Biochemical identification techniques and antibiotic susceptibility profile of lipolytic ambiental bacteria from effluents

Abstract Different methodologies have been developed throughout the years to identify environmental microorganisms to improve bioremediation techniques, determine susceptibility profiles of bacteria in contaminated environments, and reduce the impact of microorganisms in ecosystems. Two methods of bacterial biochemical identification are compared and the susceptibility profile of bacteria, isolated from residential and industrial wastewater, is determined. Twenty-four bacteria were retrieved from the bacteria bank of the Environmental Microbiology Laboratory at the Institute of Biology (IB) of the Universidade Federal de Pelotas, Pelotas, Brazil. Bacteria were identified by conventional biochemical tests and by the VITEK ®2 automated system. Further, the susceptibility profile to antibiotics was also determined by the automated system. Six species of bacteria (Raoutella planticola, K. pneumoniae ssp. pneumoniae , Serratia marcescens, Raoutella sp., E. cloacae and Klebsiella oxytoca) were identified by conventional biochemical tests, while three species of bacteria (K. pneumoniae ssp. pneumoniae, S. marcescens and K. oxytoca ) were identified by VITEK®2 automated system. VITEK ®2 indicated agreement in 19 (79.17%) isolates and difference in five (20.83%) isolates when compared to results from conventional biochemical tests. Further, antibiotic susceptibility profile results showed that all isolates (100%) were resistant to at least one out of the 18 antibiotics tested by VITEK®2. Thus, no multi-resistant bacteria that may be used in effluent treatment systems or in bioremediation processes have been reported. Results indicate VITEK ® 2 automated system as a potential methodology in the determination of susceptibility profile and identification of environmental bacteria.

摘要 多年来，科研人员已开发出多种不同方法，用于鉴定环境微生物以优化生物修复技术、明确污染环境中细菌的药敏谱，并降低微生物对生态系统的负面影响。本研究对比了两种细菌生化鉴定方法，并对从生活污水与工业废水中分离得到的细菌的药敏谱进行了测定。研究菌株取自巴西佩洛塔斯联邦大学生物研究所（Institute of Biology，简称IB）环境微生物学实验室的菌种库，共获取24株细菌。分别采用传统生化试验与VITEK®2自动化系统对细菌进行鉴定。此外，借助该自动化系统测定了细菌的抗生素药敏谱。传统生化试验共鉴定出6种细菌：植人生根杆菌（Raoutella planticola）、肺炎克雷伯菌肺炎亚种（K. pneumoniae ssp. pneumoniae）、粘质沙雷菌（Serratia marcescens）、Raoutella属菌（Raoutella sp.）、阴沟肠杆菌（E. cloacae）以及产酸克雷伯菌（Klebsiella oxytoca）；而VITEK®2自动化系统仅鉴定出3种：肺炎克雷伯菌肺炎亚种、粘质沙雷菌与产酸克雷伯菌。与传统生化试验结果相比，VITEK®2自动化系统在19株（79.17%）菌株中鉴定结果一致，在5株（20.83%）菌株中存在差异。抗生素药敏谱测定结果显示，所有受试菌株（100%）对VITEK®2检测的18种抗生素中至少1种存在耐药性。因此，本研究未发现可用于污水处理系统或生物修复流程的多重耐药细菌。研究结果表明，VITEK®2自动化系统有望成为环境细菌鉴定与药敏谱测定的可靠方法。