Congcong Tian

In this study, Candida utilis, Lactobacillus plantarum, and non-starch polysaccharide enzymes (cellulase, laccase, β-glucanase, xylanase, and mannanase) were employed to examine the effects of various microorganism–enzyme combinations on the nutritional composition, fiber structure, and fermentation quality of corn stover and wheat straw. Furthermore, the synergistic effects of these treatments were assessed through the use of in vitro rumen fermentation. The results showed that the microorganism–enzyme combinations significantly increased the crude protein content (p < 0.05), while reducing the acid detergent fiber and neutral detergent fiber levels (p < 0.05) in both substrates. The fermentation broth pH decreased (p = 0.06 for corn stover; p < 0.05 for wheat straw) as a result of the treatments, with a significant increase in the lactate concentration (p < 0.05). The reducing sugar levels varied across the treatments (p < 0.05). Mycotoxin analysis revealed trace amounts of zearalenone, well below the Chinese feed hygiene standard. Scanning electron microscopy showed structural modifications, including fiber breakage and surface wrinkling, in the treated substrates. In vitro rumen fermentation demonstrated significant changes in the NH₃-N production and volatile fatty acid profiles (p < 0.05). In conclusion, the addition of different microorganism–enzyme combinations can effectively improve the nutritional composition, fiber structure, and fermentation quality of corn stover and wheat straw. Among the treatments, the T3 group (25% each of C. utilis, L. plantarum, cellulase, and laccase, with a total addition ratio of 0.3% w/w) exhibited the most pronounced improvement in nutritional value for both corn stover and wheat straw. These findings suggest that microorganism–enzyme combinations effectively enhance the nutritional and fermentative quality of agricultural residues.

The development of probiotics capable of quickly colonizing the intestines of animals is important in promoting the healthy growth of livestock. The aim of this study was to screen lactic acid bacteria (LAB) from the intestinal microbiota of chickens with potential applications, and to evaluate their probiotic properties and antagonistic abilities against Salmonella pullorum, Staphylococcus aureus, and Escherichia coli. The results showed that a total of 79 strains with the characteristics of LAB were isolated from the chicken cecum microbiota, of which 7 strains exhibited strong inhibitory activity against S. pullorum, S. aureus, and E. coli. Performing 16s rDNA sequencing revealed that these seven strains were Lactiplantibacillus pentosus (n = 1), Lactiplantibacillus plantarum (n = 3), Lactiplantibacillus paraplantarum (n = 1), Lactiplantibacillus argentoratensis (n = 1), and Lactiplantibacillus fabifermentans (n = 1). Among them, L. pentosus R26 and L. plantarum R32 exhibited superior antibacterial activity. These two strains demonstrated high lactic acid production ability, with survival rates of 86.29% and 87.99% after 3 h of treatment at pH 1.5, 86.66% and 85.52% after 3 h of treatment with 0.5% bile salts, 90.03% and 88.16% after 2 h of treatment with simulated gastric fluid, and 98.92% and 98.22% after 2 h of treatment with simulated intestinal fluid, respectively. Co-cultivation with L. pentosus R26 for 24 h resulted in 50% of the pathogens being antagonized, while almost complete inhibition was observed following 72 h of co-cultivation. In conclusion, L. pentosus R26 and L. plantarum R32 exhibited high antibacterial activity and acid production capability, while also demonstrating satisfactory tolerance to low pH values and high concentrations of bile salts and digestive fluid. The probiotic characteristics and stress resistance of L. pentosus R26 were slightly superior to those of L. plantarum R32, indicating its potential for development as a probiotic.