IDENTIFICATION OF BACTERIAL PROTEINS INVOLVED IN INULIN METABOLISM FROM COLONDERIVED LACTOBACILLUS CASEI STRAINS

Abstract

The Lactobacillus casei strains AP and AG are lactic acid bacteria originating in the gastrointestinal tract. The strains were grown in inulin as the only carbon source to identify inulin-degrading proteins and their metabolism. To examine their inulin metabolism, sugar analysis was performed using high performance liquid chromatography (HPLC) for intracellular- and supernatant-derived samples. Sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SDSPAGE) was used to identify inulin-degrading proteins; this was followed by electrospray ionisation - liquid chromatography mass spectrometry (ESI-LC-MS/MS) analysis of specific protein bands. The cell wall protein profiles of bacterial cells grown in inulin showed different band sizes at 30 and 50 kDa from those grown in glucose. The 30-kDa proteins belonged to the phosphotransferase system mannose/fructose/sorbose-specific IID component, ATP-binding cassette transporter and ATP-binding cassette transporter substrate-binding protein. These proteins may be involved in the intracellular inulin transport in the L. casei strains AP and AG.