Ni uptake and limitation in marine Synechococcus strains

Citation:
Dupont, CL, Barbeau K, Palenik B.  2008.  Ni uptake and limitation in marine Synechococcus strains. Applied and Environmental Microbiology. 74:23-31.

Date Published:

Jan

Abstract:

Ni accumulation and utilization were studied in two strains of marine Synechococcus, isolated from both coastal (CC9311; clade I) and open-ocean (WTH8102; clade III) environments, for which complete genome sequences are available. Both strains have genes encoding an Ni-containing urease and when grown on urea without Ni become Ni-N colimited. The Ni requirements of these strains also depend upon the genomic complement of genes encoding superoxide dismutase (SOD). WH8102, with a gene encoding only an Ni-SOD, has a novel obligate requirement for Ni, regardless of the N source. Reduced SOD activity in Ni-depleted cultures of VM8102 supports the link of this strain's Ni requirement to Ni-SOD. The genome of CC9311 contains a gene for a Cu/Zn-SOD in addition to a predicted pair of Ni-SODs, yet this strain cannot grow without Ni on NO3- and can grow only slowly on NH4+ without Ni, implying that the Cu/Zn-SOD cannot completely replace Ni-SOD in marine cyanobacteria. CC9311 does have a greater tolerance for Ni starvation. Both strains increase their Ni uptake capabilities and actively bioconcentrate Ni in response to decreasing extracellular and intracellular Ni. The changes in Ni uptake rates were more pronounced in WH8102 than in CC9311 and for growth on urea or nitrate than for growth on ammonia. These results, combined with an analysis of fully sequenced marine cyanobacterial genomes, suggest that the growth of many marine Synechococcus and all Prochlorococcus strains is dependent upon Ni.

Notes:

n/a

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DOI:

10.1128/aem.01007-07