Abstract
A thermophilic cyanobacterium, Thermosynechococcus vulcanus RKN, exhibits low tepmerature/light- induced cell aggregation. We previously reported that this aggregation was dispersed by cellulase treatment. Of three putative cellulose synthase genes, disrution of only Tvtll0007 abolished the cell aggregation. Accordingly, cellulose is suggested to serve as extracellular matrix to support the cell aggregation. Here, we established a method of cellulose quantitation, and measured its accumulation. Under normal growth conditions, the cellulose content was approximately 5 μg / 4 x 109 cells. When cells were grown under the low temperature/light conditions, the level increased approximately two-fold in 24 h, and remained maintained during further growth. This accumulation appeared to slightly precede the cell aggregation. This cellulose accumulation under the induced conditions was abolished by disruption of Tvtll0007 but not by disruption of Tvtlr1795 or Tvtlr1930-33. It is thus concluded that under the low temperature/light conditions TvTll0007 produces cellulose, which is essential for the cell aggregation.
