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

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.

Fusaricidins, Polymyxins and Volatiles Produced by Paenibacillus polymyxa Strains DSM 32871 and M1

“…Five compounds were unique to M1: 2-methyl-1-propanol, 2-methylbutanenitrile, dimethyl sulfone, butyl acetate, 3-methylbutyl acetate and 2-heptanone. In comparison to other plant growth promoting rhizobacteria of the order Bacillales, such as Bacillus subtilis, Bacillus atrophaeus, Bacillus amyloliquefaciens, Bacillus velezensis, and Bacillus licheniformis [57], both P. polymyxa strains emitted a variety of alkylpyrazines. In previous studies, alkylpyrazines exhibited antibacterial, antifungal, antimycobacterial, algicidal and antiviral activities [58][59][60][61].…”

“…For the preparation of surface extracts of Paenibacillus polymyxa strains DSM 32871 and M1 were grown on agar plates using three cultivation media [57]: (a) Lysogeny broth (Luria-Bertani) (LB) medium, (b) Landy medium [82] and (c) TSA medium solidified with 1.5% agar in Petri dishes for 24, 48 and 72 h at 30 • C. In addition, liquid fermentations were carried out in 100 mL Erlenmeyer flasks at 30 • C and 200 rpm in an orbital shaker (Buehler, Germany) in the LOP and LB medium to detect products released by the strains into the culture medium. The LOP medium is a modified Landy medium which compared with the original version [82] contains higher amounts of glucose × H 2 O (42 g/L) and Na-glutamate × H 2 O (14 g/L).…”

Fusaricidins, Polymyxins and Volatiles Produced by Paenibacillus polymyxa Strains DSM 32871 and M1

“…Five compounds were unique to M1: 2-methyl-1-propanol, 2-methylbutanenitrile, dimethyl sulfone, butyl acetate, 3-methylbutyl acetate and 2-heptanone. In comparison to other plant growth promoting rhizobacteria of the order Bacillales, such as Bacillus subtilis, Bacillus atrophaeus, Bacillus amyloliquefaciens, Bacillus velezensis, and Bacillus licheniformis [50], both P. polymyxa strains emitted a variety of alkylpyrazines. In previous studies, alkylpyrazines exhibited antibacterial, antifungal, antimycobacterial, algicidal and antiviral activities [51][52][53][54].…”

“…Lysogeny broth (Luria-Bertani) (LB) medium; b.) Landy medium [71] and c.) TSA-medium [50] solidified with 1.5% agar in Petri dishes for 24; 48 and 72 h at 30 o C. In addition, liquid fermentations were carried out in 100 ml Erlenmeyer flasks at 30 o C and 200 rpm in an orbital shaker (Buehler, Germany) in the LOP and LB medium to detect products released by the strains into the culture medium. The LOP-medium is a modified Landy medium which compared with the original version [71] contains higher amounts of glucose x H2O (42 g/L) and Na-glutamate x H2O (14 g/L).…”

Exploring the Microbiota of East African Indigenous Leafy Greens for Plant Growth, Health, and Resilience

“…cinerea, F. oxysporum, F. verticillioides, S. rolfsii, and V. dahliae. Bacillus spp. have previously been shown to produce antimicrobial compounds, such as mycosubtilin and lipopeptides produced by B. subtilis (Leclère et al, 2005), or the antagonistic compound bacillomycin by B. amyloliquefaciens (Mülner et al, 2020). Sphingomonas are mainly known for their ability to degrade refractory contaminants, but have also been reported to be antagonistic against bacteria and fungi (White et al, 1996;Innerebner et al, 2011).…”