Abstract
The endophytic strain Cal.l.30, isolated from the medicinal plant Calendula officinalis, was selected among seven Bacillus strains with plant growth promoting activity and strong biological potential against the postharvest fungal pathogen Botrytis cinerea. Treatment by inoculating Cal.l.30 bacterial cell culture or cell free supernatant on harvested grapes and cherry tomato fruits, significantly reduced gray mold disease severity index and disease incidence. Based on 16S rRNA sequence analysis and whole genome phylogeny, Cal.l.30 was identified as Bacillus halotolerans. Genome mining revealed that B. halotolerans Cal.l.30 is endowed with a diverse arsenal of secondary metabolite biosynthetic gene clusters (SM-BGCs) responsible for metabolite production with antimicrobial properties. A sub-set of the identified SM-BGCs (mojavensin A, ‘bacillunoic acid’) appears to be the result of recent horizontal gene transfer events. Its genome was also mined for CAZymes associated with antifungal activity. Further UHPLC-HRMS analysis indicated that Cal.l.30 synthesizes and secretes secondary metabolites with antimicrobial activity, including the lipopeptides, fengycin, surfactin and mojavensin A, bacillaene isoforms, L-dihydroanticapsin and bacillibactin. Other compounds with known antimicrobial activity were also detected, such as azelaic acid, 15- hydroxypentadecanoid acid and 2-hydroxyphenylacetic acid. The genomic and metabolomic features of the B. halotolerans Cal.l.30 provided new perspectives on the exploitation of novel Bacillus sp. as a biocontrol agent.
Highlights
The present study focuses on B. halotolerans strain Cal.l.30, a strong biological control agents (BCAs) candidate among four B. halotolerans strains (Cal.f.4, Cal.l.11, Cal.f.2.1, Cal.r.11), one B. velezensis (Cal.r.29) and one B. subtilis strain (Cal.r.19), as previously isolated from different plant parts of the medicinal plant C. officinalis [25]
Endophytic bacteria derived from medicinal plants are an important source of potential BCAs, due to the diverse competing mechanisms they have developed in order to adapt and survive endophytically [44,61]
As presented in a previous study of ours, a total number of 119 cultivable endophytic bacterial strains were isolated from different plant parts such as roots, leaves and flowers of the medicinal plant Calendula officinalis, from which twenty-four morphologically distinct endophytic bacterial strains of the genus Bacillus were identified based on 16S rRNA
Summary
The extensive use of chemical pesticides, herbicides and fertilizers has a significant impact on environmental pollution. There has been much attention given to the study and implementation of sustainable, efficient and environmentally friendly products in agriculture [1]. The application of beneficial microorganisms, and especially bacteria, has gained a lot of interest due to their multiple plant growth promoting and plant protection mechanisms, making it necessary to find strong and effective biological control agents (BCAs) [2]. Plant growth promoting rhizobacteria (PGPR) and plant growth promoting
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
