Hagen Live Heldal, Vivekanand Vivekanand, Pope Phillip B, Eijsink Vincent G H, Horn Svein J
Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P. O. Box 5003, 1432, Ås, Norway.
Appl Microbiol Biotechnol. 2015 Jul;99(13):5749-61. doi: 10.1007/s00253-015-6623-0. Epub 2015 May 7.
A new biogas process is initiated by adding a microbial community, typically in the form of a sample collected from a functional biogas plant. This inoculum has considerable impact on the initial performance of a biogas reactor, affecting parameters such as stability, biogas production yields and the overall efficiency of the anaerobic digestion process. In this study, we have analyzed changes in the microbial composition and performance of an inoculum during storage using barcoded pyrosequencing of bacterial and archaeal 16S ribosomal RNA (rRNA) genes, and determination of the biomethane potential, respectively. The inoculum was stored at room temperature, 4 and -20 °C for up to 11 months and cellulose was used as a standard substrate to test the biomethane potential. Storage up to 1 month resulted in similar final methane yields, but the rate of methane production was reduced by storage at -20 °C. Longer storage times resulted in reduced methane yields and slower production kinetics for all storage conditions, with room temperature and frozen samples consistently giving the best and worst performance, respectively. Both storage time and temperature affected the microbial community composition and methanogenic activity. In particular, fluctuations in the relative abundance of Bacteroidetes were observed. Interestingly, a shift from hydrogenotrophic methanogens to methanogens with the capacity to perform acetoclastic methanogensis was observed upon prolonged storage. In conclusion, this study suggests that biogas inocula may be stored up to 1 month with low loss of methanogenic activity, and identifies bacterial and archaeal species that are affected by the storage.
一种新的沼气工艺是通过添加微生物群落来启动的，通常是以从功能性沼气厂采集的样品形式添加。这种接种物对沼气反应器的初始性能有相当大的影响，会影响稳定性、沼气产量以及厌氧消化过程的整体效率等参数。在本研究中，我们分别使用细菌和古菌16S核糖体RNA（rRNA）基因的条形码焦磷酸测序以及生物甲烷潜力的测定，分析了接种物在储存期间微生物组成和性能的变化。接种物在室温、4℃和-20℃下储存长达11个月，并使用纤维素作为标准底物来测试生物甲烷潜力。储存长达1个月会产生相似的最终甲烷产量，但在-20℃下储存会降低甲烷产生速率。更长的储存时间会导致所有储存条件下甲烷产量降低且产生动力学变慢，室温储存和冷冻样品分别始终表现出最佳和最差的性能。储存时间和温度都会影响微生物群落组成和产甲烷活性。特别是，观察到拟杆菌门相对丰度的波动。有趣的是，长时间储存后，观察到从氢营养型产甲烷菌向具有进行乙酸裂解产甲烷能力的产甲烷菌的转变。总之，本研究表明沼气接种物可储存长达1个月而产甲烷活性损失较小，并确定了受储存影响的细菌和古菌物种。
