Bulletin Number Four 1985

Protoplast fusion techniques for interspecific and intergeneric hybridization o f edible mushrooms *Professor S.T. Chang, Department o f Biology Because o f the complex sexual patterns and special growth habits found in the higher basidio- mycetes ， our understanding o f their genetics and breeding mechanism has been less extensive in com parison w ith both the lower fungi and higher plants. However, the development o f protoplast-based tech niques for genetic manipulations in fungi involving fusion and vector-mediated transformation, provide an opportunity for overcoming these inherent d iffi culties. Many o f the difficulties in hybridization and recombination experienced w ith intact cells may be overcome by the use o f protoplast technology. Production o f thermostable enzymes by bacteria *Dr. K. Y. Chan, Department o f Biology A number o f bacterial strains are known to produce exoenzymes o f industrial importance. Some o f these enzymes can degrade the most abundant renewable agricultural resource in the world —plant materials which include lignocellulose and starch. We are particularly interested in the production o f cellulase, α - and β -amylases by thermophilic or thermotolerant bacteria. By mutation technique and strain selection, and by optimizing the production conditions, so far we are able to obtain several hyper- production bacterial strains, which are thermophilic organisms, producing high levels o f carboxylmethyl cellulase, α - and β -amylases. Some o f these thermostable enzymes have been purified and their properties determined. Fermentation by marine bacteria *Dr. K. Y. Chan ， Department o f Biology A ll industrial fermentation processes at present are carried out by freshwater microorganisms. A number o f marine bacteria also have the ability o f fermenting agricultural materials w ith useful com pounds produced as fermentation end products. Our laboratory is particularly enthusiastic in the search for marine bacteria which can produce ethanol, poly- β -hydeoxylbutyrate and organic acids through fermentation o f cheap agricultural materials. Production o f algal metabolites through protoplast technology *Dr. K. Y. Chan ， Department o f Biology A number o f algal species are well-known producers o f proteins, lipids, glycerol, alginate, agar and carageenin. However, their usefulness in large- scale production under controlled environment is hindered by some intrinsic factors, such as slow growth rate, low yields o f the metabolites or product quality. But by the use o f algal protoplast technology, it is possible to fuse protoplasts from closely related or even distantly related algal species w ith advan­ tageous characters. The fusion products (hybrids) can express the genetic make-ups from both parents. We are now in the process o f selecting useful bio­ chemical markers encoded by either nuclear DNA or by cytoplasmic DNA in different algal species, and we hope to produce protoplast fusion products w ith desirable characters. Immobilization o f Cells *Dr. W. W. Tso, Department o f Biochemistry The ultimate goal o f biotechnology is to raise production in industry and agriculture. As the fer mentation industry is a highly developed industry in Guangdong Province, the Guangdong Institute o f Microbiology (GIM) has launched a biotechnological programme in collaboration w ith our group, the Bioreactor group (W.W. Tso and W.N. Leung), to raise the production o f a list o f biochemicals, among them, alcohol and lysine. Our project includes the genetic selection o f microbiological strains that can produce the highest yield, the transfer o f genetic materials to fast growing host(s), and the immobil ization o f such cellular bioreactors to a suitable matrix that facilitates industrial production. The group's primary target is cell immobilization. Enzymes are invaluable biocatalyst in cells that can be used to produce a wide spectrum of biochemical products. Generally speaking, the pu rifi cation o f enzyme is not only ahighly skilful technique but also a time-consuming one. Poor handling o f the enzyme leads frequently to a drastic loss o f catalytic activity. However, the catalytic activity can be tact fu lly preserved by the housing (immobilization) o f cells in an inorganic or organic matrix. This immobil ization or trapping process also prevents the previously unpreventable disposal o f cells from the reactor in either a batch process or a continuous one. The immobilized cells can be recycled 一 a great step forward in time- and expenditure-saving. In our four-year's collaboration, we have succeeded in attaching a strain o f filamentous micro organism to porous kaolinite beads. The beads were the first GIM invention. This entrapment procedure has already been shown to raise the biogas production by 2.7-fold. We have also initiated a new investigation on organic polymers as a matrix to immobilize cells for alcohol production. Cloning o f the Pasteur control protein mutant gene adhC and physiological study o f the adhC clone *Dr. K.K. Mark ， Department o f Biology Pasteur discovered the Pasteur effect (1861) over one hundred years ago, but little is known as to * The teacher(s) conducting the research RECENT DEVELOPMENTS 21