Córdova Olivia, Chamy Rolando, Guerrero Lorna, Sánchez-Rodríguez Aminael
Laboratorio de Biotecnología Ambiental, Escuela de Ingeniería Bioquímica, Facultad de Ingeniería, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.
Department of Chemical and Environmental Engineering, Universidad Técnica Federico Santa, Valparaíso, Chile.
Front Microbiol. 2018 Jun 26;9:1388. doi: 10.3389/fmicb.2018.01388. eCollection 2018.
Microalgae biomethanization is driven by anaerobic sludge associated microorganisms and is generally limited by the incomplete hydrolysis of the microalgae cell wall, which results in a low availability of microalgal biomass for the methanogenic community. The application of enzymatic pretreatments, e.g., with hydrolytic enzymes, is among the strategies used to work around the incomplete hydrolysis of the microalgae cell wall. Despite the proven efficacy of these pretreatments in increasing biomethanization, the changes that a given pretreatment may cause to the anaerobic sludge associated microorganisms during biomethanization are still unknown. This study evaluated the changes in the expression of the metatranscriptome of anaerobic sludge associated microorganisms during biomethanization without pretreatment (WP) (control) and pretreated with commercial cellulase in order to increase the solubilization of the microalgal organic matter. Pretreated microalgal biomass experienced significant increases in biogas the production. The metatranscriptomic analysis of control samples showed functionally active microalgae cells, a bacterial community dominated by γ- and δ-proteobacteria, and a methanogenic community dominated by . In contrast, pretreated samples were characterized by the absence of active microalgae cells and a bacteria population dominated by species of the Clostridia class. These differences are also related to the differential activation of metabolic pathways e.g., those associated with the degradation of organic matter during its biomethanization.
微藻生物甲烷化由厌氧污泥相关微生物驱动，通常受微藻细胞壁水解不完全的限制，这导致产甲烷群落可利用的微藻生物质较少。酶预处理的应用，例如使用水解酶，是解决微藻细胞壁水解不完全问题的策略之一。尽管这些预处理在提高生物甲烷化方面已被证明有效，但特定预处理在生物甲烷化过程中可能对厌氧污泥相关微生物造成的变化仍不清楚。本研究评估了在未预处理（WP）（对照）和用商业纤维素酶预处理以增加微藻有机物质溶解性的生物甲烷化过程中，厌氧污泥相关微生物元转录组表达的变化。预处理后的微藻生物质沼气产量显著增加。对照样品的元转录组分析显示有功能活跃的微藻细胞、以γ-和δ-变形菌为主的细菌群落以及以……为主的产甲烷群落。相比之下，预处理样品的特征是没有活跃的微藻细胞，细菌种群以梭菌属为主。这些差异也与代谢途径的差异激活有关，例如与有机物质在其生物甲烷化过程中降解相关的途径。
