Desvaux Mickaël
INRA (Institut National de la Recherche Agronomique), Centre de Clermont-Ferrand, UR454 Unité de Microbiologie, Site de Theix, Saint-Genès Champanelle, F-63122 France.
Biotechnol Prog. 2006 Sep-Oct;22(5):1229-38. doi: 10.1021/bp060016e.
Carbon metabolism in anaerobic cellulolytic bacteria has been investigated essentially in Clostridium thermocellum, Clostridium cellulolyticum, Fibrobacter succinogenes, Ruminococcus flavefaciens, and Ruminococcus albus. While cellulose depolymerization into soluble sugars by various cellulases is undoubtedly the first step in bacterial metabolisation of cellulose, it is not the only one to consider. Among anaerobic cellulolytic bacteria, C. cellulolyticum has been investigated metabolically the most in the past few years. Summarizing metabolic flux analyses in continuous culture using either cellobiose (a soluble cellodextrin resulting from cellulose hydrolysis) or cellulose (an insoluble biopolymer), this review aims to stress the importance of the insoluble nature of a carbon source on bacterial metabolism. Furthermore, some general and specific traits of anaerobic cellulolytic bacteria trends, namely, the importance and benefits of (i) cellodextrins with degree of polymerization higher than 2, (ii) intracellular phosphorolytic cleavage, (iii) glycogen cycling on cell bioenergetics, and (iv) carbon overflows in regulation of carbon metabolism, as well as detrimental effects of (i) soluble sugars and (ii) acidic environment on bacterial growth. Future directions for improving bacterial cellulose degradation are discussed.
厌氧纤维素分解菌中的碳代谢主要在嗜热栖热菌、解纤维梭菌、琥珀酸丝状杆菌、黄化瘤胃球菌和白色瘤胃球菌中进行了研究。虽然各种纤维素酶将纤维素解聚为可溶性糖无疑是细菌代谢纤维素的第一步，但并非唯一需要考虑的步骤。在厌氧纤维素分解菌中，解纤维梭菌在过去几年中得到了最多的代谢研究。通过总结使用纤维二糖（纤维素水解产生的一种可溶性纤维糊精）或纤维素（一种不溶性生物聚合物）进行连续培养的代谢通量分析，本综述旨在强调碳源的不溶性对细菌代谢的重要性。此外，还介绍了厌氧纤维素分解菌的一些一般和特定特征趋势，即（i）聚合度高于2的纤维糊精、（ii）细胞内磷酸解裂解、（iii）糖原循环对细胞生物能学的重要性和益处，以及（iv）碳溢流在碳代谢调节中的作用，以及（i）可溶性糖和（ii）酸性环境对细菌生长的有害影响。还讨论了改善细菌纤维素降解的未来方向。
