Phosphate Solubilization Research Articles

Use of a natural rock material as a precursor to inhibit corrosion of Ti alloy in an aggressive phosphoric acid medium

The mechanism of interaction between magnesite mineral and phosphoric acid (0.001–0.5 M) in addition to the determination of the protective properties for Ti alloy (working electrode) in phosphoric acid both with and without an inhibitor have been investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. Results of electrochemical tests show that the corrosion resistance of titanium alloy in phosphoric acid solution only increased and hydrogen production decreased by either decreasing acid concentration or increasing immersion time associated with the thickening of the oxide film formed on the alloy surface. On adding magnesite, the corrosion resistance of Ti alloy is enhanced by increasing the phosphoric acid concentration (0.001–0.5 M) due to the formation of sparingly soluble magnesium phosphate film on the alloy surface that inhibits the effect of increasing hydrogen evolution reaction due to the pH value decreases. The increasing adsorption behavior of the magnesite inhibitor and decreasing its diffusion were deduced from EIS measurements. Thus, the addition of 3% magnesite minimizes the corrosion by forming a new protective film (Mg3(PO4)2), which differs from the traditional passive film and prevents the effect of the increase of hydrogen evolution. The surface morphology and chemical composition of the tested alloy were determined using scanning electron microscopy (SEM), Fourier transform Infra-Red spectroscopy (FTIR), X-ray diffraction (XRD), X-ray Fluorescence (XRF) and In situ Raman spectroscopy.

Impact of Bacillus cereus SPB-10 on Growth Promotion of Wheat (Triticum aestivum L.) Under Arsenic-Contaminated Soil.

This study investigates the impact of bacteria on arsenic reduction in wheat plants, highlighting the potential of microbe-based eco-friendly strategies for plant growth. In the present study, bacterial isolate SPB-10 was survived at high concentration against both form of arsenic (As3+ and As5+). SPB-10 produced 5.2g/L and 11.3g/L of exo-polysaccharide at 20ppm of As3+ and As5+, respectively, whereas qualitative examination revealed the highest siderophores ability. Other PGP attributes such as IAA production were recorded 52.12mg/L and 95.82mg/L, phosphate solubilization was 90.23mg/L and 129mg/L at 20ppm of As3+ and As5+, respectively. Significant amount of CAT, APX, and Proline was also observed at 20ppm of As3+ and As5+ in SPB-10. Isolate SPB-10 was molecularly identified as Bacillus cereus through 16S rRNA sequencing. After 42days, wheat plants inoculated with SPB-10 had a 25% increase in shoot length and dry weight, and 26% rise in chlorophyll-a pigment under As5+ supplemented T4 treatment than control. Reducing sugar content was increased by 24% in T6-treated plants compared to control. Additionally, SPB-10 enhanced the content of essential nutrients (NPK), CAT, and APX in plant's-leaf under both As3+ and As5+ stressed conditions after 42days. The study found that arsenic uptake in plant roots and shoots decreased in SPB-10-inoculated plants, with the maximum reduction observed in As5+ treated plants. Bio-concentration factor-BCF was reduced by 90.89% in SPB-10-inoculated treatment T4 after 42days. This suggests that Bacillus cereus-SPB-10 may be beneficial for plant growth in arsenic-contaminated soil.

Study on Plant Growth Promoting Traits of PGPR Isolates From Semi-Arid Kachchh, Gujarat Under Salt Stress Conditions

Salinity is a major problem in the agricultural sector, as it turns productive agronomical land to become unproductive. Therefore, Plant-growth-promoting rhizobacteria (PGPR), that live in the plant root zone named the rhizosphere, is one of the prominent solutions to overcome this problem in an eco-friendly manner as Rhizobacteria responds to osmotic stress and support plant development. Thus, the present study was aimed to characterize various traits of the PGPR strains isolated from saline soils of Kachchh. The characterization of the traits in the presence and absence of sodium chloride was assessed including IAA production (76.97±1.68 mg/l), Ammonia production (38.59±0.19 mg/l), Siderophore production (49.21±1.83%), Phosphate solubilization (4897.73±25.53 mg/l). When assessed for the salt tolerance of the strains in the presence of NaCl between 20-50 gm/L, the strain D6 exhibited a better growth even at 5% NaCl concentration (2.047OD). Further, the effect of PGPR on the growth of V. radiata was 100% in all the experimental setup, whereas in case of B. juncea, the highest germination of 96.67% was observed only in T2 and T1+T2+T3. Further, the molecular sequencing of the strains revealed the identification of the strains as Klebsiella quasipneumoniae, Bacillus paralicheniformis and Klebsiella pneumoniae.

