一株荔枝生物保鲜乳酸菌的筛选及鉴定

Screening and Identification of a Lactic acid bacteria Strain With Lychee Fresh-keeping Function

本文旨在从荔枝果实发酵液中筛选具抑菌活性的拮抗菌,并研究其对荔枝霜疫霉菌、炭疽菌、多酚氧化酶和过氧化物酶的抑制作用。采用平板培养法筛选出拮抗菌后,采用改良的琼脂扩散法和平板对峙法研究其对炭疽菌和荔枝霜疫霉菌的影响;分别以邻苯二酚、愈创木酚为底物测定其对多酚氧化酶、过氧化物酶的抑制作用。结果显示,带菌体发酵液对荔枝霜疫病菌抑菌半径可达1.5cm,对荔枝炭疽病菌抑菌半径约为0.75 cm;代谢产物粗品对荔枝果皮多酚氧化酶的抑制率接近60%,破碎菌体、代谢产物粗品对过氧化物酶的抑制率为分别为58.8%和51.4%。根据菌株的形态特征、培养特征、生理生化特征结合16S rDNA基因序列分析、系统发育树构建来鉴定菌株,最终确定从荔枝果实发酵液中筛选到的乳酸菌是植物乳杆菌,其在荔枝生物保鲜上具有良好的应用前景。

An antagonistic bacteria from litchi fermentation medium,and the inhibitory effects of antagonism on Peronophythora litchii,Colletotrichum gloeosporioides,polyphenol oxidase（PPO） and peroxidase（POD） were studied.A strain was isolated by plating method,and the improved agar diffusion method and plate confrontation method were used to detect the effect of this strain on Colletotrichum gloeosporioidesand Peronophythora litchi,respectively.The activity of PPO and POD were determined by oxophenic acid and guaiacol as substrate.Results showed that the inhibition zone radius of fermentation broth antagonize Penorophythora litchi was 1.5 cm and Colletotrichum gloeosporioides was 0.75 cm,and the inhibition rate of crude metabolites on litchi peel PPO was close to 60%.Crude metabolites and cell homogenates on POD was 58.8% and 51.4%,respectively.This isolation was identified as a strain of lactobacillus plantarum according to the results of morphological characteristics,physiological and biochemical characteristic,the 16s rDNA analysis and phylogenetic tree construction,which had a good application prospect in litchi bio preservation.