Paenibacillus Polymyxa Research Articles

The influence of different bacteria consortium and irrigation levels on yield and physiological attributes of durum wheat (Triticum durum Desf.) grown under organic farming conditions

BackgroundInorganic fertilizers help to prevent yield and quality losses in agricultural production; however, adversely affect soil quality and human health. The rising public awareness is switching the production focus from conventional to organic farming. Therefore, obtaining higher yields under organic farming conditions is inevitable. Different bacterial consortia have been found helpful in improving crop yields under stressful and benign environments. Therefore, current study tested the impact of two bacterial consortia on yield and physiological attributes of durum wheat (Triticum durum Desf.) grown under organic farming conditions with two different irrigation levels. MethodsTwo bacteria consortiums [(consortium 1 = Bacillus megaterium RCK-869 + Pantoea agglomerans RK-120 + Paenibacillus polymyxa RCK-540 + Bacillus subtilis RCK-561), (consortium 2 = Azospirillum, Rhizobium, Azotobacter and Acetobacter) and two irrigation levels, i.e., 50 and 100% of the required moisture were included in the study. Data on chlorophyll index, flag leaf area, soluble sugar content, plant height, protein ratio, and grain yield were drecorded. ResultsThe GY in bacteria-free treatment was 3512.0 kg ha−1, which increased to 4868.3 kg ha−1 with the application of bacteria consortium 1. The application of 50% irrigation significantly reduced the yield and related traits, whereas the application of bacteria consortium 1 significantly improved these traits under normal and 50% irrigation. Overall, higher values of the studied traits were recorded during 1st year than 2nd year. The decrease in total precipitation and relative humidity, and the increase in temperature in the second year caused a decrease in grain yield, agronomic and physiological parameters. ConclusionBacteria consortium consisting of Bacillus bacteria significantly improved the yield and related traits of durum wheat under deficit and normal irrigation. Therefore, bacterial consortium consisting of B. megaterium + P. agglomerans + P. polymyxa + B. subtilis could be used to improve durum wheat production under organic farming conditions and deficit irrigation.

Thermostabilizing mechanisms of canonical single amino acid substitutions at a GH1 β-glucosidase probed by multiple MD and computational approaches.

β-glucosidases play a pivotal role in second-generation biofuel (2G-biofuel) production. For this application, thermostable enzymes are essential due to the denaturing conditions on the bioreactors. Random amino acid substitutions have originated new thermostable β-glucosidases, but without a clear understanding of their molecular mechanisms. Here, we probe by different molecular dynamics simulation approaches with distinct force fields and submitting the results to various computational analyses, the molecular bases of the thermostabilization of the Paenibacillus polymyxa GH1 β-glucosidase by two-point mutations E96K (TR1) and M416I (TR2). Equilibrium molecular dynamic simulations (eMD) at different temperatures, principal component analysis (PCA), virtual docking, metadynamics (MetaDy), accelerated molecular dynamics (aMD), Poisson-Boltzmann surface analysis, grid inhomogeneous solvation theory and colony method estimation of conformational entropy allow to converge to the idea that the stabilization carried by both substitutions depend on different contributions of three classic mechanisms: (i) electrostatic surface stabilization; (ii) efficient isolation of the hydrophobic core from the solvent, with energetic advantages at the solvation cap; (iii) higher distribution of the protein dynamics at the mobile active site loops than at the protein core, with functional and entropic advantages. Mechanisms i and ii predominate for TR1, while in TR2, mechanism iii is dominant. Loop A integrity and loops A, C, D, and E dynamics play critical roles in such mechanisms. Comparison of the dynamic and topological changes observed between the thermostable mutants and the wildtype protein with amino acid co-evolutive networks and thermostabilizing hotspots from the literature allow inferring that the mechanisms here recovered can be related to the thermostability obtained by different substitutions along the whole family GH1. We hope the results and insights discussed here can be helpful for future rational approaches to the engineering of optimized β-glucosidases for 2G-biofuel production for industry, biotechnology, and science.

GROWTH AND YIELD ATTRIBUTES OF VIGNA MUNGO L. WITH RESPONSE TO ORGANIC FERTILIZERS

At present, the specialization of organic inputs is very important and the use of locally available inputs is significant. Current experiment was conducted to evaluate the impact of Panchagavya, Casuarina needle litter and Paenibacillus polymyxa either single or in combined inoculation with each other on growth and yield of Vigna mungo under identical experimental condition. The results revealed that seedlings inoculated with Panchagavya + Casuarina needle litter powder+ Paenibacillus polymyxa recorded higher growth and yield of Vigna mungo. It was recorded that 16 % total length, 11.5% collar diameter, 46 %number of leaves and 55.7% increase over control plants. It is recemented that similar studies are needed to find out the impact of combined inoculation of Panchagavya + Casuarina needle litter + Paenibacillus polymyxa on Vigna mungo under field condition.