Growth-promoting effects of Aspergillus Elegans and the dark septate endophyte (DSE) Periconia macrospinosa on cucumber.

Cucurbits are subject to a variety of stresses that limit their sustainable production, despite their important role in ensuring food security and nutrition. Plant stress tolerance can be enhanced through fungal endophytes. In this study, two endophytes isolated from wild plant roots, were tested to determine their effect on the growth promotion of cucumber (Cucumis sativus L.) plants. The phylogenetic analysis revealed that the designated isolates were Aspergillus elegans and Periconia macrospinosa. The results of the Plant Growth Promoting Fungal (PGPF) tests showed that both Aspergillus elegans and Periconia macrospinosa have a zinc solubilizing capacity, especially A. elegans, with a solubilization index higher than 80%. Also, both have a high salt tolerance (10-15% NaCl for P. macrospinosa and A. elegans, respectively), cellulolytic activity, and inhibition indices of 40-64.53%. A. elegans and P. macrospinosa had antagonistic effects against the cucumber phytopathogenic fungi Verticillium dahliae and Fusarium oxysporum, respectively. However, A. elegans and P. macrospinosa didn't exhibit certain potential plant benefits, such as the production of hydrogen cyanide (HCN) and phosphate solubilization. The chlorophyll content and growth parameters of two-month-old cucumber plants inoculated with the fungal species were significantly better than those of the controls (non-inoculated); the shoot dry weights of inoculated plants were increased by 138% and 170% for A. elegans and P. macrospinosa, respectively; and the root colonization by fungal endophytes has also been demonstrated. In addition to the fact that P. macrospinosa has long been known as PGPF, this is the first time that the ability of A. elegans to modulate host plant growth has been demonstrated, with the potential to be used as a biofertilizer in sustainable agriculture.

Characterization of Chitinolitic Bacteria from Hermatia illucent Larvae Waste: Antifungal Activity, Hydrolytic Enzyme, and Phosphate-Potassium Solubilization

Hermetia illucens larvae, also known as the black soldier fly larvae, are best known as the decomposers of organic matter. There are many potential microbes found in the feces of BSF larvae. This research aimed to isolate the chitinolytic bacteria from chicken manure maggot waste, identify the antifugal activity, hydrolytic enzyme activity, phosphate and potassium solubilization, and bacterial species through 16S rRNA gene analysis. The initial screening focused on bacteria with chitinolytic ability. Antifungal activity tests were performed against phytopathogenic fungi, Colletotrichum sp. Isolate MKP02 showed the highest activity in inhibiting the growth of Colletotrichum sp. up to 100% and produced protease and cellulase enzymes, along with the ability to solubilize potassium. Furthermore, the potential isolate MKP04, the isolate shows the highest cellulolytic activity with a percentage of 300%. It can inhibit Colletotrichum sp. fungi, as well as having lipase enzyme content, and being able to dissolve potassium. The results of 16S rRNA gene amplification on the two isolates showed that both isolates were close to bacteria of the genus Lysinibacillus and Brevibacterium. This research is expected to provide valuable information about the bacterial content, levels of hydrolytic enzymes, and the ability to solubilize phosphate and potassium in BSF.

