Abstract:[Objective] A strain with the ability of bioleaching was isolated. Its culture condition was optimized. [Methods] The strain was isolated from the soil collected from thermoelectric plant in Chengdu, whose taxonomic status was identified based on analysis of morphology characteristics, culture characteristics and 16S rDNA sequence. The optimization experiment was designed with Box-Behnken method in the software Design-Expert, in which the four factors of culture condition that initial pH, temperature, inoculum amount and liquid volume were investigated. Then the results were analyzed with the response surface analysis (RSA) and the optimal culture condition was determined. [Results] The isolated strain was Gram-negative and short-rod, which was named as Z1 and identified as Acidithiobacillus ferrooxidans strain by analysis of its 16S rDNA sequence. The optimal culture condition of the strain was determined, which was initial pH 1.8, optimum temperature 30 °C, inoculum volume 14% and liquid volume 60 mL medium in a 250 mL flask. Under the optimum condition, the oxidation rate of ferrousion reached at 99.7%. [Conclusion] The strain Z1 was appreciated for bioleaching.

Abstract:[Objective] We studied the hemolytic activity of Vibrio alginolyticus strains, and the distribution of a hemolysin gene vah in these strains; we analyzed the functions of vah gene and the related promoter, and assessed their contributions to the hemolytic activity. [Methods] Hemolytic test was performed using 47 V. alginolyticus strains, including one type strain 1.1587 and 46 environmental strains isolated from seawater and various marine animals. The difference of hemolytic ability was compared among a wild V. alginolyticus strain ZJ051 that showed hemolytic activity, a recombinant Escherichia coli BL21 aiming at a predicted vah gene, a vah-deletion mutant, and a vah-recovery strain. The distribution of vah gene was further detected in V. alginolyticus followed by the sequence analysis of vah genes and their promoters among the hemolytic and non-hemolytic strains. [Results] Among the V. alginolyticus strains 47.8% showed hemolytic activities, and thus hemolysis was ubiquitous in environmental V. alginolyticus strains. Hemolysis was observed in the recombinant Escherichia coli BL21 and the vah-recovery strain but not in the vah-deletion mutant. The vah gene widely distributed in V. alginolyticus. The vah sequences of V. alginolyticus strains were highly similar, and they shared identical amino acid sequences. Through the vah promoter comparison between the hemolytic and non-hemolytic strains, a difference in 188-190 base sites of the promoters was discovered. [Conclusion] Hemolysis is directly caused by the vah gene, and the discrepancy of hemolytic ability among various V. alginolyticus strains has no relation with the difference of vah sequences, which is likely determined by the diversity in 188-190 base sites of vah promoters.

Abstract:[Objective] To study the influence of natural quorum sensing inhibitors (QSI) against marine functional bacterial biofilm formation. [Methods] Some marine bacterial strains, which could induce the larval settlement of fouling organism, were regarded as target bacteria. Through adding natural quorum sensing inhibitors into the target bacterial cultures during their biofilm formation process, the influence of QSI on the biofilm and planktonic bacteria quantity, biofilm morphology as well as the surface extracellular polysaccharide were studied. [Results] Furanone and pyridine significantly inhibited the biofilm formation of all target bacterial strains at the concentration of 50 mg/L, with the inhibition rate of about 80%. However, indole, penicillanic acid and coumarin exhibited good inhibitory activity only at higher concentrations of 800 mg/L. The results of growth inhibition experiment showed that the inhibitory activity of QSI molecules on target bacterial biofilm formation was much higher than them against planktonic bacteria growth at the same concentration, which indicated that the biofilm formation inhibitory effect of QSI molecules was mainly due to their interference on the quorum sensing system of target bacteria. [Conclusion] This study confirmed that QSI molecules may play an important regulatory role in marine bacterial biofilm formation process. The biofilm induced larval settlement of fouling organisms might be indirectly inhibited through the addition of QSI, which may lead to new anti-fouling substances from another point of view.

