Isolation and Characterisation of Endophytic Strain Paenibacillus polymyxa SR19 from Urtica dioica and the Study of Their Effect against Fusarium oxysporum f. sp Tomato

In an attempt to obtain biological control agents for fusariose wilt, a total of 54 endophytic bacterial strains were isolated from the root of plants Urtica dioica and screened for in vitro antagonist activity against Fusarium oxysporum. Among the 54 bacterial isolates, 27 isolates exhibited more than 60% inhibition of mycelia growth of Fusarium oxysporum. The strain R19 which exhibited the most obvious antagonistic activity was selected for greenhouse studies. The SR19 had no pathogenicity and was identified as Paenibacillus polymyxa based on its phenotypical and biochemical properties as well as its 16S rRNA gene sequence. Growth chamber studies resulted in statistically significant increases in inoculating tomato seedling with the endophytic strain SR19 which in turn resulted in improving plant seedling stand by 32% and increasing fresh weights of root and fresh weight of aerial biomass of plants over the untreated pathogen control by 6.95 g and 7.96 g, respectively. Strain SR19 is a potential biological control agent that may contribute to the protection of tomato plants against fusariose wilt.

Production optimization, purification, expression, and characterization of a novel α-L-arabinofuranosidase from Paenibacillus polymyxa

Background: α-L-Arabinofuranosidase (EC 3.2.1.55) catalyzes the hydrolysis of terminal α-L-1,2-, -1,3-, and -1,5- arabinofuranosyl residues in arabinose-containing polymers, and hence, it plays an important role in hemicellulose degradation. Herein, the bacterium Paenibacillus polymyxa, which secretes arabinofuranosidase with high activity, was selected for enzyme production, purification, and characterization. Results: Medium components and cultural conditions were optimized by the response surface method using shake flask cultures. Arabinofuranosidase production reached 25.2 U/mL under optimized conditions, which were pH 7.5, 28°C, and a basic medium supplemented with 1.5 g/L mannitol and 3.5 g/L soymeal. Furthermore, the arabinofuranosidase secreted by P. polymyxa, named as PpAFase-1, was partially purified from the supernatant using a DEAE Sepharose Fast Flow column and a hydroxyapatite column. The approximate molecular mass of the purified PpAFase-1 was determined as 56.8 kDa by SDS-PAGE. Protein identification by mass spectrometry analysis showed that the deduced amino acid sequence had significant similarity to the glycosyl hydrolase family 51. The deduced gene of 1515 bp was cloned and expressed in Escherichia coli BL21 (DE3) cells. Purified recombinant PpAFase-1 was active toward p-nitrophenyl-α-L-arabinofuranoside (pNPAraf). The Km and kcat values toward pNPAraf were 0.81 mM and 53.2 s−1 , respectively. When wheat arabinoxylan and oat spelt xylan were used as substrates, PpAFase-1 showed poor efficiency. However, a synergistic effect was observed when PpAFase-1 was combined with xylanase from Thermomyces lanuginosus. Conclusion: A novel GH51 enzyme PpAFase-1 was cloned from the genome of P. polymyxa and expressed in E. coli. This enzyme may be suitable for hemicellulose degradation on an industrial scale.

Production and characterization of carboxymethyl cellulase from Paenibacillus polymyxa using mango peel as substrate.

Mango peel, a solid mango processing waste, comprises 15-20% of total fruit weight. This, being a rich source of lignocelluloses, was used as substrate for carboxymethyl cellulase (CMCase) production using Paenibacillus polymyxa. Maximum CMCase production (7.814 U mg-1) was observed in a medium containing 7% mango peel (w/v) with 1.5% ammonium sulphate (w/v) at 37oC and pH 5.5. Purification to an extent of 28.24 fold was achieved by affinity column chromatography. Bands corresponding to 26.5 and 34.0 kDa molecular sizes were observed on 12% denaturing Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) while of 72 kDa on 10% non- denaturing Native-PAGE, proving its heteromeric multienzyme nature. The enzyme was stable over a range of 20-60oC and pH of 4.0-7.5. Michaelis-Menten equation constant (Km and Vmax) values of purified CMCase were 8.73 mg ml-1 and 17.805 mM ml-1 min-1, respectively.

