A Thermotolerant Marine Bacillus amyloliquefaciens S185 Producing Iturin A5 for Antifungal Activity against Fusarium oxysporum f. sp. cubense

Abstract

Fusarium wilt of banana (also known as Panama disease), is a severe fungal disease caused by soil-borne Fusarium oxysporum f. sp. cubense (Foc). In recent years, biocontrol strategies using antifungal microorganisms from various niches and their related bioactive compounds have been used to prevent and control Panama disease. Here, a thermotolerant marine strain S185 was identified as Bacillus amyloliquefaciens, displaying strong antifungal activity against Foc. The strain S185 possesses multiple plant growth-promoting (PGP) and biocontrol utility properties, such as producing indole acetic acid (IAA) and ammonia, assimilating various carbon sources, tolerating pH of 4 to 9, temperature of 20 to 50 °C, and salt stress of 1 to 5%. Inoculation of S185 colonized the banana plants effectively and was mainly located in leaf and root tissues. To further investigate the antifungal components, compounds were extracted, fractionated, and purified. One compound, inhibiting Foc with minimum inhibitory concentrations (MICs) of 25 μg/disk, was identified as iturin A5 by high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) and nuclear magnetic resonance (NMR). The isolated iturin, A5, resulted in severe morphological changes during spore germination and hyphae growth of Foc. These results specify that B. amyloliquefaciens S185 plays a key role in preventing the Foc pathogen by producing the antifungal compound iturin A5, and possesses potential as a cost-effective and sustainable biocontrol strain for Panama disease in the future. This is the first report of isolation of the antifungal compound iturin A5 from thermotolerant marine B. amyloliquefaciens S185.

Identification of a New Antifungal Peptide W1 From a Marine Bacillus amyloliquefaciens Reveals Its Potential in Controlling Fungal Plant Diseases

“…Besides, W1 showed higher tolerance to a variety of proteases against F. oxysporum . These characteristics were better than the antifungal peptides produced by B. amyloliquefaciens S185, PT14, and B. velezensis HNAH 17806 ( Kim et al, 2015 ; Singh et al, 2021 ; Wang et al, 2021 ), indicating that W1 has superior application potential in the biocontrol of plant diseases.…”

“…Several isolates of B. amyloliquefaciens have exhibited their application potential as plant growth promoters, probiotics, and antibiotics. As effective candidates of biocontrol microorganisms in agriculture, B. amyloliquefaciens Pc3, S185, PT14, Rdx5, FZB42, and SWB16 suppressed the growth of many fungal or bacterial pathogens, such as A. longipes , C. gloeosporioides , and F. oxysporum ( Chen et al, 2009 ; Wang et al, 2014 ; Kim et al, 2015 ; Ding et al, 2019 ; Dong et al, 2019 ; Singh et al, 2021 ). B. amyloliquefaciens W0101 isolated here could suppress 9 pathogenic fungi, such as A. longipes , C. gloeosporioides , F. oxysporum , S. sclerotiorum , and P. amygdali , showing a broad spectrum of antifungal activity.…”

Cyclic Lipopeptides of Bacillus amyloliquefaciens DHA6 Are the Determinants to Suppress Watermelon Fusarium Wilt by Direct Antifungal Activity and Host Defense Modulation

“…This study found that CLPs from B. amyloliquefaciens DHA6 significantly inhibited mycelial growth and conidia germination of Fon ( Figure 4 ), providing mechanistic insights into the direct antifungal activity of B. amyloliquefaciens DHA6 against phytopathogenic fungi. Previous studies have reported that CLPs purified from different B. amyloliquefaciens strains, such as fengycins and iturins, inhibited mycelial growth and spore germination of Fo in vitro [ 21 , 22 , 23 , 63 , 64 ]. Iturins produced by Bacillus spp.…”

Assessment of Lipopeptide Mixtures Produced by Bacillus subtilis as Biocontrol Products against Apple Scab (Venturia inaequalis)

“…Iturins family consists of a group of cyclic lipopeptides composed of a heptapeptide moiety and a chain of fatty acids linked by an α-amino bond. These are known for their strong antifungal activity against pathogenic yeasts and fungi [22,32,38].…”