Influence of xylan and microcrystalline cellulose on the American cockroach gut microbiome

The gut microbiota of the American cockroach, Periplaneta americana, is diverse and normally resistant to diet-related shifts when fed whole foods. However, chemically defined artificial diets may perturb the gut community. This experiment examines a variety of synthetic diets previously produced in the Ottesen lab that feature xylan and microcrystalline cellulose as the primary carbohydrate source. The standard artificial diet contains lab-grade ingredients that make up, as percent of dry mass, 70.5% variable carbohydrate, 17% casein, 8% peptone, 0.5% Vanderzant vitamin mixture, 3% Wesson salt mixture, and 1% cholesterol. Variations of this standard artificial diet are used to understand what conditions are associated with the alterations seen following ingestion of xylan: diets without casein/peptone, diets without vitamins/cholesterol, diets with tuna in lieu of casein/peptone, diets with mixtures of xylan/microcrystalline cellulose in set ratios, and diets with simple sugar forms of the complex carbohydrates (xylose, glucose, and cellobiose).

美洲大蠊（Periplaneta americana）的肠道菌群多样性丰富，在饲喂完整天然食物时，通常可抵御饮食因素引发的群落结构偏移。然而，化学成分明确的人工饲料可能会扰动其肠道菌群群落。本实验针对奥特森（Ottesen）实验室此前制备的多种合成饲料开展研究，此类饲料以木聚糖与微晶纤维素作为主要碳水化合物来源。标准人工饲料采用实验级原料，其干重占比组成为：可变碳水化合物70.5%、酪蛋白17%、蛋白胨8%、Vanderzant维生素混合物（Vanderzant vitamin mixture）0.5%、Wesson盐混合物（Wesson salt mixture）3%以及胆固醇1%。本研究通过该标准人工饲料的多种变体，探究木聚糖摄入后引发菌群改变的相关影响条件：包括不含酪蛋白/蛋白胨的饲料、不含维生素/胆固醇的饲料、以金枪鱼替代酪蛋白/蛋白胨的饲料、按固定比例混合木聚糖与微晶纤维素的饲料，以及使用复合碳水化合物单糖形式（木糖、葡萄糖和纤维二糖）的饲料。