Producción de proteína unicelular de Saccharomyces cerevisiae con granza de arroz e inclusión en cerdos / Production of single cell protein of Saccharomyces cerevisiae with broken rice and inclusion in pigs / Produção de proteína unicelular de Saccharomyces cerevisiae com quirera de arroz e inclusão em suínos

Resumen El contenido proteico de harinas de cereales se incrementa con proteínas microbianas mediante procesos de fermentación utilizando levaduras. El objetivo de esta investigación fue evaluar la inclusión de granza de arroz sometida a fermentación liquida con Saccharomyces cerevisiae por fermentación anaeróbica como fuente de proteína unicelular (PUC) para cerdos en crecimiento. Se realizó prueba piloto en laboratorio para producción de PUC de S. cerevisiae con granza de arroz para estandarizar y encontrar las mejores condiciones en el proceso, para su posterior producción en fermentador de 600 l. Se evalúo la granza obtenida por fermentación con S. cerevisiae por un tiempo de 30 días, en 24 cerdos de 21.72 ± 3.31 kg, distribuidos en un diseño en bloques completos al azar con cuatro tratamientos, tres bloques y seis animales por tratamiento. El ensayo consistió en cuatro niveles de inclusión: T1: 0%, T2: 10%, T3: 20% y T4: 25%, de granza de arroz post-fermentada con S. cerevisiae. Las variables evaluadas fueron peso final (kg), ganancia de peso (g/día), consumo final (kg), conversión alimenticia. El alimento pasó de 8.23% a 13.97% de PC. Se presentaron diferencias (p<0.05) en ganancia diaria de peso T1: 625.81 y T2: 618.77 respecto T3: 526.38 y T4: 542.77 g/día, y en la conversión alimenticia entre T1: 2.20 y T2: 2.16 respecto a los tratamientos T3: 2.54 y T4: 2.45. No hubo diferencias (p>0.05) para el peso final ni el consumo final. El costo de las dietas fue menor para T2, T3 y T4. En conclusión, con la fermentación anaerobia de la granza se mejoró el nivel proteico del alimento por crecimiento de la levadura S. cerevisiae y puede ser incluido en dietas para cerdos en crecimiento, presentándose buena palatabilidad y hasta un nivel de inclusión del 10% obtener buen rendimiento, con una dieta de menor costo.

Abstract Cereal flour protein content can be increased by microbial protein action through yeast-driven fermentation. This research was aimed at evaluating the anaerobic fermentation of liquid rice bran with Saccharomyces cerevisiae as a single cell protein (SCP) source for raising pigs. A pilot test for S. cerevisiae SCP production was carried out in the laboratory using rice bran to standardise and find the best process conditions regarding SCP production in a 600 L fermenter tank. The rice bran obtained by fermentation with S. cerevisiae was evaluated for 30 days using twenty-four 21.72±3.31 kg pigs; a randomised complete block design (RCBD) was used, involving four treatments, three blocks and six animals per treatment. The trial had four rice bran post-fermented with S. cerevisiae inclusion levels: T1 0% bran inclusion, T2 10%, T3 20% and T4 25%. Final weight (kg), average daily gain (g/day), final consumption (kg) and feed conversion ratio (FCR) were the variables evaluated here. SCP inclusion in food rose from 8.23% to 13.97%. There were significant statistical differences (p<0.05) regarding average daily gain for T1 (625.81 g/day) and T2 (618.77) compared to T3 (526.38) and T4 (542.77) and FCR for T1 (2.20) and T2 (2.16) compared to T3 (2.54) and T4 (2.45). There were no differences (p>0.05) regarding final weight or final consumption. Diet costs were lower for T2, T3 and T4. The anaerobic fermentation of rice bran improved feed protein content through S. cerevisiae growth and can be included in diets for raising pigs; it has good palatability and up to 10% SCP inclusion level, obtaining good yield and a lower cost diet.

