This review is written from the perspective of scientists working in lignocellulose bioconversion in a developing country and the aim of this review is to remind ourselves and other scientists working in related areas of lignocellulose research of the enormous economic potential of the bioprocessing of residual plant materials generally regarded as "waste", and secondly to highlight some of the modern approaches which potentially could be used to tackle one of the major impediments, namely high enzyme cost, to speed-up the extensive commercialisation of the lignocellulose bioprocessing.

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The aim of this study was to produce a secreted, heterologously expressed Phanerochaete chrysosporium cellobiohydrolase (CBHI.1) protein that required no in vitro chemical refolding and to investigate the cellulolytic activity of the clone expressing the glutathione S-transferase (GST) fused CBHI.1 protein. Plate enzyme activity screening of E. coli cells transformed with pGEXcbhI.1 vector on carboxy-methyl-cellulose (CMC) produced several clones which produced clearing zones on CMC when induced. A randomly selected representative pGEXcbhI.1 clone produced hydrolysis on both Avicel and CMC when induced. Crude protein extracts obtained from the induced pGEXcbhI.1 clone exhibited time dependent enzymatic activity against both CMC and Avicel.

The aim of this study was to purify and analyse a Phanerochaete chrysosporium cbhI.1 gene-product expressed as an inducible, secreted, heterologous protein from an Escerichia coli pGEXcbhI.1 clone. Using glutathione Sepharose 4B affinity chromatography, the expressed protein was purified from the supernatant of an induced E. coli transformed with pGEXcbhI.1 and ran as a single band on a Sodium dodecyl sulphate-polyacrylamide gel. The glutathione S-transferase (GST) fused CBHI.1 was approximately 80 kDa in size, approximately 2.2 kDa smaller than the theoretically predicted size. The purified protein exhibited time dependent hydrolytic reaction against carboxy-methyl-cellulose (CMC) and Avicel. On CMC the highest hydrolytic reaction occurred at 120 min. whereas for Avicel it was at 150 min. Optimum pH and temperature for activity of the protein against these cellulose substrates were pH 6 and 55 o C, respectively, and the protein remained stable under these optimum conditions for 24 h.