Ropiness in Bread-A Re-Emerging Spoilage Phenomenon.

As bread is a very important staple food, its spoilage threatens global food security. Ropy bread spoilage manifests in sticky and stringy degradation of the crumb, slime formation, discoloration, and an odor reminiscent of rotting fruit. Increasing consumer demand for preservative-free products and global warming may increase the occurrence of ropy spoilage. Bacillus amyloliquefaciens, B. subtilis, B. licheniformis, the B. cereus group, B. pumilus, B. sonorensis, Cytobacillus firmus, Niallia circulans, Paenibacillus polymyxa, and Priestia megaterium were reported to cause ropiness in bread. Process hygiene does not prevent ropy spoilage, as contamination of flour with these Bacillus species is unavoidable due to their occurrence as a part of the endophytic commensal microbiota of wheat and the formation of heat-stable endospores that are not inactivated during processing, baking, or storage. To date, the underlying mechanisms behind ropy bread spoilage remain unclear, high-throughput screening tools to identify rope-forming bacteria are missing, and only a limited number of strategies to reduce rope spoilage were described. This review provides a current overview on (i) routes of entry of Bacillus endospores into bread, (ii) bacterial species implicated in rope spoilage, (iii) factors influencing rope development, and (iv) methods used to assess bacterial rope-forming potential. Finally, we pinpoint key gaps in knowledge and related challenges, as well as future research questions.

CHARACTERIZATION OF ARSENIC RESISTANT BACTERIA ISOLATED FROM THE SOIL OF KHULNA SHIPYARD

Thirty four arsenic resistant bacterial strains were isolated from the soil samples of Khulna Shipyard. They were isolated by growing them on nutrient broth medium containing 5 mgl-1 of arsenic. From them, five strains were finally selected, and studied their morphological, biochemical and ecological characters in details. They were identified as Bacillus lichenifomis, Bacillus polymyxa, Listeria murrayi, Moraxella urethralis and Planococcus citreus. All of these strains were able to tolerate upto100 ppm (mgl-1) of arsenic (III). It is possibly due to the presence of arsenic (III) resistance mechanism(s) in these bacterial strains. The optimum pH and temperature for the growth of these bacterial strains were 8.5 and 37 °C, respectively.

Investigation of bioactivity of unsaturated oligo‑galacturonic acids produced from apple waste by Alcaligenes faecalis AGS3 and Paenibacillus polymyxa S4 Pectinases

Pectin is one of the main structural components in fruits and an indigestible fiber made of d-galacturonic acid units with α (1-4) linkage. This study investigates the microbial degradation of pectin in apple waste and the production of bioactive compounds. Firstly, pectin-degrading bacteria were isolated and identified, then pectinolytic activity was assessed by DNS. The products were evaluated by TLC and LC–MS–ESI. The antioxidative effects were investigated using DPPH and anti-cancer effects and cytotoxicity were analyzed by MTT and flow cytometry. In this study two new bacterial isolates, Alcaligenes faecalis AGS3 and Paenibacillus polymyxa S4 with the pectinolytic enzyme were introduced. Structure analysis showed that the products of enzymatic degradation include unsaturated mono, di, tri, and penta galacturonic acids with 74% and 69% RSA at 40 mg/mL for A. faecalis and P. polymyxa S4, respectively. The results of anti-tumor properties on MCF-7 cells by MTT assay, for products of AGS3 and S4 at 40 mg/mL after 48 h, showed 7% and 9% survival, respectively. In the flow cytometric assessment, the compounds of AGS3 at 40 mg/mL were 100% lethal in 48 h and regarding S4 isolate caused 98% death. Cytotoxicity evaluation on L-929 cells showed no significant toxicity on living cells.

Causes of polymyxin treatment failure and new derivatives to fill the gap.