Resumo O conteúdo protéico das farinhas de cereais é aumentado com proteínas microbianas através de processos de fermentação utilizando leveduras. O objectivo desta pesquisa foi avaliar a inclusão de quirera de arroz submetido a fermentação líquida com Saccharomyces cerevisiae por fermentação anaeróbia como fonte de proteína unicelular (PUC) para porcos em crescimento. Teste-piloto foi realizado no laboratório para a produção PUC de S. cerevisiae com quirera de arroz, a fim de padronizar e encontrar as melhores condições do processo para a produção subsequente fermentador de 600 l. Foram avaliadas a quirera de arroz obtido por fermentação com S. cerevisiae foi avaliado por um período de 30 dias, em 24 porcos 21.72 ± 3.31 kg, distribuídos em blocos casualizados com quatro tratamentos, três blocos e seis animais por tratamento. O julgamento consistiu em quatro níveis de inclusão: T1: 0%, T2: 10%, T3: 20% e T4: 25%, de quirera de arroz pós-fermentado com S. cerevisiae. As variáveis ​​estudadas foram o ganho diário de peso (g/dia), peso final (kg), consumo final (kg) e conversão de feed. A comida passou de 8.23% para 13.97% de PC. Houve diferenças (p<0,05) no ganho de peso diário T1: 625.81 e T2: 618.77 em relação a T3: 526.38 e T4: 542.77 g/dia, e na conversão alimentar entre T1: 2.20 e T2: 2.16 com relação aos tratamentos T3: 2.54 e T4: 2.45. Não houve diferenças (p>0.05) para o peso final ou consumo final. O custo das dietas foi menor para T2, T3 e T4. Em conclusão, com a fermentação anaeróbia do quirera de arroz, o nível protéico da ração foi melhorado pelo crescimento da levedura S. cerevisiae e pode ser incluído em rações para suínos em crescimento, apresentando boa palatabilidade e até um nível de inclusão de 10% obtendo boa desempenho, com uma dieta de menor custo.

Changes in freshwater sediment microbial populations during fermentation of crude glycerol

BACKGROUND: This work studied how the exposure to an unusual substrate forced a change in microbial populations during anaerobic fermentation of crude glycerol, a by-product of biodiesel production, with freshwater sediment used as an inoculum. RESULTS: The microbial associations almost completely (99.9%) utilized the glycerol contained in crude glycerol 6 g L 1 within four days, releasing gases, organic acids (acetic, butyric) and alcohols (ethanol, n-butanol) under anaerobic conditions. In comparison with control medium without glycerol, adding crude glycerol to the medium increased the amount of ethanol and n-butanol production and it was not significantly affected by incubation temperature (28 C or 37 C), nor incubation time (4 or 8 d), but it resulted in reduced amount of butyric acid. Higher volume of gas was produced at 37 C despite the fact that the overall bacterial count was smaller than the one measured at 20 C. Main microbial phyla of the inoculum were Actinobacteria, Proteobacteria and Firmicutes. During fermentation, significant changes were observed and Firmicutes, especially Clostridium spp., began to dominate, and the number of Actinobacteria and Gammaproteobacteria decreased accordingly. Concentration of Archaea decreased, especially in medium with crude glycerol. These changes were confirmed both by culturing and culture-independent (concentration of 16S rDNA) methods. CONCLUSIONS: Crude glycerol led to the adaptation of freshwater sediment microbial populations to this substrate. Changes of microbial community were a result of a community adaptation to a new source of carbon.

A review on polyhydroxyalkanoates synthesis in activated sludge system: the effects of dissolved organic compounds by using anaerobic fermentation liquid from waste activated sludge / 生物工程学报

Polyhydroxyalkanoates (PHA) synthesis by activated sludge using volatile fatty acids (VFAs) in fermentation liquid of excess sludge as carbon source is a hotspot in the field of environmental biotechnology. However, there is no unified conclusion on the effects of non-VFAs, mainly dissolved organic matter (DOM), on PHA production. Thus, this critical review mainly introduces the main characteristics and common analysis methods of DOM in anaerobic fermentation liquid. The effects of DOM on PHA production are analyzed from the aspects of microbiology, metabolic regulation and sludge properties. The results of different studies showed that high concentration of DOM is bad for PHA production, but an appropriate amount of DOM is conducive to the stability of sludge properties, reducing the final PHA purification cost. Finally, suitable strategies were proposed to regulate the PHA synthesis by activated sludge with DOM for PHA production by anaerobic fermentation liquid.

