scholarly journals Klebsiella pneumoniae—A Useful Pathogenic Strain for Biotechnological Purposes: Diols Biosynthesis under Controlled and Uncontrolled pH Levels

Pathogens ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 293 ◽  
Author(s):  
Laura Mitrea ◽  
Dan Cristian Vodnar
Keyword(s):  
Klebsiella Pneumoniae ◽  
Ph Value ◽  
Cell Factory ◽  
Anaerobic Conditions ◽  
Liquid Media ◽  
Microbial Cell Factory ◽  
Substrate Consumption ◽  
Main Carbon Source ◽  
Ph Level ◽  
Main Carbon

Despite being a well-known human pathogen, Klebsiella pneumoniae plays a significant role in the biotechnology field, being considered as a microbial cell factory in terms of valuable chemical biosynthesis. In this work, Klebsiella pneumoniae DSMZ 2026 was investigated for its potential to biosynthesize 1,3-propanediol (PDO) and 2,3-butanediol (BDO) during batch fermentation under controlled and uncontrolled pH levels. The bacterial strain was cultivated at a bioreactor level, and it was inoculated in 2 L of specific mineral broth containing 50 g/L of glycerol as the main carbon source. The process was conducted under anaerobic conditions at 37 °C and 180 RPM (rotations per minute) for 24 h. The effect of pH oscillation on the biosynthesis of PDO and BDO was investigated. Samples were taken every 3 h and specific tests were performed: pH measurement, main substrate consumption, PDO and BDO production. The cell morphology was analyzed on both solid and liquid media. After 24 h of cultivation, the maximum concentrations of PDO and BDO were 28.63 ± 2.20 g/L and 18.10 ± 1.10 g/L when the pH value was maintained at 7. Decreased concentrations of PDO and BDO were achieved (11.08 ± 0.14 g/L and 7.35 ± 0.00 g/L, respectively) when the pH level was not maintained at constant values. Moreover, it was identified the presence of other metabolites (lactic, citric, and succinic acids) in the cultivation media at the beginning of the process, after 12 h and 24 h of cultivation.

scholarly journals Klebsiella pneumoniae – a useful pathogenic strain for biotechnological purposes: 1,3-propanediol biosynthesis

2019 ◽  
Author(s):  
Laura MITREA ◽  
Monica TRIF ◽  
Alexandru RUSU ◽  
Dan-Cristian Vodnar
Keyword(s):  
Klebsiella Pneumoniae ◽  
Intermediate Compound ◽  
Batch Cultivation ◽  
Culture Broth ◽  
Blue Staining ◽  
Cell Factory ◽  
Microbial Cell Factory ◽  
Batch Bioreactor ◽  
Wet Biomass ◽  
Important Intermediate

Abstract Background Despite being a well-known human pathogen, Klebsiella pneumoniae plays a significant role in the biotechnology field, being considered as a microbial cell factory in terms of valuable chemicals biosynthesis. In fermentation processes, K. pneumoniae is mostly used to biosynthesize 1,3-propanediol (PDO), a very important intermediate compound utilized in the biodegradable bioplastics industry. This strain owns the ability to metabolize glycerol and to produce PDO under both aerobic and anaerobic circumstances, and under low oscillations of pH. Results In this work, we investigated the K. pneumoniae strain DSMZ 2026 in batch bioreactor cultivation. The bacterial strain was inoculated in 2 L culture broth containing 43.5 g·L- 1 main substrate and the pH was adjusted at 7 at the beginning of the process. After 12 h of batch cultivation, the pH values decreased to 4.77, and we obtained 51 g·L-1 wet biomass, 17 g·L-1 PDO, while the starting substrate reached 15 g·L- 1. The morphology of K. pneumoniae cells was analyzed on both solid and liquid media, by being identified large mucoid colonies on Columbia agar, and individual and grouped cells were observed by methyl blue staining. Conclusion From this study it can be concluded that K. pneumoniae can grow successfully in mineral broth under anaerobic environment and low decrease of pH, and can biosynthesize valuable chemicals like PDO.

scholarly journals Genome-scale target identification in Escherichia coli for high-titer production of free fatty acids

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lixia Fang ◽  
Jie Fan ◽  
Shulei Luo ◽  
Yaru Chen ◽  
Congya Wang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Fatty Acids ◽  
Free Fatty Acids ◽  
Stress Responses ◽  
Metabolic Networks ◽  
Target Identification ◽  
High Titer ◽  
Cell Factory ◽  
Microbial Cell Factory ◽  
Ffa Metabolism

