Simşek O, Akkoç N, Con A H, Ozçelik F, Saris P E J, Akçelik Mustafa
Department of Food Engineering, Engineering Faculty, Pamukkale University, Denizli, Kinikli, Turkey.
J Ind Microbiol Biotechnol. 2009 Jun;36(6):863-71. doi: 10.1007/s10295-009-0563-6. Epub 2009 Apr 1.
Nisin production in continuous cultures of bioengineered Lactococcus lactis strains that incorporate additional immunity and regulation genes was studied. Highest nisin activities were observed at 0.2 h(-1) dilution rate and 12.5 g l(-1) fructose concentration for all strains. Recombinant strains were able to produce greater amounts of nisin at dilution rates below 0.3 h(-1) compared to the control strain. However, this significant difference disappeared at dilution rates of 0.4 and 0.5 h(-1). For the strains LL27, LAC338, LAC339, and LAC340, optimum conditions for nisin production were determined to be at 0.29, 0.26, 0.27, and 0.27 h(-1) dilution rates and 11.95, 12.01, 11.63, and 12.50 g l(-1) fructose concentrations, respectively. The highest nisin productivity, 496 IU ml(-1) h(-1), was achieved with LAC339. The results of this study suggest that low dilution rates stabilize the high specific nisin productivity of the bioengineered strains in continuous fermentation. Moreover, response surface methodology analysis showed that regulation genes yielded high nisin productivity at wide ranges of dilution rates and fructose concentrations.
对整合了额外免疫和调控基因的基因工程乳酸乳球菌菌株连续培养过程中的乳酸链球菌素生产进行了研究。所有菌株在稀释率为0.2 h⁻¹和果糖浓度为12.5 g l⁻¹时观察到最高的乳酸链球菌素活性。与对照菌株相比，重组菌株在稀释率低于0.3 h⁻¹时能够产生更多的乳酸链球菌素。然而，在稀释率为0.4和0.5 h⁻¹时，这种显著差异消失。对于菌株LL27、LAC338、LAC339和LAC340，确定乳酸链球菌素生产的最佳条件分别为稀释率0.29、0.26、0.27和0.27 h⁻¹以及果糖浓度11.95、12.01、11.63和12.50 g l⁻¹。LAC339实现了最高的乳酸链球菌素生产率，为496 IU ml⁻¹ h⁻¹。本研究结果表明，低稀释率可在连续发酵中稳定基因工程菌株的高比乳酸链球菌素生产率。此外，响应面法分析表明，调控基因在较宽的稀释率和果糖浓度范围内产生了高乳酸链球菌素生产率。