Isolation and Molecular Profiling of Halotolerant Plant Growth Promoting Rhizosphere Fungi from Salt affected Agroforestry Plantation

Soil salinity is a major abiotic stress that adversely affects plant growth, and productivity. About 20% of irrigated lands are affected by salinity worldwide; In India, there are 6.74 million hectares of salt-affected lands. Salt-tolerant Plant Growth Promoting (PGP) microorganisms can enhance the growth of plants in such salt-stressed areas. Therefore, this study aimed to investigate the diversity of beneficial fungal communities, screen for their ability to support plant growth, and evaluate the production of various essential compounds in view of plant growth in salt-stressed lands. A total of 68 fungal colonies were isolated from 5 different agroforestry plantation sites in Karur, Tamil Nadu, South India at quarterly intervals. The isolates were screened for sodium chloride (NaCl) tolerance (0%, 5%, 10%, 15%, and 20% concentration). A total of 7 isolates showed considerable salt tolerance and were tested qualitatively in-vitro, for PGP traits such as phosphate, potassium, and zinc solubilization, nitrogen fixation, hydrogen cyanide production, siderophore production, and ACC deaminase production. Finally, 5 isolates with maximum values for PGP properties under 20% NaCl concentration were tested for the quantity of Indole-3-Acetic Acid (IAA) and Exo-polysaccharide (EPS) production. All 5 isolates were identified up to the species level using 18S rRNA gene sequencing. To the best of our knowledge, this is the first report on isolating saline-tolerant PGP Fungi (PGPF) from the rhizosphere region of Casuarina equisetifolia and Eucalyptus camaldulensis in Karur, Tamil Nadu, India. In the future, the bioformulation of PGPF and its application will boost the cultivation of tree saplings in this salt affected regions.

Antifungal Potential of Bacillus subtilis subsp. inaquosorum RLS76 for Management of Fusarium Wilt Disease of Bt- Cotton

Fusarium wilt is a destructive disease affecting Bt cotton that is caused by Fusarium oxysporum f. sp. vasinfectum. This seed and soilborne disease pose a significant risk to Bt cotton production worldwide, including India. Therefore, to cope with this problem in an eco-friendly manner, we explored the potentiality of the rhizobacterial isolate possessing antifungal activity as a natural arsenal against the fungal pathogen fusarium wilt of Bt cotton. The rhizobacterial isolate RLS76 inhibited 85.39% of the fungal phytopathogen in the dual culture method. The RLS76 isolate's 16S rRNA partial gene sequence was determined to be Bacillus subtilis subsp. inaquosorum RLS76, with a closest phylogenetic affiliation of 99.53%. The crude extract of Bacillus subtilis subsp. inaquosorum RLS76 demonstrated 34.38% inhibition of the growth of the pathogen after a week of incubation by using an agar well diffusion method. Bacillus subtilis subsp. inaquosorum RLS76 produced volatile organic compounds that inhibited the fungal growth of phytopathogens by 54.84% in a closed environment. Also, GCMS analysis of the crude extract of Bacillus subtilis subsp. inaquosorum RLS76 identified four compounds, namely Pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-; Pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl); 2,5-cyclohexadiene-1,4-dione, 2,5-Dihydroxy-3-methoxy-6-methyl-; 9,12-Octadecadienoic acid (Z,Z)-,phenylmethyl ester. Out of four compounds, three exhibit antimicrobial activity except 2,5-Dihydroxy-3-methoxy-6-methyl. The RLS76 strain of Bacillus subtilis subsp. inaquosorum displayed a transition in hue, shifting from blue to orange, surrounding the colony on CAS medium by producing siderophore qualitatively. The quantitative siderophore produced in the crude extract was 86.06 SU after 60-72 h of incubation. The RLS76 strain of Bacillus subtilis subsp. inaquosorum also showed the ability to produce a proteolytic enzyme outside the cell. This enzyme caused a noticeable clear zone around the colony when the bacteria were grown on a skim-milk agar plate. The Bacillus subtilis subsp. inaquosorum RLS76 also exhibited phosphate solubilization activity with the clear halo around the colonies on NBRIP medium. All these results suggest that Bacillus subtilis subsp. inaquosorum RLS76 exhibits good biocontrol as well as a plant growth promoting candidate against the phytopathogen of Fusarium wilt of Bt cotton.

