Research Of Simultaneous Production Of Single Cell Protein And Killer Toxin By Pichia Anomala HN1-2

Mangrove forests, with the total area being181000Km2, are widely distributedin112countries and cover60%~75%of coast lines of tropical and subtropicalzones.China hosts0.1%of the world mangrove forests.Mangrove forests are rich inmicroorganism resources and over100fungal species have been indentified fromthese ecosystems.Using rountine and molecular methods,the yeat strain HN1-2thatcan produce both single cell protein and killer toxin isolated from Chinese mangroveforests was indentified as a P. anomala strain.This is the first report of suchphenomenon.Based on the one factor optimization theory,cultural conditons for simultaneousproduction of SCP and killer toxin by P. anomala strain HN1-2were optimized.Thebest culture medium was found to be composed of4.0%(w/v) of soybean mealhydrolysate and3.0%(w/v) of glucose.The best initial pH,best inoculum size and bestfermentation temperature were found to be4.0,8.0%(v/v) and28℃,respectively.When the killer yeast cells were grown by batch cultivation in5-L fermentor, crudeprotein in the cells, cell mass, reducing sugar, and diameter of the inhibition zonereached56.0g per100g of cell dry weight,7.3g per liter,9.5g per liter, and19.0mm, respectively within12h and this yeast synthesized a large amount of theessential amino acids, such as lysine (7.8%), methionine (1.8%), and leucine (9.0%).The crude killer toxin produced by the killer yeast isolate HN1-2could kill the cellsof Lodderomyces elongisporus, Candida albicans, Metschnikowia bicuspidata, Pichiaguilliermondii, Saccharomyces cerevisiae, Yarrowia lipolytica and Kluyveromycesaestuarii, which are widely distributed in natural environments. The results alsoshowed that the undesirable yeast could be avoided during cell growth of the killeryeast,and that is very important in fermentation industry. One of the methods for SCP production is solid state fermentation(SSF). Culturalconditons for SSF when wheat bran and rice hull mixture was used as the substratewere optimized based on one factor optimization theory.The best cultural conditionswere found to be as follows: Substrate moisture45%(w/w),glucose concentration1.5%(w/w),(NH4)2SO4concentration0.3%(w/w),pH4.5,fermentation temperature28℃.After24h of fermentation,the protein content was raised from14.23%(w/w) to29.78%(w/w),and the diameter of clear zone was10.1mm.Raising protein content ofmixture using SSF method may find its future in Animal Husbandry.