include the strains registered at the central bureau voor schimmelcultures in delft under the numbers c211 cbs 499 74 r312 cbs 717 73 b222 cbs 498 74 a111 cbs 497 74 r341 cbs 496 74 r340 cbs 495 74 r332 cbs 494 74 in the case of immobilizing these microorganisms immobilization can be conducted according to any conventional process with an entrapping process using an acrylamide series polymer being particularly preferred the term 34 acrylamide series polymer 34 as used herein is a polymer containing acrylamide methacrylamide or the like as a major component and if necessary an ethylenically unsaturated monomer copolymerizable with acrylamide methacrylamide or the like immobilization can be conducted by suspending the aforesaid microbial cells in an aqueous medium containing a monomer or monomers like acrylamide and a cross linking agent like n n methylenebisacrylamide and conducting polymerization at a ph of about 5 to 10 preferably 6 to 8 and at a temperature of about 0 u00b0 to 30 u00b0 c preferably 0 u00b0 to 15 u00b0 c using a polymerization initiator thus causing gelation the content of microorganisms in the polymerization reaction solution varies depending upon the kind and the state of microorganisms used but is typically about 0 1 to 50 wt preferably 1 to 20 wt the content of monomers in the polymerization reaction solution is about 2 to 30 wt preferably about 5 to 20 wt the water soluble dialdehyde treatment is carried.