Uncovering the secret weapons of an invasive plant: The endophytic microbes of Anthemis cotula

Understanding plant-microbe interaction can be useful in identifying the microbial drivers of plant invasions. It is in this context that we explored the diversity of endophytic microbes from leaves of Anthemis cotula, an annual plant that is highly invasive in Kashmir Himalaya. We also tried to establish the role of endophytes in the invasiveness of this alien species. We collected and processed leaf samples from three populations at three different sites. A total of 902 endophytic isolates belonging to 4 bacterial and 2 fungal phyla were recovered that belonged to 27 bacterial and 14 fungal genera. Firmicutes (29.1%), Proteobacteria (24.1%), Ascomycota (22.8%) and Actinobacteria (19%) were dominant across all samples. Plant growth promoting traits, such as Ammonia production, Indole Acetic Acid (IAA) production, Phosphate solubilization and biocontrol activity of these endophytes were also studied and most of the isolates (74.68%) were positive for ammonia production. IAA production, phosphate solubilization and biocontrol activity was present in 39.24%, 36.70% and 20.26% isolates, respectively. Furthermore, Botrytis cinerea, a pathogen of A. cotula in its native range, though present in Kashmir Himalaya does not affect A. cotula probably due to the presence of leaf endophytic microbial antagonists. Our results highlight that the beneficial plant growth promoting interactions and enemy suppression by leaf endophytes of A. cotula, may be contributing to its survival and invasion in the Kashmir Himalaya.

Phosphorus starvation response genes and function coupling: A mechanism to regulate phosphorus availability in a subtropical estuary

Phosphorus (P) plays an important role in regulating primary production in estuarine environments. However, knowledge of the P-functional gene composition of microbial communities and the mechanisms of microbial adaptation to changes in available P in estuaries remain limited. This study coupling 16 s rDNA and metagenomics sequencing was conducted to reveal the relationship between P cycling functional genes, microbial interactions, and P availability in the Jiulong River Estuary. The results showed that the relative abundance of P cycling functions genes was highest in winter, and lowest in summer. Spatially, the total relative abundance of P cycling functions genes was higher in the riverward than that in the seaward. P cycling functional microbial interactions and P cycling gene coupling were strongest in summer and in the seaward. Changes in both temperature and salinity had significant direct and indirect effects on P cycling function, and the influence of salinity on P cycling function was greater than that on the microbial community in the estuary. Salinity had significant direct negative effects on inorganic P-solubilization (IP), organic P-mineralization (OP), and P uptake and transport functions (PT). Whereas, salinity had a significant positive effect on P-starvation response regulation (PR) function. Thus, salinity and microbial communities regulate the soluble reactive phosphate concentrations in estuarine environments by strengthening internal coupling among P cycling functions, promoting PR function, and facilitating PT gene expression. PR is the most important predictors, PR, PT, and PR-PT together explained 38.56 % of the overall soluble reactive phosphorus (SRP) variation. Over 66 % of the explained SRP variations can be predicted by the PR, PT, and PR-PT functional genes. This finding improves the knowledge base of the microbial processes for P cycling and provides a foundation for eutrophication management strategies in the estuary.

Assessing Microbial Diversity in Páramo Soils (Multistrategy Analysis): Effects of Potato Farming and Livestock Grazing in Nevados National Natural Park, Colombia

High Andean Páramos are very fragile neotropical ecosystems. Moreover, biodiversity in these areas is threatened by the anthropic activities of agriculture, cattle raising, and mining and has been little studied. Changes associated with potato farming and livestock grazing on microorganisms of Páramo soil of the Nevados National Natural Park (Nevados NNP) were assessed by (1) determination of physical and chemical properties (physicochemical matrix) and enzymatic activities associated (enzymatic activity matrix) with different biogeochemical cycles (C, N, and P); (2) microbial community functional diversity via evaluation of functional groups associated with carbon, nitrogen, and phosphorus cycles using cultivation-dependent techniques (arable functional group matrix and most probable number matrix); and (3) microbial diversity using cultivation-independent techniques that employ the hypervariable V5–V6 region of the 16S rRNA gene and pyrosequencing (16S-454 genus matrix and 16S-454 OTU matrix). Four of the six evaluated matrices (physicochemical, enzymatic activities, most probable number, and arable functional groups) revealed significant differences according to land use. The strategy adopted by the arable functional group matrix, in which the diversity of nitrogen fixation, phosphate solubilization, and cellulolytic compounds was evaluated, showed the most significant impacts of the different factors (land use, season, and elevation), especially those caused by potato cultivation and livestock. These results indicate that the initial impacts of potato farming and livestock grazing on the microbial community in El Bosque Village are better detected by functional diversity analysis than by molecular analysis of the 16S rRNA gene V5–V6 variable region. The results may have been caused by the type of molecular marker used in the analyses and the type of agricultural practices used by peasant farmers, which affect the functional diversity of the soil community. Among these practices are the maintenance of fallow periods greater than 7 years between each potato crop and the small proportion of cattle in relation to the total land area of the village. As the findings can be interpreted as an indicator of the early impacts of potato cultivation and livestock on microbial diversity, the effects of implementing community management plans, applying agroecological models, retaining biocultural memory, and changing agrarian structure are relevant for mitigating future changes.

