Identification and characterization of a new Bacillus atrophaeus strain B5 as biocontrol agent of postharvest anthracnose disease in soursop (Annona muricata) and avocado (Persea americana)

Abstract

Anthracnose is a fungal disease caused by Colletotrichum species that is detrimental to numerous fruit, including soursop and avocado. The use of fungicides to maintain the high quality of fruit creates a potential health risk. One alternative to this problem is the biological control, which has been applied successfully during postharvest. The Bacillus species are one of the most studied biological agents against postharvest pathogens because accomplish their biocontrol performance by producing a variety of metabolites. In this study, we evaluated the activity of metabolites contained in the cell free supernatant, obtained from Bacillus strain B5 culture, against micelial growth and spore germination of two virulent strains of C. gloeosporioides isolated from soursop and avocado. On the basis of 16S rDNA gene sequence analysis, this strain was identified as Bacillus atrophaeus. A preventive treatment using cell free supernatant, reduced severity and incidence of anthracnose disease on harvested soursop and avocado fruit. B. atrophaeus strain B5 harbors genes involved in the production of antibiotics such as surfactin, bacillomycin and iturin, which could be contributing to the efficiency of the preventive treatment during postharvest. The antagonistic role of metabolites contained in the cell free supernatant against anthracnose disease, provide a new approach by which to attack this problem and can help reduce the use of chemical pesticides, environmental pollution, leading to the safer fruit preservation.

Screening for Fusarium Antagonistic Bacteria From Contrasting Niches Designated the Endophyte Bacillus halotolerans as Plant Warden Against Fusarium

“…and rhizosphere of wheat, respectively. These two sites were selected to fit the definable environmental limits for the existence of the biological control agent (Debbi et al, 2018; Gomez-Lama Cabanas et al, 2018; Guardado-Valdivia et al, 2018). More than 140 bacterial isolates were recovered from these two sites and screened for their inhibitory effect against F. oxysporum f. sp.…”

“…Biological control relies on screening for pest or pathogen antagonists or natural enemies, originating from its area of spread or areas that closely match the climate and soil type of the infested region by the pest or pathogen. This allows researchers to match the definable environmental limits for the existence of the biological control agent (Debbi et al, 2018; Gomez-Lama Cabanas et al, 2018; Guardado-Valdivia et al, 2018). Despite the selection of definable environmental limits for the existence of the biological control agent, some biocontrol agents fail to compete or colonize the rhizosphere of inoculated plants (Mefteh et al, 2017).…”

Iturinic Lipopeptide Diversity in the Bacillus subtilis Species Group – Important Antifungals for Plant Disease Biocontrol Applications

“…It is well known that iturinic lipopeptides possess strong antifungal activity (Mhammedi et al, 1982; Peypoux et al, 1986; Ongena and Jacques, 2008; Ma et al, 2012; Guardado-Valdivia et al, 2018) and induce defense responses in plants (Farace et al, 2015; Park et al, 2016; Wu et al, 2018) which, in turn, has led to the commercialization of many Bacillus strains that manufacture these compounds (Dunlap, 2019). Interestingly, no known resistance mechanisms to iturinic lipopeptides have been reported in fungi.…”

“…Several studies have recently reported antifungal lipopeptides in B. atrophaeus , but none have identified the active compound (Zhang et al, 2013, 2016; Chen et al, 2017; Guardado-Valdivia et al, 2018). This study was first to identify B. atrophaeus as a producer of mycosubtilin.…”

Diffusible and volatile organic compounds produced by avocado rhizobacteria exhibit antifungal effects against Fusarium kuroshium

“…is an economically important commodity for Mexican agriculture, as the country produces approximately 35% of the avocado global production [1]. However, the productivity of avocado orchards has been set back by the occurrence of fast-spreading diseases such as Phytophthora root rot, caused by the oomycete Phytophthora cinnamomi [2], or anthracnose, caused by Colletotrichum gloeosporioides [3]. Recently, two fungal diseases vectored by invasive ambrosia beetles have been hindering avocado production in the USA [4][5][6], in Israel [7], and have been newly reported in South Africa [8].…”