Evaluation of the Gelling Property of Some Local Plants Seeds as Alternative Gelling Agents to Agar-Based Microbial Culture Media

Agar, an expensive gelling agent for culturing microbes affects holistic microbiological and pharmaceutical usage. Hence, plants used as thickening agents should be investigated. This work aims to evaluate the gelling properties of the seeds of Brachystegia eurycoma, Mucuna sloanei, Detarium microcarpum and Cucumeropsis mannii, as alternative gelling agents to agar in microbial culture media. The analyses were investigated in accordance with standard procedures and their modifications by pulverization, bleaching and physicochemical methods. The 3 plants showed relative gelling property when compared to that of agar-based media except for Cucumeropsis mannii which did not exhibit any gelling property at all concentrations. At the least (0.056g/mL) and highest (0.081g/mL) concentrations with equivalent gelling activity to agar at 0.015g/mL as the standard, B. eurycoma exhibited significant (p<0.05) gelling property in more concentrations compared to D. microcarpum and M. sloanei. Furthermore, there was improved gelling activities of the plants after treatment with 3% sodium hypochlorite especially with 250mm than 500mm sieve sizes. Homogeneity, consistency, surface-streaking, transparency, smoothness, hardness, friability of nutrient and sabouraud dextrose broths formulated with different seeds powder showed significant (P<0.05) disparities; while gelling strength (0.0325-0.13mg/ml), time (2-26 minutes) and colour (amber-light yellow) as well as pH (4.8-6.4) were significantly (P<0.05) comparable to that of agar with 0.0028-0.0056mg/ml, 10-15 minutes, amber colour, 5.6 and 6.6 as pH respectively. From this study, B. eurycoma exhibited good gelling properties followed by D. microcarpum and M. sloanei that are worth investigating further as possible alternative gelling agent to agar for formulation of microbial culture media.