Relationship between sodium influx and salt tolerance of nitrogen-fixing cyanobacteria

Apte, Shree Kumar ; Reddy, Bontha Rajasekhar ; Thomas, Joseph (1987) Relationship between sodium influx and salt tolerance of nitrogen-fixing cyanobacteria Applied and Environmental Microbiology, 53 (8). pp. 1934-1939. ISSN 0099-2240

PDF - Publisher Version

Official URL:


The relationship between sodium uptake and cyanobacterial salt (NaCl) tolerance has been examined in two filamentous, heterocystous, nitrogen-fixing species of Anabaena. During diazotrophic growth at neutral pH of the growth medium, Anabaena sp. strain L-31, a freshwater strain, showed threefold higher uptake of Na+ than Anabaena torulosa, a brackish-water strain, and was considerably less salt tolerant (50% lethal dose of NaCl, 55 mM) than the latter (50% lethal dose of NaCl, 170 mM). Alkaline pH or excess K+ (>25 mM) in the medium causes membrane depolarization and inhibits Na+ influx in both cyanobacteria (S. K. Apte and J. Thomas, Eur. J. Biochem. 154:395-401, 1986). The presence of nitrate or ammonium in the medium caused inhibition of Na+ influx accompanied by membrane depolarization. These experimental manipulations affecting Na+ uptake demonstrated a good negative correlation between Na+ influx and salt tolerance. All treatments which inhibited Na+ influx (such as alkaline pH, K+ above 25 mM, NO3-, and NH4+), enhanced salt tolerance of not only the brackish-water but also the freshwater cyanobacterium. The results indicate that curtailment of Na+ influx, whether inherent or effected by certain environmental factors (e.g., combined nitrogen, alkaline pH), is a major mechanism of salt tolerance in cyanobacteria.

Item Type:Article
Source:Copyright of this article belongs to American Society for Microbiology.
ID Code:761
Deposited On:25 Sep 2010 04:47
Last Modified:16 May 2016 11:57

Repository Staff Only: item control page