van Rensburg E, du Preez J C
Department of Microbial, Biochemical and Food Biotechnology, University of the Free State, Bloemfontein, South Africa.
J Appl Microbiol. 2007 May;102(5):1273-82. doi: 10.1111/j.1365-2672.2006.03205.x.
Quantification of the effects of pH, temperature and nutrient limitations on the growth and leukotoxin (LKT) production parameters of Mannheimia haemolytica in batch and chemostat culture.
Mannheimia haemolytica strains OVI-1 and PH12296 were grown aerobically in two semi-defined media. In amino acid-limited cultures, the LKT concentration and yield in terms of biomass (Y(LKT/x)) were up to eightfold greater than in carbon-limited cultures. Supplementing amino acid-limited chemostat cultures with cysteine, glutamine, ferric iron and manganese further enhanced the Y(LKT/x) values up to threefold. Supplementation of an amino acid-limited batch culture of M. haemolytica strain OVI-1 with these nutrients resulted in an LKT concentration of 1.77 g l(-1) that was 45-fold greater than that obtained in RPMI 1640 medium. Aerobiosis enhanced LKT production. High acetic acid concentrations were produced under carbon-sufficient conditions. The highest maximum specific growth rates were recorded in the range of pH 6.8 to 7.8 and 37 to 40 degrees C.
An amino acid-limited culture medium greatly improved LKT production in aerobic batch culture, which could be further enhanced by supplementation with cysteine, glutamine, ferric iron and manganese.
It was demonstrated that LKT production by M. haemolytica could be dramatically increased through manipulation of the culture medium composition, which could benefit the production of LKT-based vaccines against bovine shipping fever pneumonia.
定量分析pH值、温度和营养限制对分批培养和恒化器培养中溶血曼氏杆菌生长及白细胞毒素（LKT）产生参数的影响。
溶血曼氏杆菌菌株OVI-1和PH12296在两种半限定培养基中好氧培养。在氨基酸限制培养中，LKT浓度及基于生物量的产量（Y(LKT/x)）比碳限制培养中高至八倍。用半胱氨酸、谷氨酰胺、铁离子和锰补充氨基酸限制的恒化器培养可使Y(LKT/x)值进一步提高至三倍。用这些营养物质补充溶血曼氏杆菌菌株OVI-1的氨基酸限制分批培养，可使LKT浓度达到1.77 g l(-1)，比在RPMI 1640培养基中获得的浓度高45倍。好氧条件可提高LKT产量。在碳充足条件下会产生高浓度乙酸。在pH 6.8至7.8及37至40摄氏度范围内记录到最高的最大比生长速率。
氨基酸限制培养基极大地提高了好氧分批培养中LKT的产量，补充半胱氨酸、谷氨酰胺、铁离子和锰可进一步提高产量。
结果表明，通过控制培养基成分可显著提高溶血曼氏杆菌的LKT产量，这有助于生产针对牛运输热肺炎的基于LKT的疫苗。
