Endophytic fungi colonize the inner tissues of plants and provide direct and indirect benefits to the plant. Although Mongolia is rich in medicinal plants, due to climatic and anthropogenic reasons the resources are being depleted and many species are under the threat of gradual extinction, while the endophytic fungi of Mongolian plants are largely unknown. Understanding the diversity and metabolic potential of endophytic fungi is of great significance in terms of the utilization of beneficial fungal strains in plant propagation and the discovery of bioactive compounds. In this study, a total of 24 culturable endophytic fungal strains were isolated from Cynomorium songaricum (Rupr.), a medicinal and vulnerable plant species of Mongolia. Based on the morphological characteristics and the sequences of the rDNA internal transcribed spacer (ITS) region, the isolates were identified to 6 genera: Fusarium (8), Clonostachys (7), Penicillium (6), Alternaria (1), Aspergillus (1), and Madurella (1). The antimicrobial activity was assessed by agar-diffusion method, revealing that 15 strains were able to inhibit the growth of at least one of the test organisms. Among them, 1 strain showed inhibitory activity against Escherichia coli, 12 against Bacillus subtilis, 13 against Staphylococcus aureus, 8 against Aspergillus niger, respectively. All fungal strains were screened for their ability to solubilize complex phosphorus and zinc minerals and for their production of indole-3-acetic acid (IAA). The strains were preserved in the national culture collection for further sustainable exploitation of their biotechnological potential.

This review presents a comprehensive and systematic study of the field of bacterial plant biostimulants and considers the fundamental and innovative principles underlying this technology. Plant biostimulants are an important tool for modern agriculture as part of an integrated crop management (ICM) system; helping make agriculture more sustainable and resilient. Plant biostimulants contain substance(s) and/or microorganisms whose function when applied to plants or the rhizosphere, is to stimulate natural processes to enhance plant nutrient uptake, nutrient use efficiency, tolerance to abiotic stress, biocontrol, and crop quality. The use of plant biostimulants has gained substantial and significant heed worldwide as an environment-friendly alternative for sustainable agricultural production. Presently, there is an increasing curiosity of industry and researchers in microbial biostimulants especially, bacterial plant biostimulants (BPBs) to improve crop growth and productivity. The BPBs that are based on PGPR (plant growth-promoting rhizobacteria) play plausible roles to promote/stimulate the crop plant growth through several mechanisms that include, i) nutrient acquisition by nitrogen (N₂) fixation and solubilization of insoluble minerals (P, K, Zn), organic acids and siderophores, ii) antimicrobial metabolites and various lytic enzymes, iii) action of growth regulators and stress-responsive/induced phytohormones, iv) ameliorating abiotic stress like drought, high soil salinity, extreme temperatures, oxidative stress, and heavy metals by using different modes of action, and v) plant defense induction modes. Presenting here is a brief review emphasizing the applicability of BPBs as an innovative exertion to fulfill the current food crisis.

Bacterial endophytes (120) were isolated from six halophytes (Distichlis spicata, Cynodon dactylon, Eragrostis obtusiflora, Suaeda torreyana, Kochia scoparia, and Baccharis salicifolia). These halophiles were molecularly identified and characterized with or without NaCl conditions. Characterization was based on tests such as indole acetic acid (IAA), exopolysaccharides (EPS), and siderophores (SID) production; solubilization of phosphate (P), potassium (K), zinc (Zn), and manganese (Mn); mineralization of phytate; enzymatic activity (acid and alkaline phosphatase, phytases, xylanases, and chitinases) and mineralization/solubilization mechanisms involved (organic acids and sugars). Eleven halophiles (tolerated NaCl 2.5 M) were identified as Oceanobacillus sp. (1), Bacillus sp. (2), Nesterenkonia sp. (3), Bacillus velezensis (4), Halobacillus sp. (5), Oceanobacillus sp. (6), B. velezensis (7) Halomonas sp. (8), B. pumilus (9), Pseudomonas sp. (10) and Oceanobacillus sp. (11). Biochemical responses of nutrient solubilization and enzymatic activity varied between bacteria and the presence of NaCl. Organic acids were involved in P-mineralization and nutrient solubilization. Tartaric acid was common in the solubilization of P, Zn, and K. Maleic and vanillic acid were only detected in Zn and K solubilization, respectively. Moreover, sugars appeared to be involved in the solubilization of nutrients; fructose was detected in solubilization tests. Therefore, these bacteria should be tested as a consortium to mitigate saline stress in glycophytes under a global climate change scheme that threatens to exacerbate soil salinity.

The use of aerobic granular sludge is a promising and future-proof solution for wastewater treatment. The implementation of this technology requires the development of efficient and cost-effective methods for the management of excess sludge. The aim of the research was to evaluate the effects of hydrodynamic cavitation on the efficiency of aerobic granular sludge digestion. Respirometric measurements were performed at a temperature of 38°C and an initial organic load of 5.0 gVS/L. The changes in the properties of the pre-treated biomass, the kinetics of methane fermentation, the amount and composition of the biogas produced and an energetic evaluation of the process were carried out. A significant influence of hydrodynamic cavitation on the transfer of organic compounds into the dissolved phase was demonstrated. The degree of solubilisation was 37% for COD and 42% and for TOC. The efficiency of CH4 production from the pre-treated sludge reached a value of 496±12 mL/gVS, which corresponds to an increase of 19.6% compared to the raw biomass. The influence of cavitation on the CH4 content of the biogas was not observed. Strong correlations were found between the efficiency of anaerobic digestion and the concentration of dissolved organic compounds and the hydrodynamic cavitation time used. The highest net energy production of 2.89 Wh/gTS was achieved after 15 minutes of pre-treatment.

