Liggenstoffer Audra S, Youssef Noha H, Wilkins Mark R, Elshahed Mostafa S
Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74074, United States.
Department of Biosystems Engineering, Oklahoma State University, Stillwater, OK 74074, United States.
J Microbiol Methods. 2014 Sep;104:43-8. doi: 10.1016/j.mimet.2014.06.010. Epub 2014 Jun 24.
Members of the anaerobic fungi (Phylum Neocallimastigomycota) are efficient biomass degraders and represent promising agents for fuel and chemical production from lignocellulosic biomass. Pretreatment of lignocellulosic biomass is considered an unavoidable first step in enzyme-based saccharification schemes, but its necessity in any proposed anaerobic fungi-based schemes is still unclear. Here, we evaluated the effect of hydrothermal pretreatments on the extent of corn stover and switchgrass degradation by an anaerobic fungal isolate, Orpinomyces sp. strain C1A. Using a factorial experimental design, we evaluated the effect of three different temperatures (180, 190, and 200°C) and three hold times (5, 10, and 15min). Pretreated corn stover and switchgrass were more amenable to degradation by strain C1A when compared to untreated biomass, as evident by the higher proportion of plant biomass degraded compared to untreated controls. However, when factoring in the proportion of biomass lost during the pretreatment process (ranging between 25.78 and 58.92% in corn stover and 28.34 and 38.22% in switchgrass), hydrothermolysis provided negligible or negative improvements to the extent of corn stover and switchgrass degradation by strain C1A. Product analysis demonstrated a shift towards higher ethanol and lactate production and lower acetate production associated with increase in pretreatment severity, especially in switchgrass incubations. The results are in stark contrast to the requirement of pretreatment in enzyme-based schemes for biomass saccharification, and their implications on the potential utility of anaerobic fungi in biofuel and biochemical production are discussed.
厌氧真菌（新美鞭菌门）成员是高效的生物质降解菌，是利用木质纤维素生物质生产燃料和化学品的有潜力的菌种。木质纤维素生物质的预处理被认为是基于酶的糖化方案中不可避免的第一步，但在任何提出的基于厌氧真菌的方案中其必要性仍不明确。在此，我们评估了水热预处理对厌氧真菌菌株奥尔平氏菌（Orpinomyces）sp. 菌株C1A降解玉米秸秆和柳枝稷程度的影响。采用析因实验设计，我们评估了三种不同温度（180、190和200°C）和三种保温时间（5、10和15分钟）的影响。与未处理的生物质相比，预处理后的玉米秸秆和柳枝稷更易于被菌株C1A降解，与未处理对照相比，植物生物质降解比例更高即证明了这一点。然而，考虑到预处理过程中损失的生物质比例（玉米秸秆中为25.78%至58.92%，柳枝稷中为28.34%至38.22%），水热解对菌株C1A降解玉米秸秆和柳枝稷的程度几乎没有改善或有负面影响。产物分析表明，随着预处理强度的增加，乙醇和乳酸产量增加，乙酸产量降低，尤其是在柳枝稷培养中。这些结果与基于酶的生物质糖化方案中预处理的要求形成鲜明对比，并讨论了其对厌氧真菌在生物燃料和生化生产中潜在效用的影响。
