Carriers Of Microorganisms Research Articles

Bioreduction of ionic mercury from wastewater in a fixed-bed bioreactor with activated carbon

AbstractWide industrial use of mercury led to significant mercury pollution of the environment. It requires development of cleanup technologies which would allow treating large volumes of mercury contaminated water in a cost effective and environmentally friendly way. A novel bio-technology, developed from laboratory to industrial scale in Germany at HZI (former GBF), is based on enzymatic reduction of highly toxic Hg(II) to water-insoluble and relatively non-toxic Hg(0) using live mercury resistant bacteria immobilized on a porous carrier material in a fixed-bed bioreactor. Improvement of the original method was based on the use of activated carbon as a carrier for microorganisms and an adsorbent for mercury. Such integration of the process should increase the technology efficiency. In order to compare different carrier materials, activated carbon and pumice stones were used. The strain Pseudomonas putida was immobilized in bioreactors continuously fed with solutions of HgCl2 enriched with nutrients. Simultaneously, experiments in two more reactors were run in the absence of microorganisms to investigate the influence of nutrients on the adsorption process. In the bioreactor with activated carbon, the outlet mercury concentration was approximately 50 % of that supplied with pumice. It may be concluded that the use of activated carbon in a fixed-bed bioreactor enables improvement of the technology by process integration.

Anaerobic treatment performance and microbial population of thermophilic upflow anaerobic filter reactor treating awamori distillery wastewater

Distillery wastewater from awamori making was anaerobically treated for one year using thermophilic upflow anaerobic filter (UAF) reactors packed with pyridinium group-containing nonwoven fabric material. The microbial structure and spatial distribution of microorganisms on the support material were characterized using molecular biological methods. The reactor steadily achieved a high TOC loading rate of 18 g/l/d with approximately 80% TOC removal efficiency when non-diluted wastewater was fed. The maximum TOC loading rate increased to 36 g/l/d when treating thrice-diluted wastewater. However, the TOC removal efficiency and gas evolution rate decreased compared with that when non-diluted wastewater was used. Methanogens closely related to Methanosarcina thermophila and Methanoculleus bourgensis and bacteria in the phyla Firmicutes and Bacteroidetes were predominant methanogens and bacteria in the thermophilic UFA reactor, as indicated by 16S rRNA gene clone analysis. Fluorescence in situ hybridization (FISH) results showed that a large quantity of bacterial cells adhered throughout the whole support, and Methanosarcina-like methanogens existed mainly in the relative outside region while Methanoculleus cells were located in the relative inner part of the support. The support material used proved to be an excellent carrier for microorganisms, and a UAF reactor using this kind of support can be used for high-rate treatment of awamori/shochu distillery wastewater.

The root surface as the definitive detail for microbial transformation processes in constructed wetlands – a biofilm characteristic

It was the goal of the investigations to characterise the biofilm on the plant roots because of the demonstrable major role of these associated bacteria. The essential criteria for the research were to look at the structure of the microbial colonisation (pattern, density) and to determine properties of the rhizoplane biofilm such as thickness and structure. The root material from a hydroponic system, planted with Glyceria maxima and used for nitrogen removal, has been used for the investigations. Several properties of the bacteria became visible due to the application of specific dyes. The evaluation of the samples was performed by scanning confocal laser microscopy (CLSM). It was shown that the microbial colonisation of the root surface of Glyceria maxima was on an unexpected high level and seems to be related mainly to the permeability and therefore to the age of the plant roots. The thickness of the rhizoplane biofilm is remarkably thin; no inactive layers could be observed in contrast to biofilm growing on technical carrier material. Caused by the untypically two-sided supply with nutrients the whole biofilm is in interaction with the surroundings. This indicates the importance of the plant roots for the microbial transformation processes in wetlands and underlines the especialness of the root as carrier for microorganisms.

Biological treatment of H 2S using pellet activated carbon as a carrier of microorganisms in a biofilter

