肠道微生物对黑水虻体内中长链脂肪酸的调节作用及其机制探究

作为一种食腐昆虫，黑水虻能将有机废物转化为饲料工业需求的优质中长链脂肪酸资源。近年来营养和环境因素对黑水虻脂类代谢和脂肪酸贮量的调节作用被不断证实，然而随食物进入肠道的大量微生物能否对黑水虻体内的脂肪酸产生影响仍未可知。我们对黑水虻脂肪酸合成酶系中HiMAT和HiACP基因的调查表明，肠道是它们的主要表达场所，因此肠道中的活跃微生物可能与黑水虻互作，从而对其脂肪酸代谢产生影响。在此基础上，本项目拟利用鸟枪法宏基因组测序技术评价黑水虻肠道微生物的定植情况和脂类代谢能力；利用荧光定量PCR、荧光原位杂交技术对肠道微生物的数量和分布进行统计；通过气相色谱法判断肠道细菌对黑水虻体内中长链脂肪酸贮量的调节能力；结合体外和体内实验，分别验证细菌在饲料中的脂肪酸代谢情况，以及对黑水虻脂肪酸合成酶相关基因的表达调控，为进一步了解黑水虻脂肪酸代谢的调节机制和高效、稳定获得优质昆虫中长链脂肪酸资源提实验基础。

Black soldier fly (BSF; Hermetia illucens) is a saprophagous insect that convert organic wastes into high-quality medium- and long-chain fatty acid resources for the animal-feed industry. Recently, evidences showed that numbers of factors such as the diet quality and environmental influences play critical roles in the manipulation of BSF fatty acid metabolism. However, less is known about the impact of gut microbiota on BSF fatty acid accumulation and composition. Our investigation on a cofactor protein and a catalytic domain of fatty acid synthetase (FAS), the Malonyl/acetyl transferase (HiMAT) and the acyl carrier protein (HiACP), revealed that gut is an important tissue for the expression of these two proteins. Thus, metabolically active microbes within the gut might interact with the BSF and participate in the regulation of their fatty acid metabolism. Considering this background, we plan to investigate the colonization ability and lipid metabolism of BSF gut microbiota by shotgun metagenomic sequencing; assess the dynamic changing of gut bacteria loading and their position along the alimentary tract by real-time PCR and fluorescence in situ hybridization (FISH) method respectively; Using axenic insect and gas chromatography technology to explore bacteria that have impacts on host fatty acid metabolism; and determine the utilization of gut bacteria in vitro, as well as the expression level of BSF fatty acids synthesis genes in vivo. These analyses could provide further knowledge about the mechanism of microbially-involved host fatty acids manipulation and experimental evidences for the production of high-quality insect medium- and long-chain fatty acids..