Bacterial Heterotrophy Research Articles

Importance of particle-associated bacterial heterotrophy in a coastal Arctic ecosystem

The large quantities of particles delivered by the Mackenzie River to the coastal Beaufort Sea (Arctic Ocean) have implications for the spatial distribution, composition and productivity of its bacterial communities. Our objectives in this study were: (1) to assess the contribution of particle-associated bacteria (fraction ≥ 3 µm) to total bacterial production and their relationships with changing environmental conditions along a surface water transect; (2) to examine how particle-based heterotrophy changes over the annual cycle (Nov 2003–Aug 2004); and (3) to determine whether particle-associated bacterial assemblages differ in composition from the free-living communities (fraction < 3 µm). Our transect results showed that particle-associated bacteria contributed a variable percentage of leucine-based (BP-Leu) and thymidine-based (BP-TdR) bacterial production, with values up to 98% at the inshore, low salinity stations. The relative contribution of particle-associated bacteria to total BP-Leu was positively correlated with temperature and particulate organic material (POM) concentration. The annual dataset showed low activities of particle-associated bacteria during late fall and most of the winter, and a period of high particle-associated activity in spring and summer, likely related to the seasonal inputs of riverine POM. Results from catalyzed reporter deposition for fluorescence in situ hybridization (CARD-FISH) confirmed the dominance of Bacteria and presence of Archaea (43–84% and 0.2–5.5% of DAPI counts, respectively), which were evenly distributed throughout the Mackenzie Shelf, and not significantly related to environmental variables. Denaturing gradient gel electrophoresis (DGGE) revealed changes in the bacterial community structure among riverine, estuarine and marine stations, with separation according to temperature and salinity. There was evidence of differences between the particle-associated and free-living bacterial assemblages at the estuarine stations with highest POM content. Particle-associated bacteria are an important functional component of this Arctic ecosystem. Under a warmer climate, they are likely to play an increasing role in coastal biogeochemistry and carbon fluxes as a result of permafrost melting and increased particle transport from the tundra to coastal waters.

Increased Capacity for Polycyclic Aromatic Hydrocarbon Mineralization in Bioirrigated Coastal Marine Sediments

ABSTRACT Bioirrigation of marine sediments by benthic infauna has the potential to increase both the rate and depth of bacterial mineralization of polycyclic aromatic hydrocarbons (PAHs) by recirculating oxygenated bottom water into sediment burrows. Rates of heterotrophic bacterial production and mineralization of PAHs (naphthalene, phenanthrene, and fluoranthene) were measured in sections of sediment cores sampled from stations in San Diego Bay. Data suggest that rates of PAH biodegradation and bacterial heterotrophy were influenced by bioirrigation by benthic infauna. PAH mineralization and heterotrophic production were higher in core sections where sulfide was not detected relative to core sections containing sulfide. Depth-integrated capacity of the upper 17 cm of sediment to mineralize PAHs was 4 to 10 times higher at the station with bioirrigation coefficients that increased with depth. Remedial dredging of sediments to remove contaminant mass (and presumable lower ecological risk) will also remove benthic infauna. Removal of infauna and the subsequent lowering of bioirrigation in surface sediments would be expected to lower the capacity of intrinsic PAH bioremediation. This could cause local increases in ambient PAH concentration and consequently increase the ecological risk at the site and potentially degrade the health of the ecosystem by removing a sink for PAHs.

Key Issues Concerning Biolog Use for Aerobic and Anaerobic Freshwater Bacterial Community-Level Physiological Profiling

Bacterial heterotrophy in aquatic ecosystems is important in the overall carbon cycle. Biolog MicroPlates provide information into the metabolic potential of bacteria involved in carbon cycling. Specifically, Biolog EcoPlates™ were developed with ecologically relevant carbon substrates to allow investigators to measure carbon substrate utilization patterns and develop community-level physiological profiles from natural bacterial assemblages. However, understanding of the functionality of these plates in freshwater research is limited. We explored several issues of EcoPlate use for freshwater bacterial assemblages including inoculum density, incubation temperature, non-bacterial color development, and substrate selectivity. Each of these has various effects on plate interpretation. We offer suggestions and techniques to resolve these interpretation issues. Lastly we propose a technique to allow EcoPlate use in anaerobic freshwater bacterial studies. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The Effects of Cyanobacterial Exudates on Bacterial Growth and Biodegradation of Organic Contaminants