Abstract:[Objective] This papar was about the effects of a kind of probiotics on several kinds of biological factors in seawater ponds. The probiotics was independently researched and developed by our research team. The main components of the probiotics were Bacillus sp. and Pseudomonas sp.. The biological factors included three kinds of breeding living being and the microorganism and the plankton. The objective of this study was for establishing technical system of ecological control of microorganisms. The research methods were described below. [Methods] During the experiment, the probiotic was spilled in the experimental ponds every 15 days. The density of heterotrophic bacteria and vibrio of the water and sediment were measured at the end of the month. The species and density of plankton was investigated at the end of the month. The growth rate and survival rate of cultured organisms was measured by the end of harvest season. The experiment was carried out nearly three months. [Results] There were three results. Firstly, the probiotics could enhance the growth and survival rate of two kinds of breeding living being, including Litopenaeus vannamei and Portunus trituberculatus. The survival rate and growth rate of the Litopenaeus vannamei of test groups enhanced respectively 11.3% and 1 400% compared with the control groups. The survival rate and growth rate of the portunus trituberculatus of test groups enhanced respectively 1.2% and 37.5% compared with the control groups. Secondly, the probiotics could enhance the density of heterotrophic bacteria, and restrained the growth of vibrios. The heterotrophic bacteria density of test groups in the water was higher 58.5% than the control groups. The heterotrophic bacteria density of test groups in the sediment was higher 58.5% than the control ponds. The vibrios density of test groups in the water was lower 39.7% than control groups. Thirdly, the probiotics could improve the density of Chlorophyta algae and Bacillariophyta algae, and inhibited the growth of Cyanophyta algae and Pyrrophyta algae. [Conclusion] It came to the conclusion that the probiotics could effectively improve biology community structure and the growth rate of some farmed species in the aquaculture ponds.

Abstract:[objective] Our aim was to evaluate the ability of Bjerkandera adusta XX-2 strain in degrading Malachite Green (MG) dye in order to provide reference for its application in treating dye wastewater. [Methods] Batch experiment was carried out to decolorize MG dye in an air-opening system in this study. Experimental parameters, such as oxygen demand, initial pH value, temperature, initial dye concentration, incubation time, carbon source, nitrogen source, metal ion and salinity, was investigated to analyze their effect on the decolorization of MG. The toxicity test of decolorized products on plant, aquatic animal and microorganism was also carried out in this study. [Results] B. adusta XX-2 strain showed efficient decolorization of MG dye without supplying basic salt medium in non-sterile culture, for example, decolorization rate still reached above 60% at the initial dye concentration of 120 mg/L, using MG as sole nutrient source. Static culture presented the similar MG decolorization rate as shaken culture, indicative of low-cost application potential for B. adusta XX-2 strain. The optimal pH and temperature for decolorization were 7.0 and 25 °C, respectively. Based on the system with optimal parameters, carbon source, nitrogen source and metal ion were separately added for choosing appropriate dosage. The results indicated that carbon source (e.g. sodium citrate), nitrogen source (e.g. ammonium chloride) and metal ion (e.g. Zn2+), even at a low concentration, all could greatly improve the efficiency of decolorization. Moreover, B. adusta XX-2 could decolorize MG in dye solution with high salinity. Toxicity test showed toxicity of decolorized products on plant, aquatic animal and microorganism greatly declined, in comparison with non-decolorized MG dye. [Conclusion] B. adusta XX-2 strain had a good application potential for treating dye wastewater.

Abstract:[Objective] Toyocamycin is an important nucleoside antibiotics with diverse bioactivities and potentials for biological control of plant diseases. We expressed the vgb gene encoding Vitreoscilla hemoglobin to alleviate the dissolved oxygen (DO) limitation and to improve the toyocamycin production in Streptomyces diastatochromogenes 1628. [Methods] we used gfp gene as the report gene to test the transcription activity of erythromycin resistance gene promoter PermE* of integrative plasmid pIB139. Then, the promoter PermE* was used to drive the gene vgb expression in S. diastatochromogenes 1628. [Results] Green fluorescent of recombinant strain 1628-GFP was detected by fluorescent microscopy. The promoter PermE* was efficient for heterologous gene expression in S. diastatochromogenes 1628. The vgb gene was also expressed in engineered strain 1628-VHB by the CO-difference spectrum analysis. The engineered strain 1628-VHB improved toyocamycin production under all diverse DO condition. Specially, strain 1628-VHB increased 48.9% toyocamycin production under middle and 104.5% under high limitation DO condition, comparing with the control stain 1628. Meanwhile, strain 1628-VHB was genetically stable by the PCR and toyocamycin yield test from different generation strain. [Conclusion] Expression of vgb gene improved toyocamycin production of strain 1628.

