scholarly journals Bacterial growth and tidal variation in bacterial abundance in the Great Sippewissett Salt Marsh

1984 ◽  
Vol 19 ◽  
pp. 247-259 ◽  
Author(s):  
D Kirchman ◽  
B Peterson ◽  
D Juers
Keyword(s):  
Salt Marsh ◽  
Bacterial Growth ◽  
Bacterial Abundance ◽  
Tidal Variation ◽  
Great Sippewissett Salt Marsh

scholarly journals Rapid Determination of Bacterial Abundance, Biovolume, Morphology, and Growth by Neural Network-Based Image Analysis

1998 ◽  
Vol 64 (9) ◽  
pp. 3246-3255 ◽  
Author(s):  
Nicholas Blackburn ◽  
Åke Hagström ◽  
Johan Wikner ◽  
Rocio Cuadros-Hansson ◽  
Peter Koefoed Bjørnsen
Keyword(s):  
Neural Network ◽  
Image Analysis ◽  
Bacterial Growth ◽  
Growth Rates ◽  
Bacterial Abundance ◽  
Rapid Determination ◽  
Image Analyzer ◽  
Cell Counts ◽  
Dividing Cells ◽  
Bacterial Growth Rates

ABSTRACT Annual bacterial plankton dynamics at several depths and locations in the Baltic Sea were studied by image analysis. Individual bacteria were classified by using an artificial neural network which also effectively identified nonbacterial objects. Cell counts and frequencies of dividing cells were determined, and the data obtained agreed well with visual observations and previously published values. Cell volumes were measured accurately by comparison with bead standards. The survey included 690 images from a total of 138 samples. Each image contained approximately 200 bacteria. The images were analyzed automatically at a rate of 100 images per h. Bacterial abundance exhibited coherent patterns with time and depth, and there were distinct subsurface peaks in the summer months. Four distinct morphological classes were resolved by the image analyzer, and the dynamics of each could be visualized. The bacterial growth rates estimated from frequencies of dividing cells were different from the bacterial growth rates estimated by the thymidine incorporation method. With minor modifications, the image analysis technique described here can be used to analyze other planktonic classes.

scholarly journals Characterization, Seasonal Occurrence, and Diel Fluctuation of Poly(hydroxyalkanoate) in Photosynthetic Microbial Mats

2000 ◽  
Vol 66 (10) ◽  
pp. 4279-4291 ◽  
Author(s):  
Mary M. Rothermich ◽  
Ricardo Guerrero ◽  
Robert W. Lenz ◽  
Steve Goodwin
Keyword(s):  
Salt Marsh ◽  
Organic Carbon ◽  
Microbial Mats ◽  
Ebro Delta ◽  
Purple Sulfur Bacteria ◽  
Mole Percent ◽  
Pure Cultures ◽  
Great Sippewissett Salt Marsh ◽  
Artificial Shading

ABSTRACT In situ poly(hydroxyalkanoate) (PHA) levels and repeating-unit compositions were examined in stratified photosynthetic microbial mats from Great Sippewissett Salt Marsh, Mass., and Ebro Delta, Spain. Unlike what has been observed in pure cultures of phototrophic bacteria, the prevalence of hydroxyvalerate (HV) repeating units relative to hydroxybutyrate (HB) repeating units was striking. In the cyanobacteria-dominated green material of Sippewissett mats, the mole percent ratio of repeating units was generally 1HB:1HV. In the purple sulfur bacteria-dominated pink material the relationship was typically 1HB:2HV. In Sippewissett mats, PHA contributed about 0.5 to 1% of the organic carbon in the green layer and up to 6% in the pink layer. In Ebro Delta mats, PHA of approximately 1HB:2HV-repeating-unit distribution contributed about 2% of the organic carbon of the composite photosynthetic layers (the green and pink layers were not separated). Great Sippewissett Salt Marsh mats were utilized for more extensive investigation of seasonal, diel, and exogenous carbon effects. When the total PHA content was normalized to organic carbon, there was little seasonal variation in PHA levels. However, routine daily variation was evident at all sites and seasons. In every case, PHA levels increased during the night and decreased during the day. This phenomenon was conspicuous in the pink layer, where PHA levels doubled overnight. The daytime declines could be inhibited by artificial shading. Addition of exogenous acetate, lactate, and propionate induced two- to fivefold increases in the total PHA levels when applied in the daylight but had no effect when applied at night. The distinct diel pattern of in situ PHA accumulation at night appears to be related, in some phototrophs, to routine dark energy metabolism and is not influenced by the availability of organic nutrients.

