Breeding of probiotic bacterium by N~(+) implantation and optimization of fermentation condition
A new strain Aspergillus niger AN02 was mutated from AN01 by N~(+) implantation. The results showed that activities of acid-protease, cellulase and pectinase in Aspergillus niger were raised from 1298 U·mL~(-1), 2551 U·mL~(-1) and 5620 U·mL~(-1) to 14252 U·mL~(-1), 13016 U·mL~(-1) and 13206 U·mL~(-1) respectively. Characteristics of enzymes production in mutated strain Aspergills niger AN02 kept stable by many times subculture. At the same time we study optimum conditions suitable for enzyme production in Aspergillus niger AN02, and the results demonstrated that enzymes activities in mutated strain Aspergillus niger were highest when the cultivate condition were as follows: ferementation temperature was 30℃, cultivate time was 96 hours, the water content in culture medium was 60 percent, pH was 5.0 and (NH_(4)_(2)SO_(4) was nitrogen source.