糖浓度对维氏固氮菌发酵合成海藻酸的影响

Effects of Sucrose Concentration on Alginic Acid Fermentation by Azotobacter vinelandii

应用维氏固氮菌(Azotobacter Vinelandii)菌株 N_3在每升液体发酵培养基中,蔗糖含量分别为10、15、20、30和40克的条件下,进行30℃振荡(105次/分钟)发酵试验,发现 pH值在低糖浓度(10g/L)下,一直处于低值,而其余糖浓度则随发酵天数的延长而升高;发酵液的含氧量在初发酵24小时内,各处理组均急剧下降,随着发酵天数的延长含氧量回升,其中低糖浓度的发酵液比高糖浓度的回升幅度大。从生物细胞的生长量和海藻酸的合成量综合考虑蔗糖的消耗和利用,认为每升培养基中以15克蔗糖为最经济,不但可以节省糖用量,而且可缩短发酵周期和提高设备的利用率。

A shake fermentation experiment(105 reciprocates/min)was conducted at 30℃ using astain of A.vinelandii N_3 under the condition of sucrose concentration at 10,15,20,30and 40 g/L culture broth,It is found that pH of the broth increased with increasing of sucrose concentration and fermentation time course,but in the case of low sucrose concentration(10g sucrose/L),the pH was low throughout the fermentation and that DO of broth in each treatment dramatically dropped within first 24 h of the fermentation then rose with the fermentation time,in which the increasing degree in low sucrose brothes was larger than that in high sucrose ones。From the viewpoint of cell biomass and the amount of alginic acid biosynthesized the most economical utilization of sucrose in the fermentation is at the rate of 15 g sucrose/L broth,in this case not only sucrose consumption could be decreased,but al- so the fermentation time shortened resulting in increase of facilities utilization。