Studies On The Activity Of The Antibiotic From A Strain Of Micromonospora Cabonacea And Its Breeding By Heat Mutation

Exploring and making full use of new antibiotic will do good for the healthy and development of human beings. And it is important for the society. In the prophase studies, one strain of Micromonospora carbonacea JXNU-1 with board-spectrum antimicrobial activity, and the technology for the isolation and purification of antibiotic from the fermentation broth of the Micromonospora carbonacea, and its physical-chemical properties were also studied. Based on that, some work was done as follows:Firstly, the antibacterial activity of its antibiotics on bacterium in vitro was studied in this paper. The results showed that, the antibiotics showed antimicrobial activity against common gram-positive bacterium, such as Staphylococcus Aureus, Sarcina lutea, Bacillus thuringiensis, Bacillus subtilis, Lactobacillus acidophilus, and so on. The inhibitory effect of antibiotic on Bacillus is stronger than that of gram-positive bacterium which do not produce spores, and the Bactericidal effect is similar. And the antibiotics showed antimicrobial activity against common gram-negative bacterium, such as Pseudomonas aeruginosa, Shigella flexneri, Salmonella typhi, Enterobacter aerogenes, and so on. The minimum inhibitory concentration of the antibiotics was affected by pH, initial cell concentration, and the ionic strength; the minimum bactericidal concentration is generally 8 to 16 times of the minimum inhibitory concentration. The antibacterial mechanism of the antibiotic, that the cell division is inhibited, was proved by microscope analysis.Next the joint administer drugs of the antibiotic from Micromonospora cabonacea JXNU-1 and usual antibiotics was studied. The result showed that, when the antibiotic from Micromonospora cabonacea JXNU-1 associating with cephalosporin, they are independent with each other(FIC index=2.0). However, the antibiotic can plus or cooperate the antibiotics which restrain the synthetical of the protein or nucleic acid.At last, because of the upstanding antibacterial activity, breeding by heat mutation was done to increase the producing capacity of the antibiotic. And in order to comprehend of the application of heat treatment in breeding of microorganism and improve the work efficiency, we treat the spore suspension of the Micromonospora cabonacea JXNU-1 in the method of hot bath, and analyse of the infection of different factors, for example: age, lethality, spore concentration, spore suspension statement, dNTP mixture accession, pH altering and different culture temperature after mutation. The results showed that, the of positive mutation rate of the age of seven days are 2.2 and 2 times of the nine days and eleven days respectively. And high concentration of spore suspension is more likely give birth to positive mutation than low concentration. And 87% lethality of mutation condition is more likely give birth to positive mutation too than 73% lethality of mutation condition. But spore suspension statement, dNTP mixture accession, pH altering and different culture temperature after mutation can not improve the rate of positive mutation, although they can infect the lethality. A mutant strain ZD-2 of high-producing antibiotic was screened from lots of mutant strains. Its bacteriostatic diameter is 33 mm, 6.6 mm bigger than the parent strain.