Benefits of the red seaweed <i>Asparagopsis</i> <i>taxiformis</i> as an ingredient to manage methane (CH<sub>4</sub>) emissions from the red meat and dairy industries continue to ev...Benefits of the red seaweed <i>Asparagopsis</i> <i>taxiformis</i> as an ingredient to manage methane (CH<sub>4</sub>) emissions from the red meat and dairy industries continue to evolve. <i>Asparagopsis</i> has been demonstrated to eliminate enteric CH<sub>4</sub> emissions <i>in</i> <i>vitro</i> and reduce it greater than 80% in animals. Variability in animal studies is suspected to be associated with variable inclusion and proportions of grass and grain in the diet. This <i>in</i> <i>vitro</i> study aimed to elucidate effects of gradient grass to grain proportions in the fermentation using five steps from 100% Rhodes grass (RG) to 100% barley grain (BG). Gradient inclusion of <i>Asparagopsis</i> was in six steps of Control with no inclusion (C), Low (L), Low-Medium (LM), Medium (M), Medium-High (MH), and High (H) levels tested in three fermentation durations (24 h, 48 h, 72 h). There was significant effect of RG/BG and inclusion of <i>Asparagopsis</i> such that CH<sub>4</sub> production decreased with increasing <i>Asparagopsis</i> independent of RG/BG;however, there was enhanced reduction at greater proportions of BG. Thus, the level of <i>Asparagopsis</i> required to completely inhibit CH<sub>4</sub> production <i>in</i> <i>vitro</i> was decreased with decreasing RG/BG. Increasing the duration of fermentation had greatest effect on CH<sub>4</sub> at C, L, and LM levels of <i>Asparagopsis</i> independent of RG/BG, although magnitude of CH<sub>4</sub> production was greater for higher proportions of BG for the C and L levels. Digestibility of <i>in</i> <i>vitro</i> substrate increased with fermentation duration and increasing BG;however, there was no change associated with inclusion levels of <i>Asparagopsis</i>. Increases in total volatile fatty acids (tVFA) were observed with increased fermentation duration and concomitant with increasing substrate digestion. Increasing proportions of BG induced increase in tVFA. In contrast, and independent of changes in substrate, increasing inclusion of <i>Asparagopsis</i> had little effect on tVFA. The acetic and propionic acid ratio (AA:PA) decreased with decreasing RG/BG and increasing <i>Asparagopsis</i>. This pattern was most pronounced with 100% BG and MH-H <i>Asparagopsis</i> levels. Compared to control, there was decrease in the AA:PA ratio with addition of even L levels of <i>Asparagopsis</i> and with L compared to LM inclusion levels. Increasing levels of BG and <i>Asparagopsis</i> resulted in significant decreases in AA:PA ratios and CH4 production. This study has confirmed that gradient levels (ratio) of grass and grain in a feed mix impact the antimethanogenic efficacy of <i>Asparagopsis</i> during <i>in</i> <i>vitro</i> fermentation with rumen fluid.展开更多
Methods to optimize the production of gamma-aminobutyric acid （GABA） by Lactobacillus brevis CGMCC 1306 were investigated. Results indicated that cell growth was maximal at pH 5.0, while pH 4.5 was pref-erable to GA...Methods to optimize the production of gamma-aminobutyric acid （GABA） by Lactobacillus brevis CGMCC 1306 were investigated. Results indicated that cell growth was maximal at pH 5.0, while pH 4.5 was pref-erable to GABA formation. The optimal temperature for cell growth （35 °C） was lower than that for GABA forma-tion （40 °C）. In a two-stage pH and temperature control fermentation, cultures were maintained at pH 5.0 and 35 °C for 32 h, then adjusted to pH 4.5 and 40 °C, GABA production increased remarkably and reached 474.79 mmol·L-1 at 72 h, while it was 398.63 mmol·L-1 with one stage pH and temperature control process, in which cultivation con-ditions were constantly controlled at pH 5.0 and 35 °C. In order to avoid the inhibition of cell growth at higher L-monosodium glutamate （L-MSG） concentrations, the two-stage control fermentation with substrate feeding strat-egy was applied to GABA production, with 106.87 mmol （20 g） L-MSG supplemented into the shaking-flask at 32 h and 56 h post-inoculation separately. The GABA concentration reached 526.33 mmol·L-1 at 72 h with the fer-mentation volume increased by 38%. These results will provide primary data to realize large-scale production of GABA by L. brevis CGMCC 1306.展开更多
