Silva Suse Botelho da, Cantarelli Vlademir Vicente, Ayub Marco Antonio Záchia
Food Engineering, Polytechnic School, Vale do Rio dos Sinos University, Av. Unisinos, 950, São Leopoldo, RS, 93022-000, Brazil.
Bioprocess Biosyst Eng. 2014 Mar;37(3):469-79. doi: 10.1007/s00449-013-1016-1. Epub 2013 Jul 20.
The aims of this research were to screen and characterize a new microbial source of γ-PGA, to optimize aspects of culture conditions and medium composition using central composite design and response surface methodologies. The influence of bioreactor stirring rates on the production of γ-PGA was also investigated and the oxygen volumetric mass transfer coefficients (k La) were established. The most productive strain was identified by 16S rDNA analysis as Bacillus subtilis, and its γ-PGA production in rotatory shaker was threefold increased under optimized conditions (37 °C, pH 6.9, and 1.22 mM Zn(2+)), compared to conventional medium. In bioreactor, the γ-PGA production was further increased, reaching 17 g l(-1), 70 % higher than shaker cultures. γ-PGA production showed high dependency on oxygen transfer. At k La of 210 h(-1), the cultivation time could be reduced to 48 h, about 50 % of the time required for operations at k La 55 h(-1).
本研究的目的是筛选和鉴定一种新的γ-聚谷氨酸微生物来源，使用中心复合设计和响应面方法优化培养条件和培养基组成的各个方面。还研究了生物反应器搅拌速率对γ-聚谷氨酸产量的影响，并确定了氧体积传质系数（kLa）。通过16S rDNA分析鉴定出最具生产能力的菌株为枯草芽孢杆菌，与传统培养基相比，在优化条件（37°C、pH 6.9和1.22 mM Zn(2+)）下，其在旋转摇床中的γ-聚谷氨酸产量提高了三倍。在生物反应器中，γ-聚谷氨酸产量进一步提高，达到17 g l(-1)，比摇床培养高出70%。γ-聚谷氨酸产量对氧传递高度依赖。在kLa为210 h(-1)时，培养时间可缩短至48 h，约为kLa 55 h(-1)操作所需时间的50%。
