Characterization of Root-Associated Methanotrophs from Three Freshwater Macrophytes: Pontederia cordata, Sparganium eurycarpum, and Sagittaria latifolia†

AUTOR(ES)

Calhoun, A.

FONTE

American Society for Microbiology

RESUMO

Root-associated methanotrophic bacteria were enriched from three common aquatic macrophytes: Pontederia cordata, Sparganium eurycarpum, and Sagittaria latifolia. At least seven distinct taxa belonging to groups I and II were identified and presumptively assigned to the genera Methylosinus, Methylocystis, Methylomonas, and Methylococcus. Four of these strains appeared to be novel on the basis of partial 16S ribosomal DNA sequence analysis. The root-methanotroph association did not appear to be highly specific, since multiple methanotrophs were isolated from each of the three plant species. Group II methanotrophs were isolated most frequently; though less common, group I isolates accounted for three of the seven distinct methanotrophs. Apparent Km values for methane uptake by representative cultures ranged from 3 to >17 μM; for five of the eight cultures examined, apparent Km values agreed well with apparent Km estimates for plant roots, suggesting that these strains may be representative of those active in situ.

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