Presence Of Indigenous Bacteria Research Articles

Characterization of hydrocarbon utilizing bacteria in waste engine oil-impacted sites

Changes in soil physicochemical properties and bacterial species present in soil contaminated with waste engine oil were evaluated at three auto-mechanical workshops in Uyo, Nigeria. This work was aimed at isolating and identifying hydrocarbon degrading bacteria from waste engine oil polluted soil, and assessing their hydrocarbon-utilizing ability. Waste engine oil pollution affected soils significantly with increases in soil physicochemical properties, and heterotrophic bacterial population counts. Eight bacterial species Corynebacterium kutscheri, Pseudomonas aeruginosa, Flavobacterium aquatile, Serratia odorifera, Micrococcus agilis, Staphylococcus aureus, Micrococcus luteus and Bacillus substilis were isolated by the selective enrichment technique and screened for hydrocarbon utilization capability in mineral salt media with 1% (v/v) waste engine oil as a sole carbon and energy source. The extent of bacterial growth observed was related to the ability of organisms to biodegrade hydrocarbons present in the medium bacterium species, which showed varying hydrocarbon utilization during the 15 days of incubation. Growth in hydrocarbon medium was the most efficient in cultures of Corynebacterium kutscheri. All isolates also showed variable emulsification ability, with Corynebacterium kutscheri, showing the highest ability. These results demonstrate the presence of indigenous bacteria in hydrocarbon-polluted soils and the potential toward the remediation of hydrocarbons.

Effect of biogenic jarosite on the bio-immobilization of toxic elements from sulfide tailings

The discharge of toxic elements from tailings soils in the aquatic environments occurs chiefly in the presence of indigenous bacteria. The biotic components may interact in the opposite direction, leading to the formation of a passivation layer, which can inhibit the solubility of the elements. In this work, the influence of jarosite on the bio-immobilization of toxic elements was studied by native bacteria. In batch experiments, the bio-immobilization of heavy metals by an inhibitory layer was examined in the different aquatic media using pure cultures of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. A variety of analyses also investigated the mechanisms of metals bio-immobilization. Among different tests, the highest metal solubility yielded 99% Mn, 91% Cr, 95% Fe, and 78% Cu using A. ferrooxidans in 9KFe medium after ten days. After 22 days, these percentages decreased down to 30% Mn and about 20% Cr, Fe, and Cu, likely due to metal immobilization by biogenic jarosite. The formation of jarosite was confirmed by an electron probe micro-analyzer (EPMA), X-ray diffraction (XRD), and scanning electron microscope (SEM). The mechanisms of metal bio-immobilization by biogenic jarosite from tailings soil confirmed three main steps: 1) the dissolution of metal sulfides in the presence of Acidithiobacillus bacteria; 2) the nucleation of jarosite on the surface of sulfide minerals; 3) the co-precipitation of dissolved elements with jarosite during the bio-immobilization process, demonstrated by a structural study for jarosite. Covering the surface of soils by the jarosite provided a stable compound in the acidic environment of mine-waste.

Exiguobacterium aurantiacum mediated fermentation of bamboo shoot, and process optimization for Soibum production: A traditional food of Manipur, North-East India

Bamboo shoot are an important traditional food delicacies which are consumed as fresh, fermented, or canned in many Asian countries and is intricately related with human diet. In this study, several bamboo shoot samples (fermented and succulent bamboo shoots) were collected to determine the cynogenic glycoside content, followed by process optimization by using Exiguobacteruim aurantiacum FB6-1b, which was used for fermentation at different conditions. E. aurantiacum was isolated from bamboo shoot. The cyanide content was analyzed and fermentation process was also evaluated by estimating nutritional parameters of final product. Fresh succulent bamboo shoot had high cyanide content (approx 43 mg/g) compared with fermented samples (22.8–30.4 mg/g). It was observed that boiling the succulent bamboo shoots and fermented shoots removed all the cyanide content. The amount of protein, sugar, amino acid for fermentation of sterilized bamboo shoot with FB6-1b, against fermentation in presence of indigenous bacteria in raw bamboo shoot were found to be (2.2±0.6, 1.3±0.04, 0.38±0.004) mg/g and (2.44±0.03, 1.85±0.3, 0.31±0.006) mg/g, respectively. The nutritional parameter including concentrations of protein, sugar, amino acid were better when fermentation was done at temp 30°C (3.56±0.04, 11.1±0.2, 0.75±0.05 g/100g, respectively) and inoculum size 104 cfu/ml (2.57±0.1, 10.5±0.1, 0.27±0.04 g/100g, respectively).

