scholarly journals Rapid Enabling of Gluconobacter oxydans Resistance to High D-Sorbitol Concentration and High Temperature by Microdroplet-Aided Adaptive Evolution

2021 ◽  
Vol 9 ◽  
Author(s):  
Li Liu ◽  
Weizhu Zeng ◽  
Shiqin Yu ◽  
Jianghua Li ◽  
Jingwen Zhou
Keyword(s):  
High Temperature ◽  
Adaptive Evolution ◽  
Genomic Analysis ◽  
Gluconobacter Oxydans ◽  
Protein Translation ◽  
Comparative Genomic ◽  
Scale Production ◽  
Genetic Changes ◽  
Short Time ◽  
Industrial Scale Production

Gluconobacter oxydans is important in the conversion of D-sorbitol into l-sorbose, which is an essential intermediate for industrial-scale production of vitamin C. In a previous study, the strain G. oxydans WSH-004 could directly produce 2-keto-l-gulonic acid (2-KLG). However, its D-sorbitol tolerance was poor compared with that of other common industrial G. oxydans strains, which grew well in the presence of more than 200 g/L of D-sorbitol. This study aimed to use the microbial microdroplet culture (MMC) system for the adaptive evolution of G. oxydans WSH-004 so as to improve its tolerance to high substrate concentration and high temperature. A series of adaptively evolved strains, G. oxydans MMC1-MMC10, were obtained within 90 days. The results showed that the best strain MMC10 grew in a 300 g/L of D-sorbitol medium at 40°C. The comparative genomic analysis revealed that genetic changes related to increased tolerance were mainly in protein translation genes. Compared with the traditional adaptive evolution method, the application of microdroplet-aided adaptive evolution could improve the efficiency in terms of reducing time and simplifying the procedure for strain evolution. This research indicated that the microdroplet-aided adaptive evolution was an effective tool for improving the phenotypes with undemonstrated genotypes in a short time.

scholarly journals Efficient Optimization of Gluconobacter oxydans Based on Protein Scaffold-Trimeric CutA to Enhance the Chemical Structure Stability of Enzymes for the Direct Production of 2-Keto-L-gulonic Acid

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Lili Gao ◽  
Yuefeng Liu ◽  
Xiaoyu Zhang ◽  
Hongsheng Zhang
Keyword(s):  
Vitamin C ◽  
Chemical Structure ◽  
Gluconobacter Oxydans ◽  
Structure Stability ◽  
Scale Production ◽  
Direct Production ◽  
One Step ◽  
The One ◽  
Industrial Scale Production ◽  
Step Strain

2-Keto-L-gulonic acid (2-KLG), the direct precursor of vitamin C, is produced by a two-step fermentation route from D-sorbitol in industry. However, this route is a complicated mix-culture system which involves three bacteria. Thus, replacement of the conventional two-step fermentation process with a one-step process could be revolutionary in vitamin C industry. The one-step fermentation of 2-keto-L-gulonic acid (2-KLG) has been achieved in our previous study; 32.4 g/L of 2-KLG production was obtained by the one-step strain G. oxydans/pGUC-tufB-sdh-GGGGS-sndh after 168 h. In this study, L-sorbose dehydrogenase (SDH) and L-sorbosone dehydrogenase (SNDH) were expressed in G. oxydans after the codon optimization. Furthermore, the trimeric protein CutA was used to improve the chemical structure stability of SDH and SNDH. The recombinant strain G. oxydans/pGUC-tufB-SH3-sdh-GGGGS-sndh-tufB-SH3lig-(GGGGS)2-cutA produced 40.3 g/L of 2-KLG after 168 h. In addition, the expression levels of the cofactor PQQ were enhanced to further improve 2-KLG production. With the stepwise metabolic engineering of G. oxydans, the final 2-KLG production was improved to 42.6 g/L. The efficient one-step production of 2-KLG was achieved, and the final one-step industrial-scale production of 2-KLG is drawing near.

