Amino Acid Composition of Tightly Bound Exopolymeric Substances Produced by Corrosion-Related Bacteria in Presence of Mild Steel

Abstract

The composition of\rtightly bound exopolymeric substances (EPS) obtained from biofilm and plan- ktonic\rcell subpopulations of Stenotrophomonas\rmaltophilia 5426 UKM was analyzed to study an impact of mild steel presence\rin the cultivation medium. The overall protein production was found to increase\rin the presence of a steel coupon. Some amino acids such as lysine, valine,\riso-leucine, tyrosine and phenylalanine were found to be secreted in higher\ramounts in the presence of mild steel, while its absence leads to an increase\rof arginine, asparagine, serine, glutamine, proline, glycine, cysteine,\rleucine, methionine production levels. Biofilm cells EPS contained more\rarginine, glycine, cysteine, valine, methionine and leucine, comparing to EPS\rof planktonic cells. The chang- es of tightly bound EPS aggregation around the\rcells induced in the presence of steel coupons were revealed by transmission\relectron microscopy. The results suggested the transition of S. maltophilia 5426 UKM cells from\rplanktonic to biofilm lifestyle to be a complex process involving more than a\rsingle step.