Abstract:
【Objective】 This study aimed to investigate effects of different microbial consortia on the nutritional components， fermentation quality， and microbial diversity of fermented sugarcane bagasse， so as to provide technological support for utilizing sugarcane bagasse as feed resources. 【Method】 Using sugarcane bagasse as the raw material （RM）， six treatment groups were established： CK （no microbial agent added）， T1 （commercial mixed microbial agents， 0.2 g/kg）， T2 （
Meyerozyma guilliermondii∶
Bacillus altitudinis=1∶1，100 mL/kg）， T3（
Meyerozyma guilliermondii∶
Bacillus paralicheniformis=1∶1，100 mL/kg）， T4 （
Bacillus paralicheniformis：
Bacillus altitudinis=1∶1，100 mL/kg）， T5 （
Meyerozyma guilliermondii∶
Bacillus altitudinis∶
Bacillus paralicheniformis=1∶1∶1，100 mL/kg）. The microbial agents that thoroughly mixed with the sugarcane bagasse were packed and sealed for light-protected fermentation at room temperature for 45 d. The nutritional components， fermentation quality， and microbial community structural composition were determined. 【Result】 The supplementation with
Bacillus paralicheniformis，
Meyerozyma guilliermondii， and
Bacillus altitudinis significantly reduced the contents of crude fiber （CF）， acid detergent fiber （ADF）， and neutral detergent fiber （NDF） in fermented sugarcane bagasse， while increased the contents of crude protein （CP） and water-soluble carbohydrate （WSC）. The dry matter （DM） content in the T2 and T3 treatment groups increased by 0.37% and 0.46% （absolute values） compared to the RM， respectively， with their CF and ADF contents significantly lower than those of other groups （
P<0.05， the same below）. The addition of
Bacillus paralicheniformis，
Meyerozyma guilliermondii， and
Bacillus altitudinis also enhanced the contents of lactic acid （LA） and acetic acid （AA） in the fermented sugarcane bagasse， while inhibited butyric acid （BA） production and protein degradation in the fermented feed by undesirable microorganisms. Regarding microbial community structural composition， the relative abundances of the phylum Firmicutes and the genus
Leuconostoc were markedly higher in the T2， T3， T4， and T5 groups than in the raw material and the CK. T2 and T3 showed higher relative abundances of
Leuconostoc compared to T4 and T5. The relative abundances of
Clostridium_sensu_stricto_12 and
Clostridium_sensu_stricto_11 in T2， T3， T4， and T5 remained below 0.02%.
Leuconostoc and
Bacillus showed significant or extremely significant positive correlations （
P<0.01， the same below） with CP and WSC， and negative correlations with CF， ADF， and NDF. In contrast，
Clostridium_sensu_stricto_12 showed a significant positive correlation with propionic acid （PA）， and extremely significant positive correlations with butyric acid （BA） and ammonia-nitrogen/total nitrogen ratio （NH
4/TN）. 【Conclusion】 Supplementing a mixed microbial agent of
Meyerozyma guilliermondii to
Bacillus strains at a ratio of 1∶1 in sugarcane bagasse for fermentation could effectively increase the relative abundance of
Leuconostoc， suppress the proliferation of
Clostridium， and significantly decrease the contents of CF， ADF， and NDF， demonstrating that this microbial consortium could effectively preserve nutrients， degrade fibers， enrich lactic acid bacteria， and inhibit the growth of undesirable microorganisms.
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