饵料蛋白水平对德国小蠊肠道细菌群落的影响

昆虫肠道微生物在宿主营养代谢、生长发育、免疫以及抵御病原菌等方面具有重要作用。研究不同蛋白水平饵料饲养对德国小蠊（Blattella germanica）雄成虫肠道细菌群落组成及其功能的作用,探究德国小蠊肠道细菌对宿主营养和健康的影响,以期为发展生物防治的诱食性饵料提供理论支持。分别取连续饲喂低蛋白（LP2组：5%）、高蛋白（HP3组：65%）以及正常蛋白水平饵料（CD1组：25%）21 d的德国小蠊雄成虫,饥饿24 h后无菌条件下分离并提取肠道总基因组DNA,采用特异引物扩增细菌16S rDNA的V4可变区并进行高通量测序,分析德国小蠊肠道细菌群落组成及其功能特征。结果表明德国小蠊肠道细菌主要由拟杆菌门（Bacteroidetes）、变形菌门（Proteobacteria）、梭杆菌门（Fusobacteria）和厚壁菌门（Firmicutes）等细菌群落组成。饲喂低蛋白饵料LP2组的德国小蠊肠道细菌中拟杆菌属（Bacteroides）细菌丰度（47.44%）显著高于HP3组（23.97%）和对照CD1（7.04%）。饲喂高蛋白饵料的HP3组梭杆菌门丰度显著高于其他两组。LEfSe物种差异分析也表明HP3组德国小蠊肠道细菌中梭杆菌属（Fusobacterium）细菌与低蛋白饵料LP2组和对照CD1组有显著差异。基于Tax4Fun功能预测显示,HP3高蛋白饵料组的德国小蠊肠道细菌中与能量代谢功能相关基因的相对丰度极显著高于对照组CD1组,外源性物质代谢与降解和其他氨基酸代谢功能基因的相对丰度显著高于低蛋白LP2组。本研究结果表明饵料中蛋白质水平的差异能够显著改变德国小蠊肠道中细菌群落结构组成,并影响其代谢功能。

Effects of dietary protein levels on intestinal bacterial communities of Blattella germanica

Gut bacteria of insect play important roles in host food digestion, growth and development, immunity and resistance to pathogens. This study aims to reveal the effects of protein levels of dietary on bacterial communities and functional characteristics of intestinal microbiota in male adult Blattella Germanica. It will provide a basis for evaluating the role of the intestinal bacteria in the host nutritional metabolism and health, and developing the attractive biocontrol dietary for cockroach pests. The male B. germanica adults were separately fed with low protein (LP2 group:5%), high protein (HP3 group:65%) diets, or the normal protein level rat food (CD1 group:25%) for 21 days. Then the intestine of B. germanica was seperated under sterile condition and the total intestinal genomic DNA was extracted. The V4 variable region of bacterial 16S rDNA was amplified by high-through sequencing. The intestinal microbiota of B. germanica was mainly composed of Bacteroidetes, Proteobacteria, Fusobacteria, and Firmicutes. The abundance of Bacteroidetes in LP2 group with low protein bait was significantly higher than those in the control CD1 group and HP3 groups with 65% protein bait. LEfSe analysis demonstrated that the abundance of Fusobacterium in the intestinal microbiota of B. germanica (HP3 group) fed with high protein bait was significantly different with those in LP2 and CD1 groups. The function prediction results from Tax4Fun demonstrated that the relative abundance of genes related to energy metabolism in intestinal microbiome of male adults fed with 65% protein bait (HP3) was significantly higher than that in B. germanica fed with 25% protein bait (CD1). And the relative abundance of the gene associated with xenobiotics biodegradation and metabolism, and metabolism of other amino acid functions were also significantly higher than those of B. germanica fed with 5% protein bait (LP2). The results showed that protein levels of the feeding dietary could significantly change bacterial community composition and metabolism of intestinal microbiome in B. germanica.