Induction of Cryptic Antifungal Pulicatin Derivatives from Pantoea Agglomerans by Microbial Co-Culture

Abstract

Microbial co-culture or mixed fermentation proved to be an efficient strategy to expand chemical diversity by the induction of cryptic biosynthetic pathways, and in many cases led to the production of new antimicrobial agents. In the current study, we report a rare example of the induction of silent/cryptic bacterial biosynthetic pathway by the co-culture of Durum wheat plant roots-associated bacterium Pantoea aggolomerans and date palm leaves-derived fungus Penicillium citrinum. The initial co-culture indicated a clear fungal growth inhibition which was confirmed by the promising antifungal activity of the co-culture total extract against Pc. LC-HRMS chemical profiling demonstrated a huge suppression in the production of secondary metabolites (SMs) of axenic cultures of both species with the emergence of new metabolites which were dereplicated as a series of siderophores. Large-scale co-culture fermentation led to the isolation of two new pulicatin derivatives together with six known metabolites which were characterised using HRESIMS and NMR analyses. During the in vitro antimicrobial evaluation of the isolated compounds, pulicatin H (2) exhibited the strongest antifungal activity against Pc, followed by aeruginaldehyde (1) and pulicatin F (4), hence explaining the initial growth suppression of Pc in the co-culture environment.

Wild apple-associated fungi and bacteria compete to colonize the larval gut of an invasive wood-borer Agrilus mali in Tianshan forests

“…The most abundant gut bacteria, P. aqqlomerans, also had antifungal activity but was not able to inhibit all endophytic and saprophytic fungi. However, its antagonistic ability is reported in the literature [53,54]. It was reported that E. billingiae also has antifungal ability against pathogenic Heterobasidion annosum, Armillaria mellea and Fusarium circinatum fungi infecting Pinus radiata trees [54,55], and E. persicina has activity against A. alternata [56].…”

“…It was reported that E. billingiae also has antifungal ability against pathogenic Heterobasidion annosum, Armillaria mellea and Fusarium circinatum fungi infecting Pinus radiata trees [54,55], and E. persicina has activity against A. alternata [56]. It is likely that bacterial species within the genus could produce similar antifungal compounds, such as herbicolin, pulicatin and pyrrolnitrin [53,57,58].…”

Co-culture: stimulate the metabolic potential and explore the molecular diversity of natural products from microorganisms

“…In 2020, two new pulicatin derivatives, pulicatins H and I (85, 86) ( Supplementary Fig. S12), were isolated from the combined-culture of the fungus Penicillium citrinum from date palm leaves in ISP 2 media durum with wheat plant roots-associated bacterium Pantoea agglomerans (Thissera et al 2020). Compound 85 showed significant bioactivity against A. niger (MIC = 8.4 μmol/L).…”

Bio-Guided Isolation of Antimalarial Metabolites from the Coculture of Two Red Sea Sponge-Derived Actinokineospora and Rhodococcus spp.

“…Furthermore, a new N-methoxypyridone was discovered from a mixed fermentation of two endophytic fungi Camporesia sambuci and Epicoccum sorghinum isolated from the fruit of Rhodomyrtus tomentosa plant, collected on the Big Island in Hawaii [12]. New antifungal pulicatin derivatives H and I were induced following coculturing of plant-derived bacterium Pantoea agglomerans and the fungus Penicillium citrinum [13]. All these examples exemplify that co-cultivation of microorganisms induces new secondary metabolites that can be recommended as an appropriate way to produce diverse bioactive microbial metabolites.…”