Changes in motility and induction of enzymatic activity by nitrogen and phosphate deficiency in benthic Halamphora luciae (Bacillariophyceae) from Argentina

Abstract:

Cells of Halamphora luciae were isolated from the mudflat of the Bahía Blanca estuary. Unialgal axenic cultures were grown in f/2 with limiting concentrations of N or P and in f/2 medium deprived of one or both macronutrients. On the one hand, limited macronutrient supply did not affect growth rate, but final cell yield was lower than in the complete medium. On the other hand, N or P deprivation reduced growth rates as well as final cell yield in the stationary phase. P deficiency enhanced the secretion of soluble extracellular polymeric substances (EPS), the percentage and speed of gliding cells, as well as the activity of alkaline phosphatase, especially after a previous prolonged P starvation. Regarding the morphology of the frustules, P deprivation reduced areola size but did not alter cell biovolume. N deficiency had a deleterious effect on the motility of the cells, and reduced the secretion of soluble EPS and cell biovolume. After incubation in N-deprived media for 10 days, cells exhibited enhanced protease activity.

Key Words::

• Alkaline phosphatase
• Biovolume
• EPS
• Frustule morphology
• Halamphora
• Motility
• Nitrogen and phosphorus deficiency
• Protease

ACKNOWLEDGEMENTS

This work was funded by grants from Universidad de Buenos Aires (GC 20020100100479 and GC 20020130100216BA) and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (PIP 112-200801-00234 and PIP 11220110100208). YD is a Research Fellow of CONICET and NIM and MCM are research members of the same institution.

SUPPLEMENTARY DATA

Supplementary data associated with this article can be found online at http://dx.doi.org/10.2216/15-134.1.s1.