Anaerobic batch degradation of solid poultry slaughterhouse waste

2000 ◽  
Vol 41 (3) ◽  
pp. 33-41 ◽  
Author(s):  
E. Salminen ◽  
J. Rintala ◽  
L.Ya. Lokshina ◽  
V.A. Vavilin
Keyword(s):  
Fatty Acids ◽  
Methane Production ◽  
Long Chain Fatty Acids ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Propionate Degradation ◽  
Waste Degradation ◽  
New Generation ◽  
Rate Limiting ◽  
Long Chain

We studied anaerobic batch degradation of solid poultry slaughterhouse wastes with different initial waste and inoculum concentrations and waste-to-inoculum ratios and simulated the dynamics of the process with a new generation <METHANE> model. Our modelling results suggest that inhibited propionate degradation by long-chain fatty acids (LCFA) and inhibited hydrolysis by a high propionate concentration constituted the rate-limiting step in the waste degradation. Palmitate was the most abundant LCFA in the assays. Within 27 days of incubation, up to 0.55 to 0.67 m3 of methane (STP)/kg VS added was produced under the studied conditions. Lower waste-to-inoculum ratios exhibited a faster onset and rate of specific methane production. In all the assays, ammonification occurred within 3 to 6 days and accounted for 50 to 60% of total nitrogen.

Inhibitory effects of long-chain fatty acids on VFA degradation and β-oxidation

2003 ◽  
Vol 47 (10) ◽  
pp. 139-146 ◽  
Author(s):  
H.-S. Shin ◽  
S.-H. Kim ◽  
C.-Y. Lee ◽  
S.-Y. Nam
Keyword(s):  
Fatty Acids ◽  
Methane Production ◽  
Substrate Inhibition ◽  
Long Chain Fatty Acids ◽  
Inhibitory Effects ◽  
Inhibition Model ◽  
Propionate Degradation ◽  
Acetate Degradation ◽  
Long Chain ◽  
Chain Fatty Acids

The inhibitory effects of major long-chain fatty acids (LCFA), which have 16 or 18 carbons, not only on acetate degradation, but also on propionate degradation and β-oxidation were examined in anaerobic serum bottle tests at 35°C with the acclimated granular sludges. A modified Gompertz equation described cumulative methane production to assess the rates of VFA degradation and β-oxidation, which were applied to a simplified noncompetitive model and a simplified substrate inhibition model, respectively. The specific methane production rates on acetate decreased as LCFA concentration increased, which was in good agreement with the noncompetitive inhibition model. Unsaturated oleate (C18:1) and linoleate (C18:2) were more inhibitory than saturated stearate (C18:0) and palmitate (C16:0) on acetate degradation. LCFA inhibition on propionate degradation was similar to that for acetate; however, propionate degradation was less inhibited than acetate degradation. β-oxidation was the rate-limiting step in LCFA degradation in most cases. As LCFA concentration increased, β-oxidation rate reached the maximum value, and then decreased, which confirmed the substrate inhibition of LCFA. Oleate, the most abundant LCFA in wastewater, could be degraded more quickly than saturated LCFA containing the same or even less carbon in spite of relatively high toxicity on acetate degradation.

Mechanisms for competitively reducing ruminal methanogenesis

1999 ◽  
Vol 50 (8) ◽  
pp. 1299 ◽  
Author(s):  
R. S. Hegarty
Keyword(s):  
Fatty Acids ◽  
Methane Production ◽  
Hydrogen Gas ◽  
Dietary Fatty Acids ◽  
Long Chain Fatty Acids ◽  
End Use ◽  
Long Chain ◽  
Chain Fatty Acids ◽  
Reducing Equivalents

Methane production is the principal end use of hydrogen gas derived by phosphoroclastic reactions or the release of protons from reducing equivalents by hydrogenases in the rumen. It should therefore be possible to reduce methanogenesis by (1) inhibiting H2 liberating reactions, (2) promoting alternative reactions which accept H+ during reoxidation of reducing equivalents, and (3) promoting alternative H2-using reactions. Strategies to reduce methanogenesis by these means are discussed. Particular attention is given to increasing synthesis of propionate and long chain fatty acids in the rumen, to acetogenesis, and to the actions of chemicals such as monensin and dietary fatty acids.