Polymyxins are a class of antibiotics that were discovered in 1947 from programs searching for compounds effective in the treatment of Gram-negative infections. Produced by the Gram-positive bacterium Paenibacillus polymyxa and composed of a cyclic peptide chain with a peptide-fatty acyl tail, polymyxins exert bactericidal effects through membrane disruption. Currently, polymyxin B and colistin (polymyxin E) have been developed for clinical use, where they are reserved as "last-line" therapies for multidrug-resistant (MDR) infections. Unfortunately, the incidences of strains resistant to polymyxins have been increasing globally, and polymyxin heteroresistance has been gaining appreciation as an important clinical challenge. These phenomena, along with bacterial tolerance to this antibiotic class, constitute important contributors to polymyxin treatment failure. Here, we review polymyxins and their mechanism of action, summarize the current understanding of how polymyxin treatment fails, and discuss how the next generation of polymyxins holds promise to invigorate this antibiotic class.

Endophytic Paenibacillus polymyxa LMG27872 inhibits Meloidogyne incognita parasitism, promoting tomato growth through a dose-dependent effect.

The root-knot nematode, Meloidogyne incognita, is a major pest in tomato production. Paenibacillus polymyxa, which is primarily found in soil and colonizing roots, is considered a successful biocontrol organism against many pathogens. To evaluate the biocontrol capacity of P. polymyxa LMG27872 against M. incognita in tomato, experiments were conducted both in vitro and in vivo. A dose-response effect [30, 50, and 100% (108 CFU/mL)] of bacterial suspensions (BSs) on growth and tomato susceptibility to M. incognita with soil drenching as a mode of application was first evaluated. The results show that the biological efficacy of P. polymyxa LMG27872 against M. incognita parasitism in tomato was dose-dependent. A significantly reduced number of galls, egg-laying females (ELF), and second-stage juveniles (J2) were observed in BS-treated plants, in a dose-dependent manner. The effect of P. polymyxa on tomato growth was also dose-dependent. A high dose of BSs had a negative effect on growth; however, this negative effect was not observed when the BS-treated plants were challenged with M. incognita, indicating tolerance or a defense priming mechanism. In subsequent in vivo experiments, the direct effect of BSs was evaluated on J2 mortality and egg hatching of M. incognita. The effect of BS on J2 mortality was observed from 12 to 24 h, whereby M. incognita J2 was significantly inhibited by the BS treatment. The effect of P. polymyxa on M. incognita egg hatching was also dependent on the BS dose. The results show a potential of P. polymyxa LMG27872 to protect plants from nematode parasitism and its implementation in integrated nematode management suitable for organic productions.

Screening of new Paenibacillus polymyxa S3 and its disease resistance of grass carp (Ctenopharyngodon idellus).

A new strain of Paenibacillus polymyxa S3 with antagonistic effects on 11 major fish pathogens (especially Aeromonas hydrophila), but had no toxicity to grass carp, was screened from the sediment of fishponds. In vivo colonization studies showed that strain S3 could be colonized and distributed in the gill and abdomen of the grass carp. Bioassay results showed that the weight growth rate of grass carp in the strain S3 oral group (16.01%) and strain S3 immersion group (16.44%) was significantly higher than those of the control group (8.61%). At the same time, the activities of ACP, AKP, CAT and GSH-Px in the serum of grass carp in oral and immersion groups were significantly higher than those of the control group. In addition, the treatment with strain S3 could significantly upregulate the expression of the antioxidant-related genes and immune-related genes Keap1, Nrf2, C3, LZM, IgM, TLR-4 and MyD-88 in grass carp tissues. The challenge test showed that strain S3 treatment significantly increased the survival rate of grass carp infected with Aeromonas hydrophila. Whole genome sequencing analysis showed that strain S3 had 16 active metabolite gene clusters, indicating that it had abundant gene resources, which provided important support for its development for fish microecological preparations. In summary, a new strain of Paenibacillus polymyxa S3 with antibacterial activity against a variety of fish pathogens was screened in this study and its probiotic function was evaluated, proving its potential value in fisheries.

Effect of Some Soil Conditioners on Water-Use Efficacy, Growth, and Yield of Date Palm Siwi Grown in Sandy Soil under Different Irrigation Regimes to Mitigate Climate Change

