Population Density Of Bacteria Research Articles

Methodology for ranking internal corrosion-induced leakage susceptibility in oilfield pipelines

ABSTRACT This investigation focuses on the ranking of pipeline leakage susceptibility of two categories of pipeline systems. One consists of three oilfield water-handling pipeline systems and the other consists of five dry crude systems. Online corrosion monitoring (OCM) method was used for both systems, forthermore, in-line inspection (ILI) method, with Magnetic Flux leakage (MFL) tool, was also used for the dry crude systems. The OCM leakage susceptibility potential is derived from the combined severity of general corrosion, pitting corrosion, fluid corrosivity and sessile bacteria population density in the process streams. The ILI leakage susceptibility potential is derived from the average number of corrosion anomalies greater than 10% of the wall thickness and the maximum depth of the anomalies (as percentage of the wall thickness). In spite of such distinctions, the ranking of pipeline leakage susceptibility for the five dry crude pipeline segments turned out to be identical for the two methodologies.

Endophytic Streptomyces population induced by L-glutamic acid enhances plant resilience to abiotic stresses in tomato.

Endophyte bacteria, which colonize plants including roots, stem, flower, and fruit, it can derive their nutrients from the host, are recognized for their mutualistic relationship with the host plant. They play a critical role in promoting host growth and modulating abiotic stress. Carbon and nitrogen have a significant impact on bacterial population and secondary metabolite production, which are highly specific in various categories such as bacterial growth regulation, anti-compounds production. Application of L-glutamic acid can significantly enhance Streptomyces globisporus population buildup in plants. However, the effectiveness of this population buildup against abiotic stresses such as salinity and drought has not been investigated. Therefore, in this study, we tested the bacteria and their prebiotic activity against salinity and drought stress in tomato plants. Three different amino acids were treated on the tomato plants, and it was observed that L-asparagine and L-proline had a negative effect on plant growth and phenotype, while L-glutamic acid promoted plant growth and increased bacteria population density. The bacteria were found to colonize the rhizosphere and root endosphere, with colonization being promoted by L-glutamic acid. Additionally, Streptomyces was found to have plant growth promotion effects and provided protection against abiotic stresses. Interestingly, L-glutamic acid reduced the damage caused by salinity stress, but not drought stress. These findings suggest that L-glutamic acid plays a role in providing tolerance to salinity stress with the core microbiota, thus the current study demonstrated their prebiotic activity in the agriculture system.

A zwitterionic terpolymer based coating potentially for antibacterial and antifouling applications

Antifouling materials are highly demanded in global marine market due to increasingly aggravated marine biofouling problem and unbalanced marine ecology. Herein, poly (vinyl imidazole-co-hydroxypropyl methacrylate-co-butyl acrylate) (P(VIm-co-HPMA-co-BA)) was prepared via free radical polymerization of commercially available monomers of vinyl imidazole (VIm), hydroxypropyl methacrylate (HPMA) and butyl acrylate (BA). Then the zwitterionic terpolymer (P(VPS-co-HPMA-co-BA)) was obtained by ionicalization of P(VIm-co-HPMA-co-BA) with 1, 3-propionate lactone (1, 3-PS) in EtOH solutions. Furthermore, the membrane samples, P(VIm-co-HPMA-co-BA) and P(VPS-co-HPMA-co-BA) were prepared by tape casting method with DI water bath. Significantly, P(VPS-co-HPMA-co-BA) membranes have shown better bactericidal activity against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) with a mean area size of 3.5 cm2. Meanwhile, the bacterial adhesion assay showed that P(VPS-co-HPMA-co-BA) membranes were found the absence of adherent bacteria, and exhibited excellent anti-adhesion property with the increase of molar ratios of PVPS by the observation of bacteria population density. The mechanical testing results indicated that the molar ratios of 65/10/25 in P(VIm-co-HPMA-co-BA) membranes and P(VPS-co-HPMA-co-BA) membranes had high breaking elongation ratio and great tensile strength. Specifically, the maximum tensile strength of P(VPS-co-HPMA-co-BA) membrane could reach up to 10.9 MPa. The results showed that the novel P(VPS-co-HPMA-co-BA) membrane exhibited both anti-bacterial, anti-adhesion property and mechanical performance, manifesting its prospectively potential applications in new highly efficient and eco-friendly marine antifouling coatings.