(R)-2-Hydroxy-4-phenylbutyric acid ethyl ester((R)-HPBE)is an essential chiral intermediate in the synthesis of angiotensin-converting enzyme(ACE)inhibitors.Its production involves the highly selective asymmetric redu...(R)-2-Hydroxy-4-phenylbutyric acid ethyl ester((R)-HPBE)is an essential chiral intermediate in the synthesis of angiotensin-converting enzyme(ACE)inhibitors.Its production involves the highly selective asymmetric reduction of ethyl 2-oxo-4-phenylbutyrate(OPBE),catalyzed by carbonyl reductase(CpCR),with efficient cofactor regeneration playing a crucial role.In this study,an in-situ coenzyme regeneration system was developed by coupling carbonyl reductase(CpCR)with glucose dehydrogenase(GDH),resulting in the construction of five recombinant strains capable of NADPH regeneration.Among these,the recombinant strain E.coli BL21-pETDuet-1-GDH-L-CpCR,where CpCR is fused to the C-terminus of GDH,demonstrated the highest catalytic activity.This strain exhibited an enzyme activity of 69.78 U/mg and achieved a conversion rate of 98.3%,with an enantiomeric excess(ee)of 99.9%during the conversion of 30 mM OPBE to(R)-HPBE.High-density fermentation further enhanced enzyme yield,achieving an enzyme activity of 1960 U/mL in the fermentation broth,which is 16.2 times higher than the volumetric activity obtained from shake flask fermentation.Additionally,the implementation of a substrate feeding strategy enabled continuous processing,allowing the strain to efficiently convert a final OPBE concentration of 920 mM,producing 912 mM of(R)-HPBE.These findings highlight the system’s improved catalytic efficiency,stability,and scalability,making it highly suitable for industrial-scale biocatalytic production.展开更多
The effect of four host plant species of the herbivore Maruca vitrata Fabri- cius （Lepidoptera： Crambidae） on development time, longevity, fecundity and sex ratio of the parasitoid Apanteles taragamae Viereck （Hym...The effect of four host plant species of the herbivore Maruca vitrata Fabri- cius （Lepidoptera： Crambidae） on development time, longevity, fecundity and sex ratio of the parasitoid Apanteles taragamae Viereck （Hymenoptera： Braconidae） was investi- gated under laboratory conditions. The larvae were parasitized when in the second instar. Maruca vitrata larvae were fed with flowers of four legumes, that is, Vigna unguiculata （cowpea）, Sesbania rostrata, Lonchocarpus sericeus and Pterocarpus santalinoides, or an artificial diet both before and after parasitization. The parasitoid did not develop in hosts feeding on L. sericeus or E unguiculata at 25℃, or on P. santalinoides at 25℃ or 29℃. Apanteles taragamae had the shortest development time on artificial diet at both 25℃ and 29℃ while the longest development time was recorded on L. sericeus at 29℃. Female wasps took longer to develop compared to males at the two temperatures, regardless of the feeding substrate of their host. The longevity of the wasps at 25℃ varied among feeding substrates, but not at 29℃. Survival rate of parasitized larvae depends on the feeding sub- strate. Moreover, infection of host larvae with Maruca vitrata multi-nucleopolyhedrovirus （MaviMNPV） killed larger proportions of parasitized larvae at 25℃ than at 29℃, which was likely caused by the difference in parasitoid developmental rate. The proportion of female parasitoids was lowest on L. sericeus. The daily fecundity showed a nonlinear trend regardless of the feeding substrate, indicating that A. taragamae is a pro-ovigenic species. The data support the slow growth-high mortality hypothesis.展开更多
