ACC1, OLE1, ERG1, ERG11, ARE1 and ARE2, as well as the lipid composition and cell viability of a flor strain were compared with that of a non-flor strain during hypoxic and aerobic fermentations in the absence of lipid nutrients. While no significant differences in transcription levels or lipid compositions were observed between the two strains when oxygen was not limiting, significant differences were seen during hypoxic fermentation. In this last condition, the flor strain, in spite of higher levels of transcription of hypoxic genes, lost the abilities to desaturate fatty acids and complete ergosterol biosynthesis, and showed a dramatic loss of viability. In contrast, the non-flor strain, which showed lower transcription levels, was able to reach a balanced lipid composition and maintained a higher cell viability. One possible explanation is that the flor strain requires a higher amount of oxygen than the non-flor strain in order to carry out the oxygen-dependent steps of lipid biosynthesis under fermentative conditions.
The discovery of several healthy beneficial effects of the consumption of dairy products fermente... more The discovery of several healthy beneficial effects of the consumption of dairy products fermented with some bacterial strains led to the investigation of the functional properties of these microorganisms. One of the most studied properties is the cholesterol-lowering activity of bacteria with probiotic characteristics, mostly isolated from human gut. In this work, eight Lactobacillus plantarum and five Lactobacillus paracasei strains isolated from cheese were studied in vitro for their cholesterol-lowering action and their acid and bile tolerance. The ability of these strains to remove cholesterol was assessed in de Man, Rogosa and Sharpe (MRS) medium, supplied with cholesterol, and in ultra-high temperature (UHT) whole homogenized milk. Among all tested strains, two L. plantarum and three L. paracasei strains gave rise to a significant reduction of the cholesterol level in MRS broth; in particular, L. plantarum strains lowered the cholesterol content by an average of 19.4%, whereas L. paracasei strains lowered by an average of 6.8%. The two L. plantarum strains possessing the highest cholesterol-lowering activity in MRS broth were also tested in milk. Results showed that L. plantarum strains maintained this activity because after 24 h the cholesterol decrease ranged from about 5.0% to 8.2% without significant variations between the two strains. Results from the binding assay suggested that cholesterol was mainly removed through the adsorption on the cell wall. Data from acid and bile tolerance assays showed that the L. plantarum dairy isolates were able to maintain viability at pH 2 and to grow in a medium with bile salts, and therefore were regarded as probiotics or dairy starters for new probiotic or functional food production.
Biosynthesis of cell membrane lipids is a crucial metabolic pathway for the growth and viability ... more Biosynthesis of cell membrane lipids is a crucial metabolic pathway for the growth and viability of eucaryotic microorganisms. In Saccharomyces cerevisiae, unsaturated fatty acids and ergosterol synthesis needs molecular oxygen. Stuck and sluggish fermentations are related to this aspect of metabolism and constitute a major problem in the wine industry. Anaerobiosis, when lipids are not available in the growth medium, highly stresses cells. They release lipid biosynthesis metabolites and soon cease to multiply. This paper describes an investigation of the nutritional role of exogenous lipids from inactivated yeast cells (IYCs). Fermentations were carried out in a nitrogen-rich synthetic medium similar to grape juice with glucose and fructose as carbon sources, without lipid sources, and in anaerobiosis. The effect of the addition of IYC was assessed. Cell growth, cell lipid composition, glucose and fructose consumption, and acetic acid production were measured during fermentation. Addition of IYC boosted cell growth and sugar consumption, whereas acetic acid production decreased. Biomass yield was influenced by ergosterol availability and increased when IYCs were added. Fatty acid composition of yeast cells was changed by IYC addition.
The best metabolic conditions for the biodegradation of hydrocarbons by a selected microbial cons... more The best metabolic conditions for the biodegradation of hydrocarbons by a selected microbial consortium from a natural soil were investigated in order to improve the efficiency of bioremediation processes for cleaning of polluted waters and soils. Phenanthrene is one of the most recalcitrant pollutants to microbial decomposition and most difficult to remove. A microbial consortium was selected from a non polluted soil using a selective medium containing phenanthrene as a sole carbon source; DNA was extracted from the purified strains and the 16S rDNA was PCR-amplified and sequenced for the characterization. In order to improve the bioavailability of phenanthrene ¿-, B., y-, cyclodextrin were tested as coadjuvants. The degradation kinetics were carried out in presence of ¿, B, y-, cyclodextrin in an aqueous phase at 28°C and 37°C; in presence of ¿-cyclodextrin in slurry phase at 37°C and in solid phase at room temperature. Phenanthrene concentration was detected by HPLC. The degradat...
