枯草芽孢杆菌
纤维素酶
杆菌
食品科学
干物质
生物
饲料
瘤胃
青贮饲料
发酵
奶牛
反刍动物
酶
生物技术
微生物学
动物科学
农学
细菌
生物化学
牧场
遗传学
作者
Valeria Bontà,Marco Battelli,Erlinda Rama,Michela Casanova,Lorenzo Pasotti,G. Galassi,S. Colombini,Cinzia Calvio
标识
DOI:10.3390/microorganisms12020300
摘要
The administration of Bacilli to dairy cows exerts beneficial effects on dry matter intake, lactation performance, and milk composition, but the rationale behind their efficacy is still poorly understood. In this work, we sought to establish whether cellulases and xylanases, among the enzymes secreted by B. subtilis, are involved in the positive effect exerted by Bacilli on ruminal performance. We took advantage of two isogenic B. subtilis strains, only differing in the secretion levels of those two enzymes. A multi-factorial study was conducted in which eight feed ingredients were treated in vitro, using ruminal fluid from cannulated cows, with cultures of the two strains conveniently grown in a growth medium based on inexpensive waste. Feed degradability and gas production were assessed. Fiber degradability was 10% higher (p < 0.001) in feeds treated with the enzyme-overexpressing strain than in the untreated control, while the non-overexpressing strain provided a 5% increase. The benefit of the fibrolytic enzymes was maximal for maize silage, the most recalcitrant feed. Gas production also correlated with the amount of enzymes applied (p < 0.05). Our results revealed that B. subtilis cellulases and xylanases effectively contribute to improving forage quality, justifying the use of Bacilli as direct-fed microbials to increase animal productivity.
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