Morphological, phylogenetic and physiological diversity of cyanobacteria in the hot springs of Zerka Ma

By

Oren, Aharon
Ionescu, Danny
Hindiyeh, Muna
Malkawi, Hanan

Type

Article

Date of Publication

2009

Original Publication

BioRisk : biodiversity & ecosystem risk assessment

Volume

3

Pages

69-82

Subjects

Cyanobacteria, Jordan, Zerka Ma’in, thermophilic c

Contributed by

Pensoft Publishers

Language

English

Published by

Sofia, Bulgaria Pensoft

Identifiers

DOI: https://doi.org/10.3897/biorisk.3.29

 

Abstract

The freshwater thermal springs of Zerka Ma'in, located in Jordan in the mountains of Moab east of the Dead Sea, are densely inhabited by cyanobacteria up to the highest temperature of 63°C. We have investigated the cyanobacterial diversity of these springs and their outflow channels by microscopic examination, culture-dependent and culture-independent phylogenetic analysis, and by physiological studies of selected isolates of special interest. Both unicellular and filamentous types of cyanobacteria are present, and we identified morphological types such as Thermosynechococcus, Chroogloeocystis, Fischerella (Mastigocladus), Scytonema (occurring as large masses at lower temperatures), and others. Although morphologically similar cyanobacteria have been identified in hot springs world-wide, the Zerka Ma’in strains were phylogenetically distinct based on 16S rRNA gene sequence analysis. Considerable diversity was detected also in the gene sequences of nifH (nitrogenase reductase), encoding one of the key enzymes involved in nitrogen fixation. Nitrogen fixation in a Mastigocladus isolate obtained from the springs was investigated in further depth. The heterocystous strain could fix nitrogen (as assayed by acetylene reduction) at tem peratures up to 53°C.