The class IId bacteriocin thuricin-17 increases plant growth

Abstract

The mechanisms by which many plant growth promoting rhizobacteria (PGPR) affect plants are unknown. We recently isolated a rhizosphere bacterium (Bacillus thuringiensis NEB17), that promotes soybean growth and screened the liquid growth medium in which it grew for plant growth stimulating materials. We have also shown that it produces a bacteriocin (named by us as thuricin-17 and a member of the recently described class IId bacteriocins). Here we show that application of this bacteriocin to leaves (spray) or roots (drench) directly stimulates the growth of both a C(3) dicot (soybean) and a C(4) monocot (corn). This growth stimulation is similar in nature to that previously seen when plants are treated with Nod factors. Strain NEB17 contains three copies of the gene for thuricin 17 that code for identical amino acid sequences. These two lines of evidence suggest that the dual functions of these proteins may have constrained their evolution. This is the first report of direct plant growth enhancement by a bacteriocin.

The 3D Solution Structure of Thurincin H, a Bacteriocin with Four Sulfur to α‐Carbon Crosslinks

“…[13] If 3139 Da represents the average molecular weight of the parent [M + H] + ion, then its monoisotopic mass would be calculated as 3137 Da. Coincidentally, the open reading frame prediction for the thuricin 17 gene gives a predicted peptide sequence identical to that of thurincin H. [14] Likewise, bacthuricin F4 has a homologous N-terminal (DWTXWSXL) sequence as well as physical and biological properties that are highly similar to thuricin 17, and a molecular mass of 3160.05 Da, which also happens to be 23 Da heavier than 3137 Da. [15,16] Although further FTICR-MS/MS analysis would be needed to confirm their amino acid sequences, it is highly probable that thuricin S, cerein MRX1, thuricin 17, and bacthuricin F4 all have the same structure as thurincin H. As such, it is interesting to find that several distinct strains of Bacillus thuringiensis produce the same peptide, thus underscoring the biological and ecological importance of this molecule.…”

Comparative Study on Plant Growth Promotion by Endophytic Pseudomonas Spp. and Bacillus Spp. of Solanum Lycopersicum

“…have been found to produce bacteriocins as biocontrol compounds (Araújo et al, 2005;Ashwini and Srividya, 2013;Gray et al, 2006;I. Hammami et al, 2009;Ines Hammami et al, 2012;He et al, 2006;Hu et al, 2010;Lee et al, 2009;Mouloud et al, 2013). Hence, when, the crude endophytes were used to inoculate the seeds, Bacillus spp.…”

Future Challenges and Prospects of Bacillus thuringiensis

“…For example, when Thuricin 17, a bacteriocin isolate from B. thuringiensis NEB17 was applied to leaves or roots of soybean and corn, the growth of both plants was stimulated (Lee et al 2009). Bacteriocins can also be used to control pest that affect honeybees, for example, Entomocin 110 has growth inhibitory activity to Paenibacillus larvae, the causal agent of American foul-brood of honeybees ( A. mellifera L.) (Cherif et al 2008).…”