Diversity of culturable endophytic bacteria in Acanthus ebracteatus of Guangxi and their growth-promoting, biocontrol effect and enzyme production activity

【Objective】The aim was to analyze the diversity of culturable bacteria of Acanthus ebracteatus in Guangxi and their growth-promoting, biocontrol effect and enzyme production activity, so as to provide reference for the recovery of A. ebracteatus ilicifolius population and the screening of available strain resources. 【Method】The culturable bacteria in the roots,stems,leaves and rhizosphere soil were isolated and purified by dilution coating method. The 16S rRNA sequence of the strain was amplified by PCR, and the sequencing results were compared by EzBioCloud to determine the taxonomic status of the strain. The growth-promoting phosphate solubilization, nitrogen fixation, indoleacetic acid(IAA) production and siderophore secretion,disease prevention(banana fusarium wilt) and enzyme production(protease, amylase and cellulase) activities of the strains were analyzed by functional medium. 【Result】A total of 159 strains of bacteria were screened from the roots,stems, leaves and rhizosphere soil of A. ebracteatus. According to the colony morphology and the 16S rRNA sequencing results, 65 strains were excluded after duplication, belonging to 8 orders,7 families and 14 genera. Among them, Bacillus was the dominant genus, accounting for 64.62 % of the isolated strains. At the same time, a potential new species(Gxun-T66) was found, and the similarity with the discovered strains was only 98.49%. The results of plant growth-promoting and biocontrol effect showed that 34 strains were phosphorus-solubilizing strains,31 strains were nitrogen-fixing strains,20 strains were IAA-producing strains and 17 strains were siderophoresecreting strains. Among them,strain Burkholderia territorii Gxun-T33 had the strongest ability to dissolve phosphorus and to secrete siderophore; 29 strains had obvious inhibition effect on Fusarium oxysporum f. sp. Cubense,among which strain Bacillus siamensis Gxun-T25 had the best inhibition effect, with an inhibition rate of 69.67%. The results of the enzyme activity showed that there were 56 protease-producing strains,49 amylase-producing strains,48 cellulase-producing strains and 34 strains producing three kinds of enzyme activities at the same time, accounting for 52.31% of the isolated strains. 【Conclusion】The mangrove plant A. ebracteatus is rich in microbial resources and has the activities of promoting growth, biocontrol effect and enzyme production. At the same time, a potential new species has been.