Abstract:[Objective] To isolate and identify the antimicrobial active component extracted from fermentation broth of antagonistic actinomycetes strain G-19 against peach crown gall (Agrobacterium tumefaciens). [Methods] Sephadex LH-20 chromatography, HPLC and middle-pressure chromatography were used for isolation and purification. LC-MS, NMR were applied to identify structure of the active component. [Results] Compound G-19-I was isolated and structurally identified as 1,2-benzenedicarboxylic acid, 1,2-dibutyl ester (DBP); compound G-19-II was isolated and structurally identified as 2-(4-hydroxyphenyl)-3,4-dihydro- 2H-chromene-3,4,5,7-tetrol, commonly known as leucopelargonidin. [Conclusion] The material basis of the antibacterial constituents in antagonistic actinomycetes strain G-19 was further clarified.

Abstract:[Objective] In order to prepare strains for microbial fertilizer production, a cold-adapted cellulase-producing strain was screened and identified, and its characterization of cellulase was analyzed preliminarily. [Methods] CMC-Congo red staining was used to screen the cellulose-degrading strains initially under the condition of normal temperature. Low temperature induction was followed to screen the strain with low temperature resistance and favorable cellulase activity. Then the strain mentioned above was identified by its morphological, the physiological and biochemical properties and ITS sequence analysis. Single factor test based on temperature, pH and metal ions was used to determine the influence of the cellulase activity. [Results] Strain M11 producing extracellular cellulose under 13 °C was isolated from the straw returned soil. It was identified as a Penicillium oxalicum. The results of fermentation tests showed that, when corn straw was taken as the only carbon and nitrogen sources, the activity of cellulase was maximum as 33.08 U/mL in the ninth day, under the fermentation conditions of 13 °C, 200 r/min. The results of its cellulase characterization revealed that, the optimum pH was 5.0 and reaction temperature was 20 °C. The relative cellulase activity still reached to 90% in the range of 5 °C?20 °C. [Conclusion] The cellulose-degrading strain Penicillium oxalicum M11 could secrete cellulase under the low temperature, and was tremendous potential valuable for microbial fertilizer.

Abstract:[Objective] To optimize the culture conditions of lactic acid bacteria community (LAC-1) screened at low temperature, and investigate the micro storage effects of cornstalk inoculated with LAC-1. [Methods] The LAC-1 was screened by continuous restricted cultivation, using system pH as the only indicator. The single factor experiment, Box-Behnken design and response surface methodology were used to optimize the culture conditions of LAC-1. [Results] A community which could decrease pH rapidly was screened and named as LAC-1. LAC-1 could keep the pH and fermentation system stable, which could improve the sensory quality of fermented silage. Results showed that the pH reduction speed of LAC-1 was greatly influenced in this order: culture time, temperature and inoculated quantity. The optimal culture parameters were: culture temperature at 9.5 °C, inoculated quantity at 3.3% and culture time at 139 h. Under the optimal conditions, the fermentation time was shortened by 48 h and the number of lactic acid bacteria was increased by 20.5%. When the dry cornstalk was inoculated with LAC-1 by 5 days, the system pH fell to 4.1. The silage smelled sweet, flavor and sour, the texture was loose in appearance and bright in color. The following determination indicated the content of water-soluble carbohydrate was declined by 46.3% and the number of lactic acid bacteria was improved by 33.3%. [Conclusion] The application of LAC-1 could promote the conversion of dry cornstalk into micro storage and improve the quality of silage.

Abstract:[Objective] Demonstrate the effects of arbuscular mycorrhiza (AM) fungi on Carthamus tinctorius L. rhizosphere microbe diversity. [Methods] Dilution cultural and PCR-single stand conformational polymorphism (SSCP) were used for determing rhizosphere microbe exist in the ambient of inoculated AM fungi plants Carthamus tinctorius L. or named safflower as well. Target safflowers were inoculated with Glomus mosseae, G. intraradices and mixed group (G. mosseae, G. intraradices, G. cladoideum, G. microagregatum, G. caledonium and G. etunicatum), respectively. [Results] Total number of rhizosphere microbe around treated safflower shows an order of G. mosseae>G. intraradices>Mix. Compared with control group, inoculated group has larger quantity (p<0.05) of total microbe number according the order of 0?5 cm>5 cm?10 cm>10 cm?20 cm in most of its growth stages. Inoculated safflower, however, showed differ microbial quantity along soil vertical profile as 5 cm?10 cm> 0??5 cm>10 cm?20 cm. Clustering analysis confirmed exist as inoculation and non-inoculation plant microbial groups. [Conclusion] AM fungi have an affected on the variation pattern of rhizosphere microbe diversity of safflower by temporally and spatially varieties. This patterns not only can help us easy understanding the significance function of microbe exist in terrestrial ecosystem, could also support as a guidance in appropriate cultivation strategy on agricultural production the near future.