Characterization and microbial utilization of dissolved lipid organic fraction in arsenic impacted aquifers (India)

The coupled role of organic matter (OM) and microbial activity is widely acknowledged in arsenic (As) biogeochemical cycling in sedimentary environments. However, little is known about OM characteristics particularly the dissolved fraction in the Bengal Delta Plain aquifers – one of the worst As impacted regions in the world. Ongoing investigations in As-rich aquifers in Nadia district (West Bengal, India) indicate presence of arsenite {As(III)} oxidizing bacterial communities in the Grey Sand Aquifers (GSA), but absent in Brown Sand Aquifers (BSA). In this study, we investigate the key differences in dissolved organic carbon (DOC) characteristics and its relationship with differences in elemental concentrations, distribution of biomarkers, and utilization of DOC by in situ microbial communities in BSA and GSA. We demonstrate a new approach using ENVI™ C-18 DSK discs to pre-concentrate DOC from large volumes of water, and further extract the OM and separate it into different lipid fractions using the solid phase extraction technique. The aquifers show marked heterogeneity in terms of their DOC characteristics and elemental profiles irrespective of their grey or brown color. DOC indicates variable inputs of terrestrial derived OM sources, and OM derived from decomposition and/or microbial cellular components. DOC in the aquifers consist of predominantly n-alkanoic acids (∼80%) followed by n-alkanes and n-alcohols. The GSAs indicate high iron (Fe) and manganese (Mn) concentrations, and presence of mature petroleum derived hydrocarbons in DOC. BSA has comparatively lower concentrations of Fe and Mn, and shows absence of mature hydrocarbons in DOC. Experiments in presence of indigenous bacteria from groundwater with DOC lipid extracts as the sole carbon source indicate higher growth in the GSA samples implying preferential use of DOC. The potential availability of DOC in these aquifers can influence the community composition of indigenous heterotrophic microbial flora, which in turn can affect elemental cycles including that of As.

Arsenic release from shallow aquifers of the Hetao basin, Inner Mongolia: evidence from bacterial community in aquifer sediments and groundwater.

Indigenous microbes play crucial roles in arsenic mobilization in high arsenic groundwater systems. Databases concerning the presence and the activity of microbial communities are very useful in evaluating the potential of microbe-mediated arsenic mobilization in shallow aquifers hosting high arsenic groundwater. This study characterized microbial communities in groundwaters at different depths with different arsenic concentrations by DGGE and one sediment by 16S rRNA gene clone library, and evaluated arsenic mobilization in microcosm batches with the presence of indigenous bacteria. DGGE fingerprints revealed that the community structure changed substantially with depth at the same location. It indicated that a relatively higher bacterial diversity was present in the groundwater sample with lower arsenic concentration. Sequence analysis of 16S rRNA gene demonstrated that the sediment bacteria mainly belonged to Pseudomonas, Dietzia and Rhodococcus, which have been widely found in aquifer systems. Additionally, NO3(-)-reducing bacteria Pseudomonas sp. was the largest group, followed by Fe(III)-reducing, SO4(2-)-reducing and As(V)-reducing bacteria in the sediment sample. These anaerobic bacteria used the specific oxyanions as electron acceptor and played a significant role in reductive dissolution of Fe oxide minerals, reduction of As(V), and release of arsenic from sediments into groundwater. Microcosm experiments, using intact aquifer sediments, showed that arsenic release and Fe(III) reduction were microbially mediated in the presence of indigenous bacteria. High arsenic concentration was also observed in the batch without amendment of organic carbon, demonstrating that the natural organic matter in sediments was the potential electron donor for microbially mediated arsenic release from these aquifer sediments.