scholarly journals Comparative Genomic Analysis of Trichinella spiralis Reveals Potential Mechanisms of Adaptive Evolution

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Zigang Qu ◽  
Wenhui Li ◽  
Nianzhang Zhang ◽  
Li Li ◽  
Hongbin Yan ◽  
...  
Keyword(s):  
Adaptive Evolution ◽  
Vaccine Development ◽  
Trichinella Spiralis ◽  
Cell Formation ◽  
Genomic Analysis ◽  
Comparative Genomic Analysis ◽  
Effective Control ◽  
Parasitic Nematodes ◽  
Comparative Genomic ◽  
Low Oxygen

Trichinellosis caused by parasitic nematodes of the genus Trichinella may result in human morbidity and mortality worldwide. Deciphering processes that drive species diversity and adaptation are key to understanding parasitism and developing effective control strategies. Our goal was to identify genes that are under positive selection and possible mechanisms of adaptive evolution of Trichinella spiralis genes using a comparative genomic analysis with the genomes of Brugia malayi, Trichuris suis, Ancylostoma ceylanicum, and Caenorhabditis elegans. The CODEML program derived from the PAML package was used to deduce the most probable dN/dS ratio, a measurement to detect genes/proteins undergoing adaptation. For each pair of sequences, those with a dN/dS ratio > 1 were considered positively selected genes (PSGs). Altogether, 986 genes were positively selected (p-value < 0.01). Genes involved in metabolic pathways, signaling pathways, and cytosolic DNA-sensing pathways were significantly enriched among the PSGs. Several PSGs are associated with exploitation of the host: modification of the host’s metabolism, creation of new parasite-specific morphological structures between T. spiralis and the host interface, xenobiotic metabolism to combat low oxygen concentrations and host toxicity, muscle cell transformation, cell cycle arrest, DNA repair processes during nurse cell formation, antiapoptotic factors, immunomodulation, and regulation of epigenetic processes. Some of the T. spiralis PSGs have C. elegans orthologs that confer severe or lethal RNAi phenotypes. Fifty-seven PSGs in T. spiralis were analyzed to encode differentially expressed proteins. The present study utilized an overall comparative genomic analysis to discover PSGs within T. spiralis and their relationships with biological function and organism fitness. This analysis adds to our understanding of the possible mechanism that contributes to T. spiralis parasitism and biological adaptation within the host, and thus these identified genes may be potential targets for drug and vaccine development.

scholarly journals Identification of NAD-dependent xylitol dehydrogenase fromGluconobacter oxydansWSH-003

2019 ◽  
Author(s):  
Li Liu ◽  
Weizhu Zeng ◽  
Guocheng Du ◽  
Jian Chen ◽  
Jingwen Zhou
Keyword(s):  
Vitamin C ◽  
Gluconobacter Oxydans ◽  
Conversion Ratio ◽  
Xylitol Dehydrogenase ◽  
Industrial Scale ◽  
Scale Production ◽  
Optimum Temperature ◽  
Nadh Regeneration ◽  
High Preference ◽  
Industrial Scale Production