Abstract:[Objective] To investigate the characteristics of chloramphenicols resistance and the prevalence of resistance genes in Salmonella Indiana from chicken. [Methods] The samples were isolated from chicken hatcheries, farms and slaughterhouses in Shandong Province. The isolates were identificated and tested the drug susceptibility, designing primers for the resistance genes of chloramphenicols in strains were detected by PCR and sequence analysis. [Results] The results showed that the isolation rate of Salmonella Indiana was 23.28%. The resistance rates of Salmonella Indiana from hatcheries, farms, slaughterhouses to chloramphenicol were 50%, 83.33%, 93.30%, florfenicol were 83.33%, 100%, 100%, thiamphenicol were 63%, 65%, 77% respectively. In 80 chloramphenicols resistant strains, 54 strains had detected catA1 gene, 74 strains had detected floR gene, and the 5 strains had detected cmlA gene. [Conclusion] These results indicated that the resistance rates of Salmonella Indiana to chloramphenicols were different from hatcheries, farms and slaughterhouses. The catA1 gene and floR gene were widely existed in chloramphenicols resistant strains.

Abstract:[Objective] We identified polyketide synthase (PKS) genes from mangrove soil. [Methods] Degenerate PCR primers were used to amplify ketosynthase (KS) domains associated with type I and II PKS genes from DNA of soil samples derived from the Qinglan Harbor (Hainan, China). The molecular diversity and phylogeny of type I and II PKS genes were analyzed by PCR-RFLP based cloning approach. [Results] A total of 72 clones and 51 OTUs were obtained, there was no dominant OTU and 37 OTUs were from single clone. Twenty-six clones of different OTUs were sequenced and the DNA sequences were translated into amino acid (AA) sequences. All identified KS domains showed the identities at AA level to their closest matches in GenBank at less than 85%. Phylogenetic analysis of these sequences indicated that the identified ketosynthase (KS) domains were clustered with those from diverse bacterial group, including Cyanobacteria, Proteobacteria, Firmicutes, Actinobacteria and some uncultured bacteria. A total of 55 clones containing Type II PKS gene KS domain DNA sequences were analyzed by PCR-RFLP. Only 25 OTUs were generated and there were two dominant OTUs which present more than 10% of clones in the clone library. [Conclusion] These results suggested the presence of diverse PKS I and PKS II genes in microorganisms from mangrove rhizosphere soil, and the diversity of PKS II gene is lower than the PKS I gene. Low KS domain sequence similarities indicated they possessed unique PKS I genes. Phylogeny deduced from the sequences of KS domains in PKS I genes showed that they distributed in different bacterial phyla.

Abstract:[Objective] In the PCR-targeting system of Streptomyces, apramycin is the most widely used selection marker. However, using apramycin as selection marker at disruption stage precludes, during subsequent genetic complementation, the use of some very useful and widely used vectors with the same marker, such as pSET152. This often caused unwanted inconvenience, especially in the situation that the physiological function of interested gene is sensitive to gene dosage, such as regulatory genes. The current study aims to provide an integrative plasmid with selection marker rather than apramycin. [Methods] Fusion-PCR and λ Red recombination were adapted to construct the new vector. [Results] The bla gene from pCR2.1 and the tsr gene from pHZ1358 were fused in the tsr-bla order. This fused fragment replaced the aac(3)-IV gene on pSET152 to generate pGIM6626. This new vector was validated by successfully restoring granaticin production of a granaticin-deficient S. vietnamensis mutant by re-introducing the deleted minimal polyketide synthase genes. [Conclusion] We constructed a new pSET152 derivative vector, pGIM6626, which contains ampicillin and thiostrepton resistance genes for selection in E. coli and Streptomyces, respectively. pGIM6626 and pSET152 have similar uses, but the former is more compatible with the PCR-targeting system because of no conflict of selection marker.

