The effect of cathodic polarisation on monosaccharides of Amphora coffeaeformis, a marine fouling diatom

Abstract

The composition of monosaccharides and their variation in concentration in Amphora coffeaeformis cells on non-polarised and cathodically polarised 304 stainless steel were examined when cells were grown under continous illumination at 18~'C for 8 d in medium prepared in synthetic seawater. Lower concentrations of monosaccharides were found in A. coffeaeformis cells attached to cathodically polarised steel. Under these conditions, the abundance of monosaccharides decreased with time. In contrast, concentrations of monosaccharides were higher by a factor of 8 to 40 in A. coffeaeformis cells attached to non-polarised steel. The abundance of monosaccharides increased over the period of cultivation in the cells on non-polarised steel. Eight individual monosaccharides viz. rhamnose, fucose, ribose, arabinose, xylose, mannose, galactose and glucose were identified in cells from both non-polarised and cathodically polarised steel. Amongst these, hexoses such as mannose, glucose and galactose were most abundant in cells from both non-polarised and cathodically polarised steel; the concentration of these hexoses increased in the former and decreased in the latter