GENOTYPIC RELATIONSHIPS IN TRICHODESMIUM (CYANOPHYCEAE) BASED ON nifH SEQUENCE COMPARISONS1

The DNA sequence of a fragment of nifH was compared to natural populations of the marine cyanobacteria Trichodesmium thiebautii and T. erythraeum from the Caribbean Sea and the unialgal culture Trichodesmium sp. NIBB 1067, which was isolated from the Kuroshio waters (Japan). Through replication Of amplification, cloning, and sequencing, four nucleotides in a 359-bp fragment were identified that were identical in sequence to Trichodesmium sp. NIBB 1067 and natural populations of T. erythraeum but were distinctly different in sequence from T. thiebautii. The data indicate that Trichodesmium sp. NIBB 1067 is more closely related to T. erythraeum than to T. thiebautii.     

Ultrastructural and chemical assessment of poly-β-hydroxybutyric acid in the marine cyanobacterium Trichodesmium thiebautii

We report here on the occurrence and quantities of poly-beta-hydroxybutyric acid (PHB) in natural populations of the marine cyanobacterium Trichodesmium thiebautii. A diurnal variation in the shape and size of PHB granules and in PHB content was observed. The highest PHB levels (2.3 +/- 0.8 mg g-1 dry wt) were recorded in the early morning and the values decreased thereafter with a minimum at night (1.6 +/- 0.9 mg g-1 dry wt). Our data suggest that PHB is a prominent cell constituent in T. thiebautii and that its synthesis takes place in the early morning whereas it is utilized during the rest of the day.