No abstract

The use of halotolerant phosphate solubilizing bacteria as inoculants to convert insoluble phosphorus of salt-affected soils to an accessible form is a promising strategy to improve the phosphorus ingestion of plants in salt-affected agriculture. A total of four aerobic isolates with biggest clear halos on the 10% NaCl NBRIP medium plate containing tricalcium phosphate were isolated from the rhizospheric soils of native plants growing on the wall of Dagong Ancinet Brine Well, located in Sichuan of China. And these four isolates were classified to the same strain, named QW10-11, and closely related to Bacillus megatherium var. phosphaticum DSM 3228 and B. megaterium ATCC 14581 according to their phenotype and 16S rRNA. However, the Molecular evolutionary evidences of 16S-23S rRNA ISR further suggested that QW10-11, DSM 3228 and ATCC 14581 have respectively fall into the different sub-divisions in intra specific phylogeny. Strain QW10-11 has significantly better ability of tricalcium phosphate solubilization than that of lecithin solubilization. When it grows under pH 4.8-8.0, 24-33°C and 5-10% NaCl, it can exhibit the higher values of solubilized tricalcium phosphate between 59.3 and 71.4 lg ml -1 . Furthermore, its tricalcium phosphate solubilizing activity was associated with the release of organic acids. Taken together, our results indicted that QW10-11 from the rhizospheric soils of halobiot of Dagong Ancinet Brine Well is attractive as efficient phosphate solubilizing candidates in the salt-affected agriculture. Keywords Halotolerant phosphate solubilizing bacteria Á Tricalcium phosphate solubilizing Á 16S rRNA phylogeny Á 16S-23S rRNA ISR Abbreviations NBRIP National botanical research institute's phosphate growth medium 16S-23S rRNA ISR 16S-23S ribosomal RNA intergenic spacer regions (ISR) PSB Phosphorus solubilizing bacteria PSF Phosphorus solubilizing fungi

A novel beta-cypermethrin (Beta-CP)-degrading strain isolated from activated sludge was identified as Brevibacillus parabrevis BCP-09 based on its morphological and physio-biochemical characteristics, and 16S rRNA gene analysis. Strain BCP-09 could effectively degrade Beta-CP at pH 5.0-9.0, 20-40 °C, and 10-500 mg L Beta-CP. Under optimal conditions (pH 7.41, 38.9 °C, 30.9 mg L Beta-CP), 75.87% Beta-CP was degraded within 3 days. Beta-CP degradation (half-life, 33.45 h) and strain BCP-09 growth were respectively described using first-order-kinetic and logistic-kinetic models. Seven metabolites were detected by high-performance liquid chromatography and gas chromatography-mass spectrometry- methyl salicylate, catechol, phthalic acid, salicylic acid, 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid, 3-phenoxybenzaldehyde, and 3-phenoxybenzoic acid (3-PBA). The major Beta-CP metabolite, 3-PBA was further degraded into phenol, benzoic acid, and 4-methylhexanoic acid. BCP-09 also degraded aromatic compounds such as phenol, catechol, and protocatechuic acid. Beta-CP appears to be mainly degraded into 3-PBA, which is continuously degraded into smaller benzene or chain compounds. Thus, strain BCP-09 could form a complete degradation system for Beta-CP and might be considered a promising strain for application in the bioremediation of environments and agricultural products polluted by Beta-CP.

No abstract

Strain CY-012 isolated from garden soil sprayed with pyrethroid pesticide was able to efficiently degrade fenvalerate. The bacterium was identified as Bacillus licheniformis based on its morphology, physiological and biochemical characteristics, and 16S ribosomal DNA gene analysis. Response surface methodology analysis showed that the optimum conditions for fenvalerate degradation were fenvalerate concentration of 44.04 mg L ¡1 , pH 7.48, and ferric chloride concentration of 0.051% (w/v). Under these conditions, approximately 80.07% of fenvalerate was degraded within 60 h of incubation. Five metabolic compounds, including a-isopropyl-4-chlorobenzene acetic acid, 4-chlorobenzene acetic acid, 3-phenoxybenzyl alcohol, phenol and benzoic acid were detected during fenvalerate degradation and identified by gas chromatography-mass spectrometry. A possible degradation pathway of fenvalerate was proposed based on these identified metabolites. The results indicated that strain CY-012 could potentially be used to eliminate environmental contamination with pyrethroid insecticides.