文摘Benefits of the red seaweed <i>Asparagopsis</i> <i>taxiformis</i> as an ingredient to manage methane (CH<sub>4</sub>) emissions from the red meat and dairy industries continue to evolve. <i>Asparagopsis</i> has been demonstrated to eliminate enteric CH<sub>4</sub> emissions <i>in</i> <i>vitro</i> and reduce it greater than 80% in animals. Variability in animal studies is suspected to be associated with variable inclusion and proportions of grass and grain in the diet. This <i>in</i> <i>vitro</i> study aimed to elucidate effects of gradient grass to grain proportions in the fermentation using five steps from 100% Rhodes grass (RG) to 100% barley grain (BG). Gradient inclusion of <i>Asparagopsis</i> was in six steps of Control with no inclusion (C), Low (L), Low-Medium (LM), Medium (M), Medium-High (MH), and High (H) levels tested in three fermentation durations (24 h, 48 h, 72 h). There was significant effect of RG/BG and inclusion of <i>Asparagopsis</i> such that CH<sub>4</sub> production decreased with increasing <i>Asparagopsis</i> independent of RG/BG;however, there was enhanced reduction at greater proportions of BG. Thus, the level of <i>Asparagopsis</i> required to completely inhibit CH<sub>4</sub> production <i>in</i> <i>vitro</i> was decreased with decreasing RG/BG. Increasing the duration of fermentation had greatest effect on CH<sub>4</sub> at C, L, and LM levels of <i>Asparagopsis</i> independent of RG/BG, although magnitude of CH<sub>4</sub> production was greater for higher proportions of BG for the C and L levels. Digestibility of <i>in</i> <i>vitro</i> substrate increased with fermentation duration and increasing BG;however, there was no change associated with inclusion levels of <i>Asparagopsis</i>. Increases in total volatile fatty acids (tVFA) were observed with increased fermentation duration and concomitant with increasing substrate digestion. Increasing proportions of BG induced increase in tVFA. In contrast, and independent of changes in substrate, increasing inclusion of <i>Asparagopsis</i> had little effect on tVFA. The acetic and propionic acid ratio (AA:PA) decreased with decreasing RG/BG and increasing <i>Asparagopsis</i>. This pattern was most pronounced with 100% BG and MH-H <i>Asparagopsis</i> levels. Compared to control, there was decrease in the AA:PA ratio with addition of even L levels of <i>Asparagopsis</i> and with L compared to LM inclusion levels. Increasing levels of BG and <i>Asparagopsis</i> resulted in significant decreases in AA:PA ratios and CH4 production. This study has confirmed that gradient levels (ratio) of grass and grain in a feed mix impact the antimethanogenic efficacy of <i>Asparagopsis</i> during <i>in</i> <i>vitro</i> fermentation with rumen fluid.
基金Supported by the National＇Naturai Science Foundation of China （30970638, 21176220 and 31240054）, Zhejiang Provincial Natural Science Foundation （Z13B06008） and the National Basic Research Program of China （2007CB714305）.
文摘Methods to optimize the production of gamma-aminobutyric acid （GABA） by Lactobacillus brevis CGMCC 1306 were investigated. Results indicated that cell growth was maximal at pH 5.0, while pH 4.5 was pref-erable to GABA formation. The optimal temperature for cell growth （35 °C） was lower than that for GABA forma-tion （40 °C）. In a two-stage pH and temperature control fermentation, cultures were maintained at pH 5.0 and 35 °C for 32 h, then adjusted to pH 4.5 and 40 °C, GABA production increased remarkably and reached 474.79 mmol·L-1 at 72 h, while it was 398.63 mmol·L-1 with one stage pH and temperature control process, in which cultivation con-ditions were constantly controlled at pH 5.0 and 35 °C. In order to avoid the inhibition of cell growth at higher L-monosodium glutamate （L-MSG） concentrations, the two-stage control fermentation with substrate feeding strat-egy was applied to GABA production, with 106.87 mmol （20 g） L-MSG supplemented into the shaking-flask at 32 h and 56 h post-inoculation separately. The GABA concentration reached 526.33 mmol·L-1 at 72 h with the fer-mentation volume increased by 38%. These results will provide primary data to realize large-scale production of GABA by L. brevis CGMCC 1306.
