杂色曲霉在人胃液中体外培养产生杂色曲霉素的研究

本文用正交实验设计法探讨了杂色曲霉(Aspergillus versicolr)在加有两类不同性质营养物的人胃液中产生杂色曲霉素(Sterigmatocystin,简称ST)的条件。发现在26℃斜面静置培养12天后可产生ST。加入半合成物质的最佳配伍是:蔗糖1,000.0mg;蛋白胨50.0mg;KH_2PO_4 7.5mg;MgSO_4·7H_2O_2.5mg;人胃液10.0ml,称之为SPKM人胃液培养基。加入天然物质的最佳配伍是:玉米粉0.5g;豆腐粉0.25g,人胃液10.0ml,称之为CS人胃液培养基。还进一步研究了pH值和培养时间对杂色曲霉产毒菌株在SPKM和CS人胃液培养基中生长及产生ST的影响。根据临床胃酸缺乏程度分级标准,分为pH 1.0,3.0,6.5,8.0四个组。发现在两种人胃液培养基中,无论是杂色曲霉生长,还是产生ST,pH3.0到6.5是发生质变的范围。在两种人胃液培养基pH为6.5时,37℃静置培养8天有痕量ST产生,10天后就明显增加。所以杂色曲霉产生的ST可能是慢性萎缩性胃炎易癌变的原因之一。

STERIGMATOCYSTIN PRODUCED BY ASPERGILLUS VERSICOLOR IN HUMAN GASTRIC JUICE IN VITRO

Orthogonal design was adopted in experiments to investigate the conditions of production of sterigmatocystin (ST) by Aspergillus versicolor in the human gastric juice medium (HGJM) with the addition of two different kinds of nutrients. ST production was detected on slant of such media at 26℃ for 12-day stationary cultivation. The best combination of semisynthetic compounts is: sucrose 1,000.0 mg; peptone 50.0mg; KH_2PO_4 7.5mg;MgSO_4·7H_2O 2.5mg in 20.0ml human gastric juice, which is named SPKM HGJM.The best combination of natural substances is:cornmeal 500 mg; soybean curd flour 250mg in 10.0ml human gastric juice, which we named CS HGIM.The effects of pH and culture time on the growth and ST production of A. versicolor were further studied.According to the standard used in judging the degree of decrease of gastric acid, four levels of pH, i.e. 1.0, 3.0, 6.5 and 8.0 were adjusted.Either growth or production of ST of A. vesicolor was greatly influenced by pH 3.0—6.5 in both kinds of HGJM. In this pH range substantial changes happened. ST was produced in trace amount at pH 6.5 in poth HGJH after 8-day stationary cultivation at 37℃, being significant after 10 days. It seems that the ST produced by A. versicolor may be one the causes why the chronic grastritis easily trun to stomach cancer.