AbstractTo construct a superior microbial cell factory for chemical synthesis, a major challenge is to fully exploit cellular potential by identifying and engineering beneficial gene targets in sophisticated metabolic networks. Here, we take advantage of CRISPR interference (CRISPRi) and omics analyses to systematically identify beneficial genes that can be engineered to promote free fatty acids (FFAs) production in Escherichia coli. CRISPRi-mediated genetic perturbation enables the identification of 30 beneficial genes from 108 targets related to FFA metabolism. Then, omics analyses of the FFAs-overproducing strains and a control strain enable the identification of another 26 beneficial genes that are seemingly irrelevant to FFA metabolism. Combinatorial perturbation of four beneficial genes involving cellular stress responses results in a recombinant strain ihfAL−-aidB+-ryfAM−-gadAH−, producing 30.0 g L−1 FFAs in fed-batch fermentation, the maximum titer in E. coli reported to date. Our findings are of help in rewiring cellular metabolism and interwoven intracellular processes to facilitate high-titer production of biochemicals.

scholarly journals Metabolic engineering of Escherichia coli for de novo production of 3-phenylpropanol via retrobiosynthesis approach

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Zhenning Liu ◽  
Xue Zhang ◽  
Dengwei Lei ◽  
Bin Qiao ◽  
Guang-Rong Zhao
Keyword(s):  
Escherichia Coli ◽  
Metabolic Engineering ◽  
De Novo ◽  
Microbial Cell ◽  
Cell Factory ◽  
Phosphopantetheinyl Transferase ◽  
Chromosome Engineering ◽  
Microbial Cell Factory ◽  
E Coli ◽  
Artificial Pathway

Abstract Background 3-Phenylpropanol with a pleasant odor is widely used in foods, beverages and cosmetics as a fragrance ingredient. It also acts as the precursor and reactant in pharmaceutical and chemical industries. Currently, petroleum-based manufacturing processes of 3-phenypropanol is environmentally unfriendly and unsustainable. In this study, we aim to engineer Escherichia coli as microbial cell factory for de novo production of 3-phenypropanol via retrobiosynthesis approach. Results Aided by in silico retrobiosynthesis analysis, we designed a novel 3-phenylpropanol biosynthetic pathway extending from l-phenylalanine and comprising the phenylalanine ammonia lyase (PAL), enoate reductase (ER), aryl carboxylic acid reductase (CAR) and phosphopantetheinyl transferase (PPTase). We screened the enzymes from plants and microorganisms and reconstructed the artificial pathway for conversion of 3-phenylpropanol from l-phenylalanine. Then we conducted chromosome engineering to increase the supply of precursor l-phenylalanine and combined the upstream l-phenylalanine pathway and downstream 3-phenylpropanol pathway. Finally, we regulated the metabolic pathway strength and optimized fermentation conditions. As a consequence, metabolically engineered E. coli strain produced 847.97 mg/L of 3-phenypropanol at 24 h using glucose-glycerol mixture as co-carbon source. Conclusions We successfully developed an artificial 3-phenylpropanol pathway based on retrobiosynthesis approach, and highest titer of 3-phenylpropanol was achieved in E. coli via systems metabolic engineering strategies including enzyme sources variety, chromosome engineering, metabolic strength balancing and fermentation optimization. This work provides an engineered strain with industrial potential for production of 3-phenylpropanol, and the strategies applied here could be practical for bioengineers to design and reconstruct the microbial cell factory for high valuable chemicals.

scholarly journals A β-d-fructofuranosidase from Claviceps purpurea

1972 ◽  
Vol 129 (2) ◽  
pp. 263-272 ◽  
Author(s):  
A. G. Dickerson
Keyword(s):  
Carbon Source ◽  
Dual Role ◽  
Claviceps Purpurea ◽  
Time Transfer ◽  
Main Carbon Source ◽  
Main Carbon

Evidence suggests that sucrose is the main carbon source for growth of Claviceps spp. in the parasitic condition. The sucrose acts as substrate for an active β-fructofuranosidase, produced by the fungus, which in the first instance converts the disaccharide into glucose and an oligofructoside. In this way, 50% of the glucose, supplied as sucrