A thermal adaptation of bacteria to cold temperatures in an enhanced biological phosphorus removal system

2003 ◽  
Vol 47 (11) ◽  
pp. 123-128 ◽  
Author(s):  
U.G. Erdal ◽  
Z.K. Erdal ◽  
C.W. Randall
Keyword(s):  
Fatty Acid ◽  
Low Temperatures ◽  
Phosphorus Removal ◽  
System Performance ◽  
Effect Of Temperature ◽  
Biological Phosphorus Removal ◽  
Homeoviscous Adaptation ◽  
Cold Temperatures ◽  
Temperature Changes ◽  
Biological Phosphorus

Temperature is one of the key parameters that affects the reaction kinetics and performance of enhanced biological phosphorus removal (EBPR) systems. Although studies agree regarding the effect of temperature on kinetic reaction rates, there are contradictory results in the literature regarding the effect of temperature on EBPR system performance. Early investigators (Sell, Ekama et al., Daigger et al.) reported better performance with lower temperatures, but others have reported partial or complete loss of EBPR functions at low temperatures (McClintock et al., Brdjanovic et al., Beatons et al.). One speculation is that deterioration in the EBPR system performance at cold temperatures can be attributed to rigid-like behavior of the cell membranes. Most cells (not all) on the other hand have the ability to alter their membrane fatty acid composition as temperature changes in order to keep their membrane at nearly the same fluidity despite the temperature changes. This unique ability is known as homeoviscous adaptation. In this study, homeoviscous adaptation by EBPR activated sludge was investigated for a series of temperatures ranging from 20°C to 5°C using a lab scale continuous flow EBPR system fed with acetate and supplemental yeast extract. The fatty acid analysis results suggested that the unsaturated to saturated fatty acid ratio increased from 1.40 to 3.61 as temperature dropped from 20 to 5°C. The increased cis-9-hexadecanoic acid (C16:1) at 5°C strongly indicated the presence of homeoviscous adaptation in the EBPR bacterial community. Thus the cell membranes of the EBPR community were still in a fluid state, and solute transport and proton motive force were operable even at 5°C. It was concluded that loss of EBPR performance at low temperatures is not related to the physical state of the cellular membranes, but is possibly related to the application of unsuitable operational conditions (low SRT, excessive electron acceptors, low anaerobic detention time, non-acclimated sludge, etc.).

Effects of temperature on the structure and metabolism of cell membranes in fish

1984 ◽  
Vol 246 (4) ◽  
pp. R460-R470 ◽  
Author(s):  
J. R. Hazel
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Cold Exposure ◽  
Lipid Composition ◽  
Membrane Lipid ◽  
Effect Of Temperature ◽  
Salmo Gairdneri ◽  
Homeoviscous Adaptation ◽  
Cold Temperatures ◽  
Membrane Lipid Composition

The metabolic adjustments responsible for the “homeoviscous adaptation” of membrane lipid composition in fish are examined with special reference to the rainbow trout, Salmo gairdneri. The percentage of fatty acid lipogenesis attributable to unsaturates was elevated after an acute drop in temperature but declined with continued cold exposure (i.e., cold acclimation). In contrast, selected desaturation reactions [particularly those involved in the production of polyunsaturated fatty acids (PUFA) of the n-3 and/or n-6 families] proceeded more rapidly in cold-than in warm-acclimated trout. Different time courses for the change in monoene and PUFA levels of hepatic microsomal membranes during thermal acclimation suggest that the various desaturase enzymes contribute to the acclimatory response at different times. Certain fatty acids, particularly the delta 5-desaturation products of the n-3 (20:5 delta 5,8,11,14,17) and n-6 (20:4 delta 5,8,11,14) series, were preferentially incorporated into phospholipids at cold temperatures and by cold-acclimated trout, due in part to the direct effect of temperature on the substrate preferences of the phospho- and acyltransferase enzymes of de novo phospholipid biosynthesis; however, chain length rather than degree of unsaturation per se may determine the temperature-dependent pattern of fatty acid incorporation. Both acute and chronic cold exposure elevated the incorporation of PUFA into phosphatidylserine (PS), suggesting that the conversion of PS to phosphatidylethanolamine (PE) may be activated at cold temperatures. The rate of homeoviscous adaptation appears to be limited by the rate of membrane lipid turnover, which although generally positively correlated with acclimation temperature, did vary depending on the phospholipid moiety and tissue considered. Finally the direct acylation of lysophospholipids formed during the process of membrane turnover may contribute to both rapid and acclimatory adjustments in membrane lipid composition.