Abstract:The way in which disinfectants effect sterilization can be summarized into the following aspects: restrict the active transport of membrane; hinder the metabolism of microorganisms; disturb the DNA duplication of microorganisms; and break the microbial cells in a bid to bring about the leakage of intracellular constituents and condensation of intracellular constituents. Disinfectant plays an important role in controlling and killing bacteria, but the bacteria can also acquire resistance to disinfectants. The mechanisms of bacterial disinfectant-resistance can be active through formation of biofilm, prevention or efflux system to reduce penetrating disinfectant molecules, inactivation of the disinfectant, and some other disinfectant resistance phenotype and so on. Among these mechanisms, the biofilm has a great importance because it can prevent the disinfectant molecules from penetrating into the bacterial cells or inactivate the disinfectants before they have penetrated into the cells. It is suggested that studies centered on the resistance mechanism of major actually-contaminated bacteria have great value and practical significance in controlling the contamination of bacteria in the future.

Abstract:The main aroma ingredients in Chinese strong-flavor liquor include ethyl caproate, ethyl lactate, ethyl acetate, and ethyl butyrate. These esters are derived from organic acids and alcohol with ester synthase during grain fermentation. Functional aroma-producing microorganisms in Zaopei and pit mud of Chinese strong-flavor liquor included the aroma-producing strains and its precursor, and all kinds of ester synthase-producing strains. The progress in studies on sources, composition, identifying methods, mutual relationship and fermenting application of important functional aroma-producing microorganisms in Zaopei and pit mud of Chinese strong-flavor liquor was summarized. This review would provide some research ideas on important microorganisms of Chinese strong-flavor liquor fermentation as well as the fermenting processes.

Abstract:Microbiology is a key professional basic course for plant production, resources and environment related majors in agricultural universities. Combined with the characteristics of Microbiology course, the reforming scheme on fully advancing essential-qualities-oriented education has been put forward by the teaching group in order to promote undergraduate students the ability in learning, practice and innovation, that is, establishing the modern education concept, renewing and optimizing course teaching system, and exploring on new teaching model so as to construct a new course quality control system.

Abstract:[Objective] To establish the Restriction enzyme mediated integration (REMI) transformation system and a REMI transformants library of Lasiodiplodia theobromae. [Methods] REMI method was used to obtain transformants of L. theobromae. Linearized DNA of plasmid pUCATPH containing the hygromycin phosphotransferase gene (Hyg) was integrated into chromosomes of wild strain CSS-01s. Sensitive concentration of L. theobromae to hygromycin B was determined. Different enzymolysis systems and digest time on preparation of protoplasts were performed and effect of restriction enzyme quantity on percent conversion was also carried out. The REMI transformants library of CSS-01s was constructed with the optimal condition, and the transformants was confirmed by Southern blot. [Results] This study established REMI method of L. theobromae for the first time and constructed REMI transformants library containing about 6 000 transformants. Southern blot analysis revealed that the plasmid inserted into the corresponding restriction endonuclease sites located on the genomic DNA of five random transformants. [Conclusion] The results suggested that the optimal condition of protoplasts preparation was adding 2% Drislase+2% Snailase enzyme mixture and digested for 4 hours. The transformation efficiency reached to the highest when 30 U Hind Ⅲ was added into per transformation reaction. Transfotmants with differernt phenotype can be obtained using the above optimal conditions.

Abstract:[Objective] To establish a simple and rapid molecular typing method for Vibrio parahaemolyticus carrying and non-carrying virulence genes based on molecular motor. [Methods] Four probes specific to virulence genes tdh and trh, species-specific genes tlh and toxR of V. parahaemolyticus were synthesized, and four molecular motor biosensors were constructed by connecting probes to F0F1-ATPase molecular motors through biotin-streptavidin system, respectively. Ten strains of V. parahaemolyticus were classified by the biosensors, and the results were compared with PCR-Electrophoresis-Gel imaging results. Further more, the detection sensitivities and specificities of the molecular motor biosensors were studied. [Results] There were ten strains carrying tdh and none carrying trh, while all ten strains carry tlh and toxR, which was consisitent with the results of PCR-Electrophoresis-Gel imaging. The detection limits of molecular motor biosensors for tlh, toxR, tdh and trh were estimated to be 1 pg/reaction system, and the detection limits of PCR-Electrophoresis-Gel imaging for tlh, toxR, tdh and trh were estimated to be 10 pg/reaction system. The molecular motor biosensors could recognize tlh, toxR, tdh and trh of V. parahaemolyticus specifically. [Conclusion] A molecular typing method was constructed based on molecular motor biosensors and was used to diagnose the pathogenicity of V. parahaemolyticus rapidly and specifically. The detection limits was 10 times higher than those of PCR-Electrophoresis-Gel imaging. The method is easy, rapid, time-saving and labor-saving, especially suitable for the basic laboratories of CDC and port quarantine departments to perform suiveillance and epidemiological traceability of cholera.

