Die-away kinetics of aerosolized bacteria from sprinkler application of wastewater

[This corrects the article on p. 1193 in vol. 39.].     

Diversity of aerosolized bacteria during land application of biosolids

AIMS: The purpose of this study was to determine the diversity of bacterial communities associated with bioaerosols generated during land application of biosolids using 16S ribosomal RNA (16S rRNA) PCR. METHODS AND RESULTS: Anaerobically digested Class B biosolids were land applied to an agricultural site located in South Central Arizona. Aerosol samples were collected downwind of the biosolids operations and were collected via the use of SKC Biosamplers and subsequently extracted for the presence of bacterial community DNA. All DNA was amplified using 16S rRNA primers, cloned and sequenced. All sequences were aligned and phylogenetic trees were developed to generate community profiles. The majority of aerosolized bacterial clone sequences belonged to the Actinobacteria and alpha- and beta-proteobacterial taxa. Aerosol samples collected downwind of soil aerosolization produced similar profiles. These profiles differed from upwind and background samples. CONCLUSIONS: No one clone sequence isolated from the aerosol samples could be solely attributed to biosolids; on the contrary, the majority appeared to have arisen from soil. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrates that in dry, arid climates the majority of aerosols associated with biosolids land application appear to be associated with the onsite soil.     

Evaluation of media for recovery of aerosolized bacteria

Disease transmission by airborne bacteria is well known. Bacterial burden in indoor air is estimated by sampling the air and estimating Colony Forming Units (CFU) using a variety of media. In this study, the recovery of bacteria, after aerosolization in an aerosol chamber, and employing a variety of media, was compared to that achieved using Tryptic Soy Agar medium. The total number of cells present was determined by direct microscopy. All trials were conducted at approximately the same relative humidity (RH) and temperature using the same collection device. Twelve species of bacteria were tested and a total of 120 media or media combinations were evaluated. Recovery on 64 media formulations was significantly lower for all strains examined, and therefore, excluded from further consideration for the purposes of this study. Data for 56 of the media are presented. Three species (Bacillus subtilis, Staphylococcus aureus andSerratia marcescens) were selected as representative for reporting and testing recovery success. It is concluded that, for the media included in the study, there are large differences in recovery and successful recovery is related both to the effect of aerosolization and the type of medium employed for recovery. Brain Heart Infusion Agar (with horse serum), Tryptic Soy Agar and Mueller Hinton Agar yielded the best recoveries of aerosolized cultures. The most important finding was that only a small fraction of the airborne bacterial populations, enumerated by direct microscopy, could be recovered on any of the media tested, suggesting that culturable bacterial count is not a satisfactory means of estimating air microbial pollution.     

印染废水脱色菌的选育及其生态特性的研究

1 前言 印染工业是太湖地区小城镇的一大工业部门。随着乡镇企业的发展,印染废水排放量逐年增加,已成为严重污染区域水环境的重点污染源之一。近年国内外报道了利用微生物对印染废水进行脱色处理的可能性,为了多途径寻找适合于乡镇企业印染废水的经济、高效的生物处理技术,本研究针对目前印染废水生物处理中的菌种适应性和作用范围问题,选育出一批对多种染料有降解作用的“土著”脱色菌,并对     

Airborne enteric bacteria and viruses from spray irrigation with wastewater.

The relationship between bacterial concentrations in wastewater used for spray irrigation and in the air was examined. Aerosolized coliforms were detected when their concentration was 10(3)/ml or more in the wastewater. Relative humidity and solar irradiation appeared to affect viable bacteria in the air; a positive correlation was found between relative humidity and the number of aerosolized bacteria. The correlation between solar irradiation and bacterial level, on the other hand, was negative. During night irrigation, up to 10 times more aerosolized bacteria were detected than with day irrigation. Wind velocity did not play an important role in the survival of aerosolized bacteria. Echovirus 7 was isolated in 4 out of 12 air samples collected 40 m downwind from the sprinkler.     

Airborne enteric bacteria and viruses from spray irrigation with wastewater.

The relationship between bacterial concentrations in wastewater used for spray irrigation and in the air was examined. Aerosolized coliforms were detected when their concentration was 10(3)/ml or more in the wastewater. Relative humidity and solar irradiation appeared to affect viable bacteria in the air; a positive correlation was found between relative humidity and the number of aerosolized bacteria. The correlation between solar irradiation and bacterial level, on the other hand, was negative. During night irrigation, up to 10 times more aerosolized bacteria were detected than with day irrigation. Wind velocity did not play an important role in the survival of aerosolized bacteria. Echovirus 7 was isolated in 4 out of 12 air samples collected 40 m downwind from the sprinkler.     

Levels of bacteria, fungi, and endotoxin in bulk and aerosolized corn silage.