Biological treatment is an emerging technology for treating off-gases from wastewater treatment plants. The most commonly reported odourous compound in off-gases is hydrogen sulfide (H 2S), which has a very low odor threshold. This study aims to evaluate the feasibility of using a biological activated carbon as a novel packing material, to achieve a performance-enhanced biofiltration processes in treating H 2S through an optimum balance and combination of the adsorption capacity with the biodegradation of H 2S by the bacteria immobilized on the material. The biofilm was mostly developed through culturing the bacteria in the presence of carbon pellets in mineral media. Scanning electron microscopy (SEM) was used to identify the biofilm development on carbon surface. Two identical laboratory scale biofilters, one was operated with biological activated carbon (BAC) and another with virgin carbon without bacteria immobilization. Various concentrations of H 2S (up to 125 ppmv) were used to determine the optimum column performance. A rapid startup (a few days) was observed for H 2S removal in the biofilter. At a volumetric loading of 1600 m 3 m −3 h −1 (at 87 ppmv H 2S inlet concentration), elimination capacity of the BAC (181 gH 2S m −3 h −1) at removal efficiency (RE) of 94% was achieved. If the inlet concentration was kept at below 30 ppmv, high H 2S removal (over 99%) was achieved at a gas retention time (GRT) as low as 2 s, a value, which is shorter than most previously reported for biofilter operations. The bacteria population in the acidic biofilter demonstrated capacity for removal of H 2S in a broad pH range (pH 1–7). There are experimental evidences showing that the spent BAC could be re-used as packing material in a biofilter based on BAC. Overall, the results indicated that an unprecedented performance could be achieved by using BAC as the supporting media for H 2S biofiltration.

Ultrastructure of adhesive device in fly in families calliphoridae, muscidae and sarcophagidae, and their implication as mechanical carriers of pathogens

The ultrastructure of adhesive device or the pulvilli, pad-like structure between the tarsal claws of the legs, is presented in the blowfly (Calliphoridae), housefly and relatives (Muscidae), and flesh fly (Sarcophagidae) through scanning electron microscopy. The blowfly species were Chrysomya chani, Chrysomya nigripes, Chrysomya pinguis, and Chrysomya villeneuvi; while those of the housefly and relatives were Musca domestica and Hydrotaea chalcogaster, respectively. Fresh fly species included Boettcherisca peregrina and Liosarcophaga dux. Numerous tenent setae were observed on the ventral side of the pulvilli. Two features of the tip of the tenent setae were found as a spatula-like (in C. chani, C. pinguis, C. nigripes, M. domestica, H. chalcogaster, B. peregrina, and L. dux) and spoon-like tip (in C. villeneuvi). Transmission electron microscopy of the tenent setae in M. domestica revealed the electron-lucent centrally located, suggesting an adhesive substance. These results provided anatomical information that allow us to not only understand the successful attachment of flies to smooth surfaces but also clarify their role as a mechanical carrier of microorganisms.

Microbial Analysis and Test of Plant Pathogen Antagonism of Municipal and Farm Composts

ABSTRACT Plant disease suppression induced by compost amendment in some cases results from the activity of antagonistic microorganisms that naturally colonize compost during the curing phase of the composting process. Based on this hypothesis, extracts from seven different mature composts, two municipal and five biodynamic farm composts, were analysed qualitatively and quantitatively with respect to their microbiota involved in plant disease suppression. The role of the microorganisms colonizing these composts was investigated in vitro for their ability to suppress Verticillium longisporum, Rhizoctonia solani, Pythium ultimum and Aphanomyces euteiches. Compost microbes were characterized by some of their functional properties such as production of hydrolytic enzymes that can be of importance for their beneficial effects in plants. The composts differed from each other both qualitatively and quantitatively with respect to their microbial composition. FAME analysis of the compost extracts divided the composts into two groups with the two municipal composts in one group and two of the biodynamic farm composts in the other. Bacteria were found as the dominating group compared with the fungi. Of the total 85 representative strains isolated from different composts, most of the strains exhibited a higher degree of antagonism towards R. solani and P. ultimum than towards V. longisporum and A. euteichus. The majority of the anti-pathogenic strains originated from two types of composts, biodynamic household- and yard waste and biodynamic manure. Cellulolytic ability was positively related to antagonism against Rhizoctonia, and fluorescence was positively related to antagonism against Pythium. Significance of the results is discussed in relation to the antagonistic potential of composts as carriers of beneficial microorganisms.

New Application of Polyurethane as Porous Hydrogel Carrier for Microorganisms of Waste Water Treatment

Porous polyurethane urea hydrogel (PU-gel) was prepared by the reaction of copoly(ethyleneoxide-propyleneoxide)triol terminated with toluene diisocyanate and water. The hydrogel was highly compatible with microorganisms and had good mechanical properties. This hydrogel was found to be very suitable for the newly developed biological nitrogen removal process of wastewater. In the biological reactor of the process, the porous hydrogel cubes on which the nitrification bacteria were fixed promote very quick nitrification of the nitrogen sources in the wastewater. Here we report the characteristics of the porous polyurethane urea hydrogel and the performance of the biological nitrification process using this hydrogel as a floating carrier of microorganisms.

