نوع مقاله : مقاله پژوهشی
نویسندگان
1 استادیار گروه زیست شناسی دانشکده علوم پایه
2 گروه زیست شناسی، دانشکده علوم پایه، دانشگاه الزهرا (س)
3 استادیار پژوهش مؤسسه تحقیقات خاک
4 استادیار پژوهش مؤسسه تحقیقات خاک و آب، پژوهشگر مؤسسه تحقیقات خاک و آب
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
Reproduction of selected strains is one of the most expensive stages in the process of inoculum production. Therefore, for large scale industrial production of rhizobiums, efforts are made to use the by-products of food industry plants directly or in combination with some other ingredients as culture media. In this experiment multiplication of S. meliloti in three culture media, namely malt sprout extract, dehydrated cheese whey, and the chemical base medium of yeast extract mannitol along with three nitrogen sources: ammonium chloride, potassium nitrate, and yeast extract; four carbon sources: mannitol, glucose, galactose, and sucrose at two pH levels of 6.8 and 7.0 was investigated. The experiment was designed as a randomized complete block factorial test with three replications. Isolates of SM-11 (S. meliloti) with population densities of 2x105 cells/ml were transferred to 100 ml Erlenmeyer flasks containing the culture media mentioned before, followed by making plate counts on YMA, growth medium containing Congo-red. After two days of bacterial growth, the results of the experiment showed that the bacterial populations reached a level of 7.94x109 cells/ml in the malt culture containing mannitol as a carbon source and yeast extract as a nitrogen source with the pH of the medium adjusted to 7.0, while the population density in the same medium, but containing sucrose and potassium nitrate adjusted to pH 6.8 was measured to be 4.5x109 cells/ml, as compared with 5.24x109 cells/ml for the standard YMB culture medium. Likewise, the population density of the bacteria in the chemical base culture at pH of 6.8, was 2.07x109 cell/ml after 3 days and in the same medium containing sucrose and yeast extract at pH of 7.0 was measured to be 5.24x108 cells/ml. These results indicate that, to reproduce this isolate inexpensively on industrial scales for inoculum production, the malt sprout extract growth medium containing sucrose and potassium nitrate is recommendable.
کلیدواژهها [English]