A non-therapeutic method of accumulating a polymeric or high molecular weight molecular product within a bacterial microcompartment in bacterial cytoplasm, which method employs a recombinant bacteria which is genetically engineered to express a microcompartment containing an enzyme capable of converting a low molecular weight substrate into a polymeric or high molecular weight product, the method comprising the steps of: incubating the recombinant bacteria with the low-molecular weight substrate, or a precursor of the low molecular weight substrate which is capable of being metabolised to the substrate within the recombinant bacteria, such that the substrate or precursor is taken up by the bacteria, wherein the substrate enters the microcompartment and the enzyme within the microcompartment converts the substrate to a polymeric or high molecular weight molecular product, and wherein the polymeric or high molecular weight molecular product is accumulated within the microcompartment due to its size.

A process for producing nucleoside 5'-triphosphates (NTP) from nucleoside 5'-diphosphates (NDP) other than adenosine 5'-diphosphate, characterized by using a polyphosphate kinase as an enzyme and polyphosphoric acid as the phosphate donor; and application of this process to various glycosylation reactions. This process makes it possible to conveniently and economically synthesize NTP from NDP enzymatically. Also, it becomes possible thereby to economically recycle and synthesize sugar nucleotides and synthesize, for example, oligosaccharides associating therewith without resort to expensive phosphoenolpyruvic acid, ATP, etc. in the reactions for reproducing or converting NDP into NTP in the systems for enzymatically synthesizing oligosaccharides by combining with the synthesis of oligonucleotides, etc.