Duplex real-time PCR assay for rapid detection of ampicillin-resistant Enterococcus faecium.

Rapid and accurate identification of carriers of resistant microorganisms is an important aspect of efficient infection control in hospitals. Traditional identification methods of antibiotic-resistant bacteria usually take at least 3 to 4 days after sampling. A duplex real-time PCR assay was developed for rapid detection of ampicillin-resistant Enterococcus faecium (ARE). Primers and probes that are used in this assay specifically detected the D-Ala-D-Ala ligase gene of E. faecium and the modified penicillin-binding protein 5 gene (pbp5) carrying the Glu-to-Val substitution at position 629 (Val-629) in a set of 129 tested E. faecium strains with known pbp5 sequence. Presence of the Val-629 in the strain set from 11 different countries was highly correlated with ampicillin resistance. In a screening of hospitalized patients, the real-time PCR assay yielded a sensitivity and a specificity for the detection of ARE colonization of 95% and 100%, respectively. The results were obtained 4 h after samples were harvested from overnight broth of rectal swab samples, identifying both species and the resistance marker mutation in pbp5. This novel assay reliably identifies ARE 2 to 3 days more quickly than traditional culture methods, thereby increasing laboratory throughput, making it useful for rectal screening of ARE. The assay demonstrates the advantages of real-time PCR for detection of nosocomial pathogens.

수열반응을 이용한 미생물 담체용 다공성 세라믹스의 제조

수열반응을 이용한 미생물 담체용 다공성 세라믹스의 제조

Characterization of five agricultural by-products as potential biofilter carriers.

Biofiltration is the most commonly used biological gas treatment technology and is extensively used for the treatment of polluted air with gas flow rates of up to 2 x 10(5) m(3)/h. It involves a filter bed of organic matter serving both as carrier for microorganisms and as nutrient supplier. Polluted gas passes through the filter bed and is cleaned by biological activity. Biofiltration is not being developed in Latin America as in the USA, Canada or Europe; the main reason probably being the absence of specific technology and of potential organic carriers locally available. Five different agriculture by-products available in Latin America: peanut shells, rice husk, coconut shells, cane bagasse and maize stubble, were chemically, physically and structurally characterized for their potential use as biofilter carrier. It was found that peanut shells could be used as biofilter carrier and therefore would have potential biological application.

Water Treatment with Polyvinyl Alcohol hydrogel, Carrier of Microorganisms

Water Treatment with Polyvinyl Alcohol hydrogel, Carrier of Microorganisms

Effect of Texture and Composition of Microorganisms Carrier for Disposal of Wastewater

For cleaning-up the water quality of artificial non-fecal drainage, surface-treated porous bodies made of glass beads were used as carriers for microorganisms which have biological activity for the mitigation of pollutants in the water. The influence of chemical species used for coating the bodies and also the texture of the treated surface on the effectiveness of the mitigation of pollution was examined. Coating with calcium silicate, iron oxide and calcium oxide decreased CODMn of the artificial drainage significantly, thus indicating effectiveness for the mitigation of the pollution. The size of cavities which were generated as voids in the three dimensional arrangement of the differently-sized glass beads also affected the effectiveness of the pollution mitigation though the effectiveness was limited. It was concluded that chemical composition of the surface was the most important factor in acting as the carrier of the microorganisms.

ビール粕を原料とする成形炭の水質浄化特性

The charcoal brick made from beer lees (CBBL) was investigated as the material for purification of lake water. The beer lees containing 67wt% water were first dried and then the dried beer lees were pressed at high temperature and pressure to make beer lees brick without any binder. The beer lees brick was carbonized in a low oxygen atmosphere to produce charcoal brick.The CBBL is useful for the carrier of microorganisms and it is possible to reduce soluble organisms and soluble nitrogen as same as charcoal. The CBBL contains phosphorus at the ratio of about 2wt%, which is soluble in water. The addition of 20wt% CaCO3 to the dried beer lees in the pressing process is beneficial to prevent solubilization of phosphorus in the CBBL. The CBBL does not have a weak point that it is abased in the purification column compared with the charcoal used in usual water purification.

