DU Xue'er, Zhou Linlin, Zhang Fan, Li Yong, Zhao Congcong, Wang Lamei, Yao Junhu, Cao Yangchun
College of Animal Science and Technology, Northwest A&F University, Yangling 712100, Shaanxi, China.
Sheng Wu Gong Cheng Xue Bao. 2023 Dec 25;39(12):4927-4938. doi: 10.13345/j.cjb.230167.
In order to investigate the enzyme production mechanism of yak rumen-derived anaerobic fungus sp. YF3 under the induction of different carbon sources, anaerobic culture tubes were used for fermentation. 8 g/L of glucose (Glu), filter paper (Flp) and avicel (Avi) were respectively added to 10 mL of basic culture medium as the sole carbon source. The activity of fiber-degrading enzyme and the concentration of volatile fatty acid in the fermentation liquid were detected, and the enzyme producing mechanism of sp. YF3 was explored by transcriptomics. It was found that, in glucose-induced fermentation solution, the activities of carboxymethyl cellulase, microcrystalline cellulase, filter paper enzyme, xylanase and the proportion of acetate were significantly increased ( < 0.05), the proportion of propionate, butyrate, isobutyrate were significantly decreased ( < 0.05). The results of transcriptome analysis showed that there were 5 949 differentially expressed genes (DEGs) between the Glu group and the Flp group, 10 970 DEGs between the Glu group and the Avi group, and 6 057 DEGs between the Flp group and the Avi group. It was found that the DEGs associated with fiber degrading enzymes were significantly up-regulated in the Glu group. Gene ontology (GO) function enrichment analysis identified that DEGs were mainly associated with the xylan catabolic process, hemicellulose metabolic process, β-glucan metabolic process, cellulase activity, endo-1,4-β-xylanase activity, cell wall polysaccharide metabolic process, carbohydrate catabolic process, glucan catabolic process and carbohydrate metabolic process. Moreover, the differentially expressed pathways associated with fiber degrading enzymes enriched by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were mainly starch and sucrose metabolic pathways and other glycan degradation pathways. In conclusion, sp. YF3 with glucose as carbon source substrate significantly increased the activity of cellulose degrading enzyme and the proportion of acetate, decreased the proportion of propionate, butyrate and isobutyrate. Furthermore, the degradation ability and energy utilization efficiency of fungus in the presence of glucose were improved by means of regulating the expression of cellulose degrading enzyme gene and participating in starch and sucrose metabolism pathway, and other glycan degradation pathways, which provides a theoretical basis for the application of sp. YF3 in practical production and facilitates the application of sp. YF3 in the future.
为研究牦牛瘤胃源厌氧真菌YF3在不同碳源诱导下的产酶机制，采用厌氧培养管进行发酵。分别向10 mL基础培养基中添加8 g/L葡萄糖（Glu）、滤纸（Flp）和微晶纤维素（Avi）作为唯一碳源。检测发酵液中纤维降解酶活性和挥发性脂肪酸浓度，并通过转录组学探究YF3的产酶机制。结果发现，在葡萄糖诱导的发酵液中，羧甲基纤维素酶、微晶纤维素酶、滤纸酶、木聚糖酶的活性及乙酸比例显著升高（P<0.05），丙酸、丁酸、异丁酸比例显著降低（P<0.05）。转录组分析结果显示，Glu组与Flp组之间有5949个差异表达基因（DEGs），Glu组与Avi组之间有10970个DEGs，Flp组与Avi组之间有6057个DEGs。发现与纤维降解酶相关的DEGs在Glu组中显著上调。基因本体（GO）功能富集分析表明，DEGs主要与木聚糖分解代谢过程、半纤维素代谢过程、β-葡聚糖代谢过程、纤维素酶活性、内切-1,4-β-木聚糖酶活性、细胞壁多糖代谢过程、碳水化合物分解代谢过程、葡聚糖分解代谢过程和碳水化合物代谢过程相关。此外，京都基因与基因组百科全书（KEGG）通路分析富集的与纤维降解酶相关的差异表达通路主要是淀粉和蔗糖代谢通路以及其他聚糖降解通路。综上所述，以葡萄糖为碳源底物时，YF3显著提高了纤维素降解酶活性和乙酸比例，降低了丙酸、丁酸和异丁酸比例。此外，真菌在葡萄糖存在下通过调节纤维素降解酶基因表达并参与淀粉和蔗糖代谢通路以及其他聚糖降解通路，提高了降解能力和能量利用效率，为YF3在实际生产中的应用提供了理论依据，有助于YF3在未来的应用。
