Analysis of high-throughput sequencing for cecal microbiota diversity and function in hens under different rearing systems.

Rearing systems play an important role in animal welfare, health and the composition of the gut microbiome. Therefore, the purpose of this study was to investigate the effects of different rearing systems on the composition and function of cecal microbiota in chickens. The 120-day-old Lohmann hens of cage rearing systems (CRS) and free-range systems (FRS) were studied. The cecal bacterial populations of hens were surveyed by high-throughput sequencing (HTS) of the bacterial 16S rRNA hypervariable region V3-V4 combined with metagenomic sequencing analysis. The 16S rRNA sequencing analysis showed that the cecal microbiota differed between the FRS and CRS. The three most abundant bacteria phyla in the two systems were the Bacteroidetes (> 48%), Firmicutes (> 37%), and Proteobacteria (> 6%), the Deferribacteres (> 2.4%) were found in FRS and almost absent in CRS (< 0.01%). The three most abundant genera were the Bacteroides, Rikenellaceae_RC9, and Faecalibacterium, and we found relative abundance of the Parabacteroides (P < 0.05), Prevotellaceae_Ga6A1 (P < 0.01), unclassified Proteobacteria (P < 0.05), and unclassified Spirochaetaceae (P < 0.01) was greater in FRS, whereas abundance of Faecalibacterium, Ruminococcaceae, and Helicobacter was greater in CRS (P < 0.05). Functional gene classification of metagenomic sequencing suggested that energy production and conversion, carbohydrate transport and metabolism, as well as amino acid transport and metabolism were significantly more abundant in FRS, and we identified a range of antibiotic resistance categories in gut microbes of hens reared under both systems. We confirmed differences in microbe gut composition and function in hens reared using two contrasting systems, and ARGs were also identified in the microbiota of these hens. This work has produced new data for laying hens in different production systems and increased the understanding of intestinal microorganisms in laying hens.

A Transcriptomic Analysis of Saccharomyces cerevisiae Under the Stress of 2-Phenylethanol.

2-Phenylethanol (2-PE) is a kind of advanced aromatic alcohol with rose fragrance, which is wildly used for the deployment of flavors and fragrances. Microbial transformation is the most feasible method for the production of natural 2-PE. But a bottleneck problem is the toxicity of 2-PE on the cells. The molecular mechanisms of the toxic effect of 2-PE to Saccharomyces cerevisiae are not well studied. In this study, we analyzed the transcriptomes of S. cerevisiae in the media with and without 2-PE, respectively, using Illumina RNA-Seq technology. We identified 580 differentially expressed genes between S. cerevisiae in two different treatments. GO and KEGG enrichment analyses of these genes suggested that most genes encoding mitochondrial proteins, cytoplasmic, and plasma membrane proteins were significantly up-regulated, whereas the enzymes related to amino acid metabolism were down-regulated. These results indicated that 2-PE suppressed the synthesis of plasma membrane proteins, which suppressed the transport of nutrients required for growth. The findings in this study will provide insight into the inhibitory mechanism of 2-PE to yeast and other microbes.

High expression of a neutral endo-ß-glucanase gene from Humicola insolens in Trichoderma reesei.

The neutral endo-ß-glucanase gene cel5A from Humicola insolens was cloned and connected with the cellobiohydrolase 1 promoter from Trichoderma reesei to construct a recombinant plasmid pCB-hEG with the hygromycin B resistance marker. The plasmid was introduced into conidia of T. reesei using the Agrobacterium tumefaciens mediated transformation method. Eight transformants were obtained on screening plates with sodium carboxymethyl cellulose as the sole carbon source. Stable integration of the cel5A gene into the chromosomal DNA of T. reesei was confirmed by PCR. An obvious protein band (approximately 52 kDa) was detected by SDS-PAGE from fermentation broth, which showed that the cel5A gene in recombinant T. reesei successfully fulfilled efficient expression and extracellular secretion. After 96 h shaking-flask fermentation, the endo-ß-glucanase activity at pH 6.5 from recombinant T. reesei reached 3,068 U/ml, which was 11 times higher than that of the host strain. In a 2 m³ fermenter, the endo-ß-glucanase activity could be further increased to 8,012 U/ml after 96 h fermentation. The results showed a good prospect for application of neutral endo-ß-glucanase in the textile industry.