PSXI-16 Levels of a blend of clove, castor and cashew oils and microencapsulated active ingredients (eugenol, thymol and vanillin) on ruminal gram-positive bacteria population density

Abstract This study was realized to evaluate de effect of a blend of vegetable oils and active ingredients (Ruminatus® - safeeds@safeeds.com.br) on ruminal population density of Ruminococcus albus, Ruminococcus flavefaciens and Streptococcus bovis. The blend contained clove (Eugenia caryophyllata), castor (Ricinus communis) and cashew (Anacardium occidentale) oils and microencapsulated active ingredients (eugenol, thymol and vanillin). The experiments were designed using each bacteria exposed to doses of 1.5; 3.0; 4.5 and 6.0 mg/ml of the product and with six replicates. Bacteria were cultivated on Hobson’s M2 medium in Hungate tubes. Cultures cultivated without the addition of any oils were considered as control. Bacteria were cultivated overnight and freshly inoculated into new tubes containing medium. The antimicrobial activity was evaluated using a Spectrophotometer Evolution 201 UV-visible (Thermo Scientific) at 600 nm. Readings were performed at 0, 8, 12 and 24 hours after inoculation. Data were analyzed using the linear mixed models and the NLME Procedure in R software. The blend had no effect (P < 0.05) on growth of R. albus and R. flavefaciens. On the other hand, S. bovis was affected by all inclusion of the blend (P < 0.05). These results provide evidence of the potential of oils to modulate the ruminal environment. Such feature can impact nutrient metabolism and, consequently, production of volatile fatty acids. Therefore, the use of a blend of clove, castor and cashew essential oils and microencapsulated active ingredients (eugenol, thymol and vanillin) used influenced the growth of gram-positive bacteria.

Biorremediación de mercurio y níquel por bacterias endófitas de macrófitas acuáticas

La contaminación ambiental se ha categorizado como uno de los principales problemas que afecta la salud de las diferentes formas de vida. Las bacterias endófitas (BE), son capaces de mejorar el estado nutricional de las plantas y remover contaminantes del suelo. La subregión la Mojana funciona como zona de amortización de ríos. En este estudio, se colectaron muestras de macrófitas acuáticas de las ciénagas de Ayapel, San Marcos y San Benito Abad, de los cuales se aislaron bacterias endófitas. Se cuantificó las densidades poblacional de estas bacterias y su respectiva tolerancia a los metales pesados níquel y mercurio. Posteriormente, las cepas tolerantes fueron identificadas molecularmente y se les evaluó su capacidad de promover el crecimiento vegetal. Un total de 182 morfotipos de bacterias endófitas fueron aislados, los mayores promedios de densidad poblacional se obtuvieron en las macrófitas de la ciénaga de San Benito Abad ubicada en las coordenadas coordenadas 8°55´32.81´´ N y 75°1´13.72” O. Los mayores promedios de morfotipos tolerantes a mercurio y níquel se encontraron en la ciénaga de Ayapel en las coordenadas 8°18´51.10´´ N y 75°8´8.26” O. Los resultados muestran que los aislados con mayor potencial biotecnológico son BAT6, BAR2 y PAT2, donde los dos primeros tienen una homología del 100% con la especie Lysinibacillus fusifomis y el género Enterobacter, respectivamente, mientras que el tercer aislamiento tuvo una homología del 96% con la especie Burkholderia cepacia. El presente estudio reporta por primera vez la presencia de Lysinibacillus fusifomis y Burkholderia cepacia asociadas a macrófitas en cuerpos cenagosos de Sucre y Córdoba.