Bacteria and fungi in aerosols generated by two different types of wastewater treatment plants

Raw wastewater is a potential carrier of pathogenic microorganisms and may pose a health risk when pathogenic microorganisms become aerosolized during aeration. Two different types of wastewater treatment plants were investigated, and the amounts of cultivable bacteria and fungi were measured in the emitted aerosols. Average concentrations of 17000 CFU m −3 of mesophilic, 2100 CFU m −3 of TSA-SB bacteria (bacteria associated with certain waterborne virulence factors), 1700 CFU m −3 of mesophilic and 45 CFU m −3 of thermotolerant fungi, were found in the aerosol emitted by the aeration tank of the activated sludge plant. In the aerosol of the fixed-film reactor 3000 CFU m −3 mesophilic and 730 CFU m −3 TSA-SB bacteria, and 180 CFU m −3 mesophilic and 14 CFU m −3 thermotolerant fungi were measured. The specific emissions per population equivalent between the two types of treatment plants differed by two orders of magnitude. The microbial flux based on the open water surface area of the two treatment plants was similar. The aerosolization ratios of cultivable bacteria (expressed as CFU m −3 aerosol/m −3 wastewater) ranged between 8.4×10 −11 and 4.9×10 −9. The aerosolization ratio of fungi was one to three orders of magnitude higher and a significant difference between the two types of treatment plants could be observed.

Biological deodorization of hydrogen sulfide using porous lava as a carrier of Thiobacillus thiooxidans

Biological deodorization of hydrogen sulfide (H 2S) was studied using porous lava as a carrier of Thiobacillus thiooxidans in a laboratory-scale biofilter. Three different samples of porous lava, A, B, and C, which were obtained from Cheju Island in Korea, were used. The water-holding capacities of samples A, B and C were 0.38, 0.25, and 0.47 g-H 2O/g-lava, respectively. The pHs and densities of the lava samples ranged from 8.25–9.24 and 920–1190 kg/m 3, respectively. The buffering capacities, expressed as the amount of sulfate added to lower the pH to 4, were 60 g-SO 4 2−/kg-lava for sample A, 50 g-SO 4 2−/kg-lava for B, and 90 g-SO 4 2−/kg-lava for C. To investigate the removal characteristics of H 2S by the lava biofilters, T. thiooxidans was immobilized on the lava samples. Biofilters A and C showed a removal capacity of 428 g-S·m −3·h −1 when H 2S was supplied with 428 g-S·m −3·h −1 of inlet load at a space velocity (SV) of 300 h −1. At the same inlet load and SV, the removal capacity of biofilter B was 396 g-S·m −3·h −1. The H 2S critical loads of biofilters A, B and C at a SV of 400 h −1 were 396, 157 and 342 g-S·m −3·h −1, respectively. It is suggested that natural, porous lava is a promising candidate as a carrier of microorganisms in biofiltration.

Biological Deodorization of Hydrogen Sulfide Using Porous Lava as a Carrier of Thiobacillus thiooxidans.

Biological deodorization of hydrogen sulfide (H2S) was studied using porous lava as a carrier of Thiobacillus thiooxidans in a laboratory-scale biofilter. Three different samples of porous lava, A, B, and C, which were obtained from Cheju Island in Korea, were used. The water-holding capacities of samples A, B and C were 0.38, 0.25, and 0.47 g-H2O/g-lava, respectively. The pHs and densities of the lava samples ranged from 8.25–9.24 and 920–1190 kg/m3, respectively. The buffering capacities, expressed as the amount of sulfate added to lower the pH to 4, were 60 g-SO42−/kg-lava for sample A, 50 g-SO42−/kg-lava for B, and 90 g-SO42−/kg-lava for C. To investigate the removal characteristics of H2S by the lava biofilters, T. thiooxidans was immobilized on the lava samples. Biofilters A and C showed a removal capacity of 428 g-S·m−3·h−1 when H2S was supplied with 428 g-S·m−3·h−1 of inlet load at a space velocity (SV) of 300 h−1. At the same inlet load and SV, the removal capacity of biofilter B was 396 g-S·m−3·h−1. The H2S critical loads of biofilters A, B and C at a SV of 400 h−1 were 396, 157 and 342 g-S·m−3·h−1, respectively. It is suggested that natural, porous lava is a promising candidate as a carrier of microorganisms in biofiltration.

Effect of Suspension, Carrier and Culture Medium on D Value upon Preparation of Biological Indicator (BI)

The ISO 11138 series on biological indicator (BI) are insufficient for the concrete description on suspension, carrier and recovery culture medium of microorganisms for preparation of BI. Suspension, carrier and culture medium have a potential to affect D value of BI. Individual effect of suspension, carrier or culture medium on D value of BI was reported, but the combination effect of these factors on D value was not reported yet and the author did not confirm individual effect on D value contrary to the previous papers. The combination effect of salt from suspension when drying and pore of the carrier for entrapping microorgamisms will be speculated to prevent sterilization. D value differed depending on constitute of culture medium, so it will be required to confirm if the constitute of soybean casein digest broth in WD 14161 is appropriate or not to attain the exact D value.