Antibacterial activity of metabolite produced by Paenibacillus polymyxa strain HKA-15 against Xanthomonas campestris pv. phaseoli.

An antibacterial metabolite extracted from Paenibacillus polymyxa HKA-15 showed strong inhibition against Xanthomonas campestris pv. phaseoli strains CP-1-1 and M-5. Minimum inhibitory concentration (MIC) of crude extract against strains CP-1-1 and M-5 was found to be 1.7 mg/ml and 1.52 mg/ml, respectively. In UV-Vis range, the absorption peak of crude extract was maximum at 240 nm. The compound is resilience to wide range of temperature, pH, surfactants and organic solvents. The complete loss of activity was observed when crude metabolite was treated with pepsin (400 unit / ml). Characterization of crude metabolite suggested its hydrophobic and peptide nature. Inhibition of Xanthomonas campestris pv. phaseoli by peptide like metabolite produced by Paenibacillus polymyxa strain HKA-15 under in vitro conditions showed ecological and biotechnological potential of strain HKA-15 to control common blight disease in beans.

The nematicidal effect of some bacterial biofertilizers on Meloidogyne incognita in sandy soil

In a greenhouse experiment, the nematicidal effect of some bacterial biofertilizers including the nitrogen fixing bacteria (NFB) Paenibacillus polymyxa (four strains), the phosphate solubilizing bacteria (PSB) Bacillus megaterium (three strains) and the potassium solubilizing bacteria (KSB) B. circulans (three strains) were evaluated individually on tomato plants infested with the root-knot nematode Meloidogyne incognita in potted sandy soil. Comparing with the uninoculated nematode-infested control, the inoculation with P. polymyxa NFB7, B. megaterium PSB2 and B. circulans KSB2, increased the counts of total bacteria and total bacterial spores in plants potted soil from 1.2 to 2.6 folds estimated 60 days post-inoculation. Consequently, the inoculation with P. polymyxa NFB7 increased significantly the shoot length (cm), number of leaves / plant, shoot dry weight (g) / plant and root dry weight (g) / plant by 32.6 percent, 30.8 percent, 70.3 percent and 14.2 percent, respectively. Generally, the majority treatments significantly reduced the nematode multiplication which was more obvious after 60 days of inoculation. Among the applied strains, P. polymyxa NFB7, B. megaterium PSB2 and B. circulans KSB2 inoculations resulted in the highest reduction in nematode population comparing with the uninoculated nematode-infested control. They recorded the highest reduction in numbers of hatched juveniles/root by 95.8 percent, females/root by 63.75 percent and juveniles/1kg soil by 57.8 percent. These results indicated that these bacterial biofertilizers are promising double purpose microorganisms for mobilizing of soil nutrients (nitrogen, phosphate and potassium) and for the biological control of M. incognita.

Maturation of bone marrow-derived dendritic cells by a novel beta-glucan purified from Paenibacillus polymyxa JB115

We investigated the immunostimulatory effects of a novel beta-glucan purified from Paenibacillus (P.) polymyxa JB115 on bone marrow-derived dendritic cells (DCs), a type of potent antigen-presenting cells. beta-glucan isolated from P. polymyxa JB115 enhanced the viability and induced the maturation of DCs. beta-glucan markedly increased the cytokine production of DCs and surface expression of DC markers. In addition, DCs treated with beta-glucan showed a higher capacity to stimulate allogeneic spleen cell proliferation compared to those treated with medium alone. These results demonstrate the effect of beta-glucan on DC maturation and may increase the use of beta-glucan.