AbstractGluconobacter oxydansplays important role in conversion of D-sorbitol to L-sorbose, which is an essential intermediate for industrial-scale production of vitamin C. In the fermentation process, some D-sorbitol could be converted to D-fructose and other byproducts by uncertain dehydrogenases. Genome sequencing has revealed the presence of diverse genes encoding dehydrogenases inG. oxydans. However, the characteristics of most of these dehydrogenases remain unclear. Therefore, analyses of these unknown dehydrogenases could be useful for identifying those related to the production of D-fructose and other byproducts. Accordingly, dehydrogenases inG. oxydansWSH-003, an industrial strain used for vitamin C production, were examined. An NAD-dependent dehydrogenase, which was annotated as xylitol dehydrogenase 2, was identified, codon-optimized, and expressed inEscherichia coliBL21 (DE3) cells. The enzyme exhibited high preference for NAD+as the cofactor, while no activity with NADP+, FAD, or PQQ was noted. Although this enzyme presented high similarity with NAD-dependent xylitol dehydrogenase, it showed high activity to catalyze D-sorbitol to D-fructose. Unlike the optimum temperature and pH for most of the known NAD-dependent xylitol dehydrogenases (30°C–40°C and about 6–8, respectively), those for the identified enzyme were 57°C and 12, respectively. TheKmandVmaxof the identified dehydrogenase towards L-sorbitol were 4.92 μM and 196.08 μM/min, respectively. Thus, xylitol dehydrogenase 2 can be useful for cofactor NADH regeneration under alkaline conditions or its knockout can improve the conversion ratio of D-sorbitol to L-sorbose.ImportanceProduction of L-sorbose from D-sorbitol byGluconobacter oxydansis the first step for industrial scale production of L-ascorbic acid.G. oxydanscontains a lot of different dehydrogenases, among which only several are responsible for the conversion of D-sorbitol to L-sorbose, while others may responsible for the accumulation of byproducts, thus decreased the yield of L-sorbose on D-sorbitol. Therefore, a new xylitol dehydrogenase has been identified from 44 dehydrogenases ofG.oxydans. Optimum temperature and pH of the xylitol dehydrogenase are different to most of the known ones. Knock-out of the dehydrogenase may improve the conversion ratio of D-sorbitol to L-sorbose. Besides, the enzyme exhibits high preference for NAD+and have potential to be used for cofactor regeneration.

scholarly journals Niche-Specific Adaptive Evolution of Lactobacillus plantarum Strains Isolated From Human Feces and Paocai

2021 ◽  
Vol 10 ◽  
Author(s):  
Qiqi Pan ◽  
Shi Cen ◽  
Leilei Yu ◽  
Fengwei Tian ◽  
Jianxin Zhao ◽  
...  
Keyword(s):  
Lactobacillus Plantarum ◽  
Adaptive Evolution ◽  
Pathogenic Bacteria ◽  
Genomic Analysis ◽  
Comparative Genomic ◽  
Genetic Evolution ◽  
Gut Health ◽  
Human Feces ◽  
Structural Variations ◽  
Stagnation Period

Lactobacillus plantarum, a widely used probiotic in the food industry, exists in diverse habitats, which has led to its niche-specific genetic evolution. However, the relationship between this type of genetic evolution and the bacterial phenotype remains unclear. Here, six L. plantarum strains derived from paocai and human feces were analyzed at the genomic and phenotypic levels to investigate the features of adaptive evolution in different habitats. A comparative genomic analysis showed that 93 metabolism-related genes underwent structural variations (SVs) during adaptive evolution, including genes responsible for carbohydrate, lipid, amino acid, inorganic ion and coenzyme transport and metabolism, and energy production and conversion. Notably, seven virulence factor-related genes in strains from both habitats showed SVs — similar to the pattern found in the orthologous virulence genes of pathogenic bacteria shared similar niches, suggesting the possibility of horizontal gene transfer. These genomic variations further influenced the metabolic abilities of strains and their interactions with the commensal microbiota in the host intestine. Compared with the strains from feces, those from paocai exhibited a shorter stagnation period and a higher growth rate in a diluted paocai solution because of variations in functional genes. In addition, opposite correlations were identified between the relative abundances of L. plantarum strains and the genus Bifidobacterium in two media inoculated with strains from the two habitats. Overall, our findings revealed that the niche-specific genetic evolution of L. plantarum strains is associated with their fermentation abilities and physiological functions in host gut health. This knowledge can help guiding the exploration and application of probiotics from the specific niches-based probiotic exploitation.