The pulp and paper industry largely depends on the biodegradation activities of heterotrophic bacteria to remove organic contaminants in wastewater prior to discharge. Our recent discovery of extensive cyanobacterial communities in pulp and paper waste treatment systems led us to investigate the potential impacts of cyanobacterial exudates on growth and biodegradation efficiency of three bacterial heterotrophs. Each of the three assessed bacteria represented different taxa commonly found in pulp and paper waste treatment systems: a fluorescent Pseudomonad, an Ancylobacter aquaticus strain, and a Ralstonia eutropha strain. They were capable of utilizing phenol, dichloroacetate (DCA), or 2,4-dichlorophenoxyacetic acid (2,4-D), respectively. Exudates from all 12 cyanobacterial strains studied supported the growth of each bacterial strain to varying degrees. Maximum biomass of two bacterial strains positively correlated with the total organic carbon content of exudate treatments. The combined availability of exudate and a known growth substrate (i.e., phenol, DCA, or 2,4-D) generally had a synergistic affect on the growth of the Ancylobacter strain, whereas mixed effects were seen on the other two strains. Exudates from four representative cyanobacterial strains were assessed for their impacts on phenol and DCA biodegradation by the Pseudomonas and Ancylobacter strains, respectively. Exudates from three of the four cyanobacterial taxa repressed phenol biodegradation, but enhanced DCA biodegradation. These dissimilar impacts of cyanobacterial exudates on bacterial degradation of contaminants suggest a species-specific association, as well as a significant role for cyanobacteria during the biological treatment of wastewaters.

Environmental Impacts of Diesel Fuel on Bacteria and Phytoplankton in a Tropical Estuary Assessed Using In Situ Mesocosms.

Dissolved or dispersed petroleum hydrocarbon concentrations (DDPH) were monitored in Ponggol estuary, Singapore, fortnightly from July 1999 to June 2000. DDPH concentrations ranged from 4.4 to 248.9 microg l(-1) and 0.4 to 1099.7 microg l(-1) for surface and subsurface waters, respectively and with mean concentrations of 41.01 microg l(-1) in the water column. Absorbed or adsorbed petroleum hydrocarbon (AAPH) concentrations measured in sediments ranged from 20.6 to 541.0 mg kg(-1), with mean concentrations of 148.23 mg kg(-1). In situ mesocosm studies of bacteria and phytoplankton were based on field monitoring of environmentally measured concentrations of petroleum hydrocarbons, using diesel fuel as the source of contaminant. The mesocosm comprised of 25 L clear polycarbonate carboys incubated in situ for 6 days. Water and sediments from a clean site with undetectable levels of petroleum hydrocarbons were used in controls. The treatment mesocosms comprised of mean and highest concentrations of DDPH and AAPH. The study revealed signs of acute toxicity to autotrophs viz., phytoplankton and autotrophic bacteria in treatments simulating concentrations of diesel fuel found in the sediments. A stimulatory effect was seen at lower concentrations. Bacterial heterotrophs responded positively to all concentrations of diesel fuel because of the abundance of a carbon source, reduced grazing pressure and reduced competition for nutrients from phytoplankton.

The pinyon rhizosphere, plant stress, and herbivory affect the abundance of microbial decomposers in soils.

