Abstract:Following the isolation, cultivation and characterization of the rumen bacterium Anaerovibrio lipolyticus in the 1960s, it has been recognized as one of the major species involved in lipid hydrolysis in ruminant animals. However, there has been limited characterization of the lipases from the bacterium, despite the importance of understanding lipolysis and its impact on subsequent biohydrogenation of polyunsaturated fatty acids by rumen microbes. This study describes the draft genome of Anaerovibrio lipolytica… Show more
“…Interestingly, Zn 2+ increases its α -helix content from 45.3 to 46.8%. Moreover, Zn 2+ has also been reported to be the activator of several enzymes, including carbonyl reductase [47], xylanase [48], nattokinase [49] and lipase [50]. The tendency for a difference between Zn 2+ and other metal ions may be due to the different structural compatibility of metal ions to bind with YlER.Fig.…”
BackgroundErythritol is a natural sweetener that is used in the food industry. It is produced as an osmoprotectant by bacteria and yeast. Due to its chemical properties, it does not change the insulin level in the blood, and therefore it can be safely used by diabetics. Previously, it has been shown that erythrose reductase (ER), which catalyzes the final step, plays a crucial role in erythritol synthesis. ER reduces erythrose to erythritol with NAD(P)H as a cofactor. Despite many studies on erythritol synthesis by Yarrowia lipolytica, the enzymes involved in this metabolic pathway have ever been described.ResultsThe gene YALI0F18590g encoding the predicted erythrose reductase from Y. lipolytica was overexpressed, and its influence on erythritol synthesis was studied. The amino acid sequence of the Y. lipolytica ER showed a high degree of similarity to the previously described erythrose reductases from known erythritol producers, such as Candida magnoliae and Moniliella megachiliensis. Here, we found that the gene overexpression results in an enhanced titer of erythritol of 44.44 g/L (20% over the control), a yield of 0.44 g/g and productivity of 0.77 g/L/h. Moreover, on purification and characterization of the enzyme we found that it displays the highest activity at 37 °C and pH 3.0. The effects of various metal ions (Zn2+, Cu2+, Mn2+, Fe2+) on erythrose reductase were investigated. The addition of Zn2+ ions at 0.25 mM had a positive effect on the activity of erythrose reductase from Y. lipolytica, as well as on the erythritol production.ConclusionsIn this study we identified, overexpressed and characterized a native erythrose reductase in Y. lipolytica. Further optimizations of this strain via metabolic pathway engineering and media optimization strategies enabled 54 g/L to be produced in a shake-flask experiment. To date, this is the first reported study employing metabolic engineering of the native gene involved in the erythritol pathway to result in a high titer of the polyol. Moreover, it indicates the importance of environmental conditions for genetic targets in metabolic engineering.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-017-0733-6) contains supplementary material, which is available to authorized users.
