The aim of our research was to study the endosphere of four halophytic plants: Salicornia europaea L., Salsola australis (R.Br.), Bassia sedoides (Pall.) and Kochia prostrata (L.) Schrad. from arid and saline areas of the Stavropol Territory, Russia. In total, 28 endophyte strains were isolated from the roots and stems of these halophytic plants. Most of the isolates (23 out of 28) were identified as Bacillus sp. while others belonged to the genera Oceanobacillus, Paenibacillus, Pantoea, Alcaligenes and Myroides. Three strains of Bacillus sp. (Se5R, Se1-1R, and Se1-3S), isolated from the S. europaea were capable of growth at 55 °C and in 10% of NaCl. Strains Se1-4S, Kp20-2S, and Bs11-2S Bacillus sp. (isolated from the S. australis, K. prostrata and B. sedoides, respectively) demonstrated strong plant growth promoting activity: 85–265% over control lettuce plants and a high degree of growth suppression (59.1–81.2%) of pathogenic fungi Fusarium oxysporum, Bipolaris sorokiniana and Rhizoctonia solani. Selected strains can be promising candidates for the development of bioinoculants to facilitate salt soil phytoremediation and be beneficial for mitigating the salt stress to the plants growing in salt-affected habitats.
Some strains of
Bacillus vallismortis
have been reported to be efficient plant-growth-promoting bacteria as well as inducers of systemic resistance. Here, we report the draft genome sequence of
Bacillus vallismortis
strain BL01, isolated from the roots of
Artemisia lerchiana
Web.
The plant growth-promoting bacterium Bacillus velezensis BS89 was isolated from the rhizosphere of winter wheat. Strain BS89 has the ability to promote plant growth and produce a mix of auxins and vitamins. Here, we sequenced the complete genome of this strain to understand the molecular mechanisms underlying its beneficial activities.
Biomodified mineral fertilizers (BMFs) were produced by enriching the ammophos fertilizer with PGPR Bacillus velezensis BS89 with the use of two technologies: BMF 1, the ammophos fertilizer with the addition of spores of Bacillus velezensis BS89 on a dry carrier (diatomite); and BMF2, ammophos granules treated with spores of Bacillus velezensis BS89 in a cell suspension. The effects of BMFs on maize growth and productivity and the rhizosphere bacterial community were assessed. BMFs significantly increased maize growth, dry matter, minerals, starch and protein contents in maize grain. The application of biomodified mineral fertilizers resulted in the significant increase in the yield and some parameters of maize plants such as ear length and number of kernels in the row. The yield was increased by 7.5–7.6%, ear length by 9%, and number of kernels in the row by 6.7–7%, as compared with ammophos. However, we found no considerable differences in the composition of the bacterial community of the maize rhizosphere after the use of BMFs as compared with the use of ammophos at the level of the phyla, which was confirmed by the ecological indices of biodiversity: the Shannon index and the Simpson index. Comparison of the experimental variants with bulk soil showed differences in the microbiome composition of the dominant bacterial phyla. A greater abundance of Proteobacteria and Bacteroidetes and a lower abundance of Chloroflexi was registered in bulk soil as compared with the other experimental variants where maize plants were present. The highest percentage (5.3%) of unidentified taxonomic phyla was also found in bulk soil. Our studies showed that maize is the main structuring factor during formation of the microbiome composition in the rhizosphere. The application of biomodified fertilizers BMF1 and BMF2 considerably increased the abundance of bacteria representing the minority of the community, namely, those from the phyla Verrucomicrobia, Chloroflexi, Planctomycetes, Proteobacteria, Firmicutes and Chlamydiae, as compared with the use of ammophos. Thus, the application of biomodified mineral fertilizers is a promising agronomic and ecological strategy for boosting maize yield and the quality of grain under field conditions.
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