Studies On Culture Characteristics And Effect On Salt Stress Relieving And Growth Promoting Of The Strain Klebsiella Oxytoca Rs-5

The results of pervious studies indicated that the strain Rs-5 could increase the germination and growth of cotton under salt stress, obviously. Meanwhile, the strain got the ability to dissolve the non-soluble phosphorus in soil and produce the phytohormone IAA. For the utilizing of the bacterium better and better in the future, the studies were carried on the culture characteristics, the effect of the salt stress relieving and plant growth promoting of the strain, kinetics and mechanism of phosphorus dissolving and the relationshio between the effect of the strain with the effect of salt stress on the growth of cotton seedlings.The growth of the strain Rs-5 entered into logarithm growth phase after 3th inoculation and entered into steady phase after 24h, and keeping steady in the 48h later. The quantity of strain Rs-5 had the maximum in corn flour medium. Both nitrate and ammonium nitrogen source could be used by the strain Rs-5 and no selectivity. The soy flour was best for the growth of the strain and the urea was opposited. The best inoculated volume was 3ml and the best culture temperature was 30℃. The best pH was 7 and the best rotate speed was 180 rotate per minute, and 70ml medium volume in 250 ml shaking bottle was best for culture of the strain.The germination rate, the growth of the cotton seedlings and the dry weight were increased after the cotton seed inoculated by the strain Rs-5. And the lipid peroxidation degree was decreased remarkably. The measures such as proline, soluble sugar and soluble protein, related with the anti-salt stress ability of cotton were increased obviously. Meanwhile, the endogenous IAA content was increased and the IAA oxidase ability was decreased. It was testified that the strain Rs-5 mitigated the effect of salt stress and promoted the plant growth in some degree.The kinetics model of the strain Rs-5 for P dissolving was growth-related style. The dissolved phosphorus content was positive relationship with the biomass of the strain Rs-5. Meanwhile, the dissolved P value was negative relationship with the pH value of the fermentation broth. It was testified that some acids were produced during the P dissolving, and the content of these substances should be related with the dissolved P value. The organic acids varieties and content were determined with high performance liquid chromatogram (HPLC). Citric acid, malic acid, lactic acid and acetic acid were determined and the content of citric acid and malic acid were much more than others. It was also testified that the content of citric acid and malic acid were positive relation with the dissolved P value. It was concluded that the citric acid and malic acid produced by the strain Rs-5 were the primary reason of p dissolving. The exogenous tryptophan appended could increase the content of IAA produced by the strain. The exogenous tryptophan content was consumed rapidly as soon as the growth of the strain Rs-5 entering into steady period. And the IAA produced content increased rapidly following. The relation between the tryptophan consumption value and the IAA produced content was negative and linear relationship. The different components of fermentation broth of the strain Rs-5 were isolated and used to treat the cotton seeds. The germination and growth of cotton seedlings testified that the bacterium itself and the IAA produced by it played an important role in salt stress relieving and cotton growth promoting. And the effect of the bacterium itself was better than the effect of IAA produced. The experiment results of different IAA concentration indicated that the exogenous IAA could relief the restrain on endogenous IAA content in plant because of the salt stress.The experiment of cotton germination and growth under different salt stress intensity indicated that the germination rate and growth were decreased as the enhancement of the salt stress intensity. The effect of salt stress on cotton was mitigated in some degree when the strain existing. When the OD value of the fermentation broth of the strain less than and equal to 0.3, the germination rate and growth of cotton were increasing as the enhancement of the OD value. However, the strain fermentation broth also would restrain the germination and growth of cotton when the OD value was higher than 0.6.