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Assessment
of alkaliphilic haloarchaeal diversity in Sua pan evaporator
ponds in Botswana
Ashant Pravin Gareeb and Mathabatha Evodia Setati*
Discipline
of Microbiology, School of Biochemistry, Genetics,
Microbiology and Plant Pathology, Faculty of Science and
Agriculture, University of KwaZulu-Natal, Westville Campus,
P/Bag X54001, Durban, South Africa.
*Corresponding author. E-mail:
setatim@ukzn.ac.za.
Fax: +27 31 260 7809. Tel: +27 31 260 7405.
Accepted 20 November, 2008 |
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Cultivation-dependent and molecular-based
culture-independent methods were used to assess alkaliphilic
haloarchaeal diversity at Sua pan evaporator ponds in
Botswana. Isolates belonging to the genera Natrialba,
Natronococcus and Natronorubrum were recovered
from brine samples by enrichment and identified through a
series of biochemical tests as well as sequencing of 16S
rRNA fragments. In addition, an environmental 16S rRNA
library was constructed from brine samples of two evaporator
ponds. The library comprised members of the genera
Halorubrum (65%), Natrialba (14%),
Natronorubrum (7%) and new phylotypes (14%). The new
phylotypes consisted of two clones that exhibited low 16S
rRNA similarity (95 – 97%) with known species and could
potentially represent new species in the genus Halorubrum,
one clone with 91% similarity to
Natronolimnobius which could represent a new genus, as
well as an unidentifiable phylotype which exhibited 79%
similarity to Methanotorris formicicus. Two major
differences were observed between cultivation- and
molecular-based methods; firstly, Halorubrum species
were largely represented in the environmental clone library
but no isolates were obtained, and secondly,
Natronococcus species were isolated but not detected in
the clone library. An overlap between the archaeal isolates
and the ribosomal library clones was apparent although the
novel phylotypes detected in this study were not recovered
through cultivation.
Key words:
Haloalkaliphile, solar salterns, Natronococcus,
Natrialba, Natronorubrum, biodiversity. |