Improving Lead Phytoremediation Using Endophytic Bacteria Isolated from the Pioneer Plant Ageratina adenophora (Spreng.) from a Mining Area.

This study aimed to isolate and characterise endophytic bacteria from the pioneer plant Ageratina adenophora in a mining area. Seven strains of metal-resistant endophytic bacteria that belong to five genera were isolated from the roots of A. adenophora. These strains exhibited various plant growth-promoting (PGP) capabilities. Sphingomonas sp. ZYG-4, which exhibited the ability to secrete indoleacetic acid (IAA; 53.2 ± 8.3 mg·L-1), solubilize insoluble inorganic phosphates (Phosphate solubilization; 11.2 ± 2.9 mg·L-1), and regulate root ethylene levels (1-aminocyclopropane-1-carboxylic acid deaminase activity; 2.87 ± 0.19 µM α-KB·mg-1·h-1), had the highest PGP potential. Therefore, Sphingomonas sp. ZYG-4 was used in a pot experiment to study its effect on the biomass and Pb uptake of both host (Ageratina adenophora) and non-host (Dysphania ambrosioides) plants. Compared to the uninoculated control, Sphingomonas sp. ZYG-4 inoculation increased the biomass of shoots and roots by 59.4% and 144.4% for A. adenophora and by 56.2% and 57.1% for D. ambrosioides, respectively. In addition, Sphingomonas sp. ZYG-4 inoculation enhanced Pb accumulation in the shoot and root by 268.9% and 1187.3% for A. adenophora, and by 163.1% and 343.8% for D. ambrosioides, respectively, compared to plants without bacterial inoculation. Our research indicates that endophytic bacteria are promising candidates for enhancing plant growth and facilitating microbe-assisted phytoremediation in heavy metal-contaminated soil.

Efficient reclamation of phosphorus from wetland plant via CaCl2/NaOH-mediated hydrothermal carbonization: insights from the evolution of phosphorus

Hydrothermal carbonization (HTC) of wetland plant could achieve the recovery of phosphorus (P) via the production of P-enriched hydrochar to alleviate the crisis of phosphate resources, while the migration and transformation of P should be determined. In this study, Canna indica was derived into hydrochar through HTC at different temperatures (200°C-260°C) and liquid mediums (H2O, CaCl2, and NaOH). The P forms were systematically characterized using P K-edge X-ray absorption near edge structure (XANES), 31P liquid nuclear magnetic resonance (NMR), and sequential extraction. The total P content in hydrochar was up to 23 mg g−1 with mainly inorganic P (> 97.8%), and the recovery rate was almost 100% during NaOH-mediated HTC. The P species, monoester-P and soluble orthophosphate (ortho-P), in biomass were transformed to more stable ortho-P in hydrochars, which was highly dependent on temperature and liquid medium. With increasing temperature, Al/Mg-P was gradually replaced by Ca/Fe-P. The CaCl2 solution facilitated the transformation of Ca(H2PO4)2 into CaHPO4 by elevating the Ca/P ratio. While for the NaOH-mediated HTC, the CaHPO4 and Ca(H2PO4)2 were transformed to hydroxyapatite (74.3%-81.5%), and the proportion of MgHPO4 elevated with increasing temperature. The diffusive gradients in thin films (DGT) results implied that the addition of hydrochar greatly elevated the soil available P content, which was further promoted by high temperature and NaOH medium. These results indicate that the species and availability of P in hydrochar could be adjusted through varying liquid medium and reaction temperature, which provide guidance for the target design of P-enriched hydrochar and P reclamation.Graphical

