Natural rubber is also one of biomass made by recycling carbon dioxide by photosynthesis. Cost saving and increase productivity of natural rubber give a chance to win the competition of natural rubber against synthetic rubber made by petrochemical industry. Recently, our laboratory has developed NRSP (Natural Rubber Serum Powder) which is the spray dried product of the waste from natural rubber industry. The waste is discharged from the centrifugal machine to separate latex. The waste is subjected to digestion by papain, a proteinase, prior to spray drying. It is noted that NRSP contains strong growth promoters for various kind of microorganisms particularly anaerobes such as lactic acid bacteria (6), wide range of Bifidobacterium (7), and Zymomonas (8). Usually, anaerobic microor­ganisms require complex nutritious factors. Bifidobacterium is important intesti­nal microflora and there is a great interest in the possibility of increasing number of this microorganism in intestine by the special growth promoter. It is expected that NRSP can increase the number of Bifidobacterium in intestine to enhance the health of human.

Zymomonas mobilis is capable of producing ethanol with a higher produc­tivity than yeast, but this microorganism requires complex nutritional factors.

This microorganism thus can not grew in simple and economical medium such as that used in industrial ethanol production. By our study, the medium prepared with NRSP with soy bean hydrolysate as a source of complex nutritional factors exhibited the same fermentation capability with Z. mobilis as medium prepared using yeast extract (8).