The Antimicrobial Effect Of Actinomycetes Strains From Tea Plant And The Application In Fruit And Vegetable Postharvest Storage

Endophytic actinobacteria exist widely in plant tissues and are considered as a potential bioresource library of natural products.Tea plants play important roles in human health and in the lifestyles of Asians,especially the Chinese.However,little is known about the endophytic actinobacteria of tea plants.In this study,The main findings are as follows:16 actinobacteria of 7 different genera and 28 actinobacteria of 8 genera were isolated and analyzed by 16S rRNA gene sequencing from tea cultivars of Zijuan and Yunkang-10(Camellia sinensis var.assamica).Ten isolates from Yunkang-lOexhibited antimicrobial activity against at least one human pathogenic microorganism(Staphylococcus epidermidis,Shigella flexneri,and Escherichia coli),but none of the isolates from Zijuan exhibited antimicrobial activities.Fourteen strains were further exammined the genes of polyketide synthetase(PKS)-? and PKS-? and non-ribosomal peptide synthetase(NRPS).Brevibacterium sp.YXT131 from Yunkang-10 showed strong inhibitory activity against S.epidermidis,Sh.flexneri,and E.coli,and PKS-I and PKS-? and NRPS genes were obtained from the strain.Select the best antibacterial activity of the actinobacteria YXT131 and applied to the Shanghai silage in the process of preservation.Total 14 actinobacteria as test object,Resistance of 4 kinds of common pathogens of fruits and vegetables on the antibacterial activity test.A total of 8 strains of actinobacteria showed antibacterial activity of Staphylococcus epidermidis in the 5mm filter,YXT131 had an obvious anti-bacterial.As Sh.Flexneri,YXN112,YXT131?YKFG1121,YKFH1122 inhibitory ring size was obvious;The strains of actinobacteria YXT131 and YKFG1121 had antibacterial activity and showed the antibacterial ring in Escherichia coli.In the Bacillus cereus,none of the anti-bacterial actinobacteria were produced.For the Staphylococcus epidermidis and Sh.Flexneri,Escherichia coli,and the anti-bacterial of YXT131 and YKFG1221 were produced.As the Bacillus cereus,none of them have no Significant effect.Through further test of actinobacteria YXT131,found actinobacteria YXT131 fermentation filtrate for 4 kinds of common pathogen of fruits and vegetables has good antibacterial activity and broad-spectrum antibacterial effect.As the pathogenic microorganisms,actinobacteria YXT131 have obvious antagonistic effect.Determination of Shanghai,the decaying rate of the fermentation filtrate group was 30%lower than the control group,which showed a significant difference(p<0.05).After storage of 10d,the weightloss rate of the fermentation filtrate group was 4.5%,compared with the control group(8.9%),which decreased by 49.44%,which was a significant difference(p<0.05).In the determination of Vc content,the Vc content of the control group and the fermentation filtrate group were significantly different in 10d(p<0.01).In the determination of chlorophyll content,the content of chlorophyll in the control group decreased to 0.107 mg/g at 10d,and 47.80%lower than 0d,and the fermentation filtrate group decreased by 22.93%compared with 0d,while 47.66%in the control group showed significant difference(p<0.05).On titratable acid content determination,in 10d,titratable acid content of the control group to reduce to 0.83nmol/100g and fell by 53.57%,compared with 0d fermentation filtrate group fell by 21.14%,higher than the control group 66.27%year-on-year,show very significant difference(p<0.01).These results confirm that endophytic actinobacteria from tea plants might be an undeveloped bioresource library for active compounds.