Evidence for the production of a proteinaceous hemolytic exotoxin by wild-type strain of Synechocystis sp. PCC 6803 (Cyanobacteria)

Abstract

A proteinaceous hemolysin produced by a wildtype strain of Synechocystis sp. PCC 6803 was purified from cell-free culture supernatants by successive column chromatography on DEAE-Sepharose Fast Flow and Sephacryl S-300 High Resolution. The molecular mass of the hemolysin, determined by SDS-PAGE, was approximately 81 kDa. The hemolysin was heat labile and showed potent hemolytic activity against rabbit and sheep erythrocytes. The hemolysin started to be secreted during the exponential growth phase and accumulated maximally at the stationary phase. The production of hemolysin varied with the amount of calcium present in modified BG-11 culture medium. Hemolysin production decreased in calcium-free medium, whereas it increased in medium containing 0.48 mM calcium. In contrast, the potency of hemolysin, as shown by hemolysis assay, was enhanced by deprivation of calcium (EDTA treatment) but decreased in the presence of calcium. Our results show that calcium stimulated production and secretion of hemolysin, but inhibited hemolytic potency.

Studies on hemolysis of hemolysin produced by Synechocystis sp. PCC 6803

“…Our previous work has confirmed that the hemolytic activity of concentrated cell-free cultures of WT PCC6803 correlates well to the features of hemolysin (Liu et al, 2008). To further this line of examination, the hemolysin crude extracts were analyzed in this study.…”

“…Hemolysin is produced by many pathogenic bacteria (Parker, 2003;Tilley and Saibil, 2006) and several cyanobacteria (Hashimoto et al, 1976;Mitsui et al, 1988;Wang et al, 2007;Sakiyama et al, 2006;Liu et al, 2008). Hemolysis mechanisms are not only closely related to the virulence in pathogenic bacteria, but may also be an indicator of the toxicity for cyanobacteria invading some types of fish (Mitsui et al, 1988).…”

“…In our work, we found that the wild-type (WT) strain of PCC6803 (referred to as WT PCC 6803) produced a distinct proteinaceous hemolysin with potent hemolytic activity against rabbit and sheep erythrocytes. The molecular mass of the hemolysin produced by the WT strain is approximately 81 kDa (Liu et al, 2008). However, the hemolysis process and mechanism governing this hemolysin remain unclear.…”

Cambios fisiológicos, bioquímicos y ultraestructurales inducidos por el campo magnético en Synechocystis aquatilis

“…3 mT during the early exponential phase (day 7 th ). The β values were selected considering different criteria (Hirano, Ohta, & Abe, 1998;Y. Z. Liu, Wang, Ru, & Zhao, 2008;Singh, Tiwari, Abraham, Rai, & Rai, 1994;Zhi-Yong, Si-Yuan, Lin, & Miao-Yan, 2007).…”