Methane production by mixed ruminal cultures incubated in dual-flow fermentors.
TL;DR: Dilution rate and forage-to-concentrate ratio altered the partition of substrate by microbes and underestimated methane output at higher dilution rates and with high forage diets.
About: This article is published in Journal of Dairy Science.The article was published on 2004-01-01 and is currently open access. It has received 70 citations till now. The article focuses on the topics: Dilution.
Citations
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TL;DR: The different methods used to inhibit the H2-consuming bacteria are analyzed, such as biokinetic control, heat-shock treatment and chemical inhibitors along with their advantages/disadvantages for their application on an industrial scale.
Abstract: In this work, H2 production by anaerobic mixed cultures was reviewed. First, the different anaerobic microbial communities that have a direct relation with the generation or consumption of H2 are discussed. Then, the different methods used to inhibit the H2-consuming bacteria are analyzed (mainly in the methanogenesis phase) such as biokinetic control (low pH and short hydraulic retention time), heat-shock treatment and chemical inhibitors along with their advantages/disadvantages for their application on an industrial scale. After that, biochemical pathways of carbohydrate degradation to H2, organic acids and solvents are showed. Fourth, structure, diversity and dynamics of H2-producers communities are detailed. Later, the hydrogenase structure and activity is related with H2 production. Also, the causes for H2 production inhibition are analyzed along with strategies to avoid it. Finally, immobilized-cells systems are presented as a way to enhance H2 production.
347 citations
TL;DR: In this article, the effects of three fibrolytic enzymes (xylanase from Trichoderma viride (XYL), endoglucanase from Aspergillus niger (ASP) and Trichodorma longibrachiatum (TR)) on the fermentation of three substrates composed of grass hay:
95 citations
TL;DR: In this paper, the authors have shown that the use of nanoparticles in fermentation process along with the application of short and cyclic ultrasound is beneficial to increase the process efficiency and the augmentation in ultrasound-assisted process is due to the physical and chemical effects of ultrasound in the medium through the phenomenon of cavitation.
Abstract: The growing of food waste generation is gradually becoming a global problem due to the improper management of it. According to the Food and Agriculture Organization (FAO), United Nation, more than 1.3 million tonnes of food is being wasted. Food waste and food processing waste are abundant - which are rich in organic acids and nutrients. These acids and nutrients can be utilized for attractive and efficient generation of renewable and sustainable fuels such as biohydrogen through fermentation process. Many investigations have revealed a significant biohydrogen generation using food wastes from restaurant, dining hall and food processing industries. During the hydrogen generation through fermentation, several parameters influence the yield of hydrogen. Some of them are method of pre-treatment, feed composition, fermentation temperature, culture and substrate, solution pH, etc. Also, the presence of inert intermediates produced during the reaction in fermentation process reduces the process efficiency. Few studies have shown that the use of nanoparticles in fermentation process along with the application of short & cyclic ultrasound is beneficial to increase the process efficiency. The augmentation in ultrasound-assisted process is due to the physical and chemical effects of ultrasound in the medium through the phenomenon of cavitation. During the transient collapse of cavitation bubbles, several reactive species are produced which further participate in the thermochemical and biochemical reactions. Thus, enhances the rate of reaction by annihilation the complex sugars in food wastes. Additionally, the cavitational effect helps to reduce the growth of hydrogen inhibiting microorganism in the feed. This review demonstrates the potentiality of food waste for production of biohydrogen through fermentation process including a brief overview of process parameters that affect the fermentation process. Additionally, an overview of integrated fermentative process coupled with nanoparticles and ultrasound is also discussed for enhanced biohydrogen generation from food waste.
89 citations
TL;DR: In this paper, a random coefficients model that used each study effect as a random variable was used to select statistically significant input variables to predict rate of passage for all classes of dairy and beef cattle.
75 citations
Additional excerpts
..., 2004) and microbial growth (Eun et al., 2004; Owens and Goetsch, 1986)....
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TL;DR: In this article, an in vitro gas production technique was used to measure total gas and methane (CH4) production from commercial total mixed rations (TMR) for lactating dairy cows.
73 citations
References
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TL;DR: The mixed buffer salts of artificial saliva were incorporated at three rates: 0, 5·7 and 11·4% in pelleted diets prepared from 60% ground flaked maize and 40% dried ground grass.
Abstract: The mixed buffer salts of artificial saliva were incorporated at three rates: 0 (diet 1), 5·7 (diet 2) and 11·4% (diet 3) (w/w) in pelleted diets prepared from60% ground flaked maize and 40% dried ground grass. The control and mineral-supplemented diets were fed to sheep hourly (Expt 1) or twice daily (Expt 2).When the sheep were fed hourly or twice daily the pattern of fermentation in the rumen was altered from a predominantly propionate to mainly acetate fermentation. Dilution rate in the rumen increased from 0·036 to 0·053 to 0·064 when diets 1, 2 and 3 were fed hourly, and dilution rate was negatively related to the molar proportion of propionic acid (P < 0·05) and positively related (P < 0·05) to the molar proportion of acetic acid in rumen fluid, but these relationships were not apparent in Expt 2.Nitrogen retention was higher for lambs fed diet 2 than for those fed diets 1 and 3 (P < 0·05) in Expt 1.In sheep fed hourly, selenomonads and bacteroides were the predominant rumen bacteria associated with the control diet but the inclusion of mineral salts resulted in the bacteroides being replaced by large number of chain-forming cocci. Numbers of protozoa were variable. The relationship of these changes to the fermentation pattern is discussed. In sheep fed twice daily there was much variation between animals.
89 citations
"Methane production by mixed ruminal..." refers background in this paper
..., 1984) or lower (Thomson et al., 1978; Crawford et al., 1980) as a result of increasing dilution rates....
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...Molar percentages of propionate in ruminal fluid were reported to be higher (Isaacson et al., 1975; Hoover et al., 1984) or lower (Thomson et al., 1978; Crawford et al., 1980) as a result of increasing dilution rates....
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01 Jan 1994
89 citations
"Methane production by mixed ruminal..." refers background in this paper
...There is evidence to suggest that more than one fermentation metabolite may be used for the production of CH4 (Miller, 1995)....
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88 citations
"Methane production by mixed ruminal..." refers background or result in this paper
...Ruminal pH can also influence NH3-N production (Erfle et al., 1982), and increasing dilution rates increased NH3-N with a concomitant increase in culture pH similar to results reported earlier (Hoover et al., 1984)....
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...microbial populations. Ruminal pH can also influence NH3-N production (Erfle et al., 1982), and increasing dilution rates increased NH3-N with a concomitant increase in culture pH similar to results reported earlier ( Hoover et al., 1984 )....
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...In the study by Hoover et al. (1984) , increasing dilution rates did not seem to reduce NDF digestibility or the digestibility of the more rapidly fermentable carbohydrate fraction....
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...Similar values for DM digestibility have been reported earlier with no effect on dilution rate (Hoover et al., 1984; Carro et al., 1995)....
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...These results are similar to those reported by Isaacson et al. (1975) and Hoover et al. (1984) ....
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TL;DR: The rumen simulation system described herein is a partially stirred fermenter with an overflow placed in the bottom third of the fermentation chamber that maintains rumen microbial populations and fermentation parameters at normal numbers for at least 2 wk at liquid turnover rates of up to 2/d.
81 citations
"Methane production by mixed ruminal..." refers methods in this paper
...Approximately 700 ml of the strained ruminal fluid was transferred into each of three fermentors with a continuous dual-flow system (Teather and Sauer, 1988)....
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