Competition between polyphosphate- and glycogen-accumulating organisms in biological phosphorus removal systems – effect of temperature

2002 ◽  
Vol 46 (1-2) ◽  
pp. 191-194 ◽  
Author(s):  
L.-M. Whang ◽  
J.K. Park
Keyword(s):  
High Temperatures ◽  
Uptake Rate ◽  
Phosphorus Removal ◽  
Effect Of Temperature ◽  
Enhanced Biological Phosphorus Removal ◽  
Biological Phosphorus Removal ◽  
Batch Studies ◽  
Acetate Uptake ◽  
Polyphosphate Accumulating Organisms ◽  
Biological Phosphorus

This study demonstrated that temperature is an important factor in determining the outcome of competition between polyphosphate-accumulating organisms (PAOs) and glycogen-accumulating non-poly-P organisms (GAOs) and the resultant stability of enhanced biological phosphorus removal (EBPR) systems. At 20°C and a 10-day sludge age, PAOs were dominant in the anaerobic/aerobic (A/O) SBR, however, at 30°C and a 10-day sludge age, GAOs were dominant in the A/O SBR. For kinetic batch studies, the anaerobic specific acetate uptake rate of GAO-dominated sludge (1.34 × 10−3 mg C/mg VSS·minute) was higher than the rate of PAO-dominated sludge (0.89 × 10−3 mg C/mg VSS·minute) at 30°C, leading to the eventual failure of EBPR processes at high temperatures.

Effect of wastewater composition on microbial populations in biological phosphorus removal processes

1998 ◽  
Vol 38 (1) ◽  
pp. 159-166 ◽  
Author(s):  
J. C. Wang ◽  
J. K. Park
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Profile ◽  
Phosphorus Removal ◽  
Microbial Population ◽  
Profile Analysis ◽  
Cellular Fatty Acid ◽  
Phosphorus Concentration ◽  
Biological Phosphorus Removal ◽  
Biological Phosphorus ◽  
Cellular Fatty Acid Profile

Bench-scale sequential batch reactors (SBRs) were fed with glucose- and acetate-containing synthetic wastewaters to evaluate microbial population dynamics and types of phosphorus-accumulating organisms (PAOs) using a cellular fatty acid profile analysis. The phosphorus content in the sludge was 38% (w/w) for the acetate-fed SBR and 20% (w/w) for the glucose-fed SBR with a VSS/TSS ratio of 50%. Glucose-fed PAOs were found to remove phosphorus with accumulation of glycogen in cells without synthesizing poly-β-hydroxybutyrate (PHB) at influent phosphorus concentration < 20 mg-P/L and nitrate concentration < 2 mg-N/L. From the fatty acid profile biomarker study, it was found that the glucose-fed SBR maintained the same fatty acid profile before and after biological phosphorus removal (BPR) occurred while the acetate-fed SBR had a different fatty acid profile. The microbial population in the glucose-fed SBR was significantly different in terms of metabolic behavior and cellular fatty acid profile from that introduced in the acetate-fed SBR. Fatty acid a15:0 (anteiso methyl-branching) was abundant in the glucose-fed PAOs. Among the five PAO candidates (Acinetobacter, Pseudomonas, Arthrobacter, Aeromonas, and Micrococcus), only Arthrobacter spp. had the biomarker of fatty acid a15:0, indicating that Arthrobacter spp. may be one of the PAOs existing in the glucose-fed bioreactors.

The competition between PAOs (phosphorus accumulating organisms) and GAOs (glycogen accumulating organisms) in EBPR (enhanced biological phosphorus removal) systems at different temperatures and the effects on system performance

2003 ◽  
Vol 47 (11) ◽  
pp. 1-8 ◽  
Author(s):  
U.G. Erdal ◽  
Z.K. Erdal ◽  
C.W. Randall
Keyword(s):  
Phosphorus Removal ◽  
System Performance ◽  
Glycogen Metabolism ◽  
Reaction Rates ◽  
Synthetic Wastewater ◽  
Enhanced Biological Phosphorus Removal ◽  
Biological Phosphorus Removal ◽  
Different Temperatures ◽  
High Concentrations ◽  
Biological Phosphorus

It is well known and firmly established that the rate of chemical and biochemical reactions slow down as temperature decreases. Nevertheless, several studies have reported that the efficiency of enhanced biological phosphorus removal (EBPR) improves as temperature decreases. However, several recent studies have reported that EBPR reaction rates decrease with temperature decrease in accordance with the Arrhenius relationship. This study was designed to more thoroughly investigate this controversy using two UCT plants fed with a synthetic wastewater consisting primarily of acetate as the COD form, and a small amount of supplemental yeast extract. Experiments were performed over temperatures ranging from 5 to 20°C. The results showed that, even though the kinetic rates decrease as temperature decreases, EBPR systems perform better at colder temperatures. The reason for better system performance is apparently related to reduced competition for substrate in the non-oxic zones, which results in an increased population of PAOs and, thus, greater EBPR efficiency. The proliferation of PAOs apparently occurs because they are psychrophilic whereas their competitors are not. The experiments showed that the EBPR sludges accumulated high concentrations of both PHA and glycogen at 20°C, but accumulated more PHA and much less glycogen at 5°C. Although the results could be interpreted as the result of changes in the PAO-GAO competition, Mann-Whitney non-parametric comparisons of transmission electron microscopy examinations revealed no indication of the presence of GAOs population under any temperature conditions. Regardless, mass balances of the glycogen data showed that the involvement of glycogen is less at cold temperature, even though EBPR was greater. Unlike current EBPR models (e.g. Mino model), the results suggest that glycogen metabolism is not a precursor for EBPR biochemistry. The results also indicate that temperature not only may cause selective pressure on the dominant organisms, but also may force them to use a different metabolic pathway as temperature decreases.

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