Investigations on occupational hazards in a kitchen waste treatment plant / 中华劳动卫生职业病杂志

Objective@#To explore the distribution and intensity of kitchen waste treatment plant, providing scientific basis for occupational diseases prevention and treatment in that industry.@*Methods@#30 operating personnel in a kitchen waste disposal enterprise were selected as the research group and 16 non-operating personnel as the control group. The epidemiological survey was carried out in June 2015 and July 2016, and the results of occupational hazards and occupational health monitoring during 2015 to 2017 were analyzed.@*Results@#The results of various occupational hazards factors during 2015 to 2017 were all in accordance with the occupational health limit, but the results of occupational health examination were abnormal. The occupational correlation could not be ruled out by the abnormality of electrical audiometry, electrocardiogram and Department of Dermatology examination.@*Conclusion@#Workers in kitchen waste treatment plant are likely to suffer low-intensity, continuous health damage. There is occupational health risk in that industry. The accumulation of basic information and the improvement of relevant standards and methods are needed for further study.

Composição químico-bromatológica e perfil de fermentação da silagem de resíduo úmido de fécula de mandioca / Chemical composition and profile of the fermentation of cassava starch by-products silage

O trabalho teve como objetivo estudar a composição química e o perfil de fermentação do resíduo úmido de fécula de mandioca ensilado in natura ou após pré secagem ao sol por três horas, durante 0, 28 e 56 dias. O delineamento experimental adotado foi o inteiramente casualizado com parcelas subdivididas no tempo, com quatro repetições. Estudou-se as concentrações de proteína bruta, fibra em detergente neutro, fibra em detergente ácido, hemicelulose, celulose, lignina, cinzas, sílica, extrato etéreo, matéria orgânica e matéria seca no resíduo úmido de fécula de mandioca antes da ensilagem e após os períodos de fermentação. Nas mesmas ocasiões determinou-se a temperatura, pH, e as populações de enterobactérias, bactérias ácido láticas, Clostridium spp., fungos e leveduras e a população total de microrganismos. Apenas a sílica não foi alterada pelos tratamentos estudados. O processo de ensilagem reduziu as concentrações de FDN e hemicelulose e elevou as concentrações de FDA, lignina e hemicelulose dos resíduos, enquanto o pH e as populações de microrganismos foram reduzidas com o processo de ensilagem. A pré secagem ao sol por três horas do resíduo úmido de fécula de mandioca permitiu a ensilagem de um material com menor umidade, não promoveu alterações no perfil fermentativo e população microbiológica das silagens aos 28 e 56 dias de fermentação e reduziu a fibra em detergente neutro e hemicelulose das silagens obtidas. A silagem de resíduo úmido de fécula apresenta redução no conteúdo de proteína bruta com o decorrer do período de fermentação.

The work aimed to study the chemical composition and fermentation profile of the cassava starch by-products ensiled in nature or after pre-drying in the sun for three hours, for zero, 28 and 56 days. The experimental design was completely randomized with split plot in time, with four replications. We studied the concentrations of crude protein, neutral detergent fiber, acid detergent fiber, hemicellulose, cellulose, lignin, ashes, silica, ether extract, dry matter and organic matter in cassava starch by-products before to ensiling and after the fermentation periods. In these instances were determined temperature, pH, and the populations of enterobacteria, lactic acid bacteria, Clostridium spp., fungi and yeasts and the total population of microorganisms. Only the silica was not altered by treatments. The ensiling process reduced the concentrations of NDF and hemicellulose and increased concentrations of ADF, hemicellulose and lignin waste, while the pH and microbial populations were reduced as silage fermentation. Pre drying in the sun for three hours of wet waste cassava starch allowed ensiling of a material with lower humidity did not change in fermentative profile and microbiological population of silages at 28 and 56 days and reduced neutral detergent fiber and hemicellulose of silages. The wet waste residue silage starch showed a reduction in crude protein content in the course of the fermentation period.

