AUTHOR=Khan Noor , Martínez-Hidalgo Pilar , Ice Tyler A. , Maymon Maskit , Humm Ethan A. , Nejat Najmeh , Sanders Erin R. , Kaplan Drora , Hirsch Ann M. 

TITLE=Antifungal Activity of Bacillus Species Against Fusarium and Analysis of the Potential Mechanisms Used in Biocontrol

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.02363

DOI=10.3389/fmicb.2018.02363

ISSN=1664-302X

ABSTRACT=<p><italic>Fusarium</italic> is a complex genus of ascomycete fungi that consists of plant pathogens of agricultural relevance. Controlling <italic>Fusarium</italic> infection in crops that leads to substantial yield losses is challenging. These economic losses along with environmental and human health concerns over the usage of chemicals in attaining disease control are shifting focus toward the use of biocontrol agents for effective control of phytopathogenic <italic>Fusarium</italic> spp. In the present study, an analysis of the plant-growth promoting (PGP) and biocontrol attributes of four bacilli (<italic>Bacillus simplex</italic> 30N-5, <italic>B. simplex</italic> 11, <italic>B. simplex</italic> 237, and <italic>B. subtilis</italic> 30VD-1) has been conducted. The production of cellulase, xylanase, pectinase, and chitinase in functional assays was studied, followed by <italic>in silico</italic> gene analysis of the PGP-related and biocontrol-associated genes. Of all the bacilli included in this study, <italic>B. subtilis</italic> 30VD-1 (30VD-1) demonstrated the most effective antagonism against <italic>Fusarium</italic> spp. under <italic>in vitro</italic> conditions. Additionally, 100 μg/ml of the crude 1-butanol extract of 30VD-1’s cell-free culture filtrate caused about 40% inhibition in radial growth of <italic>Fusarium</italic> spp. Pea seed bacterization with 30VD-1 led to considerable reduction in wilt severity in plants with about 35% increase in dry plant biomass over uninoculated plants growing in <italic>Fusarium</italic>-infested soil. Phase contrast microscopy demonstrated distortions and abnormal swellings in <italic>F. oxysporum</italic> hyphae on co-culturing with 30VD-1. The results suggest a multivariate mode of antagonism of 30VD-1 against phytopathogenic <italic>Fusarium</italic> spp., by producing chitinase, volatiles, and other antifungal molecules, the characterization of which is underway.</p>