In terrestrial ecosystems, changes in environmental conditions that affect plant performance cause a cascade of effects through many trophic levels. In a 2-year field study, seasonal abundance measurements were conducted for fast-growing bacterial heterotrophs, humate-degrading actinomycetes, fungal heterotrophs, and fluorescent pseudomonads that represent the decomposers in soil. Links between plant health and soil microbiota abundance in pinyon rhizospheres were documented across two soil types: a dry, nutrient-poor volcanic cinder field and a sandy-loam soil. On the stressful cinder fields, we identified relationships between soil decomposer abundance, pinyon age, and stress due to insect herbivory. Across seasonal variation, consistent differences in microbial decomposer abundance were identified between the cinders and sandy-loam soil. Abundance of bacterial heterotrophs and humate-degrading actinomycetes was affected by both soil nutritional status and the pinyon rhizosphere. In contrast, abundance of the fungal heterotrophs and fluorescent pseudomonads was affected primarily by the pinyon rhizosphere. On the cinder field, the three bacterial groups were more abundant on 150-year-old trees than on 60-year-old trees, whereas fungal heterotrophs were unaffected by tree age. Fungal heterotrophs and actinomycetes were more abundant on insect-resistant trees than on susceptible trees, but the opposite was true for the fluorescent pseudomonads. Although all four groups were present in all the environments, the four microbial groups were affected differently by the pinyon rhizosphere, by tree age, and by tree stress caused by the cinder soil and insect herbivory.

Effects of compost-derived humic acids on vegetable biomass production and microbial growth within a plant ( Cichorium intybus)-soil system: a comparative study

The responses of chicory plants to amendments with natural and synthetic surface active substances, represented by either potassium humates from compost stabilised green waste or Tween 80, are reported from a pot trial. Results are evaluated in terms of plant biomass production and behaviour of soil microbial populations following different treatments. Amendments with humic acids stimulated vegetative growth of chicory. They also caused significative variations in the numbers of bacterial heterotrophs and autotrophic nitrifiers in the soil. The study suggests that the mechanism through which humic acids affect both plant and soil microbes may chiefly involve enhancement of cell membrane permeability to nutrients.

Utilization and turnover of labile dissolved organic matter by bacterial heterotrophs in eastern North Pacific surface waters

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 139:267-279 (1996) - doi:10.3354/meps139267 Utilization and turnover of labile dissolved organic matter by bacterial heterotrophs in eastern North Pacific surface waters Cherrier J, Bauer JE, Druffel ERM Seawater incubation experiments were conducted in June and October 1992 to examine bacterial utilization of labile dissolved organic matter (DOM) in open ocean surface waters of the eastern North Pacific. Natural plankton extract-DOM (PE-DOM) and selected model compounds were added to seawater samples to evaluate bacterial utilization and respiration rates relative to bacterial carbon production rates for the various amendments. PE-DOM always stimulated bacterial production and DOM utilization, and the primary nitrogen source supporting this bacterial production was dissolved organic nitrogen (DON). Utilization of DON during exponential growth was balanced by the production of ammonium for samples amended with PE-DOM. Bacterial growth efficiencies for samples amended with PE-DOM ranged between 3.4 and 8.8% and generally were slightly higher in June than in October. Of the model compounds tested, net bacterial biomass production was observed only in samples amended with glucose, glucose plus ammonium (glucose+NH4+), and dissolved free amino acids (DFAA). Bacterial growth efficiencies for these amendments were 0.8, 1.9, and and 9.3.%, respectively. Bacterial production at in situ DOM concentrations was observed in June but not in October. Using the bacterial dissolved organic carbon (DOC) utilization rates observed in this study together with other detailed information pertaining to bulk DOC at our study site, we estimate that the turnover time for labile DOC in these surface waters ranges from approximately 2 to 6 d depending on the lability of the standing stock of DOC. On the basis of (a) the exclusive use of DON as a nitrogen source in PE-DOM amendments, (b) the stimulation of ammonium utilization in the glucose+NH4+ amendment, and (c) the higher growth efficiencies observed for samples amended with either PE-DOM or DFAA, we suggest that bacterioplankton biomass production in eastern North Pacific surface waters is primarily energy limited. As a result of this energy limitation, bacterial production appears to be additionally constrained by the quality of the nutrients available for assimilation. Thus, the quality of the DOM substrate, specifically the DOC:DON ratio, can be a major determinant of bacterial production in pelagic marine systems. Bacterial production · Growth efficiency · DOC turnover · Plankton extract-DOM Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 139. Publication date: August 29, 1996 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1996 Inter-Research.

