Isolation And Identification Of Endophytic Bacteria From Ginger And Their Plant Growth Promotion Potential

The purpose of this paper is to isolate endophytic bacteria from ginger, and reveal the biodiversity of endophytic isolates, and then screening the high efficient plant growth promotion bacteria, which help exploit the rich endophytic bacteria source in China. In this paper, gingers were collected from Guiyang, Chongqing, Ya’an, Meishan, and the endophytic bacteria were isolated by streak plate method. The genetic diversity of endophytic bacteria was analyzed by BOX-PCR,16S rDNA PCR-RFLP and 16S rDNA sequence analysis of representative strains. Then the bio-control and growth promotion of ginger endophytic bacteria were screened; furthermore, the plant growth promoting (PGP) activity, including IAA producing ability, phosphorus dissolving ability and siderophore producing capacity, and pathogen resistance was explored. The growth promotion effect on Zea mays was evaluated by pot experiments. The results were as the follows:1. A total of 57 endophytic bacteria were isolated from ginger rhizome collected from Chongqing, Sichuan Province, and Guizhou Province, the genetic diversity was analyzed by BOX-PCR and 16S rDNA RFLP, and the phylogeny of representative isolates was constructed by 16S rDNA sequence. The results indicated endophytic bacteria isolated from ginger rhizome belonged to a-Proteobacteria, β-Proteobacteria, y-Proteobacteria and Firmicutes, including the genera Serratia, Enterobacter, Acinetobacter, Pseudomonas, Stenotrophomonas, Agrobacterium, Ochrobactrum, Bacillus and Tetrathiobacter.2. The bio-control ability of 34 representative were measured, the results showed that 11 endophytes was antagonistic to Alternaria solani; 14 endophytic strains were resistant to Fusarium graminearum, and there were 11 endophytic strains were antagonistic to Colletotrichum turcium; Seven bacterial strains were antagonistic to three different pathogenic fungi. PGP experiment of 34 strains showed that, there were 16 strains, including Ochrobactrum, Agrobacterium, Acinetobacter, Stenotrophomonas and Serratia and Bacillus, have IAA producing ability, and the IAA content was 1.02 to 45.35μg/mL; there were 18 strains produced siderophore, their siderophore producing activity was 9.47-70.66%; and there were 16 strains, including Ochrobactrum, Pseudomonas, Acinetobacter, Serratia and Bacillus, had the inorganic phosphorus dissolving ability, when adding 5g/L of Ca-P,2g/L of Al-P, and 1g/L of Fe-P into the liquid culture, and inoculation of teasted strains and incubated for days, the available phosphorus was 9.32-9.32μg/mL,1.14-9.95μg/mL and 1.14-55.42μg/mL.3. Moreover, isolates QW11 (Pseudomonas sp.), QW40 (Ochrobactrum sp.), QW45 (Serratia sp.), QW48 (Ochrobactrum sp.), QW52 (Bacillus sp.) and QW57 (Pseudomonas sp.), were inoculated into Zea mays as effective PGPB strains and PGP efficiency was evaluated. The results showed that these inoculantssignificantly increased the plant height, leaf area, shoot and root dry weight by 17.57-37.61%,20.52-48.54%,25.62-49.64% and 6.10-62.72%, respectively; as well, after inoculating PGPB, the total N, P and K of corn plant increased by 26.76-79.18%,26.32-85.53% and 8.40-26.59% than the control. However, compared with control, inoculation of PGPB and fertilization increased the plant height, leaf area, shoot and root dry weight by 11.26-27.85%,4.96-30.34%,9.79-34.04% and 16.95-48.91%, and the total N, P and K of corn plantl increased by 1.05-85.01%, 5.63-30.28% and 2.64-20.30%, respectively. Meanwhile, inoculation of PGPB increased the number of rhizospheric bacteria, and soil microbial biomass carbon, soil microbial biomass nitrogen and soil microbial biomass phosphorus.