Diel changes in the specific growth rate and mean cell volume of natural bacterial communities in two different water masses in the Irish sea

1986 ◽  
Vol 12 (3) ◽  
pp. 271-282 ◽  
Author(s):  
C. Turley ◽  
K. Lochte
2001 ◽  
Vol 67 (1) ◽  
pp. 278-283 ◽  
Author(s):  
Benedict M. Long ◽  
Gary J. Jones ◽  
Philip T. Orr

ABSTRACT Cell quotas of microcystin (Q MCYST; femtomoles of MCYST per cell), protein, and chlorophyll a(Chl a), cell dry weight, and cell volume were measured over a range of growth rates in N-limited chemostat cultures of the toxic cyanobacterium Microcystis aeruginosa MASH 01-A19. There was a positive linear relationship betweenQ MCYST and specific growth rate (μ), from which we propose a generalized model that enablesQ MCYST at any nutrient-limited growth rate to be predicted based on a single batch culture experiment. The model predicts Q MCYST from μ, μmax(maximum specific growth rate), Q MCYSTmax(maximum cell quota), and Q MCYSTmin (minimum cell quota). Under the conditions examined in this study, we predict aQ MCYSTmax of 0.129 fmol cell−1 at μmax and a Q MCYSTmin of 0.050 fmol cell−1 at μ = 0. Net MCYST production rate (R MCYST) asymptotes to zero at μ = 0 and reaches a maximum of 0.155 fmol cell−1 day−1at μmax. MCYST/dry weight ratio (milligrams per gram [dry weight]) increased linearly with μ, whereas the MCYST/protein ratio reached a maximum at intermediate μ. In contrast, the MCYST/Chla ratio remained constant. Cell volume correlated negatively with μ, leading to an increase in intracellular MCYST concentration at high μ. Taken together, our results show that fast-growing cells of N-limited M. aeruginosa are smaller, are of lower mass, and have a higher intracellular MCYST quota and concentration than slow-growing cells. The data also highlight the importance of determining cell MCYST quotas, as potentially confusing interpretations can arise from determining MCYST content as a ratio to other cell components.


2018 ◽  
pp. 57-73 ◽  
Author(s):  
O. A. Frolov ◽  
A. V. Yakushev

Ecophysiological features of the transit (passed through the intestinal lacune) bacterial hydrolytic complex Aporrectodea caliginosa were studied: a comparison of biodiversity was made in the soil and coprolites, the prevailing ecological strategy and physiological states among its members. The study was conducted by a complex structural and functional method based on the succession kinetic analysis of initiated hydrolytic bacterial communities that occur after the inoculation of a set of selective liquid nutrient media with a suspension of the test samples. In addition to hydrolytic microorganisms, non-hydrolytic bacterial satellites (oligotrophs and copyotropes) are included in initiated communities. The growth of initiated bacterial communities on eight media with biopolymers (chitin, cellulose, pectin, starch, xylan, dextran 500, tween 20, casein) was measured by optical density. It was described by two kinetic parameters used to describe the pure cultures of microorganisms: the maximum specific growth rate and the initial physiological state. The biodiversity of the initiated communities was de-termined according to the planting from liquid nutrient media with polymers on the agar medium. Rank distributions of the studied indicators were abnormal, therefore, median and nonparametric dispersion analyzes were used, as well as a direct analysis of rank distributions. The bacterial community from coprolites acquires greater sustainability - the species composition becomes more leveled (the Berger-Parker index, showing the degree of dominance of the most abundant species, decreases after the passage) and diverse (the Shannon index becomes higher after passage). The hydrolytic bacterial complex is activated at passage, as the median value of the initial physiological state of the initiated communities increases. In the bacterial block, the proportion of fast-growing bacteria of r-strategists increases (on liquid media with polymers, the share of initiated hydrolytic associations increases with large values of the maximum specific growth rate).


Aquaculture ◽  
2008 ◽  
Vol 274 (1) ◽  
pp. 87-95 ◽  
Author(s):  
S. Millot ◽  
M.-L. Bégout ◽  
J. Person-Le Ruyet ◽  
G. Breuil ◽  
C. Di-Poï ◽  
...  

2010 ◽  
Vol 45 (11) ◽  
pp. 1800-1807 ◽  
Author(s):  
S. Chenikher ◽  
J.S. Guez ◽  
F. Coutte ◽  
M. Pekpe ◽  
P. Jacques ◽  
...  

2012 ◽  
Vol 48 (2) ◽  
pp. 382-386 ◽  
Author(s):  
Juan Aguirre ◽  
Mª Rosa Rodríguez ◽  
Rodrigo González ◽  
Gonzalo García de Fernando

1999 ◽  
Vol 70 (1-3) ◽  
pp. 323-333 ◽  
Author(s):  
Marcel Janssen ◽  
Tjibbe Chris Kuijpers ◽  
Bram Veldhoen ◽  
Michel Brik Ternbach ◽  
Johannes Tramper ◽  
...  

2013 ◽  
Vol 48 (6) ◽  
pp. 645-650 ◽  
Author(s):  
Cleujosí da Silva Nunes ◽  
Gilberto Moraes ◽  
Fernando Fabrizzi ◽  
Araceli Hackbarth ◽  
Gustavo Alberto Arbeláez-Rojas

The objective of this work was to evaluate the effect of sustained swimming and dietary protein levels on growth and hematological responses of juvenile pacu (Piaractus mesopotamicus). A completely randomized design was used in a 3x2 factorial arrangement, with three levels of dietary protein (24, 28, and 32% crude protein), two rearing conditions (sustained swimming or motionless water), and 15 replicates. Fish were subjected to sustained swimming at the velocity of two body lengths per second (2 BL s-1), for 45 days. The level of dietary protein and the swimming conditions affected the performance, growth, and hematological profile of pacu. Swimming conditions influenced nutritional factors, increasing daily weight gain, specific growth rate, number of erythrocytes, mean corpuscular volume, and mean corpuscular hemoglobin. Fish under sustained swimming and fed with 24% crude protein showed better growth performance, with higher specific growth rate (4.11±0.88) and higher daily weight gain (2.19±0.47 g per day). Sustained swimming can increase the productive performance of pacu and simultaneously reduce dietary protein levels.


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