Lactic acid bacteria, corn straw and extruded corn straw enhanced nutritional quality: reshaping the microbiome to improve the silage fermentation of paper mulberry

Abstract

Background

Producing high-quality silage from fresh paper mulberry is challenging due to its elevated moisture levels, reduced amounts of water-soluble carbohydrates, and a scarce population of epiphytic lactic acid bacteria (LAB). This work evaluated the influence of corn straw (CS), extruded corn straw (ECS), and Lactiplantibacillus plantarum (L) on nutrition preservation, fermentation performance, and bacterial communities structure in paper mulberry silage.

Results

The impacts of corn straw and extruded corn straw, supplied alone or in combination with Lactiplantibacillus plantarum (CSL or ECSL), on fermentation efficiency and microbial ecology of paper mulberry silage were examined. After fermentation, all treated silages exhibited superior dry matter (DM) levels than the control (P < 0.05). In particular, the 40%CSL and 40%ECSL treatments enhanced fermentation quality by lowering pH and ammonia-N concentrations while stimulating the accumulation of lactic and acetic acids (P < 0.05). Comparative community analyses revealed pronounced shifts in bacterial composition following additive application, with treated silages exhibiting microbial communities clearly differentiated from the control. At genus level, Companilactobacillus, Levilactobacillus, and Paenibacillus became the most dominant genera in 20%ECS, 40%ECS, and 40%ECSL, whereas Companilactobacillus and Clostridium predominated in the control. At species level, Clostridium luticellarii became the most dominant bacterium in the control. In contrast, Companilactobacillus pabuli and Levilactobacillus namurensis became the dominant bacteria in 40%CS, 20%CSL, 40%CSL, 20%ECS, and 20%ECSL while Lactobacillus sp. PFC-70 was dominant in 40%ECS and 40%ECSL. Correlation analysis showed that Lactobacillus sp. PFC-70 was positively associated with fermentation acid accumulation, whereas Companilactobacillus pabuli was liked to lower ammonium-N concentration. Collectively, these findings indicated that paper mulberry silage with addition of CS, ECS, or their combinations with Lactiplantibacillus plantarum effectively promote desirable fermentation outcomes through reshaping bacterial ecological succession.

Conclusion

The incorporation of CS, ECS, and Lactiplantibacillus plantarum effectively promoted a more favorable fermentation pattern in paper mulberry, characterized by suppressed ammonia formation and enhanced lactic acid accumulation. These treatments inhibited undesirable bacteria and promoted beneficial fermentation. Overall, this combined strategy represents a practical and efficient approach to enhancing silage quality and utilization of agricultural by-products.

Graphical Abstract