Biological soil attributes in oilseed crops irrigated with oilfield produced water in the semi-arid region

Wastewater from oil is the main residue of the oil industry. Studies have shown that wastewater, or produced water, can be treated and used as an alternative source for the irrigation of oilseed crops. The aim of this work was to evaluate the effect of treated produced water on the biological properties of soil cultivated with the castor bean cv. BRS Energy and the sunflower cv. BRS 321 respectively, for two and three successive cycles of grain production. The first cycle in the sunflower and castor bean corresponds to the dry season and the second cycle to the rainy season. The third crop cycle in the sunflower relates to the dry season. The research was carried out from August 2012 to October 2013, in the town of Aracati, in the State of Ceara (Brazil), where both crops were submitted to irrigation with filtered produced water (FPW), produced water treated by reverse osmosis (OPW), or groundwater water from the Acu aquifer (ACW), and to no irrigation (RFD). The treatments, with three replications, were evaluated during the periods of pre-cultivation and plant reproduction for soil respiration (Rs), total organic carbon (TOC) and the population density of bacteria (Bact) and filamentous fungi (Fung) in the soil. In the sunflower crop, these soil attributes are sensitive to the irrigation water used. Irrigation of the castor bean affects soil respiration. Under the conditions of this study, irrigation with FPW may be a short-term alternative in the castor bean and sunflower crops.

Diversity of anaerobic bacteria in sediments from a subtropical reservoir

AbstractA descriptive analysis of microbial communities from two different sediment locations in a subtropical reservoir was undertaken, using DGGE and 16S rRNA gene clone library. This study evaluated bacterial diversity in the sediment of a subtropical reservoir, based on quantitative and qualitative analyses of sulphate‐reducing bacteria (SRB), denitrifying bacteria (DB) and hydrogen‐producing bacteria (HPB). The sediment samples were taken from a subtropical reservoir (Ibiúna, SP, Brazil), being collected at two contrasting sites, including (A) at a 4 m depth and (B) at an 11 m depth of the water column. The anaerobic bacteria population density in the sediment was estimated with the most probable number (MPN) method. The microbial diversity of the sediment was assessed by molecular biology analyses for the domain Bacteria. Increased cell count numbers were observed in sample A for DB. The count for sample B was higher for SRB and HPB. Both sediment communities (A and B samples) exhibited a high diversity. They were similar to the phyla Proteobacteria, Chloroflexi, Firmicutes, Actinobacteria, Cyanobacteria, Fusobacteria, Deferribacteres, Verrucomicrobia and uncultivated bacteria. The environmental conditions of sediments from tropical climates were mainly sunlight during the day and temperatures around 25 °C, which would favour the maintenance of nutrients and the available organic matter for establishing the anaerobic bacteria populations. The microbial diversity observed for both samples indicates new possibilities for application of the sediment reservoir in regard to biotechnological processes such as the operation of anaerobic reactors for wastewater and toxic compound treatment, bioenergy generation and production of biogases such as hydrogen and methane.

Monte Carlo simulation for kinetic chemotaxis model: An application to the traveling population wave

A Monte Carlo simulation of chemotactic bacteria is developed on the basis of the kinetic model and is applied to a one-dimensional traveling population wave in a microchannel. In this simulation, the Monte Carlo method, which calculates the run-and-tumble motions of bacteria, is coupled with a finite volume method to calculate the macroscopic transport of the chemical cues in the environment. The simulation method can successfully reproduce the traveling population wave of bacteria that was observed experimentally and reveal the microscopic dynamics of bacterium coupled with the macroscopic transports of the chemical cues and bacteria population density. The results obtained by the Monte Carlo method are also compared with the asymptotic solution derived from the kinetic chemotaxis equation in the continuum limit, where the Knudsen number, which is defined by the ratio of the mean free path of bacterium to the characteristic length of the system, vanishes. The validity of the Monte Carlo method in the asymptotic behaviors for small Knudsen numbers is numerically verified.

