scholarly journals Development of a plasmid stabilization system in Vibrio natriegens for the high production of 1,3-propanediol and 3-hydroxypropionate

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Ye Zhang ◽  
Qing Sun ◽  
Yu Liu ◽  
Xuecong Cen ◽  
Dehua Liu ◽  
...  
Keyword(s):  
Plasmid Stability ◽  
Value Added ◽  
Substrate Uptake ◽  
Stabilization System ◽  
Antibiotic Selection ◽  
Uptake Rates ◽  
Fed Batch Fermentation ◽  
High Production ◽  
Antibiotic Selection Pressure ◽  
Plasmid Stabilization

AbstractVibrio natriegens is a promising industrial chassis with a super-fast growth rate and high substrate uptake rates. V. natriegens was previously engineered to produce 1,3-propanediol (1,3-PDO) from glycerol by overexpressing the corresponding genes in a plasmid. However, antibiotic selection pressure for plasmid stability was not satisfactory and plasmid loss resulted in reduced productivity of the bioprocess. In this study, we developed an antibiotic-free plasmid stabilization system for V. natriegens. The system was achieved by shifting the glpD gene, one of the essential genes for glycerol degradation, from the chromosome to plasmid. With this system, engineered V. natriegens can stably maintain a large expression plasmid during the whole fed-batch fermentation and accumulated 69.5 g/L 1,3-PDO in 24 h, which was 23% higher than that based on antibiotic selection system. This system was also applied to engineering V. natriegens for the production of 3-hydroxypropionate (3-HP), enabling the engineered strain to accumulate 64.5 g/L 3-HP in 24 h, which was 30% higher than that based on antibiotic system. Overall, the developed strategy could be useful for engineering V. natriegens as a platform for the production of value-added chemicals from glycerol. Graphic Abstract

scholarly journals Postvaccination Increase in Serotype 19A Pneumococcal Disease in Norway Is Driven by Expansion of Penicillin-Susceptible Strains of the ST199 Complex

2012 ◽  
Vol 19 (3) ◽  
pp. 443-445 ◽  
Author(s):  
Didrik F. Vestrheim ◽  
Martin Steinbakk ◽  
Ingeborg S. Aaberge ◽  
Dominique A. Caugant
Keyword(s):  
Conjugate Vaccine ◽  
Invasive Pneumococcal Disease ◽  
Pneumococcal Conjugate Vaccine ◽  
Selection Pressure ◽  
Pneumococcal Disease ◽  
Antibiotic Selection ◽  
Serotype Replacement ◽  
Rapid Replacement ◽  
Antibiotic Selection Pressure

ABSTRACTSerotype replacement in invasive pneumococcal disease has been observed after widespread use of the 7-valent pneumococcal conjugate vaccine (PCV7). Replacement is dominated by penicillin-nonsusceptible serotype 19A in several countries. Antibiotic selection pressure has been proposed to interact with immunization, leading to rapid replacement. In Norway, where prescription of antibiotics is limited, post-PCV7 replacement by serotype 19A is dominated by penicillin-susceptible clones. Hence, serotype 19A replacement occurs, although it is not driven by antibiotic selection pressure.

scholarly journals Functional Characterization of Replication and Stability Factors of an Incompatibility Group P-1 Plasmid from Xylella fastidiosa

2010 ◽  
Vol 76 (23) ◽  
pp. 7734-7740 ◽  
Author(s):  
Min Woo Lee ◽  
Elizabeth E. Rogers ◽  
Drake C. Stenger
Keyword(s):  
Pseudomonas Syringae ◽  
Xanthomonas Campestris ◽  
Plasmid Stability ◽  
Xylella Fastidiosa ◽  
Shuttle Vector ◽  
Functional Characterization ◽  
Replication Initiation ◽  
Incompatibility Group ◽  
Antibiotic Selection ◽  
E Coli

ABSTRACT Xylella fastidiosa strain riv11 harbors a 25-kbp plasmid (pXF-RIV11) belonging to the IncP-1 incompatibility group. Replication and stability factors of pXF-RIV11 were identified and used to construct plasmids able to replicate in X. fastidiosa and Escherichia coli. Replication in X. fastidiosa required a 1.4-kbp region from pXF-RIV11 containing a replication initiation gene (trfA) and the adjacent origin of DNA replication (oriV). Constructs containing trfA and oriV from pVEIS01, a related IncP-1 plasmid of the earthworm symbiont Verminephrobacter eiseniae, also were competent for replication in X. fastidiosa. Constructs derived from pXF-RIV11 but not pVEIS01 replicated in Agrobacterium tumefaciens, Xanthomonas campestris, and Pseudomonas syringae. Although plasmids bearing replication elements from pXF-RIV11 or pVEIS01 could be maintained in X. fastidiosa under antibiotic selection, removal of selection resulted in plasmid extinction after 3 weekly passages. Addition of a toxin-antitoxin addiction system (pemI/pemK) from pXF-RIV11 improved plasmid stability such that >80 to 90% of X. fastidiosa cells retained plasmid after 5 weekly passages in the absence of antibiotic selection. Expression of PemK in E. coli was toxic for cell growth, but toxicity was nullified by coexpression of PemI antitoxin. Deletion of N-terminal sequences of PemK containing the conserved motif RGD abolished toxicity. In vitro assays revealed a direct interaction of PemI with PemK, suggesting that antitoxin activity of PemI is mediated by toxin sequestration. IncP-1 plasmid replication and stability factors were added to an E. coli cloning vector to constitute a stable 6.0-kbp shuttle vector (pXF20-PEMIK) suitable for use in X. fastidiosa.

