Marine Heterotrophic Bacteria in Continuous Culture,the Bacterial Carbon Growth Efficiency,and Mineralization at Excess Substrate and Different Temperatures |
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Authors: | Alejandrina Jiménez-Mercado Ramón Cajal-Medrano Helmut Maske |
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Institution: | (1) Facultad de Ciencias Marinas, Universidad Autónoma de Baja California, P.O. Box 453, Ensenada, Baja California, México CP 22880;(2) Centro de Investigación Científica y Educación Superior de Ensenada, Ensenada, Mexico |
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Abstract: | To model the physiological potential of marine heterotrophic bacteria, their role in the food web, and in the biogeochemical
carbon cycle, we need to know their growth efficiency response within a matrix of different temperatures and degrees of organic
substrate limitation. In this work, we present one part of this matrix, the carbon growth efficiencies of marine bacteria
under different temperatures and nonlimiting organic and inorganic substrate supply. We ran aerobic turbidostats with glucose
enriched seawater, inoculated with natural populations of heterotrophic marine bacteria at 10, 14, 18, 22, and 26°C. The average
cell-specific growth rates increased with temperature from 1.17 to 2.6 h−1. At steady-state total CO2 production, biomass production particulate organic carbon (POC) and nitrogen (PON)], and viruslike particle abundance was
measured. CO2 production and specific growth rate increased with increasing temperature. Bacterial carbon growth efficiency (BCGE), the
particulate carbon produced per dissolved carbon utilized, varied between 0.12 and 0.70. Maximum BCGE values and decreased
specific respiration rates occurred at higher temperatures (22 and 26°C) and growth rates. This trend was largely attributable
to an increase in POC per cell abundance; when the BCGE was recalculated, parameterizing the biomass as the product of cell
concentration and a constant cellular carbon content, the opposite trend was observed. |
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