Bacterial colonization and ectoenzymatic activity in phytoplankton-derived model particles. Part II. Cleavage and uptake of carbohydrates
- Author(s)
- M. Agis, M. Unanue, J. Iriberri, G. J. Herndl
- Abstract
The bacterial colonization and development of the ectoenzymatic glucosidase activity and glucose uptake were followed together with bacterial growth (measured as thymidine incorporation) in laboratory experiments, using phytoplankton-derived particles incubated in rolling tanks. Bacterial colonization of the particles was rapid. In the particles, bacterial turnover rates (production/biomass) were low (0.02 to 0.14 d-1). In the ambient water, turnover rates increased from 0.1 d-1 to 23.3 d-1, until the end of the experiment. In the control, lacking any particles, turnover of bacteria ranged from 0.3 to 7.6 d-1. Similarly, glucose uptake rates, per bacterium, were 1 to 2 orders of magnitude lower for particle-attached bacteria than for their free-living counterparts. Generally, K(m) values for glucosidase activity declined, over the incubation period, in particles and free-living bacteria until 168 h, and slightly increased, thereafter, to values of approximately 0.1 μM. Particle-attached bacteria exhibited significantly lower uptake rates of both thymidine and glucose, per bacterium, throughout the incubation. The per-cell ectoenzymatic activity was similar in particle-associated and free-living bacteria during the initial phase of the experiment, but was significantly higher after ≃200 h. Dissolved total (TCHO), as well as monomeric carbohydrates (MCHO), declined continuously in both particles and ambient water; they remained constant in the control; TCHO comprised about 50% of the dissolved organic carbon (DOC) in the particles. In ambient water TCHO contribution to DOC varied, with only one exception, between 25 and 45%; and in the control, between 20 and 50%. The shift detectable in the relation between ectoenzymatic activity and uptake of glucose between free-living and attached bacteria over the incubation period may reflect changes in the physiological status of the bacteria.
- Organisation(s)
- Functional and Evolutionary Ecology
- External organisation(s)
- University of the Basque Country
- Journal
- Microbial Ecology
- Volume
- 36
- Pages
- 66-74
- No. of pages
- 9
- ISSN
- 0095-3628
- DOI
- https://doi.org/10.1007/s002489900094
- Publication date
- 07-1998
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 106022 Microbiology
- ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics, Ecology, Soil Science
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/3b187c35-9fe9-4940-80ef-018e57b3eece