English

This study aimed to bioprospect and select halotolerantes bacteria and promoting plant growth associated with the plant Atriplex nummularia L. in saline soils. For bioprospecting of bacteria, samples were collected in five niches and two field experiments located in Serra Talhada and Ibimirim, Pernambuco, Brazil. After collecting the material it was performed the isolation and selection of bacteria based on plant growth promotion mechanisms. 107 bacterial salt tolerant isolates were obtained in which the population density of bacteria was higher in the rhizosphere (107 CFU g-1 soil), the cultivated soil (106 CFU g-1 soil) and uncultivated soil (105 CFU g-1 soil). For the solubilization rate of inorganic phosphate was obtained 65 and 25% positives isolated in 0 to 5% NaCl concentration, respectively. For the characteristics of biological fixation nitrogen, indole acetic acid production, exopolysaccharides and quorum sensing molecule, reached up to 87 percent; 100; 83.33 and 96.66% of the bacteria, respectively. Therefore, the bacterial isolates UAGAt 89 and UAGAt 101 expressed greater tolerance to salinity when analyzed in relation to the characteristics that promote plant growth, making it promising for future studies in order to contribute to the development of Atriplex plants and rehabilitation of soil affected by salts. Key words: Halophytes, quorum sensing, exopolysaccharide, phytoremediation

Suppression of Chemotactic Explosion by Mixing

Chemotaxis plays a crucial role in a variety of processes in biology and ecology. In many instances, processes involving chemical attraction take place in fluids. One of the most studied PDE models of chemotaxis is given by Keller-Segel equation, which describes a population density of bacteria or mold which attract chemically to substance they secrete. Solution of Keller-Segel equation can exhibit dramatic collapsing behavior, where the density concentrates positive mass in a measure zero region. A natural question is whether presence of fluid flow can affect singularity formation by mixing the density thus making concentration harder to achieve. In this paper, we consider parabolic-elliptic Keller-Segel equation in two and three dimensions with additional advection term modeling ambient fluid flow. We prove that for any initial data, there exist incompressible fluid flows such that the solution to the equation stays globally regular. On the other hand, it is well known that when the fluid flow is absent, there exist initial data leading to finite time blow up. Thus presence of fluid can prevent the singularity formation. We discuss two classes of flows that have the explosion arresting property. Both classes are known as very efficient mixers. The first class are relaxation enhancing (RE) flow. These flows are stationary. The second class of flows are Yao-Zlatos optimal mixing flows, which are time dependent. The proof is based on the nonlinear version of the relaxation enhancement construction of the paper by Peter Constantin, Alexander Kiselev, Lenya Ryzhik, Andrej Zlatos, and on some variations of global regularity estimate for Keller-Segel model.

Localization of kabiramides in the sponge Pachastrissa nux and sponge surface-attached bacteria

The sponge Pachastrissa nux has been reported to be a rich source of cytotoxic macrolides. In our previous study, we found that the P. nux sponge has the ability to develop the capitum part, a gorgonian-like structure that sprouts from the substratum-attached base, and accumulate the macrolides predominantly in the protruding capitum. Using kabiramides B, C, and G as markers, here we demonstrate the impact of kabiramides allocation on the sponge surface-attached bacteria. The population density of bacteria that attach to the surface of the capitum part and also on the appendage extending from the core base part was significantly less than that on the surface of the base itself. Selected bacteria were identified, but no unusual bacterial species that may be specific to the sponge were detected. Although too premature to conclude whether the sponge intentionally produces such toxic metabolites as chemical defense against the microbial foulers, or otherwise the settling microbes affect the chemical allocation, the correlation between the macrolide accumulation and the attachment of bacteria on the sponge's surface clearly shows how the sponge has adapted to fit in its specific environment and how it interacts with the microbial cohabitants.

Effect of rain simulation on Xanthomonas oryzae pv. oryzae population density in guttation fluid and on the spread of bacterial blight in rice

Bacterial blight of rice caused by Xanthomonas oryzae pv. oryzae is most serious biotic constraint of rice production in Punjab, influenced mainly by environmental factors and nutritional factors applied to the rice crop. Present study aimed at observing the relationship between rain simulation and disease spread. More number of bacterial colonies was recovered from the susceptible rice cultivar (Pusa 1121) plants where no-rain was simulated as compared to those where rain was simulated. Mean bacterial log cfu in rain simulated plant was 4.88 as compared to 5.67 in non rain simulated plots after 1day of inoculation. The population densities of bacteria increased gradually in both the treatments. The log cfu of bacteria was 5.84 in rain simulated plots as compared to 6.28 in non rain simulated plots after 7 days of inoculation. However after 14 days of inoculation, the bacterial population in guttation fluid was foundto be non-significant at 5% level of significance in rain and non rain simulated plots but the bacterial population was found to be less as compared to that after 7 days of inoculation. Rain washed off the guttation fluid which resulted in decrease of bacterial load in the infected leaf. The significant difference at 5 % level of significance was observed between the per cent disease severity and disease spread was also observed in rain simulated plots and no rain simulated plots in cultivar Pusa 1121 which is a bacterial blight resistant cultivar.

