The present study demonstrates the Ni toxicity-ameliorating and growth-promoting abilities of two different bacterial isolates when applied to wheat (Triticum aestivum L.) as the host plant. Two bacterial strains tolerant to Ni stress were isolated from wheat seeds and selected based on their ability to improve the germination of wheat plants; they were identified as Bacillus megaterium AFI1 and Paenibacillus nicotianae AFI2. The protective effects of these epiphytic bacteria against Ni stress were studied in model experiments with two wheat cultivars: Ni stress-tolerant Leningradskaya 6 and susceptible Chinese spring. When these isolates were used as the inoculants applied to Ni-treated wheat plants, the growth parameters and the levels of photosynthetic pigments of the two wheat cultivars both under normal and Ni-stress conditions were increased, though B. megaterium AFI1 had a more pronounced ameliorative effect on the Ni contents in plant tissues due to its synthesis of siderophores. Over the 10 days of Ni exposure, the plant growth promotion bacteria (PGPB) significantly reduced the lipid peroxidation (LPO), ascorbate peroxidase (APX), superoxide dismutase (SOD) activities and proline content in the leaves of both wheat cultivars. The PGPB also increased peroxidase (POX) activity and the levels of chlorophyll a, chlorophyll b, and carotenoids in the wheat leaves. It was concluded that B. megaterium AFI1 is an ideal candidate for bioremediation and wheat growth promotion against Ni-induced oxidative stress, as it increases photosynthetic pigment contents, induces the antioxidant defense system, and lowers Ni metal uptake.

Common protocols for the loading of 2-CTC and MBH-Br resins presume the application of DCM, THF, or DMF; these solvents are considered as undesirable in accordance with modern regulatory rules. An alternative option implies the usage of rather expensive 2-MeTHF. Herein, we describe the application of an EtOAc/AcN (1:1) mixture as an efficient solvent alternative for the incorporation of the first amino acid. We show that the suggested reaction conditions ensure a loading level comparable to the usage of DCM, THF, 2-MeTHF, and DMF. The described procedure was designed for the kilogram-scale synthesis of a palmitoyl-hexapeptide.

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.

No abstract