A field experiment was carried out at Al-Bahariya Oasis, Giza, Egypt, during three successive seasons to find out the effect of application of bentonite (BN) as a natural clay deposit at either 6 or 12 kg/palm tree and humic substances (HS) as organic amendment at either 0.75 or 1.0 L/palm tree incorporated with Bacillus polymyxa (BP) as a biofertilizers at 14 and 28 mL/L rates on growth, yield, and fruit weight of 10-year-old Siwi date palm cv. (Phoenix dectylifera L.). Siwi trees were cultivated in sandy texture soil at a distance of 8 × 8 m and were irrigated with 100%, 85%, and 70% of ET crop. Effects of the previous treatments on growth, date palm crop, soil properties, water relations, water-use efficiency (WUE), and economic return were also studied. The obtained results showed that the mean values of leaf length, leaflet length and width, fruit set%, bunch weight, yield/palm, yield/fed, fruit weight, flesh weight, and fruit pulp weight were increased in response to the different individual and combined treatments used in this study with various significance levels compared to the control treatment means in the studied three seasons. However, the superiority was for combining between amending the sandy soil with either low concentrations of BN (6 kg/tree) + HS (0.75 Liter/tree) + BP (14 mL/L) or high concentrations of BN (12 kg/tree) + HS (1.0 L/tree) + BP (28 mL/L) and irrigation with 85% of ETc water level, as such combinations attained the highest values in most of the mentioned values over both the sole and combined treatments in the studied three seasons. Furthermore, the results indicated that the highest monthly ETc values occurred during June and July months, while the lowest values occurred during December and January months. Additionally, water productivity (WP) increased considerably by reduction of water quantity (70% ETc) associated with soil conditioner treatment (BN.12 kg +HS 1 L + BP. 28 mL/L), and values were 2.17, 2.25, and 2.27 kg fruit/m3 of water irrigation during the growing seasons, respectively. The highest net return was attributed to irrigation with 85% of ETc water level along with the application of soil conditioners at high rates. Accordingly, it is advisable to apply the soil conditioners of bentonite (at 6 or 12 kg/tree) and humic substances (at either 0.75 or 1.0 L/tree) with B. polymyxa (at either 14 or 28 mL/L) plus irrigation with either 85% or 70% of ETc water level to obtain the best growth, highest yield, (WP), and gross return from var. Siwi date palm grown under an oasis agro-system.

GRAIN-RESIDING ENDOPHYTIC BACTERIUM Paenibacillus polymyxa P 6.3 POSSESSES GROWTH-PROMOTING ACTIVITY AND PROTECT WHEAT GRAIN FROM PATHOGENIC EFFECT OF Pseudomonas syringae

Aim. To examine the effect of endophytic bacteria Paenibacillus polymyxa P 6.3, which was isolated from grains of winter wheat variety Podolyanka, on the germination of wheat grains after the exposure Pseudomonas syringae. Methods. Growth-promoting and biocontrol activity of P. polymyxa P 6.3 were examined using roll method. Standardized wheat grains were soaked in a suspension of 24 h culture of P. polymyxa P 6.3 for 12 h, control grains were soaked in sterile distilled H2O. After soaking, both pre-treated and control grains (of 25 pcs) were put into rolls. In three days, half of both pre-treated and control grains were exposed to phytopathogen P. sуringae, and germination was continued. The lengths of coleoptile and main root were measured on the 7th day of the experiment. Results were expressed as M ± m. Differences were considered significant at P ≤ 0.05. Results. Treatment wheat grains with P. polymyxa P 6.3 resulted in increased growth of coleoptile and main root in all three varieties. Most prominent effect was registered in Favorytka variety. After the exposure to phytopathogenic pseudomonads, slowing down of the growth of coleoptile and main root occurred in all wheat varieties. Highest susceptibility to P. syringae pathogenic effect was registered in Holikovska variety. Pre-treatment of wheat grains with endophytic bacteria abrogated growth-inhibiting effects of P.syringae. Conclusion. Endophytic bacteria P. polymyxa P 6.3 exerts a growth-stimulating effect on wheat germination and a protective effect against P. syringae. The plant growth promoting potential and antagonistic activity make strain P 6.3 a promising biocontrol agent and growth stimulator as a biofertilizer.

Characterization of root endophytic Paenibacillus polymyxa isolates with biocontrol activity against Xanthomonas translucens and Fusarium graminearum

