Abstract:【Objective】 Chlorpyrifos residue poses a significant challenge to food safety. Microbial degradation which is called bioaugmentation is an effective approach for the elimination of such residues. Bioaugmentation often involves an invasion process requiring the establishment and activity of a foreign microbe in the resident community of the target environment. Interactions with resident micro-organisms, either antagonistic or cooperative, are believed to impact invasion. However, few studies have examined how the interactions between the invaded degrading bacteria and resident microorganisms in the target environment can influence microbial degradation. In this study, chlorpyrifos-degrading bacteria Shingopyxis granuli CP-2 was used as material, from the perspective of microbe-microbe interactions, to select resident bacterial helper of CP-2. 【Method】 Soils from the field were first collected, a batch of bacteria from the soil was isolated by continuous dilution method, and identified by full-length sequencing of the 16S rRNA gene. The 16S rRNA gene sequences of all isolates were aligned using MUSCLE. Sequences in the alignment were trimmed at both ends to obtain maximum overlap using the MEGA X software, which was also used to construct taxonomic cladograms. A maximum-likelihood (ML) tree was constructed, using a general time reversible (GTR) + G + I model, which yielded the best fit to our data set. Bootstrapping was carried out with 100 replicates retaining gaps. A taxonomic cladogram was created using the EVOLVIEW web tool (https: //evolgenius.info//evolview-v2/). The taxonomic status (phylum) of each rhizobacterial strain was also added as heatmap rings to the outer circle of the tree. The resident bacterial helper which could promote the growth of CP-2 was then screened by supernatant assay from the isolates isolated from soils, and the bioinformatics results of these helpers were analyzed. At last, a bacterial isolate which well promoted the growth of CP-2 was chosen, and its effect on CP-2s ability to degrade chlorpyrifos was investigated in vitro. 【Result】 109 strains of indigenous bacteria were isolated and were classified into four main phyla: Proteobacteria (54.1%), Actinobacteria (14.8%), Firmicutes (15.6%), and Bacteroidetes (15.6%). Among them, 41.3% significantly inhibited the growth of CP-2, 17.4% had no significant effect on CP-2, and 41.3% (45 bacterial strains) significantly enhanced CP-2s growth and were identified as indigenous bacterial helpers of CP-2. The 45 bacterial strains in the helper bank mainly belong to 3 phyla, 4 classes, 7 orders, 13 families and 20 genera. One strain (B72), which exhibited a strong growth-promoting effect on CP-2 was selected to assess its impact on chlorpyrifos degradation by CP-2. The results demonstrated that both the bacterial strain B72 and its supernatant significantly promoted the chlorpyrifos degrading ability of CP-2. 【Conclusion】 Together, the strains identified in this study provide valuable resources for future research and applications involving microbial degradation of soil toxicants such as chlorpyrifos or other pollutants. Furthermore, the indigenous bacterial helper of chlorpyrifos degrading bacterium CP-2 significantly promoted its ability to degrade chlorpyrifos, which offers theoretical guidance and technical support for potential co-inoculation strategies involving both chlorpyrifos-degrading bacteria and indigenous bacterial helpers aimed at pollution remediation.

Abstract:A pot experiment in greenhouse was carried out to investigate effects of application of rhamnolipid (RH), a type of biosurfactant on the effect of PAHs-specific degrading bacteria (DB) in bioremediation of soils that have long been contaminated by PAHs. Results indicate that application of RH in addition to DB inoculation significantly increased total PAHs and promoted degradation of PAHs different in number of rings in the soil. After 90 days of incubation, the PAHs degradation ratio of Treatments RH, DB and RH+DB reached 21.3%, 32.6% and 36.0%, respectively, and increased by 333.0%, 563.3% and 633.0% as compared against that (4.9%) of the control. In addition, the average PAHs degradation ratio declined with the number of rings of the 15 PAHs. It was also found that the number of PAHs degrading bacteria, dehydrogenase activity and polyphenol oxidase activity in soils of Treatments DB and RH+DB were much higher than in Treatment RH and in CK, but differed slightly between Treatment RH and CK, suggesting that the mechanism of DB promoting degradation of PAHs in the soil is different from that of RH.

Abstract:Crude oil is a kind of organic matter, relatively insoluble in water, which seriously affects its bioavailability.Some bacteria are found to be able to produce biosurfacant, which can emulsify the crude oil and enable the bacteria to adhere to the hydrophobic surface of the oil very strongly, thus enhancing bioavailability of the crude oil in the environment.It is reported that bacteria with hemolytic circle in the blood plate show emulsifying activity.Therefore strains of the bacteria were isolated from the petroleum contaminated soil through enrichment culture in BH medium with crude oil from Jianghan as the sole carbon source and hemolytic activity assay on blood agar plates.Nine strains with high degrading and emulsifying ability were isolated.Strain X13-1 was found at the top of the list of the bacteria with emulsifying ability reaching 80% and 75% at 1h and 24 h respectively.OD600nm of the culture fluid with paraffin as the sole carbon source was used to indirectly measure petroleum-degrading abilities of bacteria.The OD600nm of strain X13-1 was up to 0.566.Besides its emulsifying ability and petroleum-degrading ability, strain X13-1 was chosen for ulterior research.Cell wall composition, morphology, metabolism Biolog Microstation Identification System and the sequence analysis of 16S rDNA fragment amplified from total DNA of bacterium X13-1 were used to identify the strain of bacterium.The results show that the bacterium is G- and bacilliform.SIM (Similarity) in Biolog to typical Acinetobacter calcoaceticus is 0.826 and 16S rDNA sequence homology with typical A.calcoaceticus in the genebank is 97%.To sum up the above-described characters, it can be concluded that strain X13-1 is likely to be an A.calcoaceticus.

Abstract:To overcome limitations of the traditional enrichment culturing method for degrading bacteria isolation, two strains of bacteria, AG1 and ADG1, capable of degrading atrazine efficiently, were isolated by diluting and plating atrazine-contaminated soils directly onto plates coated with soil extracts and atrazine.They grew in medium with atrazine as the sole sources of nitrogen, carbon and energy, degrading 1 000 mgL-1 of atrazine within 44 h and 48 h, respectively, and could also grew with some other s-triazine herbicides as sole nitrogen sources.Based on their 16S rDNA sequences analysis and their physiologic and biochemical characteristics, AG1 and ADG1 were identified as Arthrobacter spp..Results of amplifying their degrading genes with PCR, showed that atrazine metabolic genotype of AG1 and ADG1 were both combination of trzN and atzBC.It is the first report in the country about atrazine-degrading bacteria with such metabolic genotypes.

Abstract:The high efficiency degrading bacteria Pseudomonas and Bacilus were obtained by circulation culture.The conditions that influence degradative efficiency were studied.98.7% of pacloutrazol can be degraded naturally in sterile medium under vibration condition 99.8% of pacloutrazol can be degraded by degrading bacteria.Pacloutrazol can be degraded down to CO2 by mixed degrading bacteria.If plenty of oxygen and light are adsorbed by soil,after 35d about 86.2% of pacloutrazol can be degraded and biomass can reach 89% of general level in soil.