1株产单宁酶戊糖片球菌的筛选及功能评价

Screening and functional evaluation of a tannase-producing strain of Pediococcus pentosaceus

本研究旨在筛选产单宁酶的乳酸菌,并对其进行生物学特征、酶学性质、功能特征和全基因组分析等方面的研究,为菌株的开发利用提供必要的理论支撑。经过筛选,成功获得了1株产单宁酶的戊糖片球菌STS-6(Pediococcus pentosaceus STS-6),该菌单宁酶主要以胞外分泌为主,单宁酶活力达到1.6U/mL,其最适反应温度为60℃、最适pH为6.0,50℃处理1 h能够维持87%以上酶活力。该菌株在人工胃、肠液处理下表现出较高的耐受性,活菌数均高于10^(8)CFU/mL,存活率分别达到94.17%和92.36%,具有良好的自聚与共聚能力。菌株STS-6的发酵上清表现出较高抗氧化活性,其中DPPH自由基的清除能力可达71.15%、总还原能力为0.83,质粒DNA损伤保护能力可达59.54%。此外,全基因组测序发现菌株P.pentosaceus STS-6的基因组由1个的环状染色体和3个质粒构成,GC含量为37.28%,包含1767个编码基因。其中,NR、Swiss-Prot、Pfam、COG分别注释了1761、1384、1539、1486个基因,进一步研究发现该菌中含有多个耐酸、耐胆盐、抗热激及抗氧化相关基因,并发现1个疑似单宁酶基因gene0906。表明P.pentosaceus STS-6是1株产单宁酶且具有良好益生特性的菌株,在食品发酵中具有广阔的应用前景。

The purpose of this study was to screen lactic acid bacteria for tannase producing,and provide necessary theoretical support for the development and utilization of strains via clarify the biological characteristics,enzymatic properties,functional characteristics and whole genome information.A strain of Pediococcus pentosaceus STS-6 was screened out to successfully produce tannase.The enzyme activity of tannase produce by this strain was 1.6 U/mL,which functioned best at temperature 60℃and pH 6.0.Treatment at 50℃for 1 h could maintain more than 87%enzyme activity.The bacterial count was higher than 10^(8)CFU/mL,and the survival rate was 94.17%and 92.36%,respectively,with good autoaggregation and copolymerization ability.The fermentation supernatant of STS-6 showed high antioxidant activity,of which DPPH free radical scavenging ability reached 71.15%,total reduction ability was 0.83,and DNA damage protection ability was 59.54%.In addition,whole genome sequencing revealed that P.pentosaceus STS-6 genome contended 37.28%GC and consisted of 1 circular chromosome and 3 plasmids encoding 1767 genes.NR,Swiss-Prot,Pfam and COG noted 1761,1384,1539 and 1486 genes,respectively.Further study found that the bacterium contained multiple genes related to acid resistance,bile salt resistance,heat shock resistance and oxidation resistance,and a suspected tannase gene gene0906 was found.In conclusion,P.pentosaceus STS-6 was a strain producing tannase with good probiotic properties,which has broad application prospects in food fermentation.