Schroeder Bruna Grosch, Logroño Washington, Rocha Ulisses Nunes da, Harms Hauke, Nikolausz Marcell
Department of Environmental Microbiology, Helmholtz Centre for Environmental Research-UFZ, 04318 Leipzig, Germany.
Microorganisms. 2022 Mar 31;10(4):761. doi: 10.3390/microorganisms10040761.
The larva have complex gut microbiota capable of the effective conversion of lignocellulosic biomass. Biotechnological utilization of these microorganisms in an engineered system can be achieved by establishing enrichment cultures using a lignocellulosic substrate. We established enrichment cultures from contents of the midgut and hindgut of the beetle larva using wheat straw in an alkaline medium at mesophilic conditions. Two different inoculation preparations were used: procedure 1 (P1) was performed in a sterile bench under oxic conditions using 0.4% inoculum and small gauge needles. Procedure 2 (P2) was carried out under anoxic conditions using more inoculum (4%) and bigger gauge needles. Higher methane production was achieved with P2, while the highest acetic acid concentrations were observed with P1. In the enrichment cultures, the most abundant bacterial families were Dysgonomonadaceae, Heliobacteriaceae, Ruminococcaceae, and Marinilabiliaceae. Further, the most abundant methanogenic genera were , and . Our observations suggest that in samples processed with P1, the volatile fatty acids were not completely converted to methane. This is supported by the finding that enrichment cultures obtained with P2 included acetoclastic methanogens, which might have prevented the accumulation of acetic acid. We conclude that differences in the inoculum preparation may have a major influence on the outcome of enrichment cultures from the larvae gut.
这种幼虫拥有复杂的肠道微生物群，能够有效转化木质纤维素生物质。通过使用木质纤维素底物建立富集培养物，可以在工程系统中对这些微生物进行生物技术利用。我们在中温条件下，于碱性培养基中使用小麦秸秆，从甲虫幼虫的中肠和后肠内容物中建立了富集培养物。使用了两种不同的接种制备方法：方法1（P1）在有氧条件下的无菌操作台中进行，使用0.4%的接种物和小口径针头。方法2（P2）在无氧条件下进行，使用更多的接种物（4%）和更大口径的针头。P2实现了更高的甲烷产量，而P1观察到了最高的乙酸浓度。在富集培养物中，最丰富的细菌科是脱硫弧菌科、太阳杆菌科、瘤胃球菌科和海栖嗜盐菌科。此外，最丰富的产甲烷菌属是 、 和 。我们的观察表明，在用P1处理的样品中，挥发性脂肪酸没有完全转化为甲烷。这一发现得到了支持，即P2获得的富集培养物中包括乙酸裂解产甲烷菌，这可能阻止了乙酸的积累。我们得出结论，接种制备方法的差异可能对来自幼虫肠道的富集培养结果产生重大影响。