Photosynthetic and bacterial production gradients in a larval fish nursery:the St. Lawrence River transition zone

Phytoplankton biomass, primary production and bacterial abundance and production were measured across the freshwater-saltwater transition zone of the St. Lawrence River [Canada) during the seasonal period of maximum concentrations of fish larvae and macrozooplankton. The estuarine front was characterized by steep gradients in b~olog~cal s well as physical properties. Maximum turbidity and high phytoplankton biomass occurred in the well-mixed, low salinity (0.2 to 4 psu) region immediately upstream of the salt wedge. Peak zooplankton and ichthyoplankton biomass occurred within and slightly downstream of this frontal region The hypothesis that lower food chain processes were controlled exclusively by allochthonous carbon and bacterial heterotrophy was not supported. Photosynthetic rates per unit chlorophyll a [chl a) remained high across the freshwater-saltwater transition and the low light penetration was offset by a shallow mean depth of mixing. Bacterial concentrations and activity remained relatively constant across the transition, while chl a declined sharply downstream of the front, consistent with grazing losses. Photosynthesis contributed 34 to 66% of the total production (bacteria + phytoplankton). Freshwater phytoplankton advected from upstream contributed another 20 to 30%. These first-order estimates underscore the combined importance of photosynthesis plus bacterial processes within the downstream food web of large river ecosystems.

Utilization and turnover of labile dissolved organic matter by bacterial heterotrophs in eastern North Pacific surface waters

Utilization and turnover of labile dissolved organic matter by bacterial heterotrophs in eastern North Pacific surface waters

Short-term changes in planktonic community structure and nitrogen transfers in a coastal upwelling system

Large changes were recorded in the mixed layer and deeper water column properties of a mid-shelf station in a coastal upwelling region (West Coast, South Island, New Zealand) after time intervals of 0·5 and 5·0 days. Throughout the period of sampling a food web based on small-celled organisms predominated. Most of the phytoplankton biomass and all of the measured nitrogen uptake and primary production were associated with particles that passed through a 20 μm filter. Species less than 2 μm accounted for at least 40% of the chlorophyll a, 60% of protein and polysaccharide biosynthesis, up to 67% of the ammonium uptake and up to 45% of the nitrate uptake. Excretion by zooplankton larger than 55 μm could account for only c. 5% of the uptake demand for ammonium, and grazing by these larger animals was equivalent to less than 4% of the average nitrate plus ammonium uptake. Large numbers of flagellates dominated the nacoplankton samples. Bacterial heterotrophy and nitrification rates, as well as picoplankton biomass and associated rate variables, greatly increased subsequent to a period of apparent upwelling. Microbial interactions (e.g. picoplankton—heterotrophic flagellates/ciliates) are likely to dominate the biological dynamics of this coastal shelf system.

Microbial and biogeochemical processes in Big Soda Lake, Nevada

Summary Meromictic, alkaline lakes represent modern-day analogues of lacustrine source rock depositional environments. In order to further our understanding of how these lakes function in terms of limnological and biogeochemical processes, we have conducted an interdisciplinary study of Big Soda Lake. Annual mixolimnion productivity (ca. 500 g m −2 ) is dominated by a winter diatom bloom (600f annual) caused by upward transport of ammonia to the epilimnion. The remainder of productivity is attributable to chemoautotrophs (30%) and photosynthetic bacteria (10%) present at the oxic-anoxic interface from May to November. Studies of bacterial heterotrophy and particulate fluxes in the water column indicate that about 900f annual productivity is remineralized in the mixolimnion, primarily by fermentative bacteria. However, high rates of sulphate reduction (9–29 mmol m −2 yr −1 ) occur in the monimolimnion waters, which could remineralize most (if not all) of the primary productivity. This discrepancy has not as yet been fully explained. Low rates of methanogenesis also occur in the monimolimnion waters and sediments. Most of the methane is consumed by anaerobic methane oxidation occurring in the monimolimnion water column. Other bacterial processes occurring in the lake are also discussed. Preliminary studies have been made on the organic geochemistry of the monimolimnion sediments. Carbon-14-dating indicates a lower depositional rate prior to meromixis and a downcore enrichment in 13 C of organic carbon and chlorophyll derivatives. Hydrous pyrolysis experiments indicate that the sediment organic matter is almost entirely derived from the water column with little or no contribution from terrestrial sources. The significance of the organics released by hydrous pyrolysis is discussed.

