Production of Biofertilizers using Rhizobium Isolated from Phaseolus Vulgaris Root Nodules

Rhizobia are special bacteria that can live in the soil or nodules formed on the roots of legumes. Phaseolus vulgaris is an important legume vegetable belonging to the family Fabaceae. Rhizobia are Gram-negative bacteria, aerobic, and non-sporulating which are associated symbiotically with the roots of leguminous plants. Overuse of chemical fertilizer and biodiversity loss are serious problems challenging the sustainable development of modern agriculture. As organic fertilizers are increasingly used in agriculture today, there is an imperative need to preserve the health of humans and the environment. This study was aimed at isolating and characterizing Rhizobium bacteria from the nodules of Phaseolus vulgaris to produce nitrogen biofertilizer that can be used to substitute chemical fertilizer. Specifically, nodules were collected from Phaseolus vulgaris roots at different stages of development in the school garden of the University of Bamenda, sterilized and used to purify and characterise morphologically and microscopically Rhizobium bacteria. These were then used to produce nitrogen biofertilizer using charcoal powder. As a result, morphological characterization of the bacteria isolated from the bean nodules revealed fast-growing bacteria in 72 h in Yeast Extract Mannitol Agar with Congo red medium. They do not absorb Congo Red, are translucent, mucoid, bulging in the Petri Dish and gram-negative which corresponds to Rhizobium bacteria. Only Yeast Extract Mannitol broth showed good multiplication of bacteria for inoculant production. The pH of charcoal powder was 7.9 which is good for rhizobia growth and three concentrations of 225g, 165g and 145g of Rhizobium biofertilizers were produced with a shelf life of six months.