Screening native Bacillus strains as potential biological control agents against ginger bacterial wilt and for promoting plant growth

Bacterial wilt, caused by Ralstonia solanacearum, is a destructive disease that causes significant loss in ginger productivity. This disease is notoriously difficult to control by chemical measures, prompting the exploration of biological control as a more sustainable and effective alternative strategy. In our research, we aimed to develop effective microbial agents to combat R. solanacearum-induced bacterial wilt in ginger. Initially, 307 Bacillus-like strains were isolated from ginger rhizosphere soil. Among these, ten strains exhibited significant antibacterial activity after extensive in vitro screening, with Bacillus-like isolate F18 being the most effective. Further tests in a co-culture assay revealed six isolates, notably L70, that significantly reduced the pathogen's fitness. To further assess their effectiveness, six isolates of L3, L72, L73, F18, HC-5, and L70 were then subjected to a hydroponics assay, where they substantially lowered disease incidence in ginger seedlings, especially strains F18, HC-5, and L73. These three strains were identified as Bacillus velezensis, exhibiting beneficial traits such as IAA production, siderophore secretion, and phosphate and potassium solubilization. Additionally, they also harbored genes related to the production of the dipeptide bacilysin and the polyketides macrolactin, bacillaene and difficidin. In greenhouse experiments, these three B. velezensis strains, particularly F18 and HC-5, demonstrated remarkable efficacy in controlling bacterial wilt. Tubers soaked in these biocontrol agents showed reduced disease severity and pathogen population. Moreover, the treatments promoted ginger growth, notably in tuber fresh weight, with HC-5 showing the greatest improvement. Conclusively, this study suggests a highly efficient strategy for biologically controlling ginger bacterial wilt, with B. velezensis strains HC-5, L73, and F18 emerging as promising biocontrol agents.

Plant-growth stimulating bacteria × environments/bio-formulations interactions on the growth-promoting activities of Serratia marcescens and Pseudomonas fluorescens on chili

Chile has been used as a spice because of its flavor and zest, which complement the minerals, vitamins, and other elements it contains when cooked. The objective of the current study was to determine how P. fluorescens and S. marcescens promote plant growth in Chili plants. The PGPR's phosphate solubilizing, IAA, NH3, HCN production, and antifungal activities were ascertained using in vitro experiments. During the study period 2020–2022, the experiment was conducted using a completely randomized block design, with three replications of the three treatments for each microorganism, as follows: 1) P. fluorescens: T0 (control, unsterile soil), T1 (P. fluorescens in rice husk), and T2 (P. fluorescens in sawdust); 2) S. marcescens: T0 (control, unsterile soil), T1 (S. marcescens in rice husk), and T2 (S. marcescens in sawdust) with no fertilizer. After seeding, the chili plant's parameters were measured at 15, 30, 45, 60, and 75 days and compared to the control using four traits: plant height, root length, shoot length, and the number of leaves per plant. The following bio-formulation, employing T0, enhanced plant height growth after seeding: In rice husk, Days 75 (B2 × D5 × T2) = 21.20 for S. marcescens > Days 75 (B1 × D5 × T2) = 20.83 for P. fluorescens > Days 60 (B1 × D4 × T2) = 19.17 for P. fluorescens Days 75 (B2 × D5 × T0) for S. marcescens in control, days 60 (B1 × D4 × T1 (16.43 cm) for P. fluorescens in sawdust, and days 75 (B1 × D5 × T0) for P. fluorescens in control. The root length (cm) for P. fluorescens in sawdust is 7.23 days (B1 × D5 × T2), which is more than P. marcescens in sawdust (days 60 B1 × D4 × T2), P. fluorescens in control (days 75 (B1 × D5 × T0) = 6.60 cm), and S. marcescens in control (days 75 (B2 × D5 × T0) = 6.60 cm), etc. Rice husk and sawdust were used to create the bio-formulations. The maximum plant growth was achieved at 75 days when S. marcescens was grown in a sawdust medium, including sawdust as a carbon source and carboxymethyl cellulose as a carrier source. When the different compositions of the bio-formulation were tested on chili plants, it was found that P. fluorescens and S. marcescens in sawdust bio-formulation were more effective.