Pineapple and citrus silage as potential feed for small ruminant diets: fermentation characteristics, intake, nutrient digestibility, and aerobic stability / Ensilaje de piña y cítricos como posible fuente de alimento en dietas de pequeños rumiantes: características de fermentación, consumo, digestibilidad de nutrientes, y estabilidad aeróbica / Ensilagem de abacaxi e cítricos como possível fonte de alimento em dietas para pequenos ruminantes: características de fermentação, o consumo, a digestibilidade de nutrientes e estabilidade aeróbia

Background: fruit by-products represent a feed resource for ruminants. However, preservation is needed to increase its life span. Objectives: to evaluate the fermentative characteristics, intake, digestibility and aerobic stability of fruit by-products. Methods: pineapple and citrus residues were fermented for 0, 4, 7, 11, 29 and 65 days (d). Samples from each by-product and fermentation period were analyzed for pH, microbial succession, chemical composition, and fermentation products. Crossbred rams were used to determine dry matter (DM) and crude protein (CP) intake and digestibility. Dietary treatments consisted of 100% tropical grass hay (TGH) and 20% substitution of TGH with pineapple (PS) or citrus silage (CS). Aerobic stability of PS and CS after 29 or 65 d of fermentation was determined during 5 d. Results: final pH at 65 d was 3.21 and 3.32 for PS and CS, respectively. During the entire fermentation for both silages, population of enterobacteriaceae was not detected, while lactic acid producing bacteria, yeast and molds showed typical microbial growth. After 65 d fermentation, lactic acid was the main product associated with the fermentation process (1.0 and 1.7 g/kg for PS and CS respectively). Concentrations of acetic acid were 0.38 in PS and 0.36 g/kg in CS. Rams consumed 98 and 85% of the DM offered as PS or CS, respectively. The DM and CP intakes and digestibility were similar among treatments. Both fermented fruit by-products were unstable upon aerobic exposure, PS after 1 d when fermented 29 d and CS after 3 d when fermented 65 d. Conclusions: results indicate that pineapple and citrus by-products could be preserved as silage and included in sheep diets at 20% substitution of TGH without adverse results; however, they are susceptible to aerobic deterioration.

Antecedentes: los subproductos de fruta representan una fuente de alimento para los rumiantes, sin embargo su preservación es necesaria para aumentar su vida útil. Objetivos: evaluar las características fermentativas, consumo, digestibilidad y estabilidad aeróbica de subproductos de frutas. Métodos: residuos de piña y cítricos se fermentaron durante 0, 4, 7, 11, 29 y 65 días (d). Muestras de cada subproducto y período de fermentación se analizaron para determinar pH, sucesión microbiana, composición química, y productos de fermentación. Carneros mestizos se utilizaron para determinar el consumo y digestibilidad de materia seca (MS) y proteína bruta (PB). Los tratamientos consistieron en: 100% heno de gramínea tropical (HGT); 20% sustitución de HGT con ensilaje de piña (EP) o ensilaje de cítricos (EC). La estabilidad aeróbica del EP y EC después de 29 o 65 días de fermentación se determinó durante 5 d. Resultados: el pH final al día 65 fue de 3,21 y 3,32 para EP y EC, respectivamente. Durante toda la fermentación y para ambos ensilajes, no se detectaron poblaciones de enterobacteriaceae, mientras que las bacterias productoras de ácido láctico, levaduras y hongos mostraron un crecimiento microbiano típico. Después de 65 d de fermentación, el ácido láctico era el producto principal asociado con el proceso de fermentación (1,0 y 1,7 g/kg para EP y EC, respectivamente). Las concentraciones de ácido acético fueron 0,38 g/kg en EP y 0,36 g/kg en EC. Los carneros consumieron 98 y 85% de la MS ofrecida como EP o EC, respectivamente. El consumo y la digestibilidad de MS y PB fueron similares entre los tratamientos. Ambos subproductos de fruta fermentados fueron inestables a la exposición aeróbica, el EP después del primer día cuando se fermenta 29 d y el EC después de 3 d cuando se fermenta 65 d. Conclusiones: los resultados indican que los subproductos de piña y cítricos podrían ser preservados como ensilaje y que podrían ser incluidos en las dietas de ovejas a 20% de sustitución de HGT sin resultados adversos, sin embargo, son susceptibles al deterioro aeróbico.

