title: Growth on urea can trigger death and peroxidation of the cyanobacterium Synechococcus sp. strain PCC 7002.
abstract: Laboratory conditions have been identified that cause the rapid death of cultures of cyanobacteria producing urease. Once the death phase had initiated in the stationary growth phase, cells were rapidly bleached of all pigmentation. Null mutations in the ureC gene, encoding the alpha subunit of urease, were constructed, and these mutants were no longer sensitive to growth in the presence of urea. High levels of peroxides, including lipid peroxides, were detected in the bleaching cells. Exogenously added polyunsaturated fatty acids triggered a similar death response. Vitamin E suppressed the formation of peroxides and delayed the onset of cell bleaching. The results suggest that these cyanobacterial cells undergo a metabolic imbalance that ultimately leads to oxidative stress and lipid peroxide formation. These observations may provide insights into the mechanism of sudden cyanobacterial bloom disappearance in nature.
authors.affiliation: Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park 16802, USA.
authors.forename: T
authors.initials: T
authors.lastname: Sakamoto
authors.forename: V B
authors.initials: VB
authors.lastname: Delgaizo
authors.forename: D A
authors.initials: DA
authors.lastname: Bryant
mesh_terms: D000458:Cyanobacteria / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D017353:Gene Deletion; D005798:Genes, Bacterial / Q000235:genetics; D006540:Herbicides / Q000494:pharmacology; D015227:Lipid Peroxidation; D010269:Paraquat / Q000494:pharmacology; D014508:Urea / Q000494:pharmacology*; D014510:Urease / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D005231:Fatty Acids, Unsaturated; D006540:Herbicides; D014508:Urea; D014510:Urease; D010269:Paraquat