Studies on the production of gentamicin by fermentation

Abstract

Using $\mbox{\underline{Micromonospora}}$ $\mbox{\underline{purourea}}$ strain, gentamicin was produced by fermentation. In this thesis, the increase of gentamicin productivity was studied by strain improvement \& systematic optimization of some important fermentation process variables. The gentamicin producing wild strain of $\mbox{\underline{M}}$. $\mbox{\underline{purpures}}$ (ATCC 15835) was improved to a high yielding strain by natural selection, irradiation with ultraviolet, induction of gentamicin resistance. Effective condition of U.V. irradiation was studied for repeated treatment. The resistance-induced mutant gave higher productivity than those mutant obtained by only/U.V. treatment. The growth characteristic of high yielding mutant differed from that of the wild strain; e.g. colony size, colony morphology, color of colony \& broth culture, growth rate etc. Slow germination of $\mbox{\underline{M}}$. $\mbox{\underline{purpurea}}$ changed to rapid rate by adjusting the pH of the germination broth to slightly alkaline condition. Potato starch \& extracted soy bean meal as the best carbon \& nitrogen sources for gentamicin fermentation were selected. The effect of metal ion such as $Mg^{++}$ ion \& $Co^{++}$ ion was tested. Addition of 10 mM -20 mM of $Mg^{++}$ ion to the fermentation medium didn``t effect positively on gentamicin production. Optimum concentration of $Co^{++}$ ion for gentamicin production was 0.08 g $CoCl_2$/ L broth. As the important fermentation process variables besides the medium, oxygen uptake rate and carbohydrate (Potato starch \& Glucose) uptake rate were measured. Maximum oxygen uptake rate was 6.25 mM $O_2$/L broth. HR. Maximum carbohydrate uptake rate was 0.8g glucose/L broth. HR and 0.41 g potato starch/L broth. HR. Also high sensitivity of the yield to the oxygen supply was observed. The optimum pH for the cell growth phase \& gentamicin production phase were different each other, they were 7.2 \& 6.8-6.9 respectively. The...