Antecedentes: os subprodutos da agroindústria de frutas são uma fonte de alimento para os ruminantes, mas sua preservação é necessária para aumentar a vida útil. Objetivos: avaliar as características fermentativas, consumo, digestibilidade e estabilidade aeróbia dos subprodutos de frutas. Métodos: resíduos de abacaxi e frutas cítricas foram fermentados durante 0, 4, 7, 11, 29 e 65 dias (d). Amostras de cada subproduto e os períodos de fermentação foram analisadas para: pH, sucessão microbiana, composição química, e produtos de fermentação. Um quadrado latino 3 x 3, com nove carneiros mestiços foi usado para determinação de consumo e digestibilidade da matéria seca (MS) e proteína bruta (PB). Os tratamentos dietéticos utilizados foram: 100% feno de capim tropical (FCT) e 20% de substituição do FCT com silagem de abacaxi (SA) ou silagem de cítricos (SC). A estabilidade aeróbia de SA e SC depois de 29 ou 65 d de fermentação foi determinada durante 5 d. Resultados: o pH final (65 d) foi de 3,21 e 3,32 para o SA e SC, respectivamente. Durante a fermentação para as duas silagens, a população de enterobactérias não foi detectada. Enquanto a bactérias produtoras de ácido láctico, leveduras e fungos as silagens mostraram um crescimento microbiano típico. Depois de 65 d de fermentação, o ácido láctico era o produto principal associado com o processo de fermentação (1,0 e 1,7 g / kg para SA e SC, respectivamente). As concentrações de ácido acético foram 0,38 g / kg em SA e 0,36 g / kg em SC. Os carneiros consumiram 98 e 85% da MS oferecida como SA ou SC, respectivamente. O consumo e a digestibilidade da MS e PB foram semelhantes entre os tratamentos. Os dois subprodutos de frutas fermentados foram instáveis após a exposição aeróbia, a SA depois de 1 d, quando foi fermentada 29 d e a SC depois de 3 d, quando foi fermentada 65 d. Conclusões: os resultados indicam que os subprodutos de abacaxi e cítricos poderiam ser preservados como silagem e serem incluídos em dietas de ovinos em 20% de substituição do FCT sem resultados adversos, ainda que, tem que ter cuidado porque as silagens são susceptíveis à deterioração aeróbia.

Desempenho e parâmetros sanguíneos de bezerros leiteiros que receberam sucedâneo lácteo ou silagem de colostro / Performance and plasma metabolites of dairy calves fed a milk replacer or colostrum silage

O objetivo deste estudo foi avaliar o desempenho e os parâmetros sanguíneos de bezerros que consumiram colostro bovino fermentado sob condições anaeróbias. Após o nascimento, 18 bezerros da raça Holandês foram alojados em abrigos individuais e passaram a receber 4L da dieta líquida, sucedâneo lácteo ou silagem de colostro, divididos em duas refeições. O consumo de concentrado inicial e o escore fecal foram registrados diariamente, enquanto a pesagem e as colheitas de amostras de sangue para a determinação das concentrações plasmáticas de glicose, nitrogênio ureico, ácidos graxos livres, β-hidroxibutirato e proteínas totais séricas foram realizadas semanalmente. Os animais alimentados com silagem de colostro apresentaram menores consumo de concentrado, ganho de peso diário e peso vivo. Todos os parâmetros sanguíneos avaliados foram afetados pelos tratamentos, exceto a concentração plasmática de proteínas totais. O escore fecal foi afetado pelos tratamentos durante a segunda semana de vida, com animais alimentados com silagem de colostro apresentando fezes anormais e secas. O fornecimento de silagem de colostro como dieta líquida exclusiva não resultou em desempenho animal adequado, não sendo uma boa alternativa de substituto de leite.

