Shelf-life enhancement of bio-inoculant formulation by optimizing the trace metals ions in the culture medium for production of DAPG using fluorescent pseudomonad R62

• Published in: Enzyme and microbial technology 2011-01, Vol.48 (1), p.33-38
• Main Authors: Saharan, K., Sarma, M.V.R.K., Prakash, A., Johri, B.N., Bisaria, V.S., Sahai, V.
• Format: Article
• Language: English
• Subjects: 2,4-Diacetylpholoroglucinol; antifungal agents; Biological and medical sciences; Bioreactors; Biotechnology; Biotechnology - methods; culture media; Culture Media - chemistry; Data Interpretation, Statistical; experimental design; fluorescence; Fluorescent pseudomonad; Fundamental and applied biological sciences. Psychology; inoculum; ions; liquid state fermentation; Magnetic Resonance Spectroscopy; manganese; manganese chloride; Mass Spectrometry; metal ions; Models, Statistical; nuclear magnetic resonance spectroscopy; Optimization; Phloroglucinol - analogs & derivatives; Phloroglucinol - chemistry; Phloroglucinol - isolation & purification; Phloroglucinol - metabolism; Pseudomonas fluorescens - growth & development; Pseudomonas fluorescens - metabolism; Response surface methodology; shelf life; sodium molybdate; Trace Elements - metabolism; zinc; zinc sulfate
• ISSN: 0141-0229; 1879-0909
• DOI: 10.1016/j.enzmictec.2010.09.002

Statistical experimental design was used to optimize the concentration of trace elements for production of antifungal compound, 2,4-diacetylphloroglucinol (DAPG), from fluorescent pseudomonad R62 in shake-flask cultivation. The selection of the trace metal ions, influencing DAPG production, was done using Plackett–Burman design (PBD). Only Zn 2+, Mn 2+ and MoO 4 2− were the most significant components ( p < 0.05). A quadratic model was used to fit the response. Application of response surface methodology (RSM) revealed that the optimum values of the salts of the trace elements Zn 2+ (ZnSO 4·7H 2O), Mn 2+ (MnCl 2·4H 2O), and MoO 4 2− (Na 2MoO 4·2H 2O) were 83, 42 and 135 μM, respectively, to achieve 125 mg/L of DAPG, which was nearly 13-fold more compared to its production in basal synthetic medium in shake flask. The studies in 14 L bioreactor resulted in 135 mg/L of DAPG at the end of 36 h of cultivation. The culture broth containing 125 mg/L of DAPG was found to be sufficient for keeping the bio-inoculant viable in non-sterile talcum powder-based formulations (which contained 25 μg DAPG/g carrier) when stored at 28 °C for 6 months. The structure of the purified DAPG was confirmed using 1H NMR and mass spectrometry.