School of Life Sciences, Anhui Agricultural University, Hefei, 230036, Anhui Province, China.
World J Microbiol Biotechnol. 2014 Feb;30(2):423-8. doi: 10.1007/s11274-013-1459-1. Epub 2013 Aug 24.
To obtain amino acid-analogue-resistant mutants the wild strain A9 of Arthrospira platensis was mutated by ethylmethane sulfonate (EMS). Mutagenic effects of strain A9 by EMS were studied. The experimental results indicated that the survival rate curve of strain A9 took a typical "exponential shape" with lethal dosage of EMS being 1%. The survival of A9 strain was 13.2% when treated with 0.4% of EMS, and the resistant mutation rates to two amino acid analogues, ρ-fluorophenylalanine (FPA) and L-canavanine sulphate (CS), were greatly increased with the highest rates being at 4.9 × 10(-4) and 3.24 × 10(-4), respectively. By repeated screening, two stable mutants resistant to amino acid analogues, A9f resistant to FPA and A9c resistant to CS, were obtained. Resistances of the two mutants to corresponding amino acid-analogues were both significantly increased. Compared with their parent strain A9, A9f appeared larger than A9 performance in filament diameter, spiral diameter, spiral pitch, filament length and spiral number, and A9c showed much longer length and spiral pitch than those of the initial strain. Analysis results on amino acids compositions and contents showed that both two mutants accumulated quite higher concentration of amino acids in cells. The two mutants might be excellent high amino acids producing strain. By this means two useful mutants with stable genetic makers for further genetic study of A. platensis were obtained, which laid a good foundation for further study on the transformation of A. platensis.
为了获得对氨基酸类似物具有抗性的突变体，采用乙磺酸乙酯（EMS）对节旋藻野生株 A9 进行诱变。研究了 EMS 对 A9 菌株的诱变效应。实验结果表明，A9 菌株的存活率曲线呈典型的“指数型”，致死剂量的 EMS 为 1%。当用 0.4%的 EMS 处理 A9 菌株时，其存活率为 13.2%，对两种氨基酸类似物 ρ-氟苯丙氨酸（FPA）和 L--canavanine 硫酸盐（CS）的抗性突变率大大提高，最高分别达到 4.9×10(-4)和 3.24×10(-4)。通过反复筛选，获得了对氨基酸类似物具有抗性的两种稳定突变体 A9f 对 FPA 有抗性，A9c 对 CS 有抗性。这两个突变体对相应的氨基酸类似物的抗性都显著增加。与亲本菌株 A9 相比，A9f 在丝径、螺旋直径、螺旋间距、丝长和螺旋数方面比 A9 表现更大，A9c 的丝长和螺旋间距比初始菌株长很多。氨基酸组成和含量分析结果表明，两个突变体细胞中氨基酸的浓度都相当高。这两个突变体可能是优良的高氨基酸产生菌株。通过这种方法获得了具有稳定遗传标记的两种有用突变体，为进一步研究节旋藻的遗传转化奠定了良好的基础。
