Dataset Information

Isolation, identification and characteristics of an endophytic quinclorac degrading bacterium Bacillus megaterium Q3.

ABSTRACT: In this study, we isolated an endophytic quinclorac-degrading bacterium strain Q3 from the root of tobacco grown in quinclorac contaminated soil. Based on morphological characteristics, Biolog identification, and 16S rDNA sequence analysis, we identified strain Q3 as Bacillus megaterium. We investigated the effects of temperature, pH, inoculation size, and initial quinclorac concentration on growth and degrading efficiency of Q3. Under the optimal degrading condition, Q3 could degrade 93% of quinclorac from the initial concentration of 20 mg/L in seven days. We analyzed the degradation products of quinclorac using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The major degradation products by Q3 were different from those of previously identified quinclorac degrading strains, which suggests that Q3 may employ new pathways for quinclorac degradation. Our indoor pot experiments demonstrated that Q3 can effectively alleviate the quinclorac phytotoxicity in tobacco. As the first endophytic microbial that is capable of degrading quinclorac, Q3 can be a good bioremediation bacterium for quinclorac phytotoxicity.

SUBMITTER: Liu M

PROVIDER: S-EPMC4171507 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Isolation, identification and characteristics of an endophytic quinclorac degrading bacterium Bacillus megaterium Q3.

Liu Min M Luo Kun K Wang Yunsheng Y Zeng Aiping A Zhou Xiaomao X Luo Feng F Bai Lianyang L

PloS one 20140922 9

In this study, we isolated an endophytic quinclorac-degrading bacterium strain Q3 from the root of tobacco grown in quinclorac contaminated soil. Based on morphological characteristics, Biolog identification, and 16S rDNA sequence analysis, we identified strain Q3 as Bacillus megaterium. We investigated the effects of temperature, pH, inoculation size, and initial quinclorac concentration on growth and degrading efficiency of Q3. Under the optimal degrading condition, Q3 could degrade 93% of qui ...[more]

PMID: 25244184

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Project description:Bacterial metabolites exhibit a variety of biologically active compounds including antibacterial and antifungal activities. It is well known that Bacillus is considered to be a promising source of bioactive secondary metabolites. Most plant pathogens have an incredible ability to mutate and acquire resistance, causing major economic losses in the agricultural field. Therefore, it is necessary to use the natural antibacterial compounds in microbes to control plant pathogens. This study was conducted to investigate the bio-active compounds of Bacillus megaterium L2. According to the activity guidance of Agrobacterium tumefaciens T-37, Erwinia carotovora EC-1 and Ralstonia solanacearum RS-2, five monomeric compounds, including erucamide (1), behenic acid (2), palmitic acid (3), phenylacetic acid (4), and β-sitosterol (5), were fractionated and purified from the crude ethyl acetate extract of B. megaterium. To our knowledge, all compounds were isolated from the bacterium for the first time. To understand the antimicrobial activity of these compounds, and their minimum inhibitory concentrations (MICs) (range: 0.98∼500 μg/mL) were determined by the broth microdilution method. For the three tested pathogens, palmitic acid exhibited almost no antibacterial activity (>500 μg/mL), while erucamide had moderate antibacterial activity (MIC = 500 μg/mL). Behenic acid showed MICs of 250 μg/mL against T-37 and RS-2 strains with an antibacterial activity. β-sitosterol showed significant antimicrobial activity against RS-2. β-sitosterol showed remarkable antimicrobial activity against RS-2 with an MIC of 15.6 μg/mL. In addition, with the antimicrobial activity, against T-37 (62.5 μg/mL) and against EC-1 (125 μg/mL) and RS-2 (15.6 μg/mL) strains notably, phenylacetic acid may be interesting for the prevention and control of phytopathogenic bacteria. Our findings suggest that isolated compounds such as behenic acid, β-sitosterol, and phenylacetic acid may be promising candidates for natural antimicrobial agents.

Project description:BackgroundFeathers are the most abundant agricultural waste produced by poultry farms. The accumulation of a large number of feathers not only seriously pollutes the environment but also causes the waste of protein resources. The degradation of feather waste by keratinase-producing strains is currently a promising method. Therefore, screening high-producing keratinase strains from marine environment and studying the fermentation conditions, enzymatic properties and feather degradation mechanism are crucial for efficient degradation of feathers.ResultsA novel efficient feather-degrading bacteria, Gxun-17, isolated from the soil sample of a marine duck farm of Beibu Gulf in Guangxi, China, was identified as Bacillus tropicus. The optimum fermentation conditions were obtained by single factor and orthogonal tests as follows: feather concentration of 15 g/L, maltose concentration of 10.0 g/L, MgSO4 concentration of 0.1 g/L, initial pH of 7.0 and temperature of 32.5 °C. The strain completely degraded the feathers within 48 h, and the highest keratinase activity was 112.57 U/mL, which was 3.18-fold that obtained with the basic medium (35.37 U/mL). Detecting the keratinase activity and the content of sulphur-containing compounds in the fermentation products showed that the degradation of feathers by the strain might be a synergistic effect of the enzyme and sulphite. The keratinase showed optimal enzyme activity at pH 7.0 and temperature of 60 °C. The keratinase had the best performance on the casein substrate. When casein was used as the substrate, the Km and Vmax values were 15.24 mg/mL and 0.01 mg/(mL·min), respectively. Mg2+, Ca2+, K+, Co2+, Al3+, phenylmethylsulphonyl fluoride and isopropanol inhibited keratinase activity, which indicated that it was a serine keratinase. Conversely, the keratinase activity strongly increased with the addition of Mn2+ and β-mercaptoethanol.ConclusionsA novel feather-degrading B. tropicus Gxun-17 was obtained from marine environment. The strain adapted the extreme conditions such as low temperature, high salt and high pressure. Thus, the keratinase had high activity, wide range of temperature and pH, salt tolerance and other characteristics, which had potential application value.

Dataset Information

Isolation, identification and characteristics of an endophytic quinclorac degrading bacterium Bacillus megaterium Q3.

Publications

Isolation, identification and characteristics of an endophytic quinclorac degrading bacterium Bacillus megaterium Q3.

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