Three samples of silage taken from the surface of a silo and from depths of 20 and 45 cm in the silo were studied for identification of the potential agents causing symptoms of organic dust toxic syndrome. The samples were examined by dilution plating before and after aerosolization in an acoustical dust generator. Aerosol samples were collected by liquid impinger and filter cassettes. The samples were examined for total aerobic bacteria, anaerobic bacteria, gram-negative bacteria, lactobacilli, listeriae, thermophilic actinomycetes, fungi, and endotoxin. Very high levels of total aerobic bacteria and fungi were found in the surface sample (up to 10(9) CFU/g in the bulk sample and up to 10(9) CFU/m3 after aerosolization), whereas the corresponding values from the deepest site were 100 to 50,000 times lower. Aspergillus fumigatus predominated among the fungi, whereas Bacillus and gram-negative organisms (Pseudomonas, Alcaligenes, Citrobacter, and Klebsiella species) prevailed among bacteria. Thermophilic actinomycetes occurred in numbers up to 10(7) CFU/g in the bulk samples, whereas anaerobic bacteria, lactobacilli, and listeriae were only few or absent. The concentration of endotoxin was high in the surface sample (up to 211.4 Endotoxin Units/mg) and about 200-fold lower in the sample from the deepest site. The results show that contact with dust from the surface of silage carries the risk of exposure to high concentrations of microorganisms, of which A. fumigatus and endotoxin-producing bacteria are the most probable disease agents.     

Identification of novel denitrifying bacteria Stenotrophomonas sp. ZZ15 and Oceanimonas sp. YC13 and application for removal of nitrate from industrial wastewater

Two novel denitrifying bacteria were successfully isolated from industrial wastewater and soil samples. Using morphological, biochemical/biophysical and 16S rRNA gene analyses, these two bacteria were identified as Stenotrophomonas sp. ZZ15 and Oceanimonas sp. YC13, respectively. Both of these two bacteria showed efficient NO₃ ⁻-N removing abilities under a semi-anaerobic condition without obvious accumulation of NO₂ ⁻-N, N₂O-N and NH₄ ⁺-N. NO₃ ⁻-N removal from paper mill wastewater was also successful by treatments with either a denitrifier or an immobilization method. Therefore, this study provides valuable denitrifying bacteria in biotreatment of industrial wastewater and other environmental pollution caused by NO₃ ⁻/NO₂ ⁻.     

Role of anammox bacteria in removal of nitrogen compounds from wastewater

The review deals with the unique microbial group responsible for anaerobic ammonium oxidation with nitrite (anammox), and with the role of this process in development of the biotechnology for removal of nitrogen compounds from wastewater. The history of the study of this process is briefly related. Up-to date knowledge on the intracellular organization, energy metabolism, growth stoichiometry, and physiology of anammox bacteria is described, and the main methods for cultivation of these microorganisms are characterized. Special attention is paid to the problems associated with practical application of anammox bacteria, which result from their extremely slow growth, the absence of pure cultures, and the interaction with other microbial groups.     

Broad diversity of conjugative plasmids in integron-carrying bacteria from wastewater environments

In this study we assessed the occurrence, diversity and conjugative potential of plasmids in integron-carrying Aeromonas and Enterobacteriaceae from wastewaters. Sixty-six strains were included as donors in mating assays using rifampicin-resistant Escherichia coli and Pseudomonas putida recipient strains. The diversity of plasmids from donors and transconjugants (resistant to tetracycline or streptomycin) was evaluated by restriction analysis and replicon typing targeting 19 incompatibility groups. Restriction patterns revealed a diverse plasmid pool present in these strains. Plasmids were assigned to FrepB (Aeromonas salmonicida, Aeromonas veronii, Aeromonas sp., E.?coli, Enterobacter sp.), FIC (A.?salmonicida, Aeromonas sp.), FIA (Shigella sp.), I1 (A.?veronii, Aeromonas sp., E.?coli), HI1 (E.?coli) and U (Aeromonas media) replicons. Nevertheless, 50% of the plasmids could not be assigned to any replicon type. Among integron-positive transconjugants, FrepB, I1 and HI1 replicons were detected. Results showed that wastewaters enclose a rich plasmid pool associated with integron-carrying bacteria, capable of conjugating to different bacterial hosts. Moreover, replicons detected in this study in Aeromonas strains expand our current knowledge of plasmid diversity in this genus.     

