Screening, identification, optimization of fermentation conditions, and extraction of secondary metabolites for the biocontrol of Rhizoctonia Solani AG-3

Abstract

In this study a strain of Streptomyces sp. was isolated from soil and identified by 16S rRNA gene sequencing technology. The strain was screened for antibiotics production effective against biocontrol of Rhizoctonia solani AG-3 to cure the target spot disease in tobacco. For enhance production of secondary metabolites, central composite design of response surface methodology (RSM) was applied in submerged fermentation. The maximum metabolite production was using medium volume of 55 mL in 250 mL flask, agitation speed of 165 rpm, incubation temperature 30 C, initial medium pH of 6.8 and inoculum size of 7%. Solvent extraction method was used to extract the secondary metabolites and active compounds were purified by silica gel column chromatography. The purified fractions were further investigated by gas chromatography-mass spectrophotometer (GC-MS). GC-MS analysis showed 48 compounds, among them 12 were active against pathogen. These findings indicated that the strain Streptomyces TA 1123 was a potential antagonist against R. solani AG-3.

Effects of Cultural Conditions in Enhancing the Production of Anti-MRSA Activity of Lasiodiplodia pseudotheobromae IBRL OS-64, an Endophytic Fungus Isolated from Leaf of Ocimum sanctum L. in Submerged Fermentation System

“…Higher inoculum sizes than the optimal may stimulate too much production of microbial biomass which lead to nutrient depletion for their secondary metabolite production (Kumar et al, 2010). According to Ahsan et al, (2017), moderate inoculum size has a significant positive effect on the antibiotic production and growth yield. Limited space and less oxygen supply might occur if higher sizes of inoculum used in cultivation.…”

“…This statement was supported by Pearce, (1997) who postulated that the fungal are able to store bioactive compounds in their mycelia. According to Ahsan et al, (2017), agitation speed influenced the dissolved oxygen temperatures and oxygen availability and therefore affecting the antibiotic production. Moreover, oxygen availability is one of the crucial factors for cell growth and production of their secondary metabolites during fermentation process (Wang et al, 2010;Dou et al, 2013).…”

Application of response surface methodology for optimization of medium components for the production of secondary metabolites by Streptomyces diastatochromogenes KX852460

“…Streptomyces strain TA1123 was isolated and identified as Streptomyces diastatochromogenes (GenBank Accession Number KX852460) on the base of morphological, biochemical and 16S ribosomal RNA gene sequence (Ahsan et al 2017a ) and submitted to Chinese general microbial collection center (CGMCC4.7384) (Ahsan et al 2017b ). R. solani AG-3 (Gene bank accession number of KX852461, Chinese general microbial collection center CGMCC3.18223) was isolated from infected tobacco leaves and identified through molecular techniques (Ahsan et al 2017b ).…”

“…After sterilization, the medium was allowed to cool at room temperature and inoculated with 7% suspension of S . diastatochromogenes and incubated at 30 °C with shaking speed of 165 rpm for 96 h. After the completion of fermentation, the culture filtrate was assessed for antifungal activity (Ahsan et al 2017a ).…”

Exometabolomic study of extracellular metabolites in tobacco plant induced by ethyl acetate extracts of Streptomyces diastatochromogenes KX852460

“…In our previous study, we isolated, identified, and characterized Streptomyces diastatochromogenes KX852460 strain for the biological control of tobacco target spot. (Ahsan, Chen, Wu, Irfan, & Shafi, 2017;Ahsan, Chen, Zhao, Irfan, & Wu, 2017;. The aim of the present study is to induce the systemic resistance in tobacco against Rhizoctonia solani AG-3.…”