Environmental microbiology

Childhood exposure to microbiological agents may influence the development of allergic and respiratory diseases. Apart from home, children spend most of their time at school, which represents an environment of significant exposure to indoor air microbes. Therefore, we aimed to assess how the prevalence of allergic sensitization and asthma in schoolchildren is affected by microbiological exposure within classrooms. Spirometry with bronchodilation, exhaled nitric oxide measurements and skin-prick tests data were retrieved from 858 children aged 8 to 10 years old attending 71 classrooms in 20 primary schools. Air samples were collected in all classrooms using a single-stage microbiological air impactor through agar plates. Gram-negative endotoxins were collected using flow control pumps and analysed by limulus amebocyte lysate assay. Diversity scores were established as the number of different fungal species found in each classroom. Classrooms with increased diversity scores showed a s...

Ideal bacterial support medium for fixed film denitrification processes/bioreactors must be inexpensive, durable and possess large surface area with sufficient porosity. The present study has been focussed on removing nitrate nitrogen at two different nitrate nitrogen loading rates (60 (NLR I) and 120 (NLR II) mg l-1) from simulated aquaculture wastewater. Coconut coir fibre and a commercially available synthetic reticulated plastic media (Fujino Spirals) were used as packing medium in two independent upflow anaerobic packed bed column reactors. Removal of nitrate nitrogen was studied in correlation with other nutrients (COD, TKN, dissolved orthophosphate). Maximum removal of 97% at NLR-I and 99% at NLR – II of nitrate nitrogen was observed in with either media. Greater consistency in the case of COD removal of upto 81% was observed at NLR II where coconut coir was used as support medium compared to 72% COD removal by Fujino Spirals. The results observed indicate that the organic support medium is just as efficient in nitrate nitrogen removal as conventionally used synthetic support medium. The study is important as it specifically focuses on denitrification of aquaculture wastewater using cheaper organic support medium in anoxic bioreactors for the removal of nitrate nitrogen; which is seldom addressed as a significant problem.

MELiSSA is a bioregenerative life support system designed by the European Space Agency (ESA) for the complete recycling of gas, liquid and solid wastes during long distance space exploration. The system uses the combined activity of different living organisms: microbial cultures in bioreactors, a plant compartment and a human crew. In this minireview, the development of a short-cut ecological system for the biotransformation of organic waste is discussed from a microorganism’s perspective. The artificial ecological model—still in full development—that is inspired by Earth’s own geomicrobiological ecosystem serves as an ideal study object on microbial ecology and will become an indispensable travel
companion in manned space exploration.

Recently, a novel approach to a highly sensitive and quantitative detection of rare earth element (REE) ions including La3+, Eu3+ and Tb3+, by the polymerase chain reaction (PCR) technique, has been reported. The detection of REE ions is based on the catalytic nature of REE ions targeting the deoxyribonucleic acid (DNA), thus monitoring of the ions can be achieved by reading the level of intact DNA by PCR. Despite of its high sensitivity (at ppb to ppt levels), the conventional PCR-based REE detection protocol requires certain length of time (1-2 hours). In the present study, we modified the PCR-based REE detection protocols by employing the high-speed PCR, and performed the automated and rapid detection of La3+ in small-sized aqueous samples within 5min.

During a six-month period, on four separate occasions, six licensed day-care centers had cultures taken from environmental surfaces as well as the hands of children and teachers. Fecal coliforms were recovered from 64 (9.5%) of the 675 surfaces sampled. Recovery rate was not influenced by a center's socioeconomic status, time of year, or presence of children who were not toilet trained. Recovery rates did differ significantly in different areas, with the kitchen showing a relatively high recovery rate (19%), and toys and toilets showing remarkably low rates (2% and 4%). Centers with formal hand-washing procedures had lower recovery rates than those without such practices. We also demonstrated a high recovery rate from hands of staff (16%); 6% of children had positive cultures. Contamination of hands and classroom objects is a potential source for the transmission of enteric diseases for children in day-care centers. A program directed at reducing contamination would be important in preventing the spread of diarrheal illness.

Here, we present the complete genome sequence of Enterobacter phage vB_EcRAM-01, isolated from waters of the Río Abajo river, in Panama City, Panama. This phage has deployed lytic activity against the Enterobacter cloacae complex, a pathogen of clinical importance in intensive care units. It belongs to the Myoviridae family and has a double-stranded DNA genome that is 178,477 bp long and contains 293 open reading frames (ORFs).

The zoophilic dermatophyte Microsporum canis has cats as natural reservoir, but it is able to infect a wide range of hosts, including humans, where different clinical features of the so-called ringworm dermatophytosis have been described. Human infections are increasingly been reported in Mediterranean countries. A reliable control program against M. canis infection in cats should include an antifungal treatment of both the infected animals and their living environment. In this article, a herbal mixture composed of chemically defined essential oils (EOs) of Litsea cubeba (1%), Illicium verum, Foeniculum vulgare, and Pelargonium graveolens (0.5% each) was formulated and its antifungal activity assessed against M. canis arthrospores which represent the infective environmental stage of M. canis. Single compounds present in higher amounts in the mixture were also separately tested in vitro. Litsea cubeba and P. graveolens EOs were most effective (minimum inhibitory concentration (MIC) 0...

Bacteriophage lambda has an archetypal immunity system, which prevents superinfection of its E. coli lysogens. It is now known that superinfection at high frequency can occur with toxigenic lambda-like phages, and here we demonstrate that superinfection of a lambda lysogen can lead to acquisition of additional lambda genomes, confirmed by Southern hybridisation and quantitative PCR. As many as 8 integration events were observed, but at very low frequency (6.4 x 10(-4)) and always as multiple insertions at the established primary integration site in E. coli. Sequence analysis of the complete immunity region demonstrated that these multiply infected lysogens were not immunity mutants. In conclusion, although lambda superinfection immunity can be confounded, it is a rare event.

