在低功率微波条件下,并采用水循环(20℃)冷却装置,对干酪乳杆菌鼠李糖亚种(Lactobacillus casei subsp.rhamnosus)CICC 6013进行诱变处理,通过对微波辐照功率和微波辐照时间做单因素平行实验,得到最高产酸量为124.15g/L的突变株W4-23,比原始菌株产酸发酵量提高了53.45%,连续遗传8代,产酸性状稳定。研究结果表明,最佳诱变条件为在400W微波功率下辐照20min。
Mutagenesis of Lactobacillus casei subsp.rhamnosus X1-12 after low power microwave irradiation was investigated.Under a microwave power of 400 W and irradiation length of 3 min,a mutated strain W4-3-9 with high-yield L-lactic acid was obtained by screening.Compared with the starting strain X1-12,the L-lactic acid production of W4-3-9 was increased by 58.0% at a concentration of 115.8 g/L.The strain maintained the capability of producing a high L-lactic acid level after 10 generations.Cell surface morphology and DNA structures of parental and mutated strains were observed by atomic force microscopy (AFM).Amplified fragment length polymorphism (AFLP) analysis suggested the difference in AFLP band pattern between the mutated and non-mutated strains.Sequencing and BLAST analysis revealed that the catalytic site of lactate dehydrogenase (DHL) was changed due to the microwave induced mutation.
