Effect of individual amino acids and glucose on activation and germination of Rhizopus oligosporus sporangiospores in tempe starter

Aim: To understand the conditions promoting activation and germination of spores, and to contribute to the control of tempe starters. Methods and Results: Using microscopic counts of fluorescent labelled spores, the following results were obtained: (1) L- alanine plays an important role ( of the same order as that of peptone) in stimulation of germination of dormant spores. Alanine can satisfy the requirements of carbon as well as nitrogen for spore germination; (2) L- proline, on the other hand, inhibits alanine uptake presumably by blocking/ congesting transporters of spore cells, resulting in apparent low viability on agar media; (3) L- leucine and L- isoleucine slightly favour spore germination while L- arginine and L- lysine do not have any stimulating effect; (4) The stimulatory role of glucose was only evident in the presence of phosphate ( in minimal medium); when glucose is used in the absence of phosphate, either alone or in combination with single amino acids its role is hardly distinguishable; (5) Phosphate plays a facilitating role in spore germination. Conclusions: Glucose and amino acids play important roles in activation and germination of sporangiospores of Rhizopus oligosporus in tempe starter ( stored for 12 months). The ability and rate of germination of dormant/ old sporangiospores of R. oligosporus, depend on their ability for uptake of individual amino acids and/ or glucose. Significance and Impact of Study: New light was shed on the counteractive role of proline and the stimulating effect of phosphate. Soybeans subjected to traditional preparation for tempe making are heavily leached; germination of starter spores on such beans is sub- optimal, and bean processing could be optimized.