Sheathless mutant of cyanobacterium Gloeothece sp strain PCC 6909 with increased capacity to remove copper ions from aqueous solutions

• Type: Article in International Scientific Journal
• Date: 2008

Authors

Micheletti, E (Author) Other; Pereira, S (Author) Other; Mannelli, F (Author) Other; Pedro Moradas Ferreira (Author) ICBAS; Paula Tamagnini (Author) FCUP; De Philippis, R (Author) Other

Journal

Title: Applied and Environmental Microbiology

Vol. 74

Pages: 2797-2804

ISSN: 0099-2240

Publisher: American Society for Microbiology

Indexing

ISI Web of Knowledge - 43 Citations

Scopus - 51 Citations

Other information

Authenticus ID: P-003-ZGV

DOI: 10.1128/aem.02212-07

Abstract (EN): The cyanobacterium Gloeothece sp. strain PCC 6909 and its sheathless mutant were tested for their abilities to remove copper ions from aqueous solutions, with the aim of defining the role of the various outermost polysaccharidic investments in the removal of the metal ions. Microscopy studies and chemical analyses revealed that, although the mutant does not possess a sheath, it releases large amounts of polysaccharidic material (released exocellular polysaccharides [RPS]) into the culture medium. The RPS of the wild type and the mutant are composed of the same 11 sugars, although they are present in different amounts, and the RPS of the mutant possesses a larger amount of acidic sugars and a smaller amount of deoxysugars than the wild type. Unexpectedly, whole cultures of the mutant were more effective in the removal of the heavy metal than the wild type (46.3 +/- 3.1 and 26.7 +/- 1.5 Mg of Cu(2+) removed per g of dry weight, respectively). Moreover, we demonstrated that the contribution of the sheath to the metal-removal capacity of the wild type is scarce and that the RPS of the mutant is more efficient in removing copper. This suggests that the metal ions are preferably bound to the cell wall and to RPS functional groups rather than to the sheath. Therefore, the increased copper binding efficiency observed with the sheathless mutant can be attributed to the release of a polysaccharide containing larger amounts and/or more accessible functional groups (e.g., carboxyl and amide groups).

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8