Abundance and trophodynamics of surface microbial loop populations in the northern Red Sea

The population densities of filter feeding ciliates in the water of the three marine protectorates of Ras Mohammed, Nabq and Abu Galoum in the northern Red Sea, were calculated during the period from November 2006 to November 2007. Also, autotrophic nanoflagellates, heterotrophic nanoflagellates and heterotrophic bacteria were enumerated to gain some indication of the food resources available for ciliates. The abundance of ciliates in the three protectorates were found to follow an annual cycle with the highest ciliate numbers of 25.3 cells ml−1 observed in the spring, and the lowest numbers of 2.1 cells ml−1 in the summer. Abundances were at times 8-fold higher than those found in comparable studies on nutrient-poor pelagic systems and, astonishingly, approached those observed in coastal waters and in more productive open ocean systems. Nanoflagellates that could provide a food supply for the filter feeding ciliates were especially numerous in the spring, while the production of bacteria was presumably a more important component at the base of this food chain in the three protectorates’ water. The filtration activities of heterotrophic flagellates and filter feeding ciliates were compared with the population densities of bacteria, nanoflagellates and ciliates in spring and summer. Moreover, filtration rates from the literature were used to calculate the potential rate of capture of prey of different categories, as well as to calculate the time required for the whole water body to be filtered by heterotrophic nanoflagellates and filter feeding ciliates.

Factors affecting the occurrence of Escherichia coli O157 contamination in irrigation ponds on produce farms in the Suwannee River Watershed

Outbreaks of enteritis caused by Escherichia coli O157 associated with fresh produce have resulted in questions about the safety of irrigation water; however, associated risks have not been systematically evaluated. In this study, the occurrence and distribution of the human pathogen E. coli O157 from vegetable irrigation ponds within the Suwannee River Watershed in Georgia were investigated, and the relationship to environmental factors was analyzed. Surface and subsurface water samples were collected monthly from 10 vegetable irrigation ponds from March 2011 to February 2012. Escherichia coli O157 was isolated from enriched filtrates on CHROMagar and sorbitol MacConkey agar media and confirmed by an agglutination test. Presence of virulence genes stx1, stx2 , and eae was tested by polymerase chain reaction. In addition, 27 environmental variables of the sampled ponds were measured. Denaturing gradient gel electrophoresis was conducted for the analysis of bacterial communities in the water samples. Biserial correlation coefficients were calculated to evaluate the log10 colony-forming unit per millilitre correlations between the environmental factors and the occurrence of E. coli O157. Stepwise and canonical discriminant analyses were used to determine the factors that were associated with the presence and absence of E. coli O157 in water samples. All 10 ponds were positive for E. coli O157 some of the time, mainly in summer and fall of 2011. The temporal distribution of this bacterium differed among the 10 ponds. Temperature, rainfall, populations of fecal coliform, and culturable bacteria were positively correlated with the occurrence of E. coli O157 (P < 0.05), while the total nitrogen concentration, oxidation-reduction potential, and dissolved oxygen concentration were negatively correlated with the occurrence of this pathogen (P < 0.05). Temperature and rainfall were the most important factors contributing to the discrimination between samples with and without E. coli O157, followed by bacterial diversity and culturable bacteria population density. Bacterial numbers and diversity, including fecal coliforms and E. coli O157, increased after rainfall (and possibly runoff from pond margins) in periods with relatively high temperatures, suggesting that prevention of runoff may be important to minimize the risk of enteric pathogens in irrigation ponds.

