Mechanism of interaction of an endofungal bacterium Serratia marcescens D1 with its host and non-host fungi

Abstract

<jats:title>Abstract</jats:title><jats:p>Association of bacteria with fungi is a major area of research in infection biology, however, very few strains of bacteria have been reported that can invade and reside within fungal hyphae. Here, we report the characterization of an endofungal bacterium <jats:italic>Serratia marcescens</jats:italic> D1 from <jats:italic>Mucor irregularis</jats:italic> SS7 hyphae. Upon re-inoculation, colonization of the endobacterium <jats:italic>S. marcescens</jats:italic> D1 in the hyphae of <jats:italic>Mucor irregularis</jats:italic> SS7 was demonstrated using stereo microscopy. However, <jats:italic>S. marcescens</jats:italic> D1 failed to invade into the hyphae of the tested Ascomycetes (except <jats:italic>Fusarium oxysporum</jats:italic>) and Basidiomycetes. Remarkably, <jats:italic>Serratia marcescens</jats:italic> D1 could invade and spread over the culture of <jats:italic>F. oxysporum</jats:italic> that resulted in mycelial death. Prodigiosin, the red pigment produced by the <jats:italic>Serratia marcescens</jats:italic> D1, helps the bacterium to invade fungal hyphae as revealed by the increasing permeability in fungal cell membrane. On the other hand, genes encoding the type VI secretion system (T6SS) assembly protein TssJ and an outer membrane associated murein lipoprotein also showed significant up-regulation during the interaction process, suggesting the involvement of T6SS in the invasion process.</jats:p>

Chemical signals driving bacterial–fungal interactions

“…This study illustrates well how a particular molecule can be beneficial at one concentration but harmful at a higher concentration. In another example, the endofungal bacterium Serratia marcescens D1 produces prodigiosin, which increases the cell membrane permeability of the soilborne host fungus Mucor irregularis SS7 and thereby helps the bacterium to invade fungal hyphae for an endosymbiotic lifestyle in rhizosphere (Hazarika et al ., 2020). Several SSMs act to promote endosymbiotic success (Table 1).…”

Production and Potential Applications of Bioconversion of Chitin and Protein-Containing Fishery Byproducts into Prodigiosin: A Review

“…PG enables S. marcescens D1 (an endofungal bacterium) to invade fungal hyphae and spread over the culture of F. oxysporum to result in mycelial death. [ 213 ].…”

In Vitro Characterization of Endophytic Bacteria Associated With Physic Nut (Jatropha Curcas L.) and Their Potential for Plant-Growth Promotion and Biocontrol / Caracterização in Vitro De Bactérias Endofíticas Associadas Ao Pinhão-Manso (Jatropha Curcas L.) E Seu Potencial De Promoção De Crescimento Vegetal E Biocontrole

“…Generally, plants have an endophytic microbiota that is important for their health and maintenance (Azevedo and Araújo 2007;Rodriguez et al, 2019). Endophytic bacteria bring many benefits to plants, such as biological control (Lacava and Azevedo, 2014;Eljounaidi, Lee, Bae, 2016), including competition of nutrients or with the production of toxins harmful to pathogens (Hazarika et al, 2019), decreasing disease susceptibility (Busby et al 2016;Christian et al 2019;, increasing resistance to abiotic stressors (Márquez et al 2007;Rodriguez et al 2008), shaping phytochemical profiles (Kusari et al 2012;Panaccione et al 2014), and mediating plant functional trait expression (Harrison and Griffin 2020). In addition, these microorganisms can influence the growth of plants, by increasing the availability of nutrients, such as biological fixation nitrogen, phosphate solubilization, and production of siderophores; or in the production of compounds that function as plant regulators, such as phytohormone indole-3-acetic acid (IAA) (Santoyo et al, 2016;Yadav and Yadav, 2019).…”