Profiling for Bioactive Peptides and Volatiles of Plant Growth Promoting Strains of the Bacillus subtilis Complex of Industrial Relevance.

Pascal Mülner,Stefanie Herfort,Tomislav Cernava,Joachim Vater,Helmut Junge,Elisa Schwarz,Peter Lasch,Kristin Dietel,Max Weydmann,Gabriele Berg

doi:10.3389/fmicb.2020.01432

Pascal Mülner, Stefanie Herfort + Show 8 more

Open Access

https://doi.org/10.3389/fmicb.2020.01432

Copy DOI

Abstract

Plant growth promoting rhizobacteria attain increasing importance in agriculture as biofertilizers and biocontrol agents. These properties significantly depend on the formation of bioactive compounds produced by such organisms. In our work we investigated the biosynthetic potential of 13 industrially important strains of the Bacillus subtilis complex by mass spectrometric methodology. Typing of these organisms was performed with MALDI-TOF mass spectrometry followed by comprehensive profiling of their bioactive peptide products. Volatiles were determined by gas chromatography-mass spectrometry. Representative products of the members of the B. subtilis complex investigated in detail were: the surfactin familiy (surfactins, lichenysins, pumilacidins); the iturin family (iturins, mycosubtilins and bacillomycins); plantazolicin and the dual lantibiotics lichenicidins, as well as a wide spectrum of volatiles, such as hydrocarbons (alkanes/alkenes), alcohols, ketones, sulfur-containing compounds and pyrazines. The subcomplexes of the B. subtilis organizational unit; (a) B. subtilis/Bacillus atrophaeus; (b) B. amyloliquefaciens/B. velezensis; (c) B. licheniformis, and (d) B. pumilus are equipped with specific sets of these compounds which are the basis for the evaluation of their biotechnological and agricultural usage. The 13 test strains were evaluated in field trials for growth promotion of potato and maize plants. All of the implemented strains showed efficient growth stimulation of these plants. The highest effects were obtained with B. velezensis, B. subtilis, and B. atrophaeus strains.

Highlights

Plant growth promoting rhizobacteria (PGPR) and endophytes attain increasing importance as efficient biofertilizers, biostimulants and biocontrol organisms for a sustainable and enviromentally friendly alternative to conventional agriculture (Saharan and Nehra, 2011; Hardoim et al, 2015)
After having classified our test strains as members of the B. subtilis complex the main aim of our work was focused on the exploration of their biosynthetic potential for the production of bioactive peptides and volatiles which play an important role in plant growth promoting and biocontrol activities of PGPR strains
Thirteen industrially relevant strains were identified by MALDITOF MS as members of the B. subtilis community and were attributed to the corresponding subcomplexes

Summary

Introduction

Plant growth promoting rhizobacteria (PGPR) and endophytes attain increasing importance as efficient biofertilizers, biostimulants and biocontrol organisms for a sustainable and enviromentally friendly alternative to conventional agriculture (Saharan and Nehra, 2011; Hardoim et al, 2015). Numerous PGPR produce a variety of antimicrobial compounds to inhibit phytopathogens (Ongena and Jacques, 2008; Pérez-García et al, 2011). Such compounds are frequently produced non-ribosomally by specific multienzyme systems. A wide spectrum of bioactive peptides of ribosomal origin, such as lantibiotics and bacteriocines are recruited for plant protection Prominent microorganisms with such abilities include members of the B. subtilis complex, Paenibacillus as well as Pseudomonas strains (Lim et al, 1991; Hong and Meng, 2003; Peighami-Ashnaei et al, 2009; Asari et al, 2016; Rybakova et al, 2016)

Objectives

Methods

Results

Discussion

Conclusion