【摘要】 本实验对干酪乳杆菌基因组改组菌株的耐酸性进行了研究,结果表明,冷冻(-80℃)和临界pH值(pH3.2)对干酪乳杆菌基因组改组菌株影响不显著,HCl和游离乳酸对该菌株生长有一定影响,游离乳酸影响更大。在pH5.0条件下发酵60h,干酪乳杆菌改组菌株获得的菌体干重为6.34g/L,乳酸产量为87.6g/L,比原始菌株耐酸性有显著提高。更多还原

【Abstract】 The acid tolerance of four strains of genome-shuffled Lactobacillus casei rhamnosus(Lc-F31,Lc-F32,Lc-F33 and Lc-F34) was characterized.The results showed after 3 passagings the viable numbers of these strains of genome-shuffled Lactobacillus casei which were spreaded on YE agar plate at pH 3.8 and 4.0 are similar.The acid tolerance of strain Lc-F34 in MRS liquidmedium at pH 3.2 is more significant compared with the original strain.The strain Lc-F31,Lc-F32,Lc-F33 and Lc-F34 still have good genetic stability after 20 passaging.Free lactic acid has more significant effect on growth of Lc-F34 than HCl in the shake-flask fermentation culture(YE medium) at differernt pHs.The batch fermentation of strain Lc-F34 was carried out in 5-L fermenter containing 3-L YE medium at the fixed pH 5.0 throughout the process.It was found that after 60-h fermentation,the produced lactate concentration of strain Lc-F34 is up to 87.6 g/L with the cell dry weight of 6.34 g/L.更多还原