Dataset Information

Influence of environmental factors on biodegradation of quinalphos by Bacillus thuringiensis.

ABSTRACT: BACKGROUND:The extensive and intensive uses of organophosphorus insecticide-quinalphos in agriculture, pose a health hazard to animals, humans, and environment because of its persistence in the soil and crops. However, there is no much information available on the biodegradation of quinalphos by the soil micro-organisms, which play a significant role in detoxifying pesticides in the environment; so research is initiated in biodegradation of quinalphos. RESULTS:A soil bacterium strain, capable of utilizing quinalphos as its sole source of carbon and energy, was isolated from soil via the enrichment method on minimal salts medium (MSM). On the basis of morphological, biochemical and 16S rRNA gene sequence analysis, the bacterium was identified as to be Bacillus thuringiensis. Bacillus thuringiensis grew on quinalphos with a generation time of 28.38 min or 0.473 h in logarithmic phase. Maximum degradation of quinalphos was observed with an inoculum of 1.0 OD, an optimum pH (6.5-7.5), and an optimum temperature of 35-37 °C. Among the additional carbon and nitrogen sources, the carbon source-sodium acetate and nitrogen source-a yeast extract marginally improved the rate of degradation of quinalphos. CONCLUSIONS:Display of degradation of quinalphos by B. thuringiensis in liquid culture in the present study indicates the potential of the culture for decontamination of quinalphos in polluted environment sites.

SUBMITTER: Gangireddygari VSR

PROVIDER: S-EPMC5339314 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Influence of environmental factors on biodegradation of quinalphos by <i>Bacillus thuringiensis</i>.

Gangireddygari Venkata Subba Reddy VSR Kalva Praveen Kumar PK Ntushelo Khayalethu K Bangeppagari Manjunatha M Djami Tchatchou Arnaud A Bontha Rajasekhar Reddy RR

Environmental sciences Europe 20170306 1

<h4>Background</h4>The extensive and intensive uses of organophosphorus insecticide-quinalphos in agriculture, pose a health hazard to animals, humans, and environment because of its persistence in the soil and crops. However, there is no much information available on the biodegradation of quinalphos by the soil micro-organisms, which play a significant role in detoxifying pesticides in the environment; so research is initiated in biodegradation of quinalphos.<h4>Results</h4>A soil bacterium str ...[more]

PMID: 28316900

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Project description:For a surrogate bacterium to be used in outdoor studies, it is important to consider environmental and human safety and ease of detection. Recently, Bacillus thuringiensis, a popular bioinsecticide bacterium, has been gaining attention as a surrogate bacterium for use in biodefense. In this study, we constructed simulant strains of B. thuringiensis with enhanced characteristics for environmental studies. Through transposon mutagenesis, pigment genes were inserted into the chromosome, producing yellow-colored colonies for easy detection. To prevent persistence of spores in the environment, a genetic circuit was designed to produce a spore without sporulation capability. Two loxP sites were inserted, one on each side of the spo0A gene, which encodes a sporulation master regulator, and a sporulation-dependent Cre expression cassette was inserted into the chromosome. This genetic circuit successfully deleted spo0A during sporulation, producing spores that lacked the spo0A gene. In addition, two major α/β-type small acid-soluble spore protein (SASP) genes, predicted by synteny analysis, were deleted. The spores of the mutant strain showed increased UV-C sensitivity and quickly lost viability when tested in a solar simulator. When the spores of the mutant strain were administered to the lungs of BALB/c mice, cells were quickly removed from the body, suggesting enhanced in vivo safety. All strains constructed in this study contain no antibiotic resistance markers and all heterologous genes were inserted into the chromosome, which are useful features for simulants to be released into the environment.IMPORTANCEB. thuringiensis has recently been receiving increasing attention as a good spore simulant in biodefense research. However, few studies were done to properly address many important features of B. thuringiensis as a simulant in environmental studies. Since spores can persist in the environment for years after release, environmental contamination is a big problem, especially when genetically engineered strains are used. To solve these problems, we report here the development of B. thuringiensis simulant strains that are capable of forming yellow colonies for easy detection, incapable of forming spores more than once due to a genetic circuit, and lacking in two major SASP genes. The genetic circuit to produce a spore without sporulation capability, together with the deletion of SASP genes, ensures the environmental and human safety of the simulant strains developed in this study. All of these features will allow wider use of B. thuringiensis as a simulant for Bacillus anthracis in environmental release studies.

Dataset Information

Influence of environmental factors on biodegradation of quinalphos by Bacillus thuringiensis.

Publications

Influence of environmental factors on biodegradation of quinalphos by <i>Bacillus thuringiensis</i>.

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