Optimization and biochemical characterization of a bacteriocin from a newly isolatedBacillus subtilisstrain 14B for biocontrol ofAgrobacteriumspp.strains

Abstract

Aims: The identification of a new compound active against Agrobacterium tumefaciens. Methods and Results: The culture conditions of a newly isolated Bacillus subtilis strain, designed 14B, were optimized, as a first step, to produce its bacteriocin (termed Bac 14B) for the biocontrol of Agrobacterium spp., the causal agents of the crown gall disease. Bac 14B was then partially purified and biochemically characterized. Bacillus subtilis 14B was observed to produce an antibacterial compound having a protinaceous nature. As estimated by sodium dodecyl sulfate‐polyacrilamide gel electrophoresis (SDS‐PAGE), the semi‐purified bacteriocin substance was found to be a monomeric protein with a molecular weight of 21 kDa. While the latter’s antimicrobial activity was completely stable during exposure to a temperature range of up to 100°C for 2 h, its initial activity was totally lost at 121°C for 20 min. The maximum bacteriocin production (4096 AU ml−1) was recorded after 96 h‐incubation in an optimized Luria Bertani medium supplemented with 10 g l−1 glucose, 15 g l−1 K2HPO4 and 5 g l−1 MgSO4 7H2O at 30°C in a shaking flask culture. Interestingly, the B. subtilis 14B culture supernatant that contained the bacteriocin under study was proved efficient in reducing both the percentage of galled plants and the number of galls in tomato. Conclusion: The findings revealed that B. subtilis 14B and its bacteriocin are efficient in reducing the percentage of infections in plants caused by Ag. tumefaciens. Significance and Impact of the Study: The results could be useful for the nurserymen who are particularly interested in the biocontrol of the crown gall disease.

Purification, biochemical characterization and antifungal activity of a novel Aspergillus tubingensis glucose oxidase steady on broad range of pH and temperatures

“…The antifungal activity of the partial purified GOD (heat treatment for 10 min at 50°C and 70 % ammonium sulfate fractionation steps) was assessed against different phytopathogen strain F. solani, V. dahlia, P. ultimum, R. bataticola and R. solani using the agar well-diffusion assay [25].…”

“…The GOD samples were serially diluted twofold and the reciprocal of the highest inhibitory dilution was used to calculate the arbitrary activity units (AU) per milliliters [25]. The radial growth of mycelium was measured at 24-h intervals for a week.…”

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

“…Endophytic Bacillus spp. 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).…”

Antagonism of Bacillus subtilis Against Sclerotinia sclerotiorum on Lactuca sativa

“…All these specifics may change the result obtained in disease control. According Hammami et al (2009) the effect in situ by exposure live B. subtilis cells may incite the growth promoting and/or biocontrol. In nature this biocontrol can be promoted directly or indirectly by producing compounds antagonistic or induce resistance in plants after application (Ryu et al, 2004;Ongena et al, 2007).…”