Microbial Distribution and Abundance in the Digestive System of Five Shipworm Species (Bivalvia: Teredinidae)

Marine bivalves of the family Teredinidae (shipworms) are voracious consumers of wood in marine environments. In several shipworm species, dense communities of intracellular bacterial endosymbionts have been observed within specialized cells (bacteriocytes) of the gills (ctenidia). These bacteria are proposed to contribute to digestion of wood by the host. While the microbes of shipworm gills have been studied extensively in several species, the abundance and distribution of microbes in the digestive system have not been adequately addressed. Here we use Fluorescence In-Situ Hybridization (FISH) and laser scanning confocal microscopy with 16S rRNA directed oligonucleotide probes targeting all domains, domains Bacteria and Archaea, and other taxonomic groups to examine the digestive microbiota of 17 specimens from 5 shipworm species (Bankia setacea, Lyrodus pedicellatus, Lyrodus massa, Lyrodus sp. and Teredo aff. triangularis). These data reveal that the caecum, a large sac-like appendage of the stomach that typically contains large quantities of wood particles and is considered the primary site of wood digestion, harbors only very sparse microbial populations. However, a significant number of bacterial cells were observed in fecal pellets within the intestines. These results suggest that due to low abundance, bacteria in the caecum may contribute little to lignocellulose degradation. In contrast, the comparatively high population density of bacteria in the intestine suggests a possible role for intestinal bacteria in the degradation of lignocellulose.

ISOLASI DAN SELEKSI BAKTERI ENDOFIT UNTUK PENGENDALIAN PENYAKIT DARAH PADA TANAMAN PISANG

Blood disease is one of the important diseases of banana in Indonesia. Endophytic bacteria have potencies as candidates of biocontrol agents to blood disease, because the bacteria colonized the same ecological niche with the plant pathogens. This research was conducted to isolate endophytic bacteria from banana root, and study their disease suppression ability to blood disease on banana. Ninety isolates of endophytic bacteria have been isolated from the root of banana. Average population densities of bacteria varied between 6,0 x 103 and 4,2 x 105 cfu/g fresh weight of root. Twenty seven isolates positively produced inhibition zone toward blood disease bacterium. Based on plant growth and disease suppression test, ten isolates promoted the growth of banana plant and four isolates suppressed the incidence of blood disease with ranged from 66,67 to 83,33%.

Densidade e diversidade fenotípica de bactérias diazotróficas não simbióticas em solos da Reserva Biológica Serra dos Toledos, Itajubá (MG)

Bactérias diazotróficas não simbióticas (BDNS) atuam no desenvolvimento das plantas por meio da fixação biológica de nitrogênio e também pela produção e liberação de substâncias reguladoras do crescimento vegetal. Este estudo objetivou avaliar a densidade e diversidade fenotípica desse grupo de bactérias em fragmentos de solo da Reserva Biológica Serra dos Toledos e entorno, em Itajubá/MG. Essa reserva localiza-se na Área de Proteção Ambiental da Mantiqueira, constituindo-se em uma importante área de recarga e de abrigo à flora e fauna endêmicas. Amostras de solo superficial foram coletadas em áreas com diferentes declividades na reserva, em épocas representativas das estações de inverno (setembro/2006) e verão (abril/2007). A densidade, avaliada pelo número mais provável, utilizando os meios de cultura NFb, JNFb e Fam, para Azospirillum spp., Herbaspirillum spp. e A. amazonense, respectivamente, variou de 0,12 a 75,60 (NMP x 10(5)) bactérias g-1 solo seco. Foram obtidos 172 e 174 isolados, respectivamente para as amostras de inverno e verão, dos quais 30 e 55 % apresentaram similaridade igual ou superior a 70 % com as estirpes-tipo Azospirillum brasilense, A. amazonense, A. lipoferum, Herbaspirillum seropedicae e Burkholderia brasilensis. O resultado do comportamento dos isolados com base na tolerância à salinidade nem sempre foi semelhante ao obtido pelas características fenotípicas culturais a 70 % de similaridade, sendo indicado para estudos complementares de diversidade desses organismos. As BDNS apresentam potencial de utilização em estudos de avaliação da qualidade e sustentabilidade de ecossistemas. No entanto, apesar da alta densidade e diversidade fenotípica em solos da reserva, maiores valores foram obtidos no entorno, evidenciando o efeito positivo da cobertura vegetal do tipo gramíneas sobre elas, independentemente da variação climática.