Study on Packing Materials for High-Temperature Compost of Livestock Manure

2013 ◽  
Vol 726-731 ◽  
pp. 2964-2969
Author(s):  
Ji Jin Li ◽  
Qin Ping Sun ◽  
Guo Yuan Zou ◽  
Jun Xiang Xu ◽  
Li Juan Gao ◽  
...  
Keyword(s):  
High Temperature ◽  
Organic Fertilizers ◽  
Chicken Manure ◽  
Nitrogen Losses ◽  
Scale Production ◽  
Packing Materials ◽  
Compost Quality ◽  
Inorganic Substances ◽  
Maize Straw ◽  
Industrial Scale Production

Packing materials made of organic or inorganic substances can improve the composting speed or increase the compost quality. Pilot experiments on outdoor composting were carried out to investigate the effect of packing materials on nitrogen losses and compost quality. The results showed that both furfural dreg and mushroom dreg can be used as packing materials in composting chicken manure. Compared with maize straw, furfural dreg and mushroom dreg were more suitable for the industrial-scale production of organic fertilizers. Packing materials can optimize the composting conditions, improve microbial activity, accelerate the composting process, reduce nitrogen losses, and maintain nutrients, thereby improving the compost quality.

Ti-679

Alloy Digest ◽  
1966 ◽  
Vol 15 (11) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Creep Strength ◽  
Heat Treating ◽  
High Temperature Alloy ◽  
Temperature Performance ◽  
Time Strength ◽  
Short Time

Abstract Ti-679 is a titanium high temperature alloy having an excellent combination of short-time strength, creep strength and stability to 900 F. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: Ti-48. Producer or source: Titanium Metals Corporation of America.

scholarly journals Differential impact of Holder and High Temperature Short Time pasteurization on the dynamic in vitro digestion of human milk in a preterm newborn model

2020 ◽  
Vol 328 ◽  
pp. 127126 ◽  
Author(s):  
Stefano Nebbia ◽  
Marzia Giribaldi ◽  
Laura Cavallarin ◽  
Enrico Bertino ◽  
Alessandra Coscia ◽  
...  
Keyword(s):  
High Temperature ◽  
Human Milk ◽  
In Vitro Digestion ◽  
Preterm Newborn ◽  
Differential Impact ◽  
High Temperature Short Time ◽  
Short Time

scholarly journals Comparative Genomic Analysis of 450 Strains of Salmonella enterica Isolated from Diseased Animals

Genes ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 1025
Author(s):  
Shaohua Zhao ◽  
Cong Li ◽  
Chih-Hao Hsu ◽  
Gregory H. Tyson ◽  
Errol Strain ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Bacterial Infections ◽  
Genomic Analysis ◽  
Heavy Metal Resistance ◽  
Metal Resistance ◽  
Comparative Genomic ◽  
Salmonella Infections ◽  
Antimicrobial Resistance Genes ◽  
Salmonella Pathogenicity Islands ◽  
Shed Light

Salmonella is a leading cause of bacterial infections in animals and humans. We sequenced a collection of 450 Salmonella strains from diseased animals to better understand the genetic makeup of their virulence and resistance features. The presence of Salmonella pathogenicity islands (SPIs) varied by serotype. S. Enteritidis carried the most SPIs (n = 15), while S. Mbandaka, S. Cerro, S. Meleagridis, and S. Havana carried the least (n = 10). S. Typhimurium, S. Choleraesuis, S. I 4,5,12:i:-, and S. Enteritidis each contained the spv operon on IncFII or IncFII-IncFIB hybrid plasmids. Two S. IIIa carried a spv operon with spvD deletion on the chromosome. Twelve plasmid types including 24 hybrid plasmids were identified. IncA/C was frequently associated with S. Newport (83%) and S. Agona (100%) from bovine, whereas IncFII (100%), IncFIB (100%), and IncQ1 (94%) were seen in S. Choleraesuis from swine. IncX (100%) was detected in all S. Kentucky from chicken. A total of 60 antimicrobial resistance genes (ARGs), four disinfectant resistances genes (DRGs) and 33 heavy metal resistance genes (HMRGs) were identified. The Salmonella strains from sick animals contained various SPIs, resistance genes and plasmid types based on the serotype and source of the isolates. Such complicated genomic structures shed light on the strain characteristics contributing to the severity of disease and treatment failures in Salmonella infections, including those causing illnesses in animals.

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