Differences in carbohydrate profiles in batch culture grown planktonic and biofilm cells of Amphora rostrata Wm. Sm

Abstract

Diatoms are abundant in biofilms developed on surfaces immersed in sunlit waters. In both the planktonic and the biofilm mode of growth, diatoms produce carbohydrate polymers which perform several functions including motility, protection, production of macro-aggregates and detoxification. However, little is known about the differences, if any, in the production and characterization at the molecular level of carbohydrates in planktonic and biofilm cells. In order to identify the differences in these two modes of growth, the concentration of total carbohydrates, carbohydrate fractions, neutral carbohydrates, uronic acids and amino sugars in planktonic and biofilm cells of Amphora rostrata were measured. The results showed that the distribution of carbohydrate fractions, uronic acids and amino sugars was different in biofilm and planktonic cells. Cell normalized concentrations of these components were two to five times greater in planktonic cells compared with biofilm cells. The concentrations of glucose and glucosamine decreased, whereas fucose increased in planktonic cells over the period of cultivation. Conversely, the concentrations of glucose and glucosamine increased while that of fucose decreased in attached cells. The study suggests that marked differences exist between the carbohydrates of the planktonic and the biofilm cells of A. rostrata.

Keywords:

• carbohydrate
• glucose
• fucose
• glucosamine
• protein
• planktonic cells
• biofilm cells
• Amphora rostrata

Acknowledgements

The authors are grateful to Dr Satish Shetye, the Director of the NIO for encouragement and facilities. The first author thanks the CSIR, New Delhi for providing a senior research fellowship for this research work. The authors appreciate the help of Mr A P Selvam in running the GC and the GC-MS. The authors also thank Professor Saroj Bhosle for her help in revising the manuscript and are grateful to Dr Maureen Callow and the three anonymous referees for their useful comments and suggestions. This is NIO contribution No. 4752.