Bioconversion of sulfoxidation of sulfides is gaining importance in synthetic chemistry as an alternative
tool for the synthesis of enantiomeric sulfoxides.
Different micro organisms belonging to the class of fungi were selected for the study. The selected
microorganisms include Rhyzopus stolonifer MTCC 2198, Rhizopus stolonifer MTCC 2591, Rhizopus
stolonifer MTCC 162, Aspergillus niger, Aspergillus ochraceous, Aspergillus flavus, Saccharomyces
cerevisiae (Soil isolates) and Baker’s yeast (Locally purchased).
The substrate chosen for biosulfoxidation was 5-Methoxy-2-[[(4-methoxy–3, 5- dimethyl-2-pyridinyl)
methyl]-sulphinyl]-1H benzimidazole.
Among the selected microorganisms used for biosulfoxidation of the above mentioned substrate,
Rhizopus stolonifer 2591 showed maximum conversion. Rhizopus stolonifer 2198 and Aspergillus
ochraceous showed less conversion while no conversion was observed with Aspergillus niger,
Aspergillus flavus, Baker’s yeast and Rhizopus stolonifer 162. Hence, Rhizopus stolonifer 2591 wasconsiderd for optimization. The parameters evaluated during optimization include pH, temperature,
substrate concentration, biomass concentration, incubation time and effect of surfactants.
The optimized conditions at which maximum bioconversion was achieved were at pH 7.6, temperature
30?C, incubation time 48hrs, substrate concentration 2mg and biomass concentration 10g for Rhizopus
stolonifer 2591. Various surfactants were used in the study, among them anionic (SLS) and cationic
(CTAB) surfactants were found to be toxic while very low conversion was observed in case of nonionic
surfactant (Tween 80). The hydrophilic carrier (?-Cyclodextrin) did not have any significant effect on the
yield of the product.
Keywords: Rhizopus stolonifer, Aspergillus niger, Aspergillus ochraceous, Aspergillus flavus,
Saccharomyces cerevisiae, Baker’s yeast, Biosulfoxidation, Optimisation
Publication date: 01/12/2023
https://ijbpas.com/pdf/2023/December/MS_IJBPAS_2023_7594.pdf
Download PDF
https://doi.org/10.31032/IJBPAS/2023/12.12.7594