AMPKα2 deficiency uncovers time dependency in the regulation of contraction-induced palmitate and glucose uptake in mouse muscle

2011 ◽  
Vol 111 (1) ◽  
pp. 125-134 ◽  
Author(s):  
Marcia J. Abbott ◽  
Lindsey D. Bogachus ◽  
Lorraine P. Turcotte
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Muscle Contraction ◽  
Glucose Uptake ◽  
Time Dependent ◽  
Substrate Uptake ◽  
Dependent Manner ◽  
Mouse Muscle ◽  
Uptake Rates ◽  
Intracellular Ca

AMP-activated protein kinase (AMPK) is a fuel sensor in skeletal muscle with multiple downstream signaling targets that may be triggered by increases in intracellular Ca2+ concentration ([Ca2+]). The purpose of this study was to determine whether increases in intracellular [Ca2+] induced by caffeine act solely via AMPKα2 and whether AMPKα2 is essential to increase glucose uptake, fatty acid (FA) uptake, and FA oxidation in contracting skeletal muscle. Hindlimbs from wild-type (WT) or AMPKα2 dominant-negative (DN) transgene mice were perfused during rest ( n = 11), treatment with 3 mM caffeine ( n = 10), or muscle contraction ( n = 11). Time-dependent effects on glucose and FA uptake were uncovered throughout the 20-min muscle contraction perfusion period ( P < 0.05). Glucose uptake rates did not increase in DN mice during muscle contraction until the last 5 min of the protocol ( P < 0.05). FA uptake rates were elevated at the onset of muscle contraction and diminished by the end of the protocol in DN mice ( P < 0.05). FA oxidation rates were abolished in the DN mice during muscle contraction ( P < 0.05). The DN transgene had no effect on caffeine-induced FA uptake and oxidation ( P > 0.05). Glucose uptake rates were blunted in caffeine-treated DN mice ( P < 0.05). The DN transgene resulted in a greater use of intramuscular triglycerides as a fuel source during muscle contraction. The DN transgene did not alter caffeine- or contraction-mediated changes in the phosphorylation of Ca2+/calmodulin-dependent protein kinase I or ERK1/2 ( P > 0.05). These data suggest that AMPKα2 is involved in the regulation of substrate uptake in a time-dependent manner in contracting muscle but is not necessary for regulation of FA uptake and oxidation during caffeine treatment.

Biodegradation of phenolic compounds by an acclimated activated sludge and isolated bacteria

1998 ◽  
Vol 37 (4-5) ◽  
pp. 371-378 ◽  
Author(s):  
Germán Buitrón ◽  
Ariel González ◽  
Luz M. López-Marín
Keyword(s):  
Activated Sludge ◽  
Uptake Rate ◽  
Specific Substrate ◽  
Substrate Uptake ◽  
Pseudomonas Sp ◽  
Uptake Rates ◽  
Viable Biomass ◽  
Substrate Uptake Rate ◽  
Chryseomonas Luteola ◽  
Acclimated Activated Sludge

The degradation of a mixture of phenol, 4-chlorophenol (4CP), 2,4-dichlorophenol (24DCP) and 2,4,6-trichlorophenol (246TCP) by acclimated activated sludge and by isolated bacteria was studied. Activated sludge was acclimated for 70 days to 40 mg phenols/l then the microorganisms responsible for the CP degradation were isolated and identified. Four types of Gram-negative bacteria (Aeromonas sp., Pseudomonas sp. Flavomonas oryzihabitans, and Chryseomonas luteola) were identified. Also, two acid-fast bacilli with distinct glycolipid patterns were isolated. From their chemical composition and their growth characteristics, both isolates appeared to be mycobacteria closely related to Mycobacterium peregrinum. The degradation kinetics of each phenol by Aeromonas sp., Pseudomonas sp. Flavomonas oryzihabitans, Chryseomonas luteola and activated sludge were determined. The acclimated activated sludge degradation rates were from one to two orders of magnitude higher than those of pure strains when uptake rates were calculated in terms of the viable biomass (CFU). The specific substrate uptake rate for acclimated activated sludge varied between 8.2 and 15.8 × 10−7 mg/CFU·d (407-784 mg/gVSS·d). Aeromonas sp. had the highest specific substrate uptake rate of the pure strains, based on a VSS basis (33-57 mg/gVSS·d) but, in terms of viable biomass (5.0-15.6 × 10−8 mg/CFU·d), the Pseudomonas sp. rate was the highest. Specific substrate uptake rates were 1.8 mg chlorinated phenols/g VSS·d for unacclimated activated sludge.

scholarly journals Antibiotic Selection Pressure and Resistance inStreptococcus pneumoniaeandStreptococcus pyogenes

2004 ◽  
Vol 10 (3) ◽  
pp. 514-517 ◽  
Author(s):  
Werner C. Albrich ◽  
Dominique L. Monnet ◽  
Stephan Harbarth
Keyword(s):  
Selection Pressure ◽  
Antibiotic Selection ◽  
Antibiotic Selection Pressure
Sign in / Sign up

Export Citation Format

Share Document