1　 Bioremediation of aliphatic chlorinated compounds contaminated sites using the power of anaerobic bacteria
PCE (tetrachloroethylene), TCE (trichloroethylene), and cDCE (cis-1,2-dichloroethylene) contaminated sites are widely distributed in the developed countries and clean-up of these sites are very important issue. We have isolated a powerful PCE and aliphatic chlorinated compounds-degrader Clostridium bifermentans DPH-1 and its physicochemical characteristics and property of PCE dehalogenase including gene structure were revealed. Also, anaerobic cDCE-degrader was newly obtained. We are now studying their application to the contaminated sites with civil engineers. One of the key for application of bioremediation is how to detect immediately bacteria which degrade the contaminated chemicals in the actual sites and for this purpose a DNA micro-array system is attractive. We are now developing a PCE-degrader detecting micro-array.

２　Exploring a new anaerobic lignin decomposition microorganisms and its application to methane fermentation
Methane fermentation efficiency is 65 % at maximum, because of tolerance of lignin to bacteria under anaerobic condition. White rot fungi is well-known microbe which decompose lignin under aerobic condition but they do not decompose lignin in fermentation system. It is necessary to find anaerobic lignin-degrader for improvement of biogas production. Especially, anaerobe which can work at 55 or 60 C is desirable. We are now trying to find it fromhot springs, rumen, soil, and etc.

３　Xylose, arabinose, and xylitol production from plants residues

Biomass is produced tremendous amount yearly and considered as only one industrial resource and energy source after the consumption of oil. We are focusing on utilization of plants residue which is not used and discarded as garbage. Combined use of newly isolated  Penicillium sp., a strong producer of xylanase and xylosidase, and Rhizomucor pusillus from Prof. M. M. Hoq, Dhaka University, Bangladesh, a producer of a-L-arabinofuranosidase, to several plants residues, respectively, have shown higher recovery yield of D-xylose and L-arabinose. For example, 100%, 75%, and 77% recovery of D-xylose from pistachio shell, walnut shell, and seed shell of sunflower, respectively. D-xylose is effectively converted to xylitol by Candida tropicalis IFO 0618 at 82% yield and 3.26 g/l production rate. Xylitol is a well-known sweetener for diabetes and food additives with anticariogenic activity and therefore used for toothpaste, candy, chocolate, and etc.