Distribution of bacteria, estimated by a viable count method, and heterotrophic activity in different size fractions of aquifer sediment

This study investigated the relationship between aquifer sediment particle fractions and bacterial counts and activity thereon. Samples of aquifer sediments were fractionated into different size fractions by filtering a sediment suspension successively through progressively smaller mesh‐sized filters (500, 100, 55, 20, 1.2, and 0.2 μm). In all sediment samples, even though the abundance of the coarser particles was high, 91.9–100% of the viable number of bacteria in the fractionated sediment was found in the 1.2–100 μm fraction, 40–96% in the 1.2–55 fan fraction (silt‐sized), and only 0.01–0.04% in the 0.2–1.2 μm fraction. The microbial heterotrophic activity (measured as the 14CO2 evolution from [14C]acetate or [I4C]glucose) showed the same pattern. After 2 days of incubation, 73–99% of the total amount of 14CO2 was evolved by the 1.2–100 μm fraction, 46–68% by the 1.2–55 fan fraction (silt‐sized), but only 0.2–5.4% by the 0.2–1.2 fan fraction. The finest fraction (0.2–1.2 fan) also included bacteria in the porewater, but the results showed that most of the bacteria and their activity were associated with small particles and thus were not free‐living in the pore‐water. The viable counts were higher (3–6 times) on small (1–2 mm) clay aggregates alone than for sediment including clay aggregates, indicating that even when clustered together, the clay particles carried most of the viable bacteria. Good correlations were found between surface area and viable counts as well as heterotrophic activity in the particle fractions, except for the finest fraction. The activity measurements showed that at least some of the sediment‐associated bacteria were active on the surfaces of the particles. The importance of small sediment particles as a carrier for microorganisms leads to the conclusion that quantitative sampling of microbial populations in aquifers must include sampling of the sediment, with sampling techniques retaining porewater with clay/silt particles.

The housefly ( Musca domestica) as a carrier of pathogenic microorganisms in a hospital environment

Houseflies have long been regarded as potential carriers of microorganisms. Since pathogenic microorganisms are widespread in the hospital environment, there is abundant opportunity for flies to become contaminated and, in turn, to contaminate the patient environment. In the present study, an attempt was made to isolate and identify pathogenic bacteria, fungi and parasites from the housefly Musca domestica collected in the surgical ward of the All India Institute of Medical Sciences Hospital and also in a remote residential area located 5 km from the hospital. A total of 113 flies were collected: 65 from a surgical ward (test) and 48 from a residential area for comparison. Ten genera of bacteria were isolated from the test group of flies compared with nine from the control group. In primary isolations, it was observed that the load of bacteria carried by the test group of flies was significantly more ( P < 0·001) than for the control flies. Pseudomonas aeruginosa, Enterococcus faecalis and viridans streptococci were isolated only from the test flies. The isolation rate of Staphylococcus aureus was significantly higher ( P < 0·001) in test houseflies than in the control houseflies. There was no significant difference in isolation of parasitic ova and cysts from test and control houseflies. Candida spp. were isolated in almost equal numbers from both groups of houseflies, yet none of these was Candida albicans. Houseflies therefore may act as vectors of potentially pathogenic bacteria in a hospital environment.

Cockroaches (Blattella germanica) as carriers of microorganisms of medical importance in hospitals

A study was conducted to isolate and identify microorganisms of medical importance from cockroaches (Blattella germanica) and to ascertain their vector potential in the epidemiology of nosocomial infections. Bacteria, fungi and parasites of medical importance were isolated and identified. Important bacterial pathogens responsible for wound infections, were further studies by antibiograms. One hundred and fifty-eight out of 159 (99.4%) cockroaches collected from hospital (test) and 113 out of 120 (94.2%) cockroaches collected from residential areas (control) were carrying medically important microorganisms (P less than 0.05). significantly higher (P less than 0.001) number of test cockroaches were carrying a higher bacterial load (1 x 10(4) and 1 x 10(5] as compared to control cockroaches. Multiple drug-resistant bacterial were isolated from test cockroaches. The diversity of drug-resistant bacterial species isolated from test cockroaches suggests their involvement in the transmission of drug-resistant bacteria. Various fungi and parasitic cysts of medical importance were also isolated from the test and control cockroaches, but the carriage rates were low. The findings suggest that cockroaches, in hospitals, can act as potential vectors of medically important bacteria/parasites/fungi.