Seasonal patterns of substrate utilization by bacterioplankton: case studies in four temperate lakes of different latitudes

Abstract

Utilization of 95 carbon sources by bacteria in 2 Canadian Shield lakes and 2 Texan reservoirs was determined using Biolog-GN microtiter plates. Triplicate plates were inoculated and incubated for 5 d, during which color development was monitored twice daily by optical density (OD 595 ). Optical densities in plate wells containing carbon substrates were corrected for blank absorbance at each measurement time. Then, data on optical densities of all substrate wells were selected from a single measurement time, to construct a community-level physiological profile. This measurement time was chosen so that plates would be compared at similar levels of color development. This data selection also generally maximized correlations of substrate utilization patterns determined from replicate plates. Multivariate analyses (ordinations) of the community-level physiological profiles identified several amino acids, carboxylic acids, and carbohydrates associated with seasonal patterns of substrate utilization. Multivariate analyses further revealed patterns in substrate utilization common to all 4 lakes: strong relative responses to amino and carboxylic acids in cool seasons and strong relative responses to carbohydrates in warm seasons. These patterns may be driven by seasonal events among phytoplankton that influence carbohydrate supply, and appear to be dampened in an oligotrophic lake, which does not support high algal abundance.KEY WORDS: Bacterioplankton · Biolog-GN · Substrate utilization pattern · Community-level physiological profileResale or republication not permitted without written consent of the publisher

Functional diversity of bacterioplankton assemblages in western Antarctic seawaters during late spring

“…Garland & Mills (1991) first proposed the use of Biolog plates to assess functional diversity of microorganisms in environmental samples, based on the patterns of community-level sole-carbon source utilization profiles. In spite of the drawbacks of the approach reviewed by Preston-Mafham et al (2002), Biolog plates have been shown to be a useful tool to detect differences in functional diversity of microbial populations in several aquatic environments such as lakes (Grover & Chrzanowski 2000), rivers (Sinsabaugh & Foreman 2001), estuaries (Schultz & Ducklow 2000) and the sea (Hollibaugh 1994).…”

Seasonal changes in the functional diversity of bacterioplankton in contrasting coastal environments of the NW Mediterranean

“…This has been improved with the introduction of the BiologEcoplates, which contain a set of carbon sources more relevant for ecological studies (Choi & Dobbs 1999). In spite of these shortcomings, Biolog plates have provided useful information on the functional diversity of bacterial communities from soils and sediments (see references in Preston-Mafham et al 2002), freshwater (Grover & Chrzanowski 2000, Sinsabaugh & Foreman 2001, Worm et al 2001) and marine plankton systems. For example, studies in marine ecosystems have shown (1) that functional diversity was strongly influenced by temperature and salinity in the York River estuary (Schultz & Ducklow 2000); (2) that there was a lack of relationship between phytoplankton abundance and bacterioplankton functional diversity in Antarctic waters (Sala et al 2005a), suggesting that bacteria could utilize carbon sources other than freshly released phytoplanktonic DOC in such waters; and (3) that phylogenetic and functional diversity can be uncoupled during blooms of harmful dinoflagellates (Sala et al 2005b).…”

Estimation of bacterial use of dissolved organic nitrogen compounds in aquatic ecosystems using Biolog plates

“…They have allowed comparisons of community-level physiological profiles of different bacterial assemblages in aquatic environments (Grover & Chrzanowski 2000, Schultz & Ducklow 2000, Sala et al 2005a). For example, Sala et al (2005b) showed that changes in the composition of bacterioplankton assemblages were associated with changes in physiological profiles in the NW Mediterranean.…”