title: Population and function analysis of cultivable bacteria associated with spores of arbuscular mycorrhizal fungus Gigaspora margarita.
abstract: This study was aimed to investigate the diversity and function of bacterial population associated with Gigaspora margarita spores. The fungus was propagated in sterilized sand/soil pots using alfalfa (Medicago sativa), grain sorghum (Sorghum bicolor), or maize (Zea mays) as host plants, or in sterilized vermiculite pots using alfalfa as host plants, respectively. Bacteria were isolated from the new-formed spores using diluted plate method, and typical bacterial isolates were identified according to 16S rRNA gene phylogenetic analysis. Total 43 bacterial isolates affiliated to three phyla and 23 genera were obtained. The spore-associated bacterial communities were obviously different among the four source spores, suggesting that plant species or substrates could influence the bacterial population. Bacillus and Streptomyces were most frequently associated with the fungal spores. Function analysis of these bacteria by plate tests, it was found that about 30.2% isolates stimulated the spore germination, five out of seven tested isolates improved the hyphal growth, total 57.5% of the tested isolates solubilized phosphorus at different levels, 15% isolates degraded chitin, and a few isolates suppressed the growth of Escherichia coli or Staphylococcus aureus. In pot experiment, three bacterial isolates (belonging to Curtobacterium, Ensifer, or Bacillus, respectively) displayed improvement effect on alfalfa growth and/or the colonization of roots by G. margarita.
authors.affiliation: College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, China. longlk602@njfu.edu.cn.
authors.forename: Liangkun
authors.identifier: http://orcid.org/0000-0001-7302-6330
authors.initials: L
authors.lastname: Long
authors.affiliation: Nanjing Institute for the Comprehensive Utilization of Wild Plants, Nanjing, 210042, China.
authors.forename: Qunying
authors.initials: Q
authors.lastname: Lin
authors.affiliation: College of Horticulture, South China Agricultural University, Guangzhou, 510642, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Yao
authors.affiliation: Guangdong Institute of Microbiology, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, State Key Laboratory of Applied Microbiology South China, Guangzhou, 510070, China. zhuhh@gdim.cn.
authors.forename: Honghui
authors.initials: H
authors.lastname: Zhu
keywords: Cultivable bacteria; Fungal spores; Plant growth promotion; Stimulation of spore germination