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Two SDS-resistant endochitinases, designated as ASCHI53 and ASCHI61, were isolated from Aeromonas schubertii in a soil sample from southern Taiwan. MALDI-TOF mass measurement indicates the molecular weights of 53,527 for ASCHI53 and 61,202 for ASCHI61. N-terminal and internal amino acid sequences were obtained, and BLAST analysis of the sequences and MS/MS peptide sequencing showed that they were novel proteins. Degradation of chitin by these two endochitinases gave rise to hexameric chitin oligosaccharide, a compound known to have several potent biomedical functions. ASCHI53 and ASCHI61 retained, respectively, 65% and 75%, of their chitinase activity in the presence of 5% SDS and 100% of their activity in the presence of 10% β-mercaptoethanol. These results demonstrate that they are SDS-resistant endochitinases and probably have a rigid structure. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009

A membrane enzyme reactor consisting of variable pieces of replaceable cell-immobilized membranes was proposed for the continuous production of bioproducts. To demonstrate the characteristics of the reactor, cell-immobilized membranes were prepared by the entrapment of permeabilized recombinant Escherichia coli cells containing penicillin G acylase within the gluten matrices. A stainless-steel net that was created with a mesh frame was used to support each gluten membrane so that the membranes could be filled into the rectangular-shaped reactor. The reactor equipped with either six or 12 pieces of cell-immobilized gluten membranes containing a biomass concentration of 5%, w/w was effective in catalyzing the production of 6-aminopenicillanic acid from penicillin G. In comparison with intact cells, the cell-immobilized preparation was more stable and the half-life time of the immobilized cell-associate enzyme in gluten membrane was estimated to be 36 days by a long-term operation. As the substrate solution was forced to flow through the reactor equipped with six membranes and in the direction perpendicular to the membranes, the pressure drop was determined to be less than 50 cm H2O with a flow-rate up to 50 mL/min. This low pressure due to the porous structure of gluten membrane would lead to a lower operational cost. Increasing either the number of membranes or the area of each cell-immobilized membrane can easily do scaling-up of this membrane reactor. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 76: 311–317, 2001.