The aim of this study was to evaluate the performance and plasma metabolites of calves fed colostrum fermented under anaerobic conditions as an exclusive liquid feed during the whole milk-feeding period. After birth, eighteen Holstein male calves were housed in individual hutches and fed four liters of liquid diet, milk replacer or colostrum silage, divided into two meals. The starter feed intake and fecal scores were recorded daily, and body weight and blood samples for the determination of plasma glucose, urea nitrogen, free fatty acids, β-hydroxybutyrate and serum total protein were taken weekly. Animals fed colostrum silage had lower intake of starter feed during the experimental period. Significant effects were also observed for average daily gain and body weight. All blood parameters measured were affected by the treatments, except the total protein plasma concentration. The fecal score was affected by treatments during the second week of life, with animals fed colostrum silage presenting abnormal and very dry feces. Feeding colostrum silage as exclusive liquid diet during the whole milk-feeding period resulted in inadequate animal performance, being considered a bad alternative as milk replacer.

Evaluating Colombian Clostridium spp. Strains hydrogen production using glycerol as substrate

Background: The ability for hydrogen production of 13 native strains of Clostridium spp. strains isolated from Colombian soil was evaluated using glycerol substrate. Glycerol to hydrogen conversion was investigated using a batch fermentation reactor and industrial glycerol source (50 g.l-1, pH 7.00). Results: The results were quantified regarding acids, hydrogen, biomass and solvent production. The selected strain gave good hydrogen over production output at 14.4 mmol H2.l-1, productivity 0.3167 mg H2.h-1 l-1 culture mediumand yield 0.1962 mol H2.mol-1 glycerol. A further fermentation assay a 4.0 liter batch reactor let to being 0.26 mg.l-1.h-1 after 18 hrs of fermentation. Logistic model, Luedeking-Piret model and Luedeking-Piret modified models were used for modeling changes in cell growth, hydrogen production and substrate consumption (Correlation coefficients R² = 0.95 for biomass substrate, R² = 0.77 hydrogen production). Conclusions: Our results indicate that hydrogen production through glycerol bioconversion by native strains is possible.

Bioconversion of glycerol for bioethanol production using isolated Escherichia coli SS1

Bioconverting glycerol into various valuable products is one of glycerol's promising applications due to its high availability at low cost and the existence of many glycerol-utilizing microorganisms. Bioethanol and biohydrogen, which are types of renewable fuels, are two examples of bioconverted products. The objectives of this study were to evaluate ethanol production from different media by local microorganism isolates and compare the ethanol fermentation profile of the selected strains to use of glucose or glycerol as sole carbon sources. The ethanol fermentations by six isolates were evaluated after a preliminary screening process. Strain named SS1 produced the highest ethanol yield of 1.0 mol: 1.0 mol glycerol and was identified as Escherichia coli SS1 Also, this isolated strain showed a higher affinity to glycerol than glucose for bioethanol production.

