Characterization of a novel antifungal protein produced by Paenibacillus polymyxa isolated from the wheat rhizosphere

Abstract

BACKGROUND Fusarium head blight (FHB) is one of the disasters that seriously harm wheat and other small grain crops. It causes spoilage and mildew of the grain leading to a significant decline in the yield and quality of the grain. This research aimed to isolate antagonistic bacteria to purify antifungal proteins. A strain was isolated from the rhizosphere of healthy wheat in a wheat field affected by a severe FHB epidemic. This isolated strain was tentatively identified as Paenibacillus polymyxa 7F1, which displayed a strong inhibitory effect against several other pathogens. One novel antifungal protein was purified from the P. polymyxa 7F1 and successfully expressed. RESULTS A crude culture of P. polymyxa 7F1 demonstrated antifungal activity that was stable at a temperature range of 60–90 °C and a pH range of 2.6–9.0. However, the antifungal activity of the P. polymyxa 7F1 was inhibited with proteinase K, trypsin, and neutral protease treatment. A 36 kDa protein with broad‐spectrum antifungal activity was purified from the P. polymyxa 7F1. A glycosyl hydrolase domain was identified from this protein through liquid chromatography–mass spectrometry (LC–MS) analysis. A recombinant plasmid pET32a(+)/36kd for prokaryotic expression was constructed, and the renatured p36kd protein demonstrated similar antifungal activity to the 36 kDa protein purified from the P. polymyxa 7F1. CONCLUSION A novel antifungal protein produced by P. polymyxa 7F1 was purified and expressed. The recombinant protein showed good antifungal activity as the novel purified protein. The novel antifungal protein provides an effective way to control the Fusarium head blight. © 2020 Society of Chemical Industry

Isolation and Characterization of Paenibacillus polymyxa B7 and Inhibition of Aspergillus tubingensis A1 by Its Antifungal Substances

“…Several protein fractions had protein molecular masses of about 37 kDa and 60 kDa (Figure 6). The results were similar to the electrophoretic results of Ran [31].…”

“…Several protein fractions had protein molecular masses of about 37 kDa and 60 kDa (Figure 6). The results were similar to the electrophoretic results of Ran [31]. As can be seen in Figure 7, after treatment with antifungal proteins, the mycelial morphology of A. tubingensis shriveled and underwent significant breakage and fragmentation.…”

“…The biocontrol mechanisms of Bacillus mainly involve competition between Bacillus and pathogens for nutrients and ecological niches [23][24][25], the production of antimicrobial substances [26], interaction between Bacillus and pathogens [27,28], induction of the plant's systemic resistance [29,30], and so on. One of the main antifungal mechanisms in Bacillus is producing compounds with antifungal effects, such as inhibitory proteins [31], inhibitory lipopeptides [19], and other secondary metabolites [32]. Paenibacillus-derived antimicrobials include polymyxins and fusaricides, which are non-ribosomal lipopeptides first isolated from strains of P. polymyxa.…”

Biocontrol potential of lipopeptides produced by Paenibacillus polymyxa AF01 against Neoscytalidium dimidiatum in pitaya

“…Compared with spore germination and germ tube elongation, hyphae growth phase was more sensitive to the effect of AF01 culture filtrate, while germ tube growth was less affected, which is in agreement with other findings on the antifungal activity of P. polymyxa and other Paenibacillus spp. against fungal species such as Cylindrocarpon destructant , Rhizoctonia solani , Fusarium sp., Sclerotinia sclerotiorum , Pythium ultimum ( Bae et al, 2004 ), Colletotrichum gloeosporioides ( Ran et al, 2021 ), Pseudoperonospora cubensis , B. cinerea , Phytophthora capsica ( Kim et al, 2009 ) and Magnaporthe oryzae ( Ali et al, 2021 ). Microscopic observations revealed that P. polymyxa AF01 hampered the fungus spore causing mycelial tip enlargement, protoplast cleavage and abnormal morphological alternations of the spores.…”

Extraction and characterization of cyclic lipopeptides with antifungal and antioxidant activities from Bacillus amyloliquefaciens

“…These factors led to reduced biofungicide residual activity, requiring multiple applications over a growing season, which increased production costs (do Nascimento et al, 2022). But, biological fungicides are still attracting more and more attention worldwide because of its effective, safe and environment‐friendly advantages (Luo et al, 2019; Ran et al, 2020; Zhang et al, 2017).…”