Fusarium crown rot (FCR), Fusarium head blight (FHB), and bacterial leaf streak (BLS) of wheat are important diseases worldwide. The lack of commercial resistant cultivars and harmful effects of using chemical poisons for controlling these diseases prompted scientists to use biological agents as eco-friendly strategies for disease management. Plants carry small community of microbes known as endophytes that have effect on plant growth regulation and also protect plants against phytopathogens. In this study, a total of 35 endophytic bacteria were isolated from wheat root. Two isolates were selected for further study based on their potential ability to control Xanthomonas translucens and Fusarium graminearum in vitro. Both isolates were identified as Paenibacillus polymyxa SeR8 and BR20 (F and B-type, respectively) according to the results of 16S rRNA gene sequencing, morphological, and physiological analysis. Light and scanning electron microscopy showed alternations in the F. graminearum structures in the presence of the endophytes. Production of protease, amylase, pectinase, cellulase, IAA, sensitivity to H2O2, biofilm formation, and phosphate solubilization in the type B was more than the type F. On the other hand, the production of lipase, catalase, ammonia, and siderophore by the F-type was more than the B-types, but they could not produce biosurfactants and ACC deaminase. None of them could produce chitinase. Kernel bioassay and mycotoxin analyses indicated that the F-type had better impact on protecting seeds and decreasing DON production. The percentages of FHB infection reduction, FCR severity reduction, and protection rate against BLS in the type F and B were 76.31, 64.10 %; 67.66, 65.41 %, and 54.96, 63.57 %, respectively. Greenhouse experiments indicated that the biomass, 1000 grains weight, chlorophyll a, b, T, and carotenoids were increased in the plants treated with the endophytic bacteria. In our study, the B-type showed better antibacterial activity in comparison with the F-type, while the F type showed better antifungal activity than the B type. This is the first report that indicates the importance of types F and B of P. polymyxa in the biocontrol of Fusarium crown rot and bacterial leaf streak diseases.

Identification and combinatorial engineering of indole-3-acetic acid synthetic pathways in Paenibacillus polymyxa

BackgroundPaenibacillus polymyxa is a typical plant growth-promoting rhizobacterium (PGPR), and synthesis of indole-3-acetic acid (IAA) is one of the reasons for its growth-promoting capacity. The synthetic pathways of IAA in P. polymyxa must be identified and modified.ResultsP. polymyxa SC2 and its spontaneous mutant SC2-M1 could promote plant growth by directly secreting IAA. Through metabonomic and genomic analysis, the genes patA, ilvB3, and fusE in the native IPyA pathway of IAA synthesis in strain SC2-M1 were predicted. A novel strong promoter P04420 was rationally selected, synthetically analyzed, and then evaluated on its ability to express IAA synthetic genes. Co-expression of three genes, patA, ilvB3, and fusE, increased IAA yield by 60% in strain SC2-M1. Furthermore, the heterogeneous gene iaam of the IAM pathway and two heterogeneous IPyA pathways of IAA synthesis were selected to improve the IAA yield of strain SC2-M1. The genes ELJP6_14505, ipdC, and ELJP6_00725 of the entire IPyA pathway from Enterobacter ludwigii JP6 were expressed well by promoter P04420 in strain SC2-M1 and increased IAA yield in the engineered strain SC2-M1 from 13 to 31 μg/mL, which was an increase of 138%.ConclusionsThe results of our study help reveal and enhance the IAA synthesis pathways of P. polymyxa and its future application.

Algicidal interaction between Paenibacillus polymyxa MEZ6 and microalgae.

Algicidal bacteria can be used for control of harmful algal bloom and extraction of algal bioproducts based on their algae-lysing activities. This work investigated the algae-lysing activity of a newly isolated algicidal bacterium, Paenibacillus polymyxa strain MEZ6 and its possible mechanisms. Algicidal bacteria were isolated from soil samples collected at the university campus. Co-inoculation tests identified that one isolate, MEZ6, can rapidly kill eukaryotic algae including Chlamydomonas reinhardtii, Tribonema minus, Haematococcus pluvialis, and Chlorella ellipsoidea. The strain was determined as Paenibacillus polymyxa MEZ6 based on 16S rRNA gene sequence and genome comparisons. The algicidal activity was detected in both living cells and cell-free supernatant of spent culture medium, suggesting cell-cell contact is not required for algicidal activity. Strain MEZ6 was less active towards cyanobacterial strains compared to algae. Genomic sequence and comparative proteomic analyses were performed to explore the possible algicidal mechanisms of the strain. Differentially expressed protein analysis identified a number of proteins related to polysaccharides degradation and antimicrobial secondary metabolite biosynthesis that may be involved in the algicidal activity of MEZ6. Paenibacillus polymyxa MEZ6 is a newly discovered gram-positive algicidal bacterial strain with high lytic activity towards several algal species. Our study extends the understanding of the versatile characters of Paenibacillus polymyxa and sheds new insights into its application in algae biotechnology.

Maximizing Recovery of Paenibacillin, a Bacterially Produced Lantibiotic, Using Continuous Foam Separation from Bioreactors.