Fish Development in Lake Ecosystems, Effect of Heavy Metals

Heavy metals enter the water bodies and combine with the water buffer system, then turn into poorly soluble hydroxides, carbonates, sulfides and phosphates, and also form metal-organic complexes, accumulate in the bottom sediments and in general in the bodies of the fish fauna of the reservoirs of the area, seriously affecting their development. It was determined that the amount of Ca2+ ions varied from 17 mg/l to 112 mg/l, and the amount of Mg2+ ions from 5.5 mg/l to 83.5 mg/l, in other words, towards autumn. water hardness has increased. The amount of alkali metal (Na+ + K+) ions is much lower in spring than in summer and autumn. According to the cations, the amount of chloride and sulfate ions increases in autumn. Thus, the impact of anthropogenic factors on fish is diverse and manifests itself primarily in morphological anomalies and changes in the basic biological parameters of fish populations. The main of them is the reduction of productivity and the complete loss of their natural forms, the increase of individuals and the increase of mortality.

Cultivation of Microalgae in Liquid Digestate to Remove Nutrients and Organic Contaminants

The goal of this research was to assess the efficiency of the liquid digestate treatment conducted with algal, environmental isolates illuminated entirely with sunlight. The photobioreactor was exposed to natural conditions and evaluated based on the reduction of chemical oxygen demand (COD), nitrogen compounds, and soluble phosphates. Microalgal and bacterial communities growing during the treatment process were studied. A high removal rate of soluble COD (= 91%) and nutrients (= 86%) was achieved. The average concentrations of nitrogen, phosphates, and COD in the reactor effluent were 95 mgN/L, 49 mg/L, and 735 mg O2/L, respectively. The overall algae-bacteria biomass productivity of 22 mg/L/d, calculated on the total suspended solids (TSS) basis, was recorded. The microbial analysis revealed the dominance of Tetradesmus obliquus followed by Microglena sp. in the first 14 weeks of the experiment. At the end of the experimental run, Chlorella sorokiniana cells appeared as a result of illumination intensity changes. The dominating bacteria belonged to Firmicutes (26.31%), Patescibacteria (17.38%), and Actinobacteriota (14.86%) and could have been responsible for the transformation of nitrogen and oxidation of organic contaminants. The research demonstrated that natural sunlight can successfully be used for efficient liquid digestate treatment with the algae-bacterial community.

Integrated omics approach reveals the molecular pathways activated in tomato by Kocuria rhizophila, a soil plant growth-promoting bacterium

Plant microbial biostimulants application has become a promising and eco-friendly agricultural strategy to improve crop yields, reducing chemical inputs for more sustainable cropping systems. The soil dwelling bacterium Kocuria rhizophila was previously characterized as Plant Growth Promoting Bacteria (PGPB) for its multiple PGP traits, such as indole-3-acetic acid production, phosphate solubilization capability and salt and drought stress tolerance. Here, we evaluated by a multi-omics approach, the PGP activity of K. rhizophila on tomato, revealing the molecular pathways by which it promotes plant growth. Transcriptomic analysis showed several up-regulated genes mainly related to amino acid metabolism, cell wall organization, lipid and secondary metabolism, together with a modulation in the DNA methylation profile, after PGPB inoculation. In agreement, proteins involved in photosynthesis, cell division, and plant growth were highly accumulated by K. rhizophila. Furthermore, “amino acid and peptides”, “monosaccharides”, and “TCA” classes of metabolites resulted the most affected by PGPB treatment, as well as dopamine, a catecholamine neurotransmitter mediating plant growth through S-adenosylmethionine decarboxylase (SAMDC), a gene enhancing the vegetative growth, up-regulated in tomato by K. rhizophila treatment. Interestingly, eight gene modules well correlated with differentially accumulated proteins (DAPs) and metabolites (DAMs), among which two modules showed the highest correlation with nine proteins, including a nucleoside diphosphate kinase, and cytosolic ascorbate peroxidase, as well as with several amino acids and metabolites involved in TCA cycle. Overall, our findings highlighted that sugars and amino acids, energy regulators, involved in tomato plant growth, were strongly modulated by the K. rhizophila-plant interaction.