Abstract:[Objective] To establish the 16S rDNA sequence analysis method to identifiy Brucella and evaluate the specificity and feasibility of this method. [Methods] 16S rDNA were amplified from Brucella by polymerase chain reaction (PCR) method and the purified product were directly sequenced for further analysis. The 16S rDNA sequence of the bacteria that are known to cross-react serologically with Brucella were downloaded from the GenBank. DNAMAN was used for comparison of 16S rDNA sequence. [Results] Brucella 16S rDNA sequence similarity reached 99.74%, Brucella 16S rDNA sequence to serologically related bacteria had more pronounced differences. [Conclusion] 16S rDNA sequence analyses is a rapid, simple diagnostic and specific method.

Abstract:[Objective] The SD-EMA-PCR was established by incorporating sodium deoxycholate (SD) into EMA-PCR assay for discrimination viable and dead cells of Vibrio parahaemolyticus. [Methods] The optimal concentration of the sodium deoxycholate, the concentration of ethidium bromide monoazide (EMA) for discrimination viable and dead cells, the optimal light exposure time for acativating and photolyzing EMA were determined respectively. And the detection limit value of V. parahaemolyticus in the mixtures of viable and dead cells was obtained by SD-EMA-PCR. [Results] The results showed that when the concentration of sodium deoxycholate is less than or equal to 0.5 g/L, the concentration of EMA is ranged from 3.2 to 34.0 mg/L, the light exposure time is 25 min, the DNA amplification from the dead cells by SD-EMA-PCR were inhibited. The detection limit of the SD-EMA-PCR assay for the viable cells was 10 CFU/mL. [Conclusion] SD-EMA-PCR can be used to minimize the false-positive results by inhibiting the EMA-PCR amplification of V. parahaemolyticus dead cells from a mixed bacterial population. It is an efficient new approach for distinction between the viable and dead cells and efficiently avoid false positive results.

Abstract:[Objective] In order to obtain more resources of endophytic actinomyctes, the aim of the study is to establish an effective method of isolating endophytic actinomycetes. [Methods] Disinfectant and sterilization procedures, pretreatment method, isolation medium were compared. The isolates were identified based on morphology and 16S rRNA gene sequence analysis. [Results] It is very effective for samples sterilized 4?7 minute with 5% NaClO. The pretreatment method of processing sample 15 minutes at 100 °C have a good effect on reducing the interference of fungi and bacteria. Isolation mediums containing sodium propionate and sodium succinate have good effect on isolation. [Conclusion] The isolation method that plant samples were surface sterilized and dried, processed 15 minutes at 100 °C, broken in a sterile mixing cup, and then were separated on isolation medium is very useful.

Abstract:

Abstract:[Objective] The aim of this study was to study the main serotypes and the biological characteristics of Avian Pathogenic Escherichia coli (APEC) isolated from Jiangsu and Anhui provinces. [Methods] The tested strains were isolated from sick poultry and identified by slide agglutination to determine serotypes. Virulence-associated genes were identified by PCR and the drug susceptibilities were detected according to Clinical and Laboratory Standards Institute (CLSI). Moreover, the biofilm-forming abilities were detected through improved crystal violet semi-quantitative method. [Results] In total 56 strains were isolated and identified. Slide agglutination results show that O78 was the main serotype accounted for 64.29% of the isolates. PCR amplification results of the virulence-associated genes showed that fimC, pfs, ompA and luxS were amplified from more than 90% of the tested strains. Drug sensitivity test results showed that 58.93% of the strains were resistant to more than 8 antibiotics. Biofilm formation assay showed that 16 isolates produced moderate or strong biofilm in vitro, in which 68.75% were resistant to more than 8 antibiotics. [Conclusion] O78 was the main serotype among the isolates. The genes of fimC, pfs, ompA and luxS were conserved in APEC. Multi-antibiotic resistance was very common and drug resistance seemed relative to biofilm-forming ability.

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