“…Interestingly, Zn 2+ increases its α -helix content from 45.3 to 46.8%. Moreover, Zn 2+ has also been reported to be the activator of several enzymes, including carbonyl reductase [47], xylanase [48], nattokinase [49] and lipase [50]. The tendency for a difference between Zn 2+ and other metal ions may be due to the different structural compatibility of metal ions to bind with YlER.Fig.…”
BackgroundErythritol is a natural sweetener that is used in the food industry. It is produced as an osmoprotectant by bacteria and yeast. Due to its chemical properties, it does not change the insulin level in the blood, and therefore it can be safely used by diabetics. Previously, it has been shown that erythrose reductase (ER), which catalyzes the final step, plays a crucial role in erythritol synthesis. ER reduces erythrose to erythritol with NAD(P)H as a cofactor. Despite many studies on erythritol synthesis by Yarrowia lipolytica, the enzymes involved in this metabolic pathway have ever been described.ResultsThe gene YALI0F18590g encoding the predicted erythrose reductase from Y. lipolytica was overexpressed, and its influence on erythritol synthesis was studied. The amino acid sequence of the Y. lipolytica ER showed a high degree of similarity to the previously described erythrose reductases from known erythritol producers, such as Candida magnoliae and Moniliella megachiliensis. Here, we found that the gene overexpression results in an enhanced titer of erythritol of 44.44 g/L (20% over the control), a yield of 0.44 g/g and productivity of 0.77 g/L/h. Moreover, on purification and characterization of the enzyme we found that it displays the highest activity at 37 °C and pH 3.0. The effects of various metal ions (Zn2+, Cu2+, Mn2+, Fe2+) on erythrose reductase were investigated. The addition of Zn2+ ions at 0.25 mM had a positive effect on the activity of erythrose reductase from Y. lipolytica, as well as on the erythritol production.ConclusionsIn this study we identified, overexpressed and characterized a native erythrose reductase in Y. lipolytica. Further optimizations of this strain via metabolic pathway engineering and media optimization strategies enabled 54 g/L to be produced in a shake-flask experiment. To date, this is the first reported study employing metabolic engineering of the native gene involved in the erythritol pathway to result in a high titer of the polyol. Moreover, it indicates the importance of environmental conditions for genetic targets in metabolic engineering.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-017-0733-6) contains supplementary material, which is available to authorized users.
“…Its lipase was first studied by Henderson () and its genome contains three genes coding for lipases (Privé et al . ). The characteristics of A. lipolyticus lipases are summarized in Table .…”
Section: Rumen Bh: a Microbiota Response To Dietary Ufasmentioning
confidence: 97%
“…Its relative 16S rRNA gene abundance is around 0Á05% in the rumen (Minuti et al 2015). Its lipase was first studied by Henderson (1971) and its genome contains three genes coding for lipases (Priv e et al 2013). The characteristics of A. lipolyticus lipases are summarized in Table 4.…”
Section: Lipolytic and Biohydrogenating Micro-organisms And Enzymesmentioning
Summary
Although fat content in usual ruminant diets is very low, fat supplements can be given to farm ruminants to modulate rumen activity or the fatty acid (FA) profile of meat and milk. Unsaturated FAs, which are dominant in common fat sources for ruminants, have negative effects on microbial growth, especially protozoa and fibrolytic bacteria. In turn, the rumen microbiota detoxifies unsaturated FAs (UFAs) through a biohydrogenation (BH) process, transforming dietary UFAs with cis geometrical double‐bonds into mainly trans UFAs and, finally, into saturated FAs. Culture studies have provided a large amount of data regarding bacterial species and strains that are affected by UFAs or involved in lipolysis or BH, with a major focus on the Butyrivibrio genus. More recent data using molecular approaches to rumen microbiota extend and challenge these data, but further research will be necessary to improve our understanding of fat and rumen microbiota interactions.
“…(7) Lipolytic: Hydrolyze triglycerides into glycerol and fatty acids such as Anaerovibrio lipolytica; despite the importance of understanding lipolysis and its impact on subsequent biohydrogenation of polyunsaturated fatty acids by rumen microbes. According to Prive et al (2013), the enzymes had higher activities at neutral to alkaline pH and had higher hydrolytic activity against caprylate (C8:0), laurate (C12:0), and myristate (C14:0). (8) Ureolitics: Adhered to the ruminal epithelium, hydrolyze urea and release ammonia in the rumen, as Enterococcus faecium (Khattab and Ebeid, 2014).…”
A great diversity of species of microorganisms are present in the rumen environmental with specific functions in the degradation of carbohydrates, protein and lipids. However, the knowledge of the interactions between the different species of microorganisms in the rumen ecosystem and their specific substrates were used to improve nutritional management and can increase production of meat or milk. A balanced nutritional management is very important. When inappropriate feedstuffs are used on diet formulation for cattle, there is a decrease in the growth of microorganisms in the rumen. And the availability of the use of protein synthesized in rumen for all metabolisms of the animal.
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