Chemical and microbiological studies of sea-surface films in the Southern Gulf of California and off the West Coast of Baja California

Sea-surface films and the corresponding 10-cm subsurface waters were sampled on three cruises to the eutrophic and oligotrophic waters in the Gulf of California and off the west coast of Baja California. The following constituents and properties were measured: NH 4 +, NO 2 −, NO 3 −, PO 4 3−, SiO 3 2−, urea, ATP and Chl- a; dissolved and particulate organic carbon and nitrogen; lipid, protein and carbohydrate; total viable and nitrifying bacteria; simulated in situ bacterial heterotrophy; microplankton and simulated in situ primary productivity; surface potential and film pressures; ultraviolet absorption; and film-formation rates using surface potential and chemical methods. Mean enrichment factors (film concentration/10-cm concentration) for the three cruises were: 1.1–2.4 for the soluble inorganic nutrients, dissolved organic carbon, nitrogen, urea, carbohydrate, and lipid; 1.3–2.0 for ATP, Chl- a, microplankton and bacteria; and 1.1–3.7 for particulate carbon and nitrogen and both dissolved and particulate protein. Particulate and dissolved carbon and nitrogen were the only constituents never depleted in the films relative to the subsurface waters. Systematic, significant correlations between the various chemical and biological parameters measured were few, reflecting the complexity of processes which form and maintain surface films. Protein, carbohydrate and lipid carbon accounted for 15–114% (mean = 50%) of the total particulate organic carbon and 14–42% (mean = 28%) of the total dissolved organic carbon in both the films and 10-cm waters. Lipid was not the major identified constituent of films, averaging 18% of the particulate organic carbon and 2.5% of the dissolved organic carbon. There was more protein relative to carbohydrate in film samples compared to 10-cm water; there was also more protein relative to carbohydrate in particulate compared to dissolved mater. Microplankton plus bacterial carbon averaged 16% of the particulate organic carbon in films and 19% in 10-cm waters.

Ureolytic and nitrifying bacterial heterotrophs from acid soils

Nitrification following ureolysis in soil samples from tea growing soils (pH 4.5–5.5) was found to be chiefly due to the activity of heterotrophic bacteria belonging to generaBacillus, Arthrobacter, Sporosarcina, Micrococcus, Clostridium, Pseudomonas andProteus. A correlation between the intensity of ureolytic activity of organisms in a given soil sample and the yield levels of tea was observed. In culture media the increase in the quantity of NH 4 + -N indicating ureolysis was not accompanied by proportional increase in biomass. Ureolysis and nitrification in sterile soil sample inoculated with the isolates improved through amendment of organic carbon to the soil.

Use of Treated Sewage in Aquaculture1

ABSTRACTSix experimental brackish water ponds, three of which received secondary treated sewage waste and three as controls, were seeded with larval and postlarval species to study productivity, nutrient cycling and development of communities. A number of faculty and students from the University of North Carolina studied various phases, productivity, carbon metabolism, phosphorus budget, nitrogen, bacterial heterotrophy; standing crops of phytoplankton, decapod crustaceans, fishes, mollusks, algae, etc. Ponds receiving treated waste had high productivity, wide fluctuations in oxygen and pH, and dense algal blooms. Some functions of tertiary treatment and promise for production of selected marketable species are indicated.