Studies On Plant Growth-Promoting Rhizobacteria Of Tea Rhizosphere

Rhizosphere microbes is an important biological group in rhizosphere micro-ecology which greatly impacted on plant growth. In this study, rhizosphere microbes were isolated through selective medium, quantity analysis of rhizosphere bacteria, fungi, actinomyces in different tea plantation were conducted. Azotobacter, Phosphobacteria and Bacillus mucilaginosus were selected through selective medium. Some Plant Growth-Promoting Rhizobacteria of tea rhizosphere were selected by biological method and were identified further, which were supposed to be with the potential of secreting plant hormone or to be with significant antibiotic ability against plant pathogeny. One strain antibiotic material was purified and its Physico-chemical qualities were studied. The results as following.1, Rich tea plantation soils had higher rhizosphere microbe population densities than poor tea plantation soils. In the tea plantations of similar fertility, the population density of rhizosphere bacteria varied with cultivation age of the plantations, following a pattern of 10 year > 4 year > 20 year. The population density of rhizosphere fungi in rich tea plantations was more than that in normal and poor tea plantations. The population density of actinomyces in 20 years old tea plantations was significantly higher than that in 4 or 10 year old tea plantations; and moreover, poor tea plantation soils had the greatest population density of actinomyces.In the same fertility soil, the population of azotobacter became smaller with the tea age increase, especially in poor soil. Phosphobacteria and Bacillus mucilaginosus showed the same trend. As to same tea age, the population of azotobacter became smaller with the soil fertility decrease. In 4 years' tea plantation, the population of Phosphobacteria and Bacillus mucilaginosus had no apparently relationship with soil fertility; in 10 years' tea plantation, that of two kinds of bacteria decreased with the soil fertility decrease; in 20 years' tea plantation, however, that of two kinds of bacteria increased with the soil fertility decrease.2, In this experiment, 3 strains with the potential ability of secreting plant hormone, 10 azotobacter strains, 8 Phosphobacteria strains, 2 Bacillus mucilaginosus strains and 1 antibiotic strain were selected.3 , By cell form , colony observation and the bio-chemical analysis, N42, N50, N80 and N119 were identified as Beijerinckia; N46 and N49 were identified as Azomonas; N107 and N152 were identified as Xanthobacter; N120 and N115 were identified as Azotobacter, P54, P121, P126, P129 and PG7 were identified as Pseudomonas; P38, P55, P124, P127, K44 , K46 and PG36 w ere i dentified as Bacillus, PG20 w ere i dentified as Agrobacterium; By cell form and colony observation, bio-chemical analysis and 16SrDNA BLAST, A95 was identified as Bacillus globisporus, GENE BANK accession number is AY292989.4, A95 Culture was concentrated by ammonium sulphate, column chromatography on Sephadex G-100, DEAE-Sepharose Fast Flow and Sephadex G-50. And what's more, antibiotic protein was purified and detected molecular weights as 40.7KD by SDS-PAGE. This purified proteinis insensitive to heat .resistant to trypin, proteinase K, however, it is sensitive chloroform. Its pH active range was wide from 4.0 to 11.0.