广西北部湾近海产胞外多糖细菌多样性及其抗氧化活性分析

Diversities and antioxidant activities of exopolysaccharide-producing marine bacteria isolated from Beibu Gulf Coast in Guangxi

【目的】鉴定广西北部湾近海产胞外多糖(EPS)的海洋细菌种类多样性,并测定其EPS生物学活性,为后续研究EPS活性及其开发利用打下基础。【方法】采用黏液比色法、乙醇沉法和苯酚硫酸法初筛产EPS细菌,通过16S rDNA序列鉴定细菌种属并进行遗传进化分析,以1,1-二苯基-2-三硝基苯肼(DPPH)测定EPS的抗氧化活性。【结果】从广西北部湾近海海水、沙粒和红树林泥土中共分离出205株产EPS细菌,结合分离株的菌落特征和形态观察结果可将所分离获得的细菌归为28种细菌。对28株代表细菌株进行鉴定,结果显示分属于2个纲(芽孢杆菌纲和γ-变形菌纲)、4个目(芽孢杆菌目、假单胞菌目、弧菌目和肠杆菌目)、4个科(芽孢杆菌科、莫拉菌科、弧菌科和肠杆菌科)、6个属(芽孢杆菌属、葡萄球菌属、弧菌属、发光杆菌属、变形杆菌属和不动杆菌属)、15个种;优势菌属为芽孢杆菌属,占所鉴定菌株的71.43%,其次为葡萄球菌属、弧菌属、发光杆菌属、变形杆菌属和不动杆菌属。EPS活性检测结果显示,不同种属细菌所产EPS均具有一定的DPPH清除作用,但不同菌株间差异明显,清除率为9.43%~71.10%。【结论】从广西北部湾近海地区共分离鉴定出2纲4目4科6属15种产EPS的海洋细菌,以芽孢杆菌属为主,存在种类多样性,且各类细菌分泌产生的EPS均具有一定抗氧化活性。

【Objective】The present study identified the diversity of exopolysaccharide-producing marine bacterial species isolated from Beibu Gulf area of Guangxi and determined the biological activities of exopolysaccharide(EPS),which would provide references for further study of its activity and development.【Method】The EPS-producing bacteria were screened by using mucilage colorimetry,ethanol precipitation and phenol sulfuric acid.The bacterial species were identified by 16S rDNA sequence,as well as their genetic evolution analysis.Finally,the antioxidant activities of bacterial EPS was determined by 1,1-diphenyl-2-trinitrophenyl hydrazine(DPPH)method.【Result】As a result,205 strains of EPSproducing bacteria were isolated from the seawater,sea mud and sand samples of Beibu Gulf in Guangxi.Based on the colony characteristics and morphological observation,all the bacteria isolated were classified into 28 strains.The 28 representative strains were selected and further identified by 16S rDNA sequencing,and the results showed that 28 strains belonged to 2 classes(Bacilli andγ-Proteobacteria),4 orders(Bacillales,Pseudomonadales,Vibrionales and Enterobacte riales),4 families(Bacillaceae,Moraxellaceae,Vibrionaceae and Enterobacteriaceae),6 genera(Bacillus,Staphylococcus,Acinetobacter,Vibrios,Photobacterium and Proteus),and 15 species.The dominant genus was Bacillus,accounting for 71.43%of the identified strains,followed by Staphylococcus,Vibrios,Photobacterium,and finally Proteus and Acinetobacter.The antioxidant activity test results showed that,the EPS from different species of identified bacteria showed a certain DPPH scavenging effects,however,the effect varied greatly among different strains,and the scavenging rates varied between 9.43%-71.10%.【Conclusion】Fifteen species of EPS-producing marine bacteria,which belong to 6 genera,4 families,4 orders,2 classes,are isolated and identified from mangrove soil samples in Beibu Gulf of Guangxi.The dominant genus is Bacillus.And species diversity exists among the EPS-producing marine bacteria.The EPS secreted by these identified bacterial strains has certain antioxidant activity.