基金supported by the Zhejiang Provincial Science and Technology Plan Project(2024C03014)the National Nature Science Foundation of China(Project Nos.21978267,and 22078300)as well as the Natural Science Foundation of Heilongjiang Province(LH2022H107).
文摘(R)-2-Hydroxy-4-phenylbutyric acid ethyl ester((R)-HPBE)is an essential chiral intermediate in the synthesis of angiotensin-converting enzyme(ACE)inhibitors.Its production involves the highly selective asymmetric reduction of ethyl 2-oxo-4-phenylbutyrate(OPBE),catalyzed by carbonyl reductase(CpCR),with efficient cofactor regeneration playing a crucial role.In this study,an in-situ coenzyme regeneration system was developed by coupling carbonyl reductase(CpCR)with glucose dehydrogenase(GDH),resulting in the construction of five recombinant strains capable of NADPH regeneration.Among these,the recombinant strain E.coli BL21-pETDuet-1-GDH-L-CpCR,where CpCR is fused to the C-terminus of GDH,demonstrated the highest catalytic activity.This strain exhibited an enzyme activity of 69.78 U/mg and achieved a conversion rate of 98.3%,with an enantiomeric excess(ee)of 99.9%during the conversion of 30 mM OPBE to(R)-HPBE.High-density fermentation further enhanced enzyme yield,achieving an enzyme activity of 1960 U/mL in the fermentation broth,which is 16.2 times higher than the volumetric activity obtained from shake flask fermentation.Additionally,the implementation of a substrate feeding strategy enabled continuous processing,allowing the strain to efficiently convert a final OPBE concentration of 920 mM,producing 912 mM of(R)-HPBE.These findings highlight the system’s improved catalytic efficiency,stability,and scalability,making it highly suitable for industrial-scale biocatalytic production.
文摘The effect of four host plant species of the herbivore Maruca vitrata Fabri- cius （Lepidoptera： Crambidae） on development time, longevity, fecundity and sex ratio of the parasitoid Apanteles taragamae Viereck （Hymenoptera： Braconidae） was investi- gated under laboratory conditions. The larvae were parasitized when in the second instar. Maruca vitrata larvae were fed with flowers of four legumes, that is, Vigna unguiculata （cowpea）, Sesbania rostrata, Lonchocarpus sericeus and Pterocarpus santalinoides, or an artificial diet both before and after parasitization. The parasitoid did not develop in hosts feeding on L. sericeus or E unguiculata at 25℃, or on P. santalinoides at 25℃ or 29℃. Apanteles taragamae had the shortest development time on artificial diet at both 25℃ and 29℃ while the longest development time was recorded on L. sericeus at 29℃. Female wasps took longer to develop compared to males at the two temperatures, regardless of the feeding substrate of their host. The longevity of the wasps at 25℃ varied among feeding substrates, but not at 29℃. Survival rate of parasitized larvae depends on the feeding sub- strate. Moreover, infection of host larvae with Maruca vitrata multi-nucleopolyhedrovirus （MaviMNPV） killed larger proportions of parasitized larvae at 25℃ than at 29℃, which was likely caused by the difference in parasitoid developmental rate. The proportion of female parasitoids was lowest on L. sericeus. The daily fecundity showed a nonlinear trend regardless of the feeding substrate, indicating that A. taragamae is a pro-ovigenic species. The data support the slow growth-high mortality hypothesis.
