Abstract

‘Los Negritos” is an extremophile geothermal site from Michoacan State, Mexico. Evidence of the diversity of its microbiota and its potential is still lacking. This study aimed to evaluate the bacterial communities by 16S metagenomics of the site and the potential of culturable bacteria isolated from the site by promoting growth plants (PGP) traits. Gemmatimonadetes phylum was the most abundant, followed by Actinobacteria, Alphaproteobacteria, and Firmicutes. A total of 15 culturable strains were isolated and identified. They belong to five different species: Bacillus seohaeanensis, Jeotgalibacillus alkaliphilus, Halobacillus andaensis, Thalassobacillus devorans, and Halobacillus campisalis. The phytohormone indole-3-acetic acid (IAA) production was in the interval from 14.78 to 46.52 mg L⁻¹. The best IAA producers were T. devorans E18 and H. campisalis E20 with tryptophan and H. andaensis, T. devorans, and H. campisalis without tryptophan ranging 39.8 to 51.5 mg L⁻¹. Phosphorous solubilization capability was detected in J. alkaliphilus and T. devorans, whereas B. seohaeanensis was the highest ammonium producer (34.1 ± 0.52 mg L⁻¹) and H. andaensis was positive for siderophore production. These results demonstrate that, despite the low diversity, bacteria isolated from ‘Los Negritos’ have the potential for plant growth promotion.

摘要

“ Los Negritos”是来自墨西哥米却肯州的极端极端地热站点。仍然缺乏其微生物群多样性及其潜力的证据。这项研究旨在通过该部位的16S宏基因组学评估细菌群落，以及通过促进生长植物（PGP）性状从该部位分离出可培养细菌的潜力。门芽孢杆菌最丰富，其次是放线菌属，丙酸杆菌属和Firmicutes。总共分离并鉴定了15种可培养菌株。他们属于五个不同的种类：seohaeanensis芽孢杆菌，Jeotgalibacillus alkaliphilus，Halobacillus为andaensis，Thalassobacillus devorans和Halobacillus为campisalis。植物激素吲哚-3-乙酸（IAA）的产量介于14.78至46.52 mg L ^-1之间。IAA的最佳生产者是带色氨酸的德氏嗜血杆菌E18和喜树嗜血杆菌E20，不带色氨酸的安达氏嗜血杆菌，喜树嗜酸杆菌和喜树嗜血杆菌的生产范围为39.8至51.5 mg L ^-1。在嗜碱芽孢杆菌和嗜热芽孢杆菌中检出了磷的增溶能力，而南美黑藻（B. seohaeanensis）是最高的铵产生者（34.1±0.52 mg L ^-1）和安达拉斯汉ensis。对铁载体的生产是积极的。这些结果表明，尽管多样性低，但从“ Los Negritos”中分离出的细菌仍具有促进植物生长的潜力。