Isolation of Bacteria with Antifungal Activity against the Phytopathogenic Fungi Stenocarpella maydis and Stenocarpella macrospora

Abstract

Stenocarpella maydis and Stenocarpella macrospora are the causal agents of ear rot in corn, which is one of the most destructive diseases in this crop worldwide. These fungi are important mycotoxin producers that cause different pathologies in farmed animals and represent an important risk for humans. In this work, 160 strains were isolated from soil of corn crops of which 10 showed antifungal activity against these phytopathogens, which, were identified as: Bacillus subtilis, Pseudomonas spp., Pseudomonas fluorescens, and Pantoea agglomerans by sequencing of 16S rRNA gene and the phylogenetic analysis. From cultures of each strain, extracellular filtrates were obtained and assayed to determine antifungal activity. The best filtrates were obtained in the stationary phase of B. subtilis cultures that were stable to the temperature and extreme pH values; in addition they did not show a cytotoxicity effect against brine shrimp and inhibited germination of conidia. The bacteria described in this work have the potential to be used in the control of white ear rot disease.

<i>Bacillus subtilis Strains</i> with Antifungal Activity against the Phytopathogenic Fungi

“…The appearance of such anomalous formations in mycelium in the presence of metabolites of bacterial antagonists was frequently noticed by others [33] [34]. Antifungal action of Bacillus metabolites may be due to disruption of fungal cell wall and inhibition of normal conidia development.…”

Importance of Endophytic Strains Pantoea agglomerans in the Biological Control of Rhizoctonia solani

“…They also limited the growth of Macrophomina phaseolina, a causal agent of charcoal rot of soybean [35] as well as Stenocarpella maydis and S. macrospora, causing ear rot in corn [36]. The above mentioned research papers showed that Pantoea strains inhibited the growth of pathogens to a different degree depending on the following parameters: the growth phase, enzymatic activity, ability to produce metabolites, density of inoculum.…”

The impact of plant growth promoting bacteria (PGPB) on the development of phytopathogenic fungi

“…As shown in other research, some of isolated bacterial strains can increase plant growth due to the inhibition of plant pathogenic fungi (Petatán-Sagahón et al 2011, Weller 2007. Despite this, complementary experiments should be carried out with other fungal genera, like Pythium, Phytophthora, or Sclerotinia, to confirm the biocontrol capacity of each strain.…”