Anaerobic Biohydrogen Production Bacteria Selection and Its Optimization of Biohydrogen Fermentation Process / 微生物学通报

This research adopted silt as the sample,and the five highest hydrogen production performing strains contained in the sample were isolated. The strain whose hydrogen production was the highest was identified as Enterobacter cloacae by the analysis of 16S rDNA sequencing and comparison. It is showed by Plackett-Burman Experimental Design that only glucose,citric buffer and reducing agent had significant effects on hydrogen production by Enterobacter cloacae FML-C1. The path of steepest ascent was undertaken to approach the optimal response region of those three factors. Central Composite Design(CCD) and Response Surface Methodology(RSM) were employed to investigate the interaction of the variables and to ascertain the optimal values of the factors,which finally led to the maximum hydrogen production(VH2) . The theoretical optimal medium conditions were:glucose 21.5 g/L,citric buffer 13.6 mL/L,reducing agent10.0 mL/L. The five tentative tests matched this model well. The final VH2 was up to 2347.4 mL/L,which was 127.42% enhanced in comparison to the original. The result shows that PB experiment design and RSM analytical method work well in selecting factors which have significant influences on the hydrogen production and,moreover,achieve the ideal optimal result.

Isolation and Characterization of a New High Efficient H2-producing Bacterium Enterococcus sp. LG1 / 微生物学通报

12 strains of H2-producing bacteria were isolated and purified from anaerobic sludge, aerobic sludge and river bottom sludge by Hungate method. A new species of high efficient hydrogen production bacterium Enterococcus sp. LG1 (registration number: EU258743 ) was studied deeply. It was showed that the Enterococcus sp. LG1 was an anaerobic and Gram-negative bacterium. Sequence analysis of this type of clones showed that it was affiliated with the genus Enterococcus and it was not reported yet in other paper at present. Meanwhile, batch tests of anaerobic fermentative hydrogen production by Enterococcus sp. LG1 were investigated by using sterilization pretreated sludge as substrate. The changes of soluble COD, protein, carbohydrate and pH value during hydrogen fermentation were monitored. It was found that only hydrogen and carbon dioxide were produced by this strain and no methane was detected during fermentation. The maximal hydrogen yield was 36.48 mL/g TCOD and the hydrogen concentration in the gas phase was 73.5%. The Enterococcus sp. LG1 was a butyrate fermentation bacteria analyzed by metabolites.

Effect of Overexpression of NAD+-dependent Malic Enzyme on Anaerobic Mixed Acid Fermentation of E.coli FMJ39 / 中国生物工程杂志

In order to investigate the effect of malic enzyme on anaerobic mixed acid fermentation,the gene encoding NAD+-dependent malic enzyme was amplified from E.coli DH5? genome by using PCR and cloned into vector pTrc99a to give an expression vector pTrc99a-sfcA.Malic enzyme was overproduced by E.coli FMJ39(ldh,pfl)harboring pTrc99a-sfcA under the condition of IPTG induction.The results of anaerobic fermentation indicated overexpression of malic enzyme would have influence on the pathway of formate,acetate and succinate of FMJ39.The concentration of formate and acetate was 17.58% and 15.27% higher than FMJ39,the succinate concentration was reduced by 26.87%.There was no obvious citrate concentration change.The experimental results also indicated that high concentration of L-Thr and L-Ser would induce the Tdc operon to convert pyruvate into formate and acetate even when pfl gene encoding the pyruvate formate lyase was inactivated.

Research Process of Anaerobic Fermentative Hydrogen Production and Its Development Future / 中国生物工程杂志

Hydrogen is an ideal energy due to its high conversion efficiency, recyclability and nonpolluting nature. Compared with conventional methods, biological hydrogen production process is found to be less energy intensive and more environmental friendly, and nowadays more and more attentions are being paid on its fermentative way. A survey of fermentative bio-hydrogen production process was provided, followed by its new approaches in the future development.

Screening and Identification of a Strain of Actinobacillus succinogenes Producing Succinic Acid by Anaerobic Fermentation / 微生物学通报

A strain,Actinobacillus succinogenes CGMCC 1593,producing succinic acid was isolated from bovin rumen,which could pro- duces succinic acid by anaerobic fermentation.A series of morphological and biochemical characteristics and sequence analysis of 16S rDNA reveal that it belongs to Actinobacillus succinogenes.When cultured anaerobically in medium containing 60 g/L glucose as carbon source,the strain produces 25.8 g/L of succnic acid.