The Dynamic Microbiota Profile During Pepper (Piper nigrum L.) Peeling by Solid-State Fermentation.

White pepper (Piper nigrum L.), a well-known spice, is the main pepper processing product in Hainan province, China. The solid-state method of fermentation can peel pepper in a highly efficient manner and yield high-quality white pepper. In the present study, we used next-generation sequencing to reveal the dynamic changes in the microbiota during pepper peeling by solid-state fermentation. The results suggested that the inoculated Aspergillus niger was dominant throughout the fermentation stage, with its strains constituting more than 95% of the fungi present; thus, the fungal community structure was relatively stable. The bacterial community structure fluctuated across different fermentation periods; among the bacteria present, Pseudomonas, Tatumella, Pantoea, Acinetobacter, Lactococcus, and Enterobacter accounted for more than 95% of all bacteria. Based on the correlations among the microbial community, we found that Pseudomonas and Acinetobacter were significantly positively related with A. niger, which showed strong synergy with them. In view of the microbial functional gene analysis, we found that these three bacteria and fungi were closely related to the production of pectin esterase (COG4677) and acetyl xylan esterase (COG3458), the key enzymes for pepper peeling. The present research clarifies the solid-state fermentation method of pepper peeling and lays a theoretical foundation to promote the development of the pepper peeling process and the production of high-quality white pepper.

Comparative study of the gut microbiome potentially related to milk protein in Murrah buffaloes (Bubalus bubalis) and Chinese Holstein cattle.

Previous studies suggested a close relationship between ruminant gut microbes and the mammary gland. In this study, shotgun metagenomic sequencing was used to reveal the differences in the intestinal microbiome potentially related to milk components in Murrah buffaloes and Chinese Holstein cattle. A PCoA based on the weighted Unifrac distances showed an apparent clustering pattern in the structure of intestinal microbiota between buffalo and cattle. We could attribute the structural difference to the genera of Sutterella, Coprococcus and Dorea. A further analysis of microbial functional features revealed that the biosynthesis of amino acids (including lysine, valine, leucine and isoleucine), lipopolysaccharide biosynthesis and cofactor/vitamin biosynthesis were enriched in the buffalo. In contrast, dairy cattle had higher levels of pyruvate metabolism and carbon fixation in photosynthetic organisms. A further correlation analysis based on different milk components and the typical microbiome uncovered a significant positive correlation between milk protein and the microbial biosynthesis of amino acids, which was also positively correlated in the genera of Parabacteroides, Dorea and Sutterella. This study will expand our understanding of the intestinal microbiome of buffalo and cattle as representative ruminants, as well as provide new views about how to improve the production and nutritional qualities of animal milk.

Key Microbiota Identification Using Functional Gene Analysis during Pepper (Piper nigrum L.) Peeling.

Pepper pericarp microbiota plays an important role in the pepper peeling process for the production of white pepper. We collected pepper samples at different peeling time points from Hainan Province, China, and used a metagenomic approach to identify changes in the pericarp microbiota based on functional gene analysis. UniFrac distance-based principal coordinates analysis revealed significant changes in the pericarp microbiota structure during peeling, which were attributed to increases in bacteria from the genera Selenomonas and Prevotella. We identified 28 core operational taxonomic units at each time point, mainly belonging to Selenomonas, Prevotella, Megasphaera, Anaerovibrio, and Clostridium genera. The results were confirmed by quantitative polymerase chain reaction. At the functional level, we observed significant increases in microbial features related to acetyl xylan esterase and pectinesterase for pericarp degradation during peeling. These findings offer a new insight into biodegradation for pepper peeling and will promote the development of the white pepper industry.

Metagenomic approach reveals microbial diversity and predictive microbial metabolic pathways in Yucha, a traditional Li fermented food.

Yucha is a typical traditional fermented food of the Li population in the Hainan province of China, and it is made up of cooked rice and fresh fish. In the present study, metagenomic approach and culture-dependent technology were applied to describe the diversity of microbiota and identify beneficial microbes in the Yucha. At the genus level, Lactobacillus was the most abundant genus (43.82% of the total reads), followed by Lactococcus, Enterococcus, Vibrio, Weissella, Pediococcus, Enterobacter, Salinivibrio, Acinetobacter, Macrococcus, Kluyvera and Clostridium; this result was confirmed by q-PCR. PCoA based on Weighted UniFrac distances showed an apparent clustering pattern for Yucha samples from different locations, and Lactobacillus sakei, Lactobacillus saniviri and Staphylococcus sciuri represented OTUs according to the major identified markers. At the microbial functional level, it was observed that there was an enrichment of metabolic functional features, including amino acid and carbohydrate metabolism, which implied that the microbial metabolism in the Yucha samples tended to be vigorous. Accordingly, we further investigated the correlation between the predominant microbes and metabolic functional features. Thirteen species of Lactobacillus (147 strains) were isolated, and Lactobacillus plantarum (60 isolates) and Lactobacillus pentosus (34 isolates) were isolated from every sample.