Industrial production of paenibacillin, and similar rare antimicrobial peptides, is hampered by low productivity of the producing microorganisms and lack of efficient methods to recover these peptides from fermentor or bioreactor end products. Preliminary data showed that paenibacillin was preferentially partitioned in foam accumulated during growth of the producer, Paenibacillus polymyxa, in aerated liquid media. This research was initiated to improve the production and recovery of paenibacillin in bioreactors by maximizing partitioning of this antimicrobial agent in the collected foam. This was completed through harvesting foam continuously during paenibacillin production, using modified bioreactor, and optimizing bioreaction conditions through response surface methodology (RSM). During initial screening, the following factors were tested using 400 mL inoculated media in 2 L bioreactors: medium (tryptic soy broth, TSB, with or without added yeast extract), airflow (0 or 0.8 L/min; LPM), stir speed (300 or 500 revolution/min; RPM), incubation temperature (30 or 36 °C), and incubation time (16 or 24 h). Results showed that airflow, time, and stir speed had significant effects (p < 0.05) on paenibacillin recovery in the collected collapsed foam (foamate). These factors were varied together to follow the path of steepest assent to maximize paenibacillin concentration. Once the local maximum was found, RSM was completed with a central composite design to fine-tune the bioreaction parameters. The optimization experiments proved that the significant parameters and their optimal conditions for paenibacillin concentration in the foam were: incubation at 30 °C for 23 h with airflow of 0.95 LPM, and agitation speed of 450 RPM. These conditions increased paenibacillin concentration, predicted by RSM, from 16 µg/mL in bioreaction without foam collection to 743 µg/mL collected in foamate. The optimized conditions also almost doubled the yield of paenibacillin measured in the foam collected from a bioreaction run (12,674 µg/400 mL bioreaction) when compared to that obtained from a run without foam collection (6400 µg/400 mL bioreaction). Results of this study could improve the feasibility of commercial production and downstream processing of paenibacillin and similar novel antimicrobial peptides. Availability of such peptides will eventually help in protecting perishable products against pathogenic and spoilage bacteria.

Effects of plant growth-promoting rhizobacteria (PGPR) and different fertilizer combinations on yield and quality properties in cauliflower (Brassica oleracea L. var. botrytis)

Purpose: This study was carried out to determine the influence of plant growth promoting rhizobacteria (PGPR) (Paenibacillus polymyxa RC14, Bacillus subtilis RC63 and Pseudomonas fluorescens RC77), organic chicken manure (OCM) (4000 kg/da), 3 levels of mineral fertilizer [(NPK1 (80 kg/ha N+50 kg/ha P+80 kg/ha K), NPK2 (160 kg/ha N+75 kg/ha P+160 kg/ha K) and NPK3 (200 kg/ha N+100 kg/ha P+200 kg/ha K)] and combination of these applications on growth, yield and quality of cauliflower under field conditions. Materials and Methods: Field experiments were conducted in randomized complete block design with four replications. Treatments were 1. Control (No Fertilizer Application; 0 kg /ha NPK), 2. NPK1 (80-50-80 kg / ha NPK), 3. NPK2 (160-75-160 kg /ha NPK), 4. NPK3 (200-100-200 kg /ha NPK), 5. PGPR, 6. Organic Chicken Manure (OCM), 7. PGPR + OCM, 8. NPK1+PGPR, 9. NPK2+PGPR, 10. NPK3+PGPR, 11. NPK1+ OCM, 12. NPK2+ OCM, 13. NPK3+ OCM, 14. NPK1+PGPR+ OCM, 15. NPK2+PGPR+ OCM, 16. NPK3+PGPR+ OCMResults: The highest curd weight and marketable yield were observed in NPK2+ OCM in 2014 while in NPK1+PGPR+OCM and NPK2+PGPR+OCM in 2015. NPK2+ OCM elevated the curd weight and marketable yield by 300% compared to the control in 2014. NPK1+PGPR+OCM increased the curd weight and marketable yield by 200% compared to the control in 2015. The highest TSS was observed in the control in 2014 whereas NPK1+PGPR+OCM gave the highest value. NPK treatments elevated the NO3 content of cauliflower curds. In 2014 the highest ascorbic acid content was determined in PGPR while the control gave the highest content in 2015. The highest oxalic acid contents were observed in NPK treatments. Furthermore, PGPR and OCM treatments generally reduced the oxalic acid contents of the cauliflower. Conclusion: NPK with OCM and PGPR applications could be advisable for the yield and quality parameters of cauliflower. Furthermore, the PGPRxOCM combination was advisable for efficiently using in organic agricultural production.