Impact of long-term wastewater application on microbiological properties of vadose zone

Impact of wastewater irrigation on some biological properties was studied in an area where treated sewage water is being supplied to the farmers since 1979 in the western part of National Capital Territory of New Delhi under Keshopur Effluent Irrigation Scheme. Three fields were selected which had been receiving irrigation through wastewater for last 20, 10 and 5years. Two additional fields were selected in which the source of irrigation water was tubewell. The soil bacterial and fungal population density was studied in soil layers of 0-15, 15-30, 30-60 and 60-120cm depths. Groundwater samples were collected from the piezometers installed in the field irrigated with sewage water for last 20, 10 and 5years. Results indicate that there was significant increase in bacterial and fungal count in sewage-irrigated soils as compared to their respective control. The population density of bacteria and fungi in waste water-irrigated soils increased with the duration of sewage water application and decreased with increasing depth. The bacterial and fungal count was also directly proportional to organic carbon, sand and silt content and negatively correlated to the clay content, electrical conductivity, pH and bulk density of the soil. Groundwater under sewage-irrigated fields had higher values of most probable number (MPN) index as compared to that of tubewell water-irrigated fields. All the shallow and deep groundwaters were found to be contaminated with faecal coliforms. The vadose zone had filtered the faecal coliform to the tune of 98-99%, as the MPN index was reduced from ≥18,000 per 100ml of applied waste water to 310 per 100ml of groundwater under 20years sewage-irrigated field. The corresponding values of MPN were 250 and 130 per 100ml of shallow groundwater under 10 and 05years sewage-irrigated fields, respectively. Rapid detection of faecal contamination suggested that the Citrobacter freundii and Salmonella were dominant in shallow groundwater, while Escherichia coli was dominant in deep groundwater collected from sewage-irrigated field.

Removal of polychlorinated dioxins by semi-aerobic fed-batch composting with biostimulation of “Dehalococcoides”

A semi-aerobic, mesophilic, fed-batch composting (FBC) reactor loaded with household garbage was used to remove polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs). The reactor was packed with woodchips as the solid matrix and PCDD/F-contaminated soil or flyash and then operated at a waste-loading rate of 0.5 kg (wet wt) day(-1). All congeners of PCDD/Fs (initial concentration, 200-830 pmol g(-1) [dry wt]) were totally reduced during the over period of operation, with a half reduction time of 4 months. Direct cell counting and respiratory quinone profiling showed that the reactors at the fully acclimated stage harbored a high population density of bacteria (10(11) g(-1) [dry wt]) with members of the Actinobacteria predominating. Real-time quantitative PCR showed that the population of "Dehalococcoides" and its phylogenetic relatives of Chloroflexi as the possible dechlorinators varied between at the order of 10(7) to 10(8) g(-1) (dry wt). A "Dehalococcoides"-containing dechlorinating culture from the soil-treating reactor was successfully enriched with a model PCDD/F compound, fthalide. 16S rRNA gene-targeted PCR-denaturated gradient gel electrophoresis and clone library analyses showed that this culture comprised at least three major phylogenetic groups of bacteria, Acidaminobacter, "Dehalococcoides," and Rhizobium. These results suggest that the semi-aerobic FBC process is applicable for the bioremediation of PCDD/Fs and possibly other haloorganic compounds with the biostimulation of "Dehalococcoides" and its relatives as the potent dechlorinators.

THE EFFECT OF POTATO LECTIN ONTO DIAZOTROF GROWTH ACTIVITY

It are presented the results of the research of рotato lectin effect onto the growth activity of bacteria Azotobacter and Azospirillum genera. Dependence of growth of microorganisms on its content in the nutrient medium containing of it at the level of 0,2–20 mсg/ml was studied. It have been established the optimal рotato lectin concentration for Аzotobacter vinelandii and Аzotobacter chroococcum M-70/2 (1,0 mсg/ml) and Azospirillum brasilense 410 (1,5 mcg/ml), when the bacteria population density, specific growth rate are increased, biomass doubling time is decreased.