Growth, nutrient removal, and lipid productivity promotion of Chlorella sorokiniana by phosphate solubilizing bacteria Bacillus megatherium in swine wastewater: Performances and mechanisms

Effects of a phosphorus-solubilizing bacteria (PSB) Bacillus megatherium on growth and lipid production of Chlorella sorokiniana were investigated in synthesized swine wastewater with dissolved inorganic phosphorus (DIP), insoluble inorganic phosphorus (IIP), and organic phosphorus (OP). The results showed that the PSB significantly promoted the algal growth in OP and IIP, by 1.10 and 1.78-fold, respectively. The algal lipid accumulation was also greatly triggered, respectively by 4.39, 1.68, and 1.38-fold in DIP, IIP, and OP. Moreover, compared with DIP, OP improved the oxidation stability of algal lipid by increasing the proportion of saturated fatty acids (43.8 % vs 27.9 %), while the PSB tended to adjust it to moderate ranges (30.2–41.6 %). Further, the transcriptome analysis verified the OP and/or PSB-induced up-regulated genes involving photosynthesis, lipid metabolism, signal transduction, etc. This study provided novel insights to enhance microalgae-based nutrient removal combined with biofuel production in practical wastewater, especially with complex forms of phosphorus.

Assessment of Plant-Growth Promoting Potential of Bacteria Isolated from Amazonian Black Pepper Roots

Purpose: In the Amazon, farmers use chemical fertilizers on a large scale to meet the nutritional requirements of some crops. Plant-growth promoting bacteria (PGPB) offer a sustainable alternative to enhance crop productivity. This study aimed to prospect novel PGPB from Amazonian black pepper (Piper nigrum L.) roots. Methods: Bacterial isolates were obtained from plant roots, evaluated for their biofertilizing potential, and the most promising strain was selected for genome sequencing. Taxonomic classification was based on 16 S rRNA gene sequencing. ACC deaminase activity, phosphate solubilization, and nitrogen fixation were assessed. Genome sequencing was performed using the Ion GeneStudio S5 platform. Results: The 20 isolates were affiliated to Enterobacter (7 isolates), Klebsiella (4 isolates), Kosakonia (5 isolates), Bacillus (2 isolates), and two unclassified bacteria. Seven isolates were positive for ACC deaminase activity, while four were positive for the presence of the nifH gene. Nitrogenase gene was found only in Kosakonia isolates. Ninety isolates were able to solubilize phosphate. The isolate Pn16 was the most promising and presented a genome of 6,432,985 bp, GC content of 55%, 6,465 Coding Sequences, 10 Symbiotic Islands, 28 biosynthetic gene clusters, and several genes involved in plant-growth promotion such as phoU-pstSCAB-phoBR, oqxAB, ipdC, speADEGF, nifHDK. Conclusions: We were able to isolate a bacterium with potential for biofertilization. Based on phylogeny and Average Nucleotide Identity, we propose the classification of the Pn16 isolate as Kosakonia pseudosacchari Pn16.

Study on the Effect of Trichoderma viride on Phosphate Solubilizing Microorganisms in Paddy Cultivation with the Combination of Chemical Fertilizer on soil Fertility Parameters

Trichoderma viride, biological control with Trichoderma viride is an eco-friendly and has potential approach for managing plant diseases. It also aids in phosphate solubilization. Phosphate Solubilizing Microorganisms are ubiquitous, whose number varies from soil to soil. The present work on, ‘Effect of Trichoderma viride on Phosphate Solubilizing Microorganism in Paddy cultivation” was conducted under lower gangetic alluvial region from 2016-2017(December to May) at Agricultural Experimental Station of Calcutta University, Baruipur, 24 Parganas (South), West Bengal. The Rice variety “Satabdi (IET-4786)” from the department of Genetics and Plant Breeding was sown and recommended fertilizer dose of 80:40:40 kg per hectare. The experiment was carried out with six treatments replicated four times. Out of the six treatments, T3 which received T.V and P.S showed highest Carbon, Phosphorus and Potassium content and T6 showed highest Nitrogen content in the soil