Protective and Curative Activities of Paenibacillus polymyxa against Zucchini yellow mosaic virus Infestation in Squash Plants.

Simple SummaryZucchini yellow mosaic virus (ZYMV) is one of the most prevalent plant viruses and represents a great challenge for crop production sustainability and human food supplementation. Conventional approaches to disease control depend on the heavy application of hazardous chemicals, which implies severe environmental, animal, and human health challenges. Using natural and microbial products represents a promising tool for sustainable and eco-friendly agricultural applications. The foliar application of the rhizobacteria Paenibacillus polymyxa strain SZYM revealed significant enhancements in squash growth parameters and enzyme production when compared to the non-treated plants. On the other hand, there was also a significant decrease in ZYMV accumulation, accompanied with a significant increase in the transcriptional levels of defense-related genes on plants inoculated with P. polymyxa. Additionally, a significant decrease in non-enzymatic oxidative stress markers was observed, as well as a considerable increase in reactive oxygen species scavenging enzymes. The present study showed that the P. polymyxa strain SZYM could be considered a promising rhizobacterium for enhancing plant growth and defense, and consequently a possible biocontrol agent of plant viral infections.The use of microbial products as natural biocontrol agents to increase a plant’s systemic resistance to viral infections is a promising way to make agriculture more sustainable and less harmful to the environment. The rhizobacterium Paenibacillus polymyxa has been shown to have strong biocontrol action against plant diseases, but its antiviral activity has been little investigated. Here, the efficiency of the culture filtrate of the P. polymyxa strain SZYM (Acc# ON149452) to protect squash (Cucurbita pepo L.) plants against a Zucchini yellow mosaic virus (ZYMV, Acc# ON159933) infection was evaluated. Under greenhouse conditions, the foliar application of the culture filtrate of SZYM either in protective or curative treatment conditions enhanced squash growth, reduced disease severity, and decreased ZYMV accumulation levels in the treated plants when compared to the non-treated plants. The protective treatment group exhibited the highest inhibitory effect (80%), with significant increases in their total soluble carbohydrates, total soluble protein content, ascorbic acid content, and free radical scavenging activity. Furthermore, a considerable increase in the activities of reactive oxygen species scavenging enzymes (superoxide dismutase, polyphenol oxidase, and peroxidase) were also found. In addition, the induction of systemic resistance with a significant elevation in the transcriptional levels of polyphenolic pathway genes (CHS, PAL, and C3H) and pathogenesis-related genes (PR-1 and PR-3) was observed. Out of the 14 detected compounds in the GC–MS analysis, propanoic acid, benzenedicarboxylic acid, tetradecanoic acid, and their derivatives, as well as pyrrolo [1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl) were the primary ingredient compounds in the ethyl acetate extract of the SZYM-culture filtrate. Such compounds may act as elicitor molecules that induce systemic resistance against viral infection. Consequently, P. polymyxa can be considered a powerful plant growth-promoting bacterium (PGPB) in agricultural applications as well as a source of bioactive compounds for sustainable disease management. As far as we know, this is the first time that P. polymyxa has been shown to fight viruses in plants.

Bacteriota and Antibiotic Resistance in Spiders.

Simple SummaryThe microbiomes of insects are known for having a great impact on their physiological properties for survival, such as nutrition, behavior, and health. In nature, spiders are one of the main insect predators, and their microbiomes have remained unclear yet. It is important to explore the microbiomes of spiders with the positive effect in the wild to gain an insight into the host–bacterial relationship. The insects have been the primary focus of microbiome studies from all arthropods. Although the research focused on the microbiome of spiders is still scarce, there is a possibility that spiders host diverse assemblages of bacteria, and some of them alter their physiology and behavior. According to our findings, there is a need for holistic microbiome studies across many organisms, which would increase our knowledge of the diversity and evolution of symbiotic relationships. Antimicrobial resistance is one of the most serious global public health threats in this century. Therefore, the knowledge and some information about insects and their ability to act as reservoirs of antibiotic-resistant microorganisms should be determined in order to ensure that they are not transferred to humans. It is important to monitor the microbiome of spiders found in human houses and the transmission of resistant microorganisms, which can be dangerous in relation to human health.Arthropods are reported to serve as vectors of transmission of pathogenic microorganisms to humans, animals, and the environment. The aims of our study were (i) to identify the external bacteriota of spiders inhabiting a chicken farm and slaughterhouse and (ii) to detect antimicrobial resistance of the isolates. In total, 102 spiders of 14 species were collected from a chicken farm, slaughterhouse, and buildings located in west Slovakia in 2017. Samples were diluted in peptone buffered water, and Tryptone Soya Agar (TSA), Triple Sugar Agar (TSI), Blood Agar (BA), and Anaerobic Agar (AA) were used for inoculation. A total of 28 genera and 56 microbial species were isolated from the samples. The most abundant species were Bacillus pumilus (28 isolates) and B. thuringensis (28 isolates). The least isolated species were Rhodotorula mucilaginosa (one isolate), Kocuria rhizophila (two isolates), Paenibacillus polymyxa (two isolates), and Staphylococcus equorum (two isolates). There were differences in microbial composition between the samples originating from the slaughterhouse, chicken farm, and buildings. The majority of the bacterial isolates resistant to antibiotics were isolated from the chicken farm. The isolation of potentially pathogenic bacteria such as Salmonella, Escherichia, and Salmonella spp., which possess multiple drug resistance, is of public health concern.