Aggregates of Resident Bacteria Facilitate Survival of Immigrant Bacteria on Leaf Surfaces

The fate of immigrant bacterial cells on leaves under stressful conditions was determined as a function of the anatomical features and the local spatial density of resident cells at their landing site. Pantoea agglomerans 299R was established on bean leaves and the survival of immigrant cells of Pseudomonas fluorescens A506 and Pseudomonas syringae B728a, as well as P. agglomerans itself, was determined by epifluorescence microscopy following subsequent exposure of plants to desiccation stress. Resident and immigrant bacterial strains constitutively expressed the cyan and the green fluorescent protein, respectively, and the viability of individual cells was assessed directly on leaf surfaces following propidium iodide staining. Although only a small fraction of the immigrant cells landed on established bacterial aggregates, their fate was usually strongly influenced by the presence of indigenous bacteria at the site at which they landed. Immigrants of P. agglomerans 299R or P. fluorescens A506 that arrived as solitary cells had about double the probability of survival when landing on aggregates formed by P. agglomerans 299R than when landing on uncolonized areas of the leaf surface. In contrast, the survival of P. syringae B728a was similar irrespective of whether it landed on colonized or uncolonized parts of a leaf. The nature of plant anatomical features at which immigrant bacteria landed also strongly influenced the fate of immigrant bacteria. The fraction of immigrant cells of each species tested that landed on veins, glandular trichomes, or epidermal cells altered by P. agglomerans that died was always less than when they landed on normal epidermal cells or at the base of hooked trichomes. Depending on the process by which immigrants arrive at a leaf, only a small fraction of cells may be deposited on existing bacterial aggregates. Although uncolonized sites differed greatly in their ability to influence the survival of immigrant cells, the fate of an immigrant bacterium will depend on the nature of the leaf structure on which it is deposited, and apparently indirectly on the amount of nutrients and water available at that site to support the development of bacterial aggregates.

Oral administration of food antigen induces T cell mediated intestinal inflammation: A model using TCR‐transgenic mice

To investigate the mechanisms inducing food-sensitive intestinal inflammation, we focused on the OVA23-3 mouse, a transgenic mouse strain expressing a T cell receptor that recognizes ovalbumin (OVA). Mice administered an egg-white (EW) diet containing OVA showed a trend of loose feces and significant weight loss. Histology of the jejunum showed severe inflammation with villous atrophy. Thus, we studied the role of T cells and intestinal microflora in the development of the inflammation. Severe villous disruption was observed in sections of the jejunum from OVA23-3 mice and RAG-2 gene-deficient OVA23-3 mice fed with EW-diet. Further, a larger number of T cells was found in the lamina propria of the jejunum of EW-diet fed OVA23-3 mice, RAG-2 gene-deficient mice and germfree OVA23-3 mice compared with those of control-diet fed mice. However, severe inflammation was not detected in the jejunum of germfree OVA23-3 mice. CD4+ T cells from the MLN of EW-diet fed OVA23-3 mice showed a Th2 cytokine secretion profile. These observations have thus clarified that antigen-specific Th2 cells play important roles in the development of intestinal inflammation. Although the presence of indigenous bacteria was not essential for the inflammation, T cells could mediate a more severe inflammatory response in their presence.

A colorimetric assay for the enumeration of Candida albicans in biological samples after amplification in a selective medium

The MTT (3 (4,5-dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide) colorimetric assay was redesigned to enumerate C. albicans in biological samples. Major modifications include the total permeabilization of the Candida cells to the tetrazolium salt and the solubilization of the intracellular purple-colored formozan for spectrophotometric analysis. A preliminary amplification of the Candida population to be quantified is carried out using a low pH antibiotic-containing synthetic selective medium. Growth curves are logarithmic and similar for 11 strains of C. albicans. All strains grew in the blastopore phase whether inoculated as blatospores or hyphae. C. guillermondii and C. pseudotropicalis also grow in this selective medium and give similar standard curves, whereas C. tropicalis, krusei, parapsilosis and glabrata cannot be amplified due to the presence of cycloheximide. The assay was used to enumerate Candida in aqueous mouth washes and in mucosal tissues. The presence of indigenous bacteria, debris and host cells do not interfere with Candida growth and enumeration. The sensitivity and the adaptability of the test make it a powerful tool in epidemiological and diagnostic studies as well as in vitro assays of Candida growth or growth inhibition.