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Hundreds of strains of methanol-assimilating yeasts were isolated in pure culture from a wide variety of natural sources through investigations on industrial cell production and the metabolism of methanol. Seven of these strains showed heavy growth on a methanol medium. Taxonomic studies on these strongly methanol-assimilating yeasts indicated that five strains were the same species and belonged to a new species, Pichia methanolica, one strain Pichia pastoris, and another Candida boidinii.

The cell-wall D -mannans of Candida parapsilosis, Endomycopsis fibuliger, Saccharomyces rouxii, Torulopsis apicola (Hajsig strain), and Torulopsis bombi were degraded with an exo α- D -mannosidase from Arthrobacter GJM-1 to their α-(1→6)-linked D -mannopyranose main-chains, as demonstrated by p.m.r. spectroscopy. D -galacto- D -mannans from Candida lipolytica, Torulopsis gropengiesseri, Torulopsis lactis-condensi, Torulopsis magnoliae, and Trichosporon fermentans could be degraded to polysaccharides containing mainly 6- O -linked α- D -mannopyranosyl residues following preferential removal of their enzyme-resistant, D -galactopyranosyl non-reducing end-units with acid. The D -mannans of Saccharomyces lodderi, Citeromyces matritensis , and Pichia pastoris could also be enzymically degraded to polysaccharides containing predominantly α-(1→6)-linked D -mannopyranosyl residues after hydrolysis of most of the β- D -linked residues in their side chains with acid. The exo α- D -mannosidase, as would be expected, produced β- D -mannose on splitting of an α-(1→2)-linked D -mannopyranose tetramer. It is, however, very selective in its action since it did not cleave α- D -Man p -(1→2)-β- D -Man p -(1→2)-β- D -Man p -(1→2)-β- D -Man p -(1→2)- D -Man. Apparently a D -mannopyranose non-reducing end-unit and two consecutive α- D -mannopyranose residues are required by the enzyme for cleavage of a substrate to take place.

Phytases catalyze the hydrolysis of phytate (myo-inositol hexakisphosphate), one of the major storage form of phosphate in plants, with subsequent release of myo-inositol, phosphate and phytate-bound minerals. Non-ruminant animals such as chicken, swine and fish can't use the organic phosphorus and minerals from their diet because there is no phytase activity in their digestive tract. Phytate degrading enzyme is added to the animal feed diet to improve phosphorus availability from the dietary phytate and at the same time this lessen the phosphate pollution level in areas of intensive animal production as the phosphate would not be excreted out to the environment. ASUIA279, a bacterial strain isolated from Malaysian soil has potentially shown good phytase activity. In the present work, the gene encoding for phytase has been amplified from the plasmid DNA of recombinant ASUIA279(5) obtained from a previous study (unpublished data) by a polymerase chain reaction (PCR) methodology. The amplified phytase gene was extracted, purified then cloned into the pPICZA plasmid and transformed into Pichia pastorisX-33 strain for enzyme production.ABSTRAK: Fitase pemangkinan hidrolisis fitat (myo-inositol hexakisphosphate), merupakan salah satu cara penyimpanan utama fosfat dalam tumbuhan, dengan pelepasan berturut myo-inositol , fosfat dan galian terikat fitat. Haiwan bukan ruminan seperti ayam, khinzir dan ikan tidak dapat memanfaatkan fosforus organik serta galian yang diperolehi daripada makanan kerana tidak mempunyai aktiviti fitase di dalam saluran pencernaan mereka. Enzim pengecilan fitase dicampurkan ke dalam pemakanan haiwan untuk mempertingkatkan keperolehan fosforus dari fitat diet. Pada masa yang sama ia dapat mengurangkan tahap pencemaran fosfat di kawasan yang terdapat penternakan haiwan secara intensif agar fosfat tidak dikumuhkan ke persekitaran. ASUIA279, satu strain bakteria yang diasingkan daripada tanih di Malaysiamenunjukkan aktiviti fitase yang memberansangkan. Buat masa kini, pengekodan gen fitase telah diperkuatkan dengan plasmid DNA dari ASUIA279(5), rekombinan yang diperolehi daripada kajian terdahulu (data tak diterbitkan) berdasarkan kaedah tindak balas berantai polimerase (polymerase chain reaction (PCR)). Gen fitase yang diperkuatkan, ditulenkan dan kemudian diklonkan menjadi plasmid pPICZαA dan berubah menjadi strain Pichia pastorisX-33 untuk penghasilan enzim.KEYWORDS: Phytase, animal feed, pollution, polymerase chain reaction (PCR), Pichia pastoris