Response of Paenibacillus polymyxa to iron: alternations in cellular chemical composition and the production of fusaricidin type antimicrobial compounds

In this work, growth, cellular chemical composition and production of fusaricidin type antimicrobial compounds by P. polymyxa SQR-21 were compared in tryptone broth supplemented with four concentrations of iron (25, 50, 100 and 200 µM). The data revealed that the growth of P. polymyxa SQR-21 was increased by 3-8 percent with the increase in concentration of ferric ion (Fe3+). The production of fusaricidin type compounds was increased by 33-49 percent only up to 50 µM Fe3+ and the highest level of Fe3+ was inhibitory. Increase in the liquid culture Fe3+concentration increased the intracellular protein (2 percent), intracellular carbohydrate (14 percent), extracellular protein (7 percent) and polysaccharide contents (18 percent) while the intracellular lipid contents were increased (11 percent) only up to 50 µM Fe3+. In addition, the regulatory effects of Fe3+ were also reflected by the increase in total RNA contents and relative expression of the fusaricidin synthetase gene (FusA) by 3-13 and 35-56 percent, respectively, up to 50 µM Fe3+, after that a continuous decrease was observed.

Tipo compostos do fusaricidin do produto das tensões do polymyxa de Paenibacillus que é ativo de encontro a uma variedade larga das bactérias e de fungos gram-positive. O crescimento, a composição química celular e a produção do fusaricidin datilografam compostos antimicrobial pelo P. o polymyxa SQR-21 foi comparado no caldo de carne do tryptone suplementado com as quatro concentrações (25, µM 50, 100 e 200) do ferro. Os dados revelaram que o crescimento do P. o polymyxa foi aumentado por 3-8 por cento com o aumento na concentração do íon férrico (Fe3+) e o tipo produção do fusaricidin dos compostos foi aumentado 33-49 por cento somente até 50 pelo µM Fe3+ quando o nível o mais elevado de Fe3+ era inhibitory. O aumento na concentração de Fe3+ na cultura líquida aumentou a proteína intracellular (2 por cento) e os índices de hidrato de carbono (14 por cento) e a proteína extracellular (7 por cento) e os índices do polysaccharide (18 por cento) quando os índices intracellular do lipid eram (11 por cento) somente até 50 o µM aumentado Fe3+. Além, os efeitos regulatory de Fe3+ foram refletidos também pelo aumento em índices totais do RNA e na expressão relativa do gene do synthetase do fusaricidin (FusA) por 3-13 e por 35-56 por cento respectivamente, até 50 o µM Fe3+, em seguida que uma diminuição contínua estêve observada.

A novel beta-glucan produced by Paenibacillus polymyxa JB115 induces nitric oxide production in RAW264.7 macrophages

The effect of extracellular beta-(1-->3), (1-->6)-glucan, produced by Paenibacillus polymyxa JB115, on nitric oxide (NO) production in RAW264.7 macrophages was investigated. beta-glucan induced the production of NO by RAW264.7 macrophages in a concentration- and time-dependent manner. Moreover, beta-glucan stimulation increased the mRNA expression of iNOS, COX-2 and IL-6 in RAW264.7 macrophages in a concentration-dependent manner.

Isolation and Identification of a Pesticide-degrading and Biocontrol Bacterium / 微生物学通报

One biocontrol bacillus B3 was isolated from peanut rhizosphere, which showed a broad inhibition spectrum against various soil-borne plant phytopathogenic fungi. It was also found to be capable of utilizing beta-cypermethrin, chlorpyrifos and imidacloprid as the sole source of carbon for growth. The extent of degradation of them at initial concentration of 100 mg/L was 54.42%, 57.44% and 49.24% respectively within 7 days. Strain B3 was identified as Paenibacillus polymyxa based on morphological, physiological-biochemical properties, and 16S rRNA sequence analysis. This study indicated that strain B3 had potential application in biological control and soil bioremediation.

Research Advances in Paenibacillus polymyxa and Their Bioactive Substances / 微生物学通报

Many beneficial bioactive substances were produced by Paenibacillus polymyxa such as antibiotics, antimicrobial proteins, plant hormones and flocculants. These bioactive substances also could be produced by Paenibacillus polymyxa making it show excellent prospect in biological control of plant diseases, treatment of mankind and animals. This article summarizes research advances in Paenibacillus polymyxa and their bioactive substances.