Journal of Microbiology

Research Support, Non-U.S. Gov'ts

Alternative Alert System for Cyanobacterial Bloom, Using Phycocyanin as a Level Determinant: Chi-Yong Ahn , Seung-Hyun Joung , Sook-Kyoung Yoon , Hee-Mock Oh; J. Microbiol. 2007;45(2):98-104.; DOI: https://doi.org/2527 [pii]

Abstract: Chlorophyll a concentration and cyanobacterial cell density are regularly employed as dual criteria for determinations of the alert level for cyanobacterial bloom. However, chlorophyll a is not confined only to the cyanobacteria, but is found universally in eukaryotic algae. Furthermore, the determination of cyanobacterial cell counts is notoriously difficult, and is unduly dependent on individual variation and trained skill. A cyanobacteria-specific parameter other than the cell count or chlorophyll a concentration is, accordingly, required in order to improve the present cyanobacterial bloom alert system. Phycocyanin has been shown to exhibit a strong correlation with a variety of bloom-related factors. This may allow for the current alert system criteria to be replaced by a three-stage alert system based on phycocyanin concentrations of 0.1, 30, and 700 μg/L. This would also be advantageous in that it would become far more simple to conduct measurements without the need for expensive equipment, thereby enabling the monitoring of entire lakes more precisely and frequently. Thus, an alert system with superior predictive ability based on highthroughput phycocyanin measurements appears feasible.

Molecular Characterization of Marine Cyanobacteria from the Indian Subcontinent Deduced from Sequence Analysis of the Phycocyanin Operon (cpcB-IGS-cpcA) and 16S-23S ITS Region: Jagadeesan Premanandh , Balakrishnan Priya , Ivanka Teneva , Balik Dzhambazov , Dharmar Prabaharan , Lakshmanan Uma; J. Microbiol. 2006;44(6):607-616.; DOI: https://doi.org/2467 [pii]

Abstract: Molecular characterization of ten marine cyanobacterial isolates belonging to the order Oscillatoriales was carried out using the phycocyanin locus (cpcBA-IGS) and the 16S-23S internally transcribed spacer region. DNA sequences from the phycocyanin operon discriminated ten genotypes, which corresponded to seven morphotypes identified by traditional microscopic analysis. The cpcB coding region revealed 17% nucleotide variation, while cpcA exhibited 29% variation across the studied species. Phylogenetic analyses support the conclusion that the Phormidium and Leptolyngbya genera are not monophyletic. The nucleotide variations were heterogeneously distributed with no or minimal informative nucleotides. Our results suggest that the discriminatory power of the phycocyanin region varies across the cyanobacterial species and strains. The DNA sequence analysis of the 16S-23S internally transcribed spacer region also supports the polyphyletic nature of the studied oscillatorian cyanobacteria. This study demonstrated that morphologically very similar strains might differ genotypically. Thus, molecular approaches comprising different gene regions in combination with morphological criteria may provide better taxonomical resolution of the order Oscillatoriales.

Functional Characterization of the Gene Encoding UDP-glucose: Tetrahydrobiopterin [alpha]-Glucosyltransferase in Synechococcus sp. PCC 7942: En-Young Cha , Jeong Soon Park , Sireong Jeon , Jin Seon Kong , Yong Kee Choi , Jee-Youn Ryu , Youn-Il Park , Young Shik Park; J. Microbiol. 2005;43(2):191-195.; DOI: https://doi.org/2162 [pii]

Abstract: In this study, we attempted to characterize the Synechococcus sp. PCC 7942 mutant resultant from a disruption in the gene encoding UDP-glucose: tetrahydrobiopterin [alpha]-glucosyltransferase (BGluT). 2D-PAGE followed by MALDI-TOF mass spectrometry revealed that phycocyanin rod linker protein 33K was one of the proteins expressed at lower level in the BGluT mutant. BGluT mutant cells were also determined to be more sensitive to high light stress. This is because photosynthetic O_2 exchange rates were significantly decreased, due to the reduced number of functional PSIs relative to the wild type cells. These results suggested that, in Synechococcus sp. PCC 7942, BH4-glucoside might be involved in photosynthetic photoprotection.

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