Isolation of beneficial microbes from biofertilizer products

Since the uses of chemical fertilizers have threatened human health and food safety, many people have approached the use of biofertilizer as an alternative input for plant growth in order to maintain soil and water quality, and sustain the natural ecosystem. There are various biofertilizer products in the market which claimed to have beneficial microbes and effective for plant growth. Thus, this study was conducted to identify and assess the microbial contents of various biofertilizer products available in the market. A total of 13 isolates of bacteria were identified from these biofertilizer products which were imported from Thailand, China and Australia. Bacillus group was the most dominant strain found in these products, while the other bacteria belong to genera Azospirillum, Corynebacterium, Pseudomonas and Proteus mirabilis. These bacteria have potential to fix atmospheric nitrogen, able to produce IAA with the range of 3.75-12.2 mg/litre when supplemented with 100 mg/litre of tryptophan, and showed some P-solubilizing activity (5.7-9.0 mg/litre).