Effect Of Indigenous Bacteria Research Articles

Remediation and regulatory factors of petroleum hydrocarbon contaminated soil on site through Fe2+/Na2S2O8-Enterobacter himalayensis GZ6

The low-dose Fe2+/Na2S2O8-Enterobacter himalayensis GZ6 process can provide green, efficient, and sustainable remediation of organic contaminated soil. Adding 1.5 % (v/v) persulfate (PS) for oxidation, the residual concentration of total petroleum hydrocarbon (TPH) in the soil decreased from 16,622.87 mg/kg to 7663.10 mg/kg, with a removal rate of 53.90 %. After 103 days of PS-Enterobacter himalayensis GZ6 group, the degradation rate of TPH was 15 % higher than that of PS-indigenous bacteria group (71 %) and single bioremediation group (71 %). The effects of indigenous bacteria and abiotic environmental parameters on the remediation performance of PS-Enterobacter himalayensis GZ6 were quantified. Both C10-C17 and C18-C30 were oxidized and biodegradable, with PS mainly oxidizing C18-C30 and microorganisms mainly degrading C10-C17, and C30-C40 could only be removed by biodegradation. Enterobacter himalayensis GZ6 made an important contribution in the middle stage of remediation, and activated indigenous dominant archaea and bacteria, such as Nitrosopumilales archaeon and Acinetobacter indicus. The research results provided theoretical and technical support for in-situ remediation of petroleum hydrocarbons contaminated sites.

Composition and profiles of volatile organic compounds during waste decomposition by the anaerobic bacteria purified from landfill

Volatile organic compounds (VOCs) become concerned pollutants in landfill gases, and their composition and concentration varied significantly during waste decomposition. Many environmental factors are known to affect VOC emissions, while the effect of indigenous bacteria in wastes on VOC production remains elusive. In this study, a simplified anaerobic degradation experiment, with the single substrate and the purified bacteria from a landfill, was set up to measure the degradation process and the dynamic changes of VOCs. The experiment excluded the abiotic factors for VOC variation. The two isolated bacteria, identified as Sporanaerobacter acetigenes and Clostridium sporogenes, could anaerobically ferment amino acids by Stickland reaction. They produced 51 and 57 species of VOCs in the experiment, respectively. The concentration changes of VOCs over bacterial growth and fermentation were clustered into four types by principal component analysis: three profiles were regular, similar to the variation of nitrate, hydrogen sulfide, and the major fermentation products (carbon dioxide, ammonium, and volatile organic acids), respectively; while one profile was unique to any degradation indicator. The various concentration profiles indicated different origins for VOCs, possibly from the extracellular environment, fermentation, and secondary reactions. The findings provide insights into the understanding of VOC diversity and variability during waste decomposition.

Chlorella vulgaris and Its Phycosphere in Wastewater: Microalgae-Bacteria Interactions During Nutrient Removal.

Microalgae-based bioenergy production is a promising field with regard to the wide variety of algal species and metabolic potential. The use of liquid wastes as nutrient clearly improves the sustainability of microalgal biofuel production. Microalgae and bacteria have an ecological inter-kingdom relationship. This microenvironment called phycosphere has a major role in the ecosystem productivity and can be utilized both in bioremediation and biomass production. However, knowledge on the effects of indigenous bacteria on microalgal growth and the characteristics of bacterial communities associated with microalgae are limited. In this study municipal, industrial and agricultural liquid waste derivatives were used as cultivation media. Chlorella vulgaris green microalgae and its bacterial partners efficiently metabolized the carbon, nitrogen and phosphorous content available in these wastes. The read-based metagenomics approach revealed a diverse microbial composition at the start point of cultivations in the different types of liquid wastes. The relative abundance of the observed taxa significantly changed over the cultivation period. The genome-centric reconstruction of phycospheric bacteria further explained the observed correlations between the taxonomic composition and biomass yield of the various waste-based biodegradation systems. Functional profile investigation of the reconstructed microbes revealed a variety of relevant biological processes like organic acid oxidation and vitamin B synthesis. Thus, liquid wastes were shown to serve as valuable resources of nutrients as well as of growth promoting bacteria enabling increased microalgal biomass production.

Effect of indigenous bacteria on geochemical behavior of arsenic in aquifer sediments from the Hetao Basin, Inner Mongolia: Evidence from sediment incubations

Abstract Incubation studies were carried out using 5 freshly collected sediments from shallow aquifers of the Hetao Basin, Inner Mongolia. The aquifer sediments covering a range of redox conditions, as indicated by their deep grey to yellow color were mixed with degassed artificial As solution or degassed deionized water at a ratio of solid to water of about 1:10 (wt./wt.). Suspensions which were either amended with glucose or autoclaved, were incubated in parallel with unamended suspensions. Five microcosm cultures of unamended sediments gradually release the equivalent of 0.03–0.30 μg/g As to the dissolved phase. The addition of glucose as a potential electron donor results in a marked stimulation in the mobilization of As (0.71–3.81 μg/g) in the amended incubations for all sediments. The quantity of As released accounts for 60–70% of As bound to Fe/Mn oxides in the original sediments. The microbially mediated mobilization of As with the organic nutrient as an electron donor is strongly associated with the As bound to Fe/Mn oxides, as well as the exchangeable As. During the incubations amended with glucose, 2–4% of the sediment Fe is released. The results suggest that the introduction of labile dissolved organic C into the yellowish sediment aquifers with As-free groundwater would reduce a significant proportion of the Fe(III) oxyhydroxides mediated by anaerobic bacteria respiration and increase groundwater As concentrations.

Effects of indigenous bacteria on Cr(VI) reduction in Cr-contaminated sediment with industrial wastes

Black, clay-like sediments have been obtained from the area of the pigment manufacturing factories in Dongducheon city, Korea. These sediments were contaminated by heavy metals, especially chromium (700 mg/kg). Indigenous bacteria in the sediments were isolated to investigate their ability to reduce Cr(VI) to Cr(III). The enriched bacterial consortium reduced over 99% of dissolved Cr(VI) in 96 h from the onset of the experiments under anaerobic condition, while there was no change in Cr(VI) concentration until 300 h in abiotic controls. Total amount of dissolved Cr decreased simultaneously when Cr(VI) was reduced, which was likely due to precipitation of Cr(OH) 3 after microbial reduction of Cr(VI) to Cr(III). Under aerobic condition, only 30% of dissolved Cr(VI) was reduced by indigenous bacteria until 900 h. The reduction of Cr(VI) did not accompany bacterial growth since the amount of protein did not show a significant change with time both in the presence and absence of O 2. These indigenous bacteria may play a role in the treatment of Cr(VI)-contaminated sediments.

The effect of indigenous bacteria on virus survival in ground water

Abstract Over one‐half of the waterborne disease outbreaks in the United States are due to the consumption of contaminated ground water. Although viruses are a major cause of illness in these outbreaks, very little is known about the factors which influence how long viruses can remain infective in ground water. Experiments were conducted using several ground water samples obtained from drinking water wells to determine the effects of the naturally‐occurring bacteria on the survival of coliphage MS‐2 and poliovirus type 1 inoculated into the samples. The numbers of bacteria and viruses were monitored over a 30‐day period. Parallel experiments were conducted using water which had been filtered to remove the bacteria. The increase in bacterial numbers in the first 24 hours of incubation was significantly correlated with the decay rate of coliphage MS‐2. However, consistent trends were found in the ability of the viruses to persist in the presence or absence of bacteria.