Removal of triethylamine from synthetic wastewater by acclimated mixed bacteria cultures

This aim of this study was to remove triethylamine by a biological method, as well as to understand the ability of mixed bacteria cultures to treat a triethylamine compound from synthetic wastewater. The mixed bacteria cultures could not remove triethylamine, whether the activated sludge came from an acrylonitrile–butadiene–styrene resin manufactured wastewater treatment system or a waterborne polyurethane resin manufactured wastewater treatment system. When the mixed bacteria cultures were acclimated to triethylamine, they could utilize 650 mg l⁻¹ triethylamine for growth. When the initial triethylamine concentration was below 200 mg l⁻¹, the triethylamine removal efficiency could reach 100%. The triethylamine removal rate of the acclimated GMIX sludge was faster than the acclimated EMIX sludge.     

The measurement of aerosolized endotoxin from land application of Class B biosolids in Southeast Arizona

The purpose of this study was to determine aerosolized endotoxin concentrations downwind of a biosolids land application site. Aerosol samples were collected from biosolids land application sites, tractor operation, and an aeration basin located within an open-air wastewater treatment plant. Aerosolized endotoxin above background concentrations was detected from all sites, at levels ranging from below detection up to 1800 EU m-3 of air. Biosolids loading operations resulted in the greatest concentrations of endotoxin (mean 344 EU m-3). As downwind (perpendicular to wind vector) distance increased from sources (2-200 m), levels of endotoxin decreased to near background (without biosolids application) concentrations. Overall, the detected levels of aerosolized endotoxin were within past proposed aerosolized endotoxin limits (250-2000 EU m-3) by other occupational exposure studies. Occasionally, peak concentrations were found to be above these limits. Sites in which soil was being aerosolized resulted in greater concentrations of endotoxin with or without biosolids, which suggested that the majority of endotoxin may in fact be of soil origin. This study evaluated the presence of aerosolized endotoxin from the land application of biosolids and showed that these levels were within ranges for concern suggested by other studies and that this area of research needs further investigation.     

Cellulomonas taurus sp. nov., a novel bacteria with multiple hydrolase activity isolated from livestock,and potential application in wastewater treatment

Antonie van Leeuwenhoek - A Gram-positive, smooth, sub-transparent, faint yellow,0.5–0.7 µm diameter, rod shaped aerobic or facultative aerobic strain P40-2Twas isolated from...     

Diversity and enrichment of nitrite-dependent anaerobic methane oxidizing bacteria from wastewater sludge

Recently discovered microorganisms affiliated to the bacterial phylum NC10, named "Candidatus Methylomirabilis oxyfera", perform nitrite-dependent anaerobic methane oxidation. These microorganisms could be important players in a novel way of anaerobic wastewater treatment where ammonium and residual dissolved methane might be removed at the expense of nitrate or nitrite. To find suitable inocula for reactor startup, ten selected wastewater treatment plants (WWTPs) located in The Netherlands were screened for the endogenous presence of M. oxyfera using molecular diagnostic methods. We could identify NC10 bacteria with 98% similarity to M. oxyfera in nine out of ten WWTPs tested. Sludge from one selected WWTP was used to start a new enrichment culture of NC10 bacteria. This enrichment was monitored using specific pmoA primers and M. oxyfera cells were visualized with fluorescence oligonucleotide probes. After 112 days, the enrichment consumed up to 0.4 mM NO(2)(-) per day. The results of this study show that appropriate sources of biomass, enrichment strategies, and diagnostic tools existed to start and monitor pilot scale tests for the implementation of nitrite-dependent methane oxidation in wastewater treatment at ambient temperature.     

Quantification of Nitrosomonas oligotropha-like ammonia-oxidizing bacteria and Nitrospira spp. from full-scale wastewater treatment plants by competitive PCR.

Utilizing the principle of competitive PCR, we developed two assays to enumerate Nitrosomonas oligotropha-like ammonia-oxidizing bacteria and nitrite-oxidizing bacteria belonging to the genus NITROSPIRA: The specificities of two primer sets, which were designed for two target regions, the amoA gene and Nitrospira 16S ribosomal DNA (rDNA), were verified by DNA sequencing. Both assays were optimized and applied to full-scale, activated sludge wastewater treatment plant (WWTP) samples. If it was assumed that there was an average of 3.6 copies of 16S rDNA per cell in the total population and two copies of the amoA gene per ammonia-oxidizing bacterial cell, the ammonia oxidizers examined represented 0.0033% +/- 0.0022% of the total bacterial population in a municipal WWTP. N. oligotropha-like ammonia-oxidizing bacteria were not detected in an industrial WWTP. If it was assumed that there was one copy of the 16S rDNA gene per nitrite-oxidizing bacterial cell, Nitrospira spp. represented 0.39% +/- 0.28% of the biosludge population in the municipal WWTP and 0.37% +/- 0.23% of the population in the industrial WWTP. The number of Nitrospira sp. cells in the municipal WWTP was more than 62 times greater than the number of N. oligotropha-like cells, based on a competitive PCR analysis. The results of this study extended our knowledge of the comparative compositions of nitrifying bacterial populations in wastewater treatment systems. Importantly, they also demonstrated that we were able to quantify these populations, which ultimately will be required for accurate prediction of process performance and stability for cost-effective design and operation of WWTPs.     

