Breeding of D(-)-lactic acid high producing strain by low-energy ion implantation and preliminary analysis of related metabolism.
The low-energy nitrogen ion beam implantation technique was used in the breeding of mutant D(-)-lactic-acid-producing strains. The wild strain Sporolactobacillus sp. DX12 was mutated by an N(+) ion beam with energy of 10keV and doses ranging from 0.4 x 10(15) to 6.60 x 10(15) ions/cm(2). Combined with an efficient screening method, an efficient mutant Y2-8 was selected after two times N(+) ion beam implantation. By using the mutant Y2-8, 121.6g/l of D-lactic acid was produced with the molar yields of 162.1% to the glucose. The yield of D-lactic acid by strain Y2-8 was 198.8% higher than the wild strain. Determination of anaerobic metabolism by Biolog MT2 was used to analyze the activities of the concerned enzymes in the lactic acid metabolic pathway. The results showed that the activities of the key enzymes responded on the substrates such as 6-phosphofructokinase, pyruvate kinase, and D-lactate dehydrogenase were considerably higher in the mutants than the wild strain. These might be affected by ion beam implantation.
Xu
Ting-Ting
TT
Nanjing University of Technology, Jiangsu, China.
Bai
Zhong-Zhong
ZZ
Wang
Li-Juan
LJ
He
Bing-Fang
BF
D056449:Bacillales / Q000201:enzymology / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects*; D001426:Bacterial Proteins / Q000378:metabolism; D007477:Ions / Q000737:chemistry; D045022:Lactate Dehydrogenases / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism*; D016296:Mutagenesis; D010732:Phosphofructokinase-1 / Q000378:metabolism; D011091:Polyesters; D011108:Polymers / Q000378:metabolism*; D011770:Pyruvate Kinase / Q000378:metabolism
D001426:Bacterial Proteins; D007477:Ions; D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide); D045022:Lactate Dehydrogenases; C071195:D-lactate dehydrogenase; D010732:Phosphofructokinase-1; D011770:Pyruvate Kinase