Xiyue Zhao

Biosynthesis of benzoylformic acid from benzoyl cyanide by a newly isolated Rhodococcus sp. CCZU10-1 in toluene–water biphasic system

Benzoylformic acid was synthesized from the hydrolysis of benzoyl cyanide by a newly isolated Rhodococcus sp. CCZU10-1. In this study, an aqueous-toluene biphasic system was developed for highly efficient production of benzoylformic acid from the hydrolysis of benzoyl cyanide. In the aqueous-toluene biphasic system, the phase volume ratio, buffer pH and reaction temperature were optimized. Using fed-batch method, a total of 932 mM benzoylformic acid accumulated in the reaction mixture after the 10th feed. Moreover, enzymatic hydrolysis of benzoyl cyanide using calcium alginate entrapped resting cells was carried out in the aqueous-toluene biphasic system, and efficient biocatalyst recycling was achieved as a result of cell immobilization in calcium alginate, with a product-to-biocatalyst ratio of 14.26g benzoylformic acid g(-1) dry cell weight (DCW) cell after 20 cycles of repeated use.

Microbial Degradation Mechanism and Pathway of the Novel Insecticide Paichongding by a Newly Isolated Sphingobacterium sp. P1-3 from Soil

Using 1-((6-chloropydidin-3-yl)methyl)-7-methyl-8-nitro-5propoxy-1,2,3,5,6,7-hexahydroimidazo[1,2-α-]-pyridine (IPP) as the sole carbon source, we isolated a strain with a higher activity of IPP-degrading bacterium Sphingobacterium sp. P1-3 from soil. At 30 °C, pH 7.0 ,and 10 mg L(-1) IPP content, the degradation rate of IPP by Sphingobacterium sp. P1-3 could reach 57.75 and 62.47% in 20 and 30 days, respectively. The value of DT50 of IPP was 27 d at the level of 30 mg L(-1) IPP, while DT50 in the blank test was 151 d. During the IPP biodegradation process, five intermediates (M1-M5) were monitored and identified. On the basis of the identified metabolites and their biodegradation courses, a possible biodegradation pathway was proposed. IPP biodegradation mainly occurred on the tetrahydropyridine ring. IPP was transformed to five different metabolites by strain P1-3 through the oxidation and elimination of methyl, propyl, and nitro groups. Moreover, a new pathway involving M2 (1-((6-chloropydidin-3-yl)methyl)-7-methyl-8-hydroxy-5-propoxy-1,2,3,5,6,7-hexahydroimidazo [1,2-α-]-pyridine), M3 (1-((6-chloropydidin-3-yl)methyl)-7-methyl-5-carbonyl-1,2,3,5,6,7-hexahydroimidazo[1,2-α-]-pyridine), and M5 (8-amino-1,2,3,5,6,7-hexahydroimidazo[1,2-α-]-pyridine) was first monitored and identified.

Pyrosequencing Reveals Soil Enzyme Activities and Bacterial Communities Impacted by Graphene and Its Oxides

Graphene (GN) and graphene oxides (GOs) are novel carbon nanomaterial; they have been attracting much attention because of their excellent properties and are widely applied in many areas, including energy, electronics, biomedicine, environmental science, etc. With industrial production and consumption of GN/GO, they will inevitably enter the soil and water environments. GN/GO may directly cause certain harm to microorganisms and lead to ecological and environmental risks. GOs are GN derivatives with abundant oxygen-containing functional groups in their graphitic backbone. The structure and chemistry of GN show obvious differences compared to those of GO, which lead to the different environmental behaviors. In this study, four different types of soil (S1-S4) were employed to investigate the effect of GN and GO on soil enzymatic activity, microbial population, and bacterial community through pyrosequencing of 16S rRNA gene amplicons. The results showed that soil enzyme activity (invertase, protease, catalase, and urease) and microbial population (bacteria, actinomycetes, and fungi) changed after GN/GO release into soils. Soil microbial community species are more rich, and the diversity also increases after GO/GN application. The phylum of Proteobacteria increased at 90 days after treatment (DAT) after GN/GO application. The phylum of Chloroflexi occurred after GN application at 90 DAT in S1 soil and reached 4.6%. Proteobacteria was the most abundant phylum in S2, S3, and S4 soils; it ranged from 43.6 to 71.4% in S2 soil, from 45.6 to 73.7% in S3 soil, and from 38.1 to 56.7% in S4 soil. The most abundant genera were Bacillus (37.5-47.0%) and Lactococcus (28.0-39.0%) in S1 soil, Lysobacter and Flavobacterium in S2 soil, Pedobacter in S3 soil, and Massilia in S4 soil. The effect of GN and GO on the soil microbial community is time-dependent, and there are no significant differences between the samples at 10 and 90 DAT.

Eukaryal composition and diversity in anaerobic soils influenced by the novel chiral insecticide Paichongding

Paichongding (IPP) is a neonicotinoid chiral insecticide with independent intellectual property in China. IPP application can increase crop yield, and also lead to insecticide residue and pollution in soils, which will affect microbial population and community composition in soils. In this study, four different types of soils were employed to inquire into the impact of IPP on eukaryal community and species-group through pyrosequencing of 18S rRNA gene amplicons. Fungal population differed in different soils at different days after IPP treatment (DAT). Eukaryal community species in CK (control check) groups were more rich than that with Paichongding sprayed at 5 DAT, while eukaryal species in CK soils at 60 DAT was relatively slight. Shannon’s H’ analysis indicated fungal species in CK soils were also higher at 5 DAT and relative lower at 60 DAT, except in soil C. There are also differences in the phyla and genus levels of the eukaryotic communities in the soil. After IPP application, the relative abundance of Nectriaceae increased 3–4 times in soil C. In soil F, Phaeosphaeriaceae increased to 57.3% at 5 DAT. The genus of Guehomyces, Aspergillus and Alternaria increased from 3.1 to 9.7, 1.1 to 4.6, 1.5 to 6.7% in soil H, respectively.