Production and characterization of bioflocculants from bacteria isolated from wastewater treatment plant in South Africa

Bioflocculants produced by six bacteria obtained from activated sludge at a wastewater treatment plant were quantified, purified, and characterized. Effects of pH, temperature, cationic salt content, and specific potential inhibitors on the flocculating activities of the bioflocculants were also determined. Bioflocculants produced by the different bacterial isolates ranged between 6.33 and 27.66 g/L in concentration and were composed of both carbohydrate and protein in varying amounts, as well as a relatively high concentration of uronic acid. The flocculating activity of the broth culture increased during the logarithmic phase of bacterial growth with a maximum ranging from 2.395 to 3.709/OD. Optimum pH for the flocculating activity of the bioflocculants was between 8 and 9, with generally higher flocculating activity observed at 28°C. Of the cations tested, Mg²⁺ and Mn²⁺ improved flocculating activity up to 5.2 fold. The stability of these bacterial bioflocculants under various environmental and nutritional conditions suggests their possible use in the industries and environmental applications. Therefore, this study details important implications in providing a safer alternative flocculation method for wastewater treatment.     

Levels of bacteria, fungi, and endotoxin in bulk and aerosolized corn silage

Three samples of silage taken from the surface of a silo and from depths of 20 and 45 cm in the silo were studied for identification of the potential agents causing symptoms of organic dust toxic syndrome. The samples were examined by dilution plating before and after aerosolization in an acoustical dust generator. Aerosol samples were collected by liquid impinger and filter cassettes. The samples were examined for total aerobic bacteria, anaerobic bacteria, gram-negative bacteria, lactobacilli, listeriae, thermophilic actinomycetes, fungi, and endotoxin. Very high levels of total aerobic bacteria and fungi were found in the surface sample (up to 10(9) CFU/g in the bulk sample and up to 10(9) CFU/m3 after aerosolization), whereas the corresponding values from the deepest site were 100 to 50,000 times lower. Aspergillus fumigatus predominated among the fungi, whereas Bacillus and gram-negative organisms (Pseudomonas, Alcaligenes, Citrobacter, and Klebsiella species) prevailed among bacteria. Thermophilic actinomycetes occurred in numbers up to 10(7) CFU/g in the bulk samples, whereas anaerobic bacteria, lactobacilli, and listeriae were only few or absent. The concentration of endotoxin was high in the surface sample (up to 211.4 Endotoxin Units/mg) and about 200-fold lower in the sample from the deepest site. The results show that contact with dust from the surface of silage carries the risk of exposure to high concentrations of microorganisms, of which A. fumigatus and endotoxin-producing bacteria are the most probable disease agents.     

Separation of bacteria from a methanogenic wastewater population by utilizing a self-generating Percoll gradient

Bacteria from a methanogenic wastewater population could be separated with a self-generating density gradient of Percoll. The separation was performed by centrifugation for 30 min at 30000 g in a simple angle-head rotor. Three types of bacteria were concentrated to apparent homogeneity in different bands; these were attributed to the methanogens Methanosarcina and Methanothrix , and to the dissimilatory sulphate-reducing bacterium Desulfovibrio. The described technique will contribute to a rapid diagnosis of the bacterial types that are active in waste-water treatment.     

Detection of polyhydroxyalkanoate-accumulating bacteria from domestic wastewater treatment plant using highly sensitive PCR primers

Polyhydroxyalkanoate (PHA) is a class of biodegradable plastics that have great potential applications in the near future. In this study, the micro-biodiversity and productivity of PHA-accumulating bacteria in activated sludge from a domestic wastewater treatment plant were investigated. A previously reported primer set and a selfdesigned primer set (phaCF1BO/phaCR2BO) were both used to amplify the PHA synthase (phaC) gene of isolated colonies. The new primers demonstrated higher sensitivity for phaC, and combining the PCR results of the two primer sets was able to widen the range of detected genera and raise the sensitivity to nearly 90%. Results showed that 85.3% of the identified bacteria were Gram-negative, with Ralstonia as the dominant genus, and 14.7% were Gram-positive. In addition, Zoogloea and Rhizobium contained the highest amounts of intracellular PHA. It is apparent that glucose was a better carbon source than pentone or tryptone for promoting PHA production in Micrococcus. Two different classes, class I and class II, of phaC were detected from alphaproteobacteria, betaproteobacteria, and gammaproteobacteria, indicating the wide diversity of PHA-accumulating bacteria in this particular sampling site. Simultaneous wastewater treatment and PHA production is promising by adopting the high PHAaccumulating bacteria isolated from activated sludge.