Rmm. Abed et F. Garcia-pichel, Long-term compositional changes after transplant in a microbial mat cyanobacterial community revealed using a polyphasic approach, ENVIRON MIC, 3(1), 2001, pp. 53-62
Using a polyphasic approach that included microscopy, cultivation and 16S r
RNA-based cultivation-independent molecular fingerprinting, we compared the
cyanobacterial composition of Solar Lake microbial mats and samples thereo
f transplanted and maintained in new settings for extended periods of time.
Significant changes in community composition, with clear replacement of th
e dominant cyanobacterium, Microcoleus chthonoplastes, were detected in all
cases. The most dramatic shifts occurred in a sample kept in the laborator
y for 3 years, which resulted in dominance by an Oscillatoria-like cyanobac
terium whose 16S rRNA closely matched that of a morphologically similar iso
late from mats in Mexico. Transfer of Solar Lake mat to an artificial exper
imental pond with incubation under seminatural conditions resulted in an in
crease in cyanobacterial diversity. Judging from the molecular signatures,
two novel, previously unrecognized and phylogenetically well-delimited cyan
obacterial populations became dominant. Through cultivation, one population
was shown to correspond to a filamentous, non-heterocystous group of Cyano
bacteria with very narrow trichomes (approximate to 0.75-1.5 mum). The most
dominant novel molecular signature, however, could not be identified by cu
ltivation efforts or correlation with microscopy and, upon phylogenetic ana
lyses, its 16S rRNA genes showed no particular close association to known c
yanobacterial groups.