scholarly journals Waste lipids to energy: how to optimize methane production from long-chain fatty acids (LCFA)

2009 ◽  
Vol 2 (5) ◽  
pp. 538-550 ◽  
Author(s):  
M. Madalena Alves ◽  
M. Alcina Pereira ◽  
Diana Z. Sousa ◽  
Ana J. Cavaleiro ◽  
Merijn Picavet ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Methane Production ◽  
Long Chain Fatty Acids ◽  
Long Chain ◽  
Chain Fatty Acids

Absorption of glucose polymers from canine jejunum deprived of pancreatic amylase

1986 ◽  
Vol 250 (6) ◽  
pp. G824-G829
Author(s):  
B. Kerzner ◽  
H. R. Sloan ◽  
H. J. McClung ◽  
C. C. Chidi ◽  
A. H. Ailabouni ◽  
...  
Keyword(s):  
Glucose Absorption ◽  
Pancreatic Amylase ◽  
Perfusion Rate ◽  
Carbohydrate Absorption ◽  
Rate Limiting Step ◽  
Medium Length ◽  
Limiting Step ◽  
Chain Fraction ◽  
Rate Limiting ◽  
Long Chain

We evaluated the absorption of glucose polymers in canine jejunal Thiry-Vella fistulas proven to be free of pancreatic amylase. Medium-length oligomers with degrees of polymerization of 6 through 10 glucose units (DP 6–10) and long-chain material (DPavg23) were isolated from a cornstarch hydrolysate. We perfused 90, 180, and 360 mg/dl solutions of glucose, DP 6–10, and DPavg23 at 0.4, 1.9, and 3.4 ml/min. At all perfusion rates carbohydrate absorption decreased as the chain length of the oligomers increased, and these differences persisted even at the slowest perfusion rate employed. In two additional animals the fistulas were perfused at 3.4 ml/min with the three test carbohydrates at concentrations of 90, 180, 225, 270, 315, 360, 405, and 450 mg/dl. At this flow rate, the assimilative process of DP 6–10 and the long-chain fraction appeared to be saturated at carbohydrate concentrations above 360 mg/dl, whereas the absorption of glucose was linearly related to concentration throughout the range studied. With both groups of polymers, the fluid emerging from the fistula was virtually free of glucose, a finding that suggests that polymer digestion, not glucose absorption, is the rate-limiting step for polymer assimilation.

scholarly journals Structural elucidation of the heterodimeric cis-prenyltransferase NgBR/DHDDS complex reveals novel insights in regulation of protein glycosylation

2020 ◽  
Author(s):  
Ban Edani ◽  
Kariona A. Grabińska ◽  
Rong Zhang ◽  
Eon Joo Park ◽  
Benjamin Siciliano ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Active Site ◽  
Protein Glycosylation ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Chain Synthesis ◽  
Rate Limiting ◽  
Activity Comparison ◽  
Long Chain ◽  
Resolution Structure

SummaryCis-prenyltransferase (cis-PTase) catalyzes the rate-limiting step in the synthesis of glycosyl carrier lipids required for protein glycosylation in the lumen of endoplasmic reticulum. Here we report the crystal structure of the human NgBR/DHDDS complex, which represents the first atomic resolution structure for any heterodimeric cis-PTase. The crystal structure sheds light on how NgBR stabilizes DHDDS through dimerization, participates in the enzyme’s active site through its C-terminal -RXG- motif, and how phospholipids markedly stimulate cis-PTase activity. Comparison of NgBR/DHDDS with homodimeric cis-PTase structures leads to a model where the elongating isoprene chain extends beyond the enzyme’s active site tunnel, and an insert within the α3 helix helps to stabilize this energetically unfavorable state to enable long chain synthesis to occur. These data provide unique insights into how heterodimeric cis-PTases have evolved from their ancestral, homodimeric forms to fulfill their function in long chain polyprenol synthesis.

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