Minas cheese is a popular dairy product in Brazil that is traditionally produced using raw or pas... more Minas cheese is a popular dairy product in Brazil that is traditionally produced using raw or pasteurized cow milk. This study proposed an alternative production of Minas cheese using raw goat milk added of a nisin producer Lactococcus lactis subsp. lactis GLc05. An in situ investigation was carried on to evaluate the interactions between the L. lactis subsp. lactis GLc05 and the autochthonous microbiota of a Minas cheese during the ripening; production of biogenic amines (BAs) was assessed as a safety aspect. Minas cheese was produced in two treatments (A, by adding L. lactis subsp. lactis GLc05, and B, without adding this strain), in three independent repetitions (R1, R2, and R3). Culture dependent (direct plating) and independent (rep-PCR and PCR-DGGE) methods were employed to characterize the microbiota and to assess the possible interferences caused by L. lactis subsp. lactis GLc05. BA amounts were measured using HPLC. A significant decrease in coagulase-positive cocci was observed in the cheeses produced by adding L. lactis subsp. lactis GLc05 (cheese A). The rep-PCR and PCR-DGGE highlighted the differences in the microbiota of both cheeses, separating them into two different clusters. Lactococcus sp. was found as the main microorganism in both cheeses, and the microbiota of cheese A presented a higher number of species. High concentrations of tyramine were found in both cheeses and, at specific ripening times, the BA amounts in cheese B were significantly higher than in cheese A (p<0.05). The interaction of nisin producer L. lactis subsp. lactis GLc05 was demonstrated in situ, by demonstration of its influence in the complex microbiota naturally present in a raw goat milk cheese and by controlling the growth of coagulase-positive cocci. L. lactis subsp. lactis GLc05 influenced also the production of BA determining that their amounts in the cheeses were maintained at acceptable levels for human consumption.
Communications in agricultural and applied biological sciences
Biolog methodology was used for the preliminary screening of different cultural conditions in ord... more Biolog methodology was used for the preliminary screening of different cultural conditions in order to detect the best combination/s of factors influencing the metabolic performance of bacterial consortia active in the degradation of hydrocarbons. Two microbial consortia were tested for their activity on 2 hydrocarbons (nonadecane and eicosane) in presence of the following cultural coadjuvants: vegetal oil, beta-cyclodextrine, sodium acetate, mineral solution. Tests were conducted in Biolog MT plates, where only the redox indicator of microbial growth (tetrazolium violet) and no carbon sources are provided. The microwells were filled with various combinations of hydrocarbons, microbial inoculum and coadjuvants. Blanks were prepared with the same combinations but without hydrocarbons. The results obtained show the suitability of the methodology developed to identify the most active consortium and the conditions for its best degradation performance. The efficacy of Biolog methodology ...
the volatile composition of aromatic grape varieties at harvest is a very important criterion in ... more the volatile composition of aromatic grape varieties at harvest is a very important criterion in the choice of vinification technique to yield the optimal quality of the final product. the berry mechanical characteristics are important for assessing resistance to fungal attacks and for the estimation of shattering. In this study the effect of irrigation on the volatile fingerprint and the mechanical properties of the Muscat blanc (Vitis vinifera L.) grapes grown in mountain north-west region of Italy was investigated. three water regimes were compared: standard irrigation, moderate irrigation and drought.
Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2007
In situ bioremediation of polycyclic aromatic hydrocarbons (PAH) polluted soils can be improved b... more In situ bioremediation of polycyclic aromatic hydrocarbons (PAH) polluted soils can be improved by the augmentation of degrading microbial populations and by the increase of hydrocarbon bioavailability. b-cyclodextrin (b-CD) significantly accelerate the induction of hydrocarbon biodegradation, but it is not still clear its effectiveness during final, slower stages of degradation. Moreover, it is yet not known if the PAH uptake from plants is influenced by the presence of CD. A field study was carried out by creating two plots (A and B). Diesel fuel was spread on the surface, and on plot B a commercial microbial consortium and b-CD were spread. Soybean was seeded in both plots. Soil samples were withdrawn every 10 cm layers from 0 to 60 cm depth, before fuel spreading, immediately after seeding and after soya harvesting. Chemical and microbial analyses were carried out throughout the process to characterize the soil and to determine residual PAHs. Soybean seeds were analyzed for PAH content. It was observed that b-CD induced a significant increase of PAH degradation rate. The microbial inoculum did not improve the degradation; biodegradation activity was strong in superficial layers, and some PAH leaching was observed, that was reduced by CD. The analysis of PAH in soyabeans revealed that an uptake of hydrocarbons occurred, and that it was more significant in plot B. This suggests that the b-CDenhanced bioremediation process can further be improved by phytoremediation, that could also allow to simultaneously reach an additional profit from a non-food yield for biofuel production.
To verify a possible correlation between cell lipid composition, expression of key genes in lipid... more To verify a possible correlation between cell lipid composition, expression of key genes in lipid metabolism and fermentative behaviour of Saccharomyces cerevisiae wine strains. Methods and Results: The fermentative abilities of two commercial wine strains of S. cerevisiae were tested under stressful conditions. Cell number, glucose and fructose concentrations, expression of ACS1, ACS2, ACC1, OLE1, ERG9, ERG10, ARE1 and ARE2 and lipid content were evaluated. The strain that failed to complete the fermentation had lower amounts of C16:1 and C16:0 fatty acids at the beginning of fermentation (0 h) and late logarithmic phase (72 h). While the amount of C18:1 in this strain was lower than that in the strain that completed the fermentation at 0 h, same levels were observed for both strains at 72 h. The sterol levels were generally higher in the strain that failed to complete the fermentation. Gene expression generally increased from the beginning of the fermentation to the late logarithmic phase in both strains. Conclusion: A positive correlation between good fermentative ability, elevated fatty acid content and ACC1 gene expression has been identified. Significance and Impact of the Study: The cell lipid content at the time of inoculum and expression of ACC1 gene of starter strains should be carefully considered in order to identify the possible stuck ⁄ sluggish fermentations.
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