scholarly journals Vegetation-Dependent Response to Drought in Salt Marsh Ammonia-Oxidizer Communities

2019 ◽  
Vol 8 (1) ◽  
pp. 9
Author(s):  
Jack K. Beltz ◽  
Hayley McMahon ◽  
Isis Torres Nunez ◽  
Anne E. Bernhard
Keyword(s):  
Salt Marsh ◽  
Community Composition ◽  
Bacterial Abundance ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Ammonia Oxidizer ◽  
N Availability ◽  
Ammonia Oxidizing Archaea ◽  
Vegetation Zones ◽  
Total Bacterial Community

We investigated the impacts of drought on ammonia-oxidizing archaea (AOA) and bacteria (AOB) in a salt marsh and compared the response to the total bacterial community. We analyzed abundance and community composition of amoA genes by QPCR and TRFLP, respectively, in three vegetation zones in 2014 (pre-drought), 2016 (drought), and 2017 (post-drought), and analyzed bacterial 16S rRNA genes by QPCR, TRFLP, and MiSeq analyses. AOA and AOB abundance in the Spartina patens zone increased significantly in 2016, while abundance decreased in the tall S. alterniflora zone, and showed little change in the short S. alterniflora zone. Total bacterial abundance declined annually in all vegetation zones. Significant shifts in community composition were detected in 2016 in two of the three vegetation zones for AOA and AOB, and in all three vegetation zones for total bacteria. Abundance and community composition of AOA and AOB returned to pre-drought conditions by 2017, while bacterial abundance continued to decline, suggesting that nitrifiers may be more resilient to drought than other bacterial communities. Finding vegetation-specific drought responses among N-cycling microbes may have broad implications for changes in N availability and marsh productivity, particularly if vegetation patterns continue to shift as predicted due to sea level rise.

scholarly journals Assessing approaches to determine the effect of ocean acidification on bacterial processes

2016 ◽  
Vol 13 (15) ◽  
pp. 4379-4388 ◽  
Author(s):  
Timothy J. Burrell ◽  
Elizabeth W. Maas ◽  
Paul Teesdale-Spittle ◽  
Cliff S. Law
Keyword(s):  
Organic Matter ◽  
Ocean Acidification ◽  
Bacterial Growth ◽  
Extracellular Enzymes ◽  
Bacterial Abundance ◽  
Aminopeptidase Activity ◽  
Labile Organic Matter ◽  
Fluorescent Substrate ◽  
Co2 Gas ◽  
Carbohydrate Degradation

Abstract. Bacterial extracellular enzymes play a significant role in the degradation of labile organic matter and nutrient availability in the open ocean. Although bacterial production and extracellular enzymes may be affected by ocean acidification, few studies to date have considered the methodology used to measure enzyme activity and bacterial processes. This study investigated the potential artefacts in determining the response of bacterial growth and extracellular glucosidase and aminopeptidase activity to ocean acidification as well as the relative effects of three different acidification techniques. Tests confirmed that the observed effect of pH on fluorescence of artificial fluorophores, and the influence of the MCA fluorescent substrate on seawater sample pH, were both overcome by the use of Tris buffer. In experiments testing different acidification methods, bubbling with CO2 gas mixtures resulted in higher β-glucosidase activity and 15–40 % higher bacterial abundance, relative to acidification via gas-permeable silicon tubing and acid addition (HCl). Bubbling may stimulate carbohydrate degradation and bacterial growth, leading to the incorrect interpretation of the impacts of ocean acidification on organic matter cycling.

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