Bioactive Nitrosylated and Nitrated N-(2-hydroxyphenyl)acetamides and Derived Oligomers: An Alternative Pathway to 2-Amidophenol-Derived Phytotoxic Metabolites.

Incubation of Aminobacter aminovorans, Paenibacillus polymyxa, and Arthrobacter MPI764 with the microbial 2-benzoxazolinone (BOA)-degradation-product 2-acetamido-phenol, produced from 2-aminophenol, led to the recently identified N-(2-hydroxy-5-nitrophenyl) acetamide, to the hitherto unknown N-(2-hydroxy-5-nitrosophenyl)acetamide, and to N-(2-hydroxy-3-nitrophenyl)acetamide. As an alternative to the formation of phenoxazinone derived from aminophenol, dimers- and trimers-transformation products have been found. Identification of the compounds was carried out by LC/HRMS and MS/MS and, for the new structure N-(2-hydroxy-5-nitrosophenyl)acetamide, additionally by 1D- and 2D-NMR. Incubation of microorganisms, such as the soil bacteria Pseudomonas laurentiana, Arthrobacter MPI763, the yeast Papiliotrema baii and Pantoea ananatis, and the plants Brassica oleracea var. gongylodes L. (kohlrabi) and Arabidopsis thaliana Col-0, with N-(2-hydroxy-5-nitrophenyl) acetamide, led to its glucoside derivative as a prominent detoxification product; in the case of Pantoea ananatis, this was together with the corresponding glucoside succinic acid ester. In contrast, Actinomucor elegans consortium synthesized 2-acetamido-4-nitrophenyl sulfate. 1 mM bioactive N-(2-hydroxy-5-nitrophenyl) acetamide elicits alterations in the Arabidopsis thaliana expression profile of several genes. The most responsive upregulated gene was pathogen-inducible terpene synthase TPS04. The bioactivity of the compound is rapidly annihilated by glucosylation.

Biocontrol activity and action mechanism of Paenibacillus polymyxa strain Nl4 against pear Valsa canker caused by Valsa pyri.

Pear Valsa canker caused by Valsa pyri is among the most destructive diseases of pear, which causes significant economic loss. The present study was developed to explore the biocontrol efficiency and underlying antagonistic mechanism of Paenibacillus polymyxa strain Nl4 against V. pyri. P. polymyxa strain Nl4, one of the 120 different endophytic bacterial strains from pear branches, exhibited strong inhibitory effects against the mycelial growth of V. pyri and caused hyphal malformation. Culture filtrate derived from strain Nl4 was able to effectively suppress mycelial growth of V. pyri, and was found to exhibit strong protease, cellulase and β-1, 3-glucanase activity. Through re-isolation assay, strain Nl4 was confirmed to be capable of colonizing and surviving in pear branch. Treatment with strain NI4 effectively protected against pear Valsa canker symptoms on detached pear twigs inoculated with V. pyri. Moreover, strain Nl4 promoted enhanced plant growth probably through the solubilization of phosphorus. Comparative transcriptomic analyses revealed that strain NI4 was able to suppress V. pyri growth in large part through the regulation of the expression of membrane- and energy metabolism-related genes in this pathogen. Further transcriptomic analyses of pear trees indicated that strain NI4 inoculation was associated with changes in the expression of genes associated with secondary metabolite biosynthesis, signal transduction, and cutin, suberine, and wax biosynthesis. Together, these data highlighted P. polymyxa strain Nl4 as a promising biocontrol agent against pear Valsa canker and investigated the possible mechanisms of strain Nl4 on control of this devastating disease.