Data/hora: 09/06/2024 22:15:17

Biblioteca(s): | Embrapa Pantanal.
Data corrente: | 09/01/1998
Data da última atualização: | 05/04/2017
Autoria: | SIMON, M.; AZAM, F.
Título: | Protein content and protein synthesis rates of planktonic marine bacteria.
Ano de publicação: | 1989
Fonte/Imprenta: | Marine Ecology Progress Series, v.51, p.201-213, Feb. 1989.
Idioma: | Inglês
Conteúdo: | Bacterial carbon production is an important parameter in understanding the flows of carbon and energy in aquatic ecosystems, but has been difficult to measure. Present methods are based on measuring the rate of cell production, and thus require a knowledge of cellular carbon content of the growing bacteria to convert cell production into carbon production. We have examined the possibility that protein synthesis rate of pelagic bacteria might serve as the basis for directly estimating bacterial carbon production. We measured bacterial protein content and protein production of pelagic bacteria. Bacterial protein content was measured as amino acids high performance liquid chromatography of cell hydrolysates of bacterial assemblages of mean diameters from 0.026 to 0.4 um. Cellaular protein: volume (w/v) in the largest bacteria was 15.2 % (similar to cultured Escherichia coli) but increased with decreasing cell size to 46.5 % in 0.026 um bacteria. Protein per bacterium was correlated with cell volume by the power function y = 88.6x0.59 (r2 = 0.67; p < 0.01; n = 25). An inventory of major bacterial macro,olecular pools revealed that cell protein: dry and cell protein: carbon were esentially constant (63% and 54%, respectively) for the entire cell size range although cell protein: volume increased with decreasing cell size. Thus, the smaller cells in the size range were rich in carbon and dry weight and poor in water compared with larger cells. We established the experimental conditions for estimating protein synthesis on the basis of 3H leucine incorporation by bacteria, and determined the necessary parameters (including the intracellular isotope dillution by HPLC) for converting 3H leucine incorporation into protein synthesis rate. In samples from Scripps Institution of Oceanography pier the intracellular isotope dillution was only 2-fold. In a field study in Southern California Bight bacterial protein production and 3H-thymidine incorporation methods yielded comparable rates of bacterial production. Bacterial protein production method was an order of magnitude more sensitive and yielded bacterial carbon production directly without the need to know the cell size of the part of the assemblage in growth state.
Palavras-Chave: | Aquatic ecosystem; Ecossistema aquatico; Planctonico marinho; Planktonic marine; Protein.
Thesagro: | Bactéria; Limnologia; Proteína.
Thesaurus Nal: | limnology.
Categoria do assunto: | --
Registro original: | Embrapa Pantanal (CPAP)
Exemplares: | CPAP - (35171-1) - ADC - SP - PP - SP15468 -  - 15468 - DIS