Postbiotic studies of mixed cultures of Schleiferilactobacillus harbinensis LH991 and Pichia kudriavzevii B-5P produced by in vitro rumen producing short-chain fatty acid.

Background and aim: Postbiotics are functional bioactive compounds or bioactive molecules with beneficial effects on health and functional activities in humans or livestock, produced by probiotic bacteria or yeast. Several postbiotics, including enzymes, short-chain fatty acids, amino acids, extracellular polysaccharides, microbial cell fragments, and teichoic acids, are currently being widely studied. This study aimed to explore the potential of secondary metabolites of Schleiferilactobacillus harbinensis LH 991 and Pichia kudriavzevii B-5P as lactic acid bacteria (LAB) and yeast isolated from Budu (fermented fish) which can act as postbiotics through in vitro rumen fermentation.

Materials and methods: The method used a completely randomized design 5 × 4, with five treatments and four replications. The substrate diet consisted of 60% forage and 40% concentrate. The culture mixture was 1.3 × 10¹¹ CFU/mL with a 50%:50% ratio of S. harbinensis LH 991 and P. kudriavzevii B-5P. The inoculum concentrations used in this study were 0% (control), 1%, 2%, 3%, and 4%. Treatments are arranged based on differences in inoculum concentration as follows: T0: control (0%); T1: 1%; T2: 2%; T3: 3%; and T4: 4%.

Results: The T4 group showed a significant increase (p < 0.01) in short-chain fatty acids (SCFA), including acetate, propionate, butyrate, valerate, isobutyrate, and isovalerate acids, compared with the other treatments. Meanwhile, T4 shows that there is no significant (p > 0.01) effect on in vitro digestibility (in vitro dry matter digestibility, in vitro organic matter digestibility, and in vitro crude fiber digestibility). However, a highly significant (p < 0.01) effect was on volatile fatty acid total, NH₃, and microbial crude protein synthesis.

Conclusion: It is concluded that the treatment with a 4% inoculum concentration (T4) containing a mixture of S. harbinensis LH 991 and P. kudriavzevii B-5P as LAB and yeast isolated from Budu (fermented fish) in 50%:50% ratio increased SCFA and rumen fermentation significantly, whereas it did not affect in vitro digestibility.