Human noroviruses (HuNoVs) are the most common cause of acute viral gastroenteritis worldwide and are a leading cause of foodborne disease. Their environmental persistence and purported resistance to disinfection undoubtedly contribute to their success as foodborne disease agents. The purpose of this study was to compare the efficacy of three commonly used disinfectant active ingredients against representative HuNoV strains and cultivable surrogates. Ethanol (50, 70, and 90%), sodium hypochlorite (5, 75, 250, 500, and 1,000 ppm), and a quaternary ammonium compound blend (at 0.1×, 1.0×, and 10× concentrations) were evaluated against two norovirus (NoV) genogroup II strains (GII.2 and GII.4) and two surrogates (feline calicivirus [FCV] and murine norovirus [MNV-1]). Virucidal suspension assays (30-s exposure) were conducted in accordance with ASTM International standard E-1052. Virus inactivation was quantified using reverse transcription quantitative PCR targeting the ORFI-ORFII junc...

Phylodynamic analysis of genome-wide single-nucleotide polymorphism (SNP) data is a powerful tool to investigate underlying evolutionary processes of bacterial epidemics. The method was applied to investigate a collection of 65 clinical and environmental isolates of Vibrio cholerae from Haiti collected between 2010 and 2012. Characterization of isolates recovered from environmental samples identified a total of four toxigenic V. cholerae O1 isolates, four non-O1/O139 isolates, and a novel nontoxigenic V. cholerae O1 isolate with the classical tcpA gene. Phylogenies of strains were inferred from genome-wide SNPs using coalescent-based demographic models within a Bayesian framework. A close phylogenetic relationship between clinical and environmental toxigenic V. cholerae O1 strains was observed. As cholera spread throughout Haiti between October 2010 and August 2012, the population size initially increased and then fluctuated over time. Selection analysis along internal branches of t...

Interactions between pesticides and parasites are believed to be responsible for increased mortality of honey bee (Apis mellifera) colonies in the northern hemisphere. Previous efforts have employed experimental approaches using small groups under laboratory conditions to investigate influence of these stressors on honey bee physiology and behaviour, although both the colony level and field conditions play a key role for eusocial honey bees. Here, we challenged honey bee workers under in vivo colony conditions with sublethal doses of the neonicotinoid thiacloprid, the miticide tau-fluvalinate and the endoparasite Nosema ceranae, to investigate potential effects on longevity and behaviour using observation hives. In contrast to previous laboratory studies, our results do not suggest interactions among stressors, but rather lone effects of pesticides and the parasite on mortality and behaviour, respectively. These effects appear to be weak due to different outcomes at the two study si...

Little is known about the role of immigration in shaping bacterial communities or the factors that may dictate success or failure of colonization by bacteria from regional species pools. To address these knowledge gaps, the influence of bacterial colonization into an ecosystem (activated sludge bioreactor) was measured through a disturbance gradient (successive decreases in the parameter solids retention time) relative to stable operational conditions. Through a DNA sequencing approach, we show that the most abundant bacteria within the immigrant community have a greater probability of colonizing the receiving ecosystem, but mostly as low abundance community members. Only during the disturbance do some of these bacterial populations significantly increase in abundance beyond background levels and in few cases become dominant community members post-disturbance. Two mechanisms facilitate the enhanced enrichment of immigrant populations during disturbance: 1) the availability of resour...

Coal is one of the most commonly utilized fossil fuel for energy production across the globe leading to higher amount of emission of sulfur dioxide (SO2) in the atmosphere. Combustion of coal containing higher contents of sulfur is a major factor responsible for acid rain and associated environmental degradation. The currently used physico-chemical approaches for removal of sulfur from coal are expensive, toxic in nature and inappropriate for different types of coal. The application of microbial resources for removal of sulfur from coal is an ecofriendly technique and could be successfully employed at industrial scale after laboratory scale process optimization. The process of sulfur removal by microbes is carried out by enzymes and is considerably influenced by different factors including pH, temperature, nutrient composition, shaking or standing condition, coal types and most importantly type of microorganisms used. Different bacteria and fungi isolated from coal contaminated site as well as non-contaminated site exhibiting sulfur removal potential can be used as next generation tool for development of clean coal technology. Furthermore, through the application of modern genetic manipulation techniques, enhanced expression of genes responsible for desulfurization can be performed in order to accelerate the process of sulfur removal from coal. The present chapter is prepared with an aim to discuss the diverse microbial population participating in desulfurization, their efficiency, mechanism of sulfur elimination, role of important environmental factors along with possible applications and challenges in industrial scale sulfur removal.

Microorganisms are present in stormwater. Their numbers and diversity is influenced by the microbial flora of that environment and they can come from different sources namely the air, soil and through human activity. Stormwater runoffs carry pollutants including microorganisms. Stormwater runoffs that contain organic materials and some pathogenic microorganisms when discharged into bodies of water can lead to outbreaks of infections if such receiving bodies of water are not treated to remove the microbial contaminants. Another effect of microbial presence in a stormwater runoff discharged into a body of water without treatment is the possibility of creating anoxic condition in the receiving water body. This happens when the aerobic heterotrophic bacteria in the water body multiplies thereby utilizing the dissolved oxygen in the water. The end result is the death of fish and other aquatic organisms that require oxygen for survival. Stormwater runoffs can be treated biologically through activated sludge process, trickling filter or through the oxidation pond method to reduce the organic and microbial load. The effluents resulting from such treatment can then be disinfected to destroy the remaining microorganisms and organic matter in the water.

Keywords: stormwater, microorganisms, runoff, pollution