发酵时间对罗汉果渣发酵品质及微生物多样性的影响

Effects of Fermentation Time on Quality and Microbial Diversity on Fermented Monk Fruit Pomace

试验旨在探究发酵时间对罗汉果渣发酵品质和微生物多样性的影响。以罗汉果渣为原料自然发酵,在发酵的0(D0)、5(D5)、15(D15)、35(D35)、60(D60)、90 d(D90)开包取样,分析常规营养成分、发酵参数及微生物多样性。结果表明:罗汉果渣发酵过程中干物质(DM)含量随发酵时间延长逐渐降低,粗蛋白(CP)水平随发酵时间延长呈先降低后升高再降低趋势,D35粗蛋白水平高于D60、D90。D35的罗汉果渣发酵饲料pH低、乳酸(LA)含量高,D35的乳酸(LA)水平显著高于其他发酵时间(P<0.05)。厚壁菌门(Firmicutes)、变形菌门(Proteobacteria)为罗汉果渣发酵原料的优势菌门,乳杆菌属(Lactobacillus)为其优势菌属。发酵5 d的罗汉果渣中厚壁菌门(Firmicutes,93.32%)的乳杆菌属(Lactobacillus,78.58%)占据绝对优势。D60的罗汉果渣发酵饲料中拟杆菌门(Bacteroidetes,58.08%)的普雷沃氏菌属(Prevotella,57.92%)取代乳杆菌属(Lactobacillus)占据优势。相关性分析显示,双歧杆菌属(Bifidobacterium)、梭状芽孢杆菌属-12(Clostridium_sensu_stricto_12)、小杆菌属(Dialister)丰度与乙酸(AA)、丁酸(BA)、丙酸(PA)含量及氨态氮/总氮(NH_(3)-N/TN)呈正相关。说明罗汉果渣适宜用于制备发酵饲料,自然发酵时间以35 d为宜。

This experiment was conducted to ex⁃plore the effects of fermentation time on quality and microbial diversity of fermented monk fruit pomace.The test took the fresh monk fruit pom⁃ace as material,weighed into breathing bag and stored at ambient temperature.Fermented monk fruit pomace were taken at days 0(D0),5(D5),15(D15),35(D35),60(D60)and 90(D90)of fermenta⁃tion.Nutrient contents,fermentation indexes and microbial diversity were analyzed.The results showed as follows:the dry matter(DM)content decreased with the extension of the fermentation time,the crude protein(CP)level decreased first and then increased with the fermentation time,and the crude protein level of D35 was higher than that of D60 and D90.The fermented monk fruit pomace showed low pH and high lactic acid content at 35 days of fermentation.However,the acetic acid content of D60 and D90 were significantly increased compared with the other days.Firmicutes(65.37%)and Pro⁃teobacteria(33.37%)were the dominant bacteria at the phylum level of the fresh monk fruit pomace,and Lactobacillus(32.83%)was the dominant bacteria at the genus level.Lactobacillus(93.32%)was the dominant bacteria at the genus level of D5,and Prevotella(58.08%)of D60 was the dominant bacte⁃ria at the genus level.Correlation showed that Bifidobacterium,Clostridium_sensu_stricto_12,Dialister abundance were positively correlated with acetic acid,butyric acid,NH_(3)-N/TN,propionic acid levels.It is concluded that monk fruit pomace is suitable for the preparation of fermented feed,and the fermenta⁃tion time is 35 days.