Cadmium (Cd) is a heavy metal that suppresses plant growth; however, application of endophytic bacteria can increase resistance of plants against Cd, as well as improve plant growth. Two bacterial endophytic strains were isolated from Solanum nigrum and were identified as Serratia sp. AI001 and Enterobacter sp. AI002 by 16S DNA sequencing. Strains AI001 and AI002, tolerated up to 25 mg/mL Cd in broth culture and showed phosphate solubilization potential in Pikovskaya agar medium. AI001 and AI002 produced indole-3-acetic acid, which was confirmed by gas spectrometry-mass chromatography. Brassica plants stressed with 0, 5, 15, and 25 mg/L Cd showed significant decrease in plant growth, chlorophyll content and biomass, and significant increase in Cd dose-dependent electrolyte leakage. Inoculation of strain AI001 or AI002 significantly enhanced the plant growth attributes of shoot length, root length, chlorophyll content, and biomass as compared to those in uninoculated plants. Reduced glutathione contents in plants stressed with different concentrations of Cd also increased with inoculation of AI001 and AI002. The reason of Cd resistance enhancement in plants by inocula could be due to their greater plant growth promoting activities as well as their antioxidative response.

This work compares the multi-element analysis of human hair and nails using inductively coupled plasma mass spectrometry (ICP-MS) with an easy, fast, cheap, non-destructive method using energy dispersive x-ray fluorescence (EDX-RF). The ICP-MS-based method was more sensitive (over 30 elements could be quantified) and costly (requiring more time, sample, and chemicals). The EDX-based method required laboratory and certified reference materials made of hair for instrument calibration. It was less sensitive (16 elements could be quantified: S, Si, Ca, Br, Fe, Cu, Cr, Mg, Si, K, Mn, Ni, Zn, Se, Sr, Pb), but it allowed to replace troublesome grinding with the dissolution of keratin-based material with alkalic agent (tetramethylammonium hydroxide, TMAH) and formation of stable for days pellets. The method is simple, enables automation, and, due to the modification of wells in the autosampler of the EDX system by immersion of home-designed inserts, it requires smaller amounts of biological material and binder (down to 70 mg instead of 500 mg required by commercially available instrument) to perform analysis. It was concluded that the EDX-based method offers complementary selectivity and sensitivity to ICP-MS with the possibility of the reuse of the sample for further analysis.

Phosphorus (P) is the second-most important element after nitrogen that is required for plant growth. Although this element is abundant in most soils, it is rarely available in plant-accessible forms since most of it normally exists in soil in insoluble forms such as phosphates. In conventional agriculture, P is normally supplied as chemical fertilizer to satisfy plant P requirements. This, to a large extent, boosts plant production. However, chemical fertilizers are costly, have a huge carbon footprint, and are environmentally-unsustainable owing to the high energy requirements during their synthesis. Besides, P-containing agricultural run-offs contribute hugely to the eutrophication of water bodies and environmental degradation. Moreover, plants can consume only a small amount of chemically-supplied P since between 75 and 90% of this form of P normally get precipitated into complexes and rapidly become fixed in soil. These issues and concerns necessitate research into alternative and viable ways of supplying P to plants. Rhizobacteria have for decades been investigated in vivo and in planta as suitable tools in sustainable agriculture due to the plant-growth-promoting activities such as nutrients’ solubilization, nitrogen fixation, and production of phytohormones. Although a lot of research has been done on different nutrients-solubilizing rhizobacteria and their potential in sustainable agriculture, their mechanisms of action and prospects in sustainable agriculture remain to be fully understood. This review particularly focuses on the P solubilizing rhizobacteria and evaluates their diversity, mechanisms of action, and prospects in sustainable agriculture based on the present and future scenario of their application. Such information is useful in determining their potential and evaluating their prospects in promoting sustainable agricultural systems.

Endophytic insect pathogenic fungi have a multifunctional lifestyle; in addition to its well-known function as biocontrol agents, it may also help plants respond to other biotic and abiotic stresses, such as iron (Fe) deficiency. This study explores M. brunneum EAMa 01/58-Su strain attributes for Fe acquisition. Firstly, direct attributes include siderophore exudation (in vitro assay) and Fe content in shoots and in the substrate (in vivo assay) were evaluated for three strains of Beauveria bassiana and Metarhizium bruneum. The M. brunneum EAMa 01/58-Su strain showed a great ability to exudate iron siderophores (58.4% surface siderophores exudation) and provided higher Fe content in both dry matter and substrate compared to the control and was therefore selected for further research to unravel the possible induction of Fe deficiency responses, Ferric Reductase Activity (FRA), and relative expression of Fe acquisition genes by qRT-PCR in melon and cucumber plants.. In addi-tion, root priming by M. brunneum EAMa 01/58-Su strain elicited Fe deficiency responses at transcriptional level. Our results show an early up-regulation (24, 48 or 72 h post inoculation) of the Fe acquisition genes FRO1, FRO2, IRT1, HA1, and FIT as well as the FRA. These results highlight the mechanisms involved in the Fe acquisition as mediated by IPF M. brunneum EAMa 01/58-Su strain.