Background: Putrescine is the intermediate product of arginine decarboxylase pathway in Escherichia coli which can be used as an alternative nitrogen source. Transaminase and dehydrogenase enzymes seem to be implicated in the degradative pathway of putrescine, in which this compound is converted into γ-aminobutyrate. But genes coding for these enzymes have not been identified so far.

The gluconic acid batch fermentation was conducted using mutant Aspergillus niger NCIM 530 strain under submerged condition in 50 L semiautomatic stirred-tank fermenter. Certain cost-effective source as golden syrup was effectively utilized instead of glucose for successful industrial fermentation process. The significant level of gluconic acid (85.2 gL -1 ) production was observed with maximum 86.97% glucose conversion over 44 hours. This process provides great advantages over traditional submerged fermentation strategies and substrates, as showed by effective production of gluconic acid by utilizing novel substrate as a golden syrup. To reduce analysis time with better accuracy, an effort has been made to use a method for evaluation of parameters like conversion of substrate and production of gluconic acid during the fermentation by using High Performance Thin Layer Chromatography (HPTLC).

The yicM gene of Escherichia coli was found by selection for resistance to 6-mercaptopurine. Translation and transcription initiation sites of yicM were determined. Overexpression of yicM increased resistance of sensitive cells to inosine and guanosine, decreased E. coli growth rate in medium containing these ribonucleosides as the sole carbon source, led to inosine accumulation by the E. coli strain deficient in purine nucleoside phosphorylase and enhanced the rate of inosine excretion by an inosine-producing strain. These results suggest that yicM encodes a purine ribonucleoside exporter and we have accordingly renamed it nepI (for 'nucleoside efflux permease-inosine').