Statistical optimization of antifungal iturin A production from Bacillus amyloliquefaciens RHNK22 using agro-industrial wastes

Abstract

Biosurfactants are secondary metabolites with surface active properties and have wide application in agriculture, industrial and therapeutic products. The present study was aimed to screen bacteria for the production of biosurfactant, its characterization and development of a cost effective media formulation for iturin A production. A total of 100 bacterial isolates were isolated from different rhizosphere soil samples by enrichment culture method and screened for biosurfactant activity. Twenty isolates were selected for further studies based on their biosurfactant activity [emulsification index (EI%), emulsification assay (EA), surface tension (ST) reduction] and antagonistic activity. Among them one potential isolate Bacillus sp. RHNK22 showed good EI% and EA with different hydrocarbons tested in this study. Using biochemical methods and 16S rRNA gene sequence, it was identified as Bacillus amyloliquefaciens. Presence of iturin A in RHNK22 was identified by gene specific primers and confirmed as iturin A by FTIR and HPLC. B. amyloliquefaciens RHNK22 exhibited good surface active properties and antifungal activity against Sclerotium rolfsii and Macrophomina phaseolina. For cost-effective production of iturin A, 16 different agro-industrial wastes were screened as substrates, and Sunflower oil cake (SOC) was favouring high iturin A production. Further, using response surface methodology (RSM) model, there was a 3-fold increase in iturin A production (using SOC 4%, inoculum size 1%, at pH 6.0 and 37 °C temperature in 48 h). This is the first report on using SOC as a substrate for iturin A production.

Isolation and Characterization of Fengycins Produced by Bacillus amyloliquefaciens JFL21 and Its Broad-Spectrum Antimicrobial Potential Against Multidrug-Resistant Foodborne Pathogens

“…To our knowledge, this study is the first report that fengycin is a primary active compound of B. amyloliquefaciens against a broad range of foodborne pathogens including Gram-positive pathogens, Gram-negative pathogens, and fungal pathogens. However, unlike some previous studies, which displayed that surfactin and iturin presented important antibacterial and antifungal activity, respectively (Loiseau et al, 2015;Narendra Kumar et al, 2017;Sudarmono et al, 2019). Surfactins produced by B. subtilis LQG17 showed a weak antibacterial effect against few bacterial indicators, and surfactins and iturins produced by B. amyloliquefaciens JFL21 were not able to inhibit either bacteria or fungi.…”

Draft Genome Sequence of Bacillus amyloliquefaciens Strain RHNK22, Isolated from Rhizosphere with Biosurfactant (Surfactin, Iturin, and Fengycin) and Antifungal Activity

“…B. amyloliquefaciens RHNK22 has been used to produce industrially important biosurfactants with surface tension reduction and antifungal activity (2), plant growth-promoting traits, and antioxidant and probiotic properties (unpublished data) and was thus subjected to genomic sequencing.…”

Two Novel Bacillus Strains (subtilis and simplex Species) with Promising Potential for the Biocontrol of Zymoseptoria tritici, the Causal Agent of Septoria Tritici Blotch of Wheat

“…Many microorganisms are reported as biocontrol agents and show the potential to control plant pathogens [ 14 ]. Bacillus species including B. subtilis , B. licheniformis , B. pumilus , B. amyloliquefaciens , B. cereus , B. mycoides , and B. thuringiensis are mostly exploited as biopesticides [ 15 , 16 ] and are of great agriculture importance. These species are known to suppress the growth of several fungal pathogens such as Rhizoctonia , Fusarium , Sclerotinia , Sclerotium , Gaeummanomyces , Nectria , Pythium , Phytophthora , and Verticillium [ 17 , 18 ].…”