Isolation and selection of endophytic spore-forming bacteria with plant growth promoting properties isolated from Ilex paraguariensis St. Hil. (yerba mate)

Abstract

Yerba mate (Ilex paraguariensis St. Hil.) is a species native to the subtropical regions of South America. Despite being an important crop for the region, there are few studies on the use of microorganisms to improve the growth of seedlings in the nursery stage. The objective of this study was to isolate spore-forming endophytic bacteria with plant growth promoting properties associated with yerba mate seedlings and determine their phytobeneficial effect under controlled laboratory conditions. Isolates were selected based on their sporulation capacity and evaluated for in vitro plant growth promoting properties (nitrogen fixation, phosphate solubilization, production of siderophores and synthesis of indolic compounds). Yerba mate seedlings were inoculated with the most promising isolates, which were identified via analyses of the sequence of their 16S rDNA gene as Bacillus circulans (12RS3) and Bacillus altitudinis (19RS3, T5S-T4). After 120 days plants showed higher root dry weight when inoculated with isolate 19RS3 and higher shoot dry weight with 19RS3 and T5S-T4. In conclusion, further studies to determine the ability of these isolates to adapt to the climatic conditions and to survive amidst the native soil microflora in yerba mate cultivated native soils, will be crucial for developing such strains as biofertilizer.

De novo genome assembly of Bacillus altitudinis 19RS3 and Bacillus altitudinis T5S-T4, two plant growth-promoting bacteria isolated from Ilex paraguariensis St. Hil. (yerba mate)

“…The presence of nif (U) and nif(S) was also determined in both genomes suggesting the possibility of the strain to fix environmental nitrogen. The properties mentioned above are consistent with the in vitro and in vivo PGP activities determined experimentally in previous studies for both strains [41].…”

“…In the present study, we predicted genes and enzymes associated with PGP mechanisms in the B. altitudinis 19RS3 and B. altitudinis T5S-T4 genomes. We detected genes related to the conversion pathway of tryptophan to indole, which is consistent with the determined indole production observed in the in vitro assays [41]. The presence of the bacillibatin gene cluster showed the potential of siderophore production, while the detection of Pi transporters and the Pho regulon indicated a possibility for inorganic phosphate solubilization.…”

“…altitudinis 19RS3 and B. altitudinis T5S-T4 were isolated from roots of I. paraguariensis St. Hil. seedlings [41]. Both strains were identified by analysis of 16S rRNA gene sequencing (accession number MH883312 and MH883235, respectively) and characterized as Gram-positive endospore-forming rod-shaped bacteria.…”

“…Both strains were identified morphologically and molecularly as Bacillus altitudinis. Also, B. altitudinis 19RS3 and B. altitudinis T5S-T4 showed in vivo growth promotion in yerba mate seedlings in greenhouse conditions with promising results [41].…”

Selección y caracterización de microorganismos con capacidad antifúngica y fertilizante aislados de la rizosfera de plantas de yerba mate de la provincia de Misiones para su aplicación como promotores del crecimiento vegetal

“…de la raíz de yerba mate presentaron la capacidad de promoción del crecimiento en vivero en plantas de yerba mate (Laczeski et al, 2020).…”