Zhang Qin, Lo Chi-Ming, Ju Lu-Kwang
Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH 44325-3906, USA.
Bioresour Technol. 2007 Mar;98(4):753-60. doi: 10.1016/j.biortech.2006.04.006. Epub 2006 Jun 8.
Coupling fermentation with in situ foam fractionation may be beneficial to cellulase production in optimizing oligomer inducer generation, minimizing catabolite repression and reducing cellulase degradation by proteases. In this study, the potential factors that may affect the foaming behavior of broth from Trichoderma reesei Rut C-30 fermentation were examined. These factors included solid (both cell and cellulose) concentrations, cellulase activity and extracellular protein concentration. The loss of cellulase activity caused by the foaming process was minimal. The foamate generation was lower in the presence of higher solids (cell and/or cellulose) concentrations. Cellulase appeared to promote the broth foaming ability but its enrichment ratio was not high (lower than 1.2). The enrichment ratios for the individual component enzymes (beta-glucosidase, endo- and exo-glucanases) were found to be similarly low. None of the cellulase components were likely the primary foaming factors. The foam also carried out cells and cellulose solids. The hydrophobicity of cell surface, studied at various fermentation stages and in both media with and without cellulose, increased as the fermentation approached the stationary phase and then decreased gradually after entering the stationary phase.
将发酵与原位泡沫分离相结合，在优化低聚物诱导剂生成、最小化分解代谢物阻遏以及减少蛋白酶对纤维素酶的降解方面，可能有利于纤维素酶的生产。在本研究中，考察了可能影响里氏木霉Rut C-30发酵液起泡行为的潜在因素。这些因素包括固体（细胞和纤维素）浓度、纤维素酶活性和细胞外蛋白浓度。起泡过程导致的纤维素酶活性损失最小。在较高固体（细胞和/或纤维素）浓度存在下，泡沫产物的生成量较低。纤维素酶似乎能促进发酵液的起泡能力，但其富集率不高（低于1.2）。发现各组分酶（β-葡萄糖苷酶、内切和外切葡聚糖酶）的富集率同样较低。纤维素酶的任何组分都不太可能是主要的起泡因素。泡沫还携带细胞和纤维素固体。在不同发酵阶段以及有和没有纤维素的两种培养基中研究的细胞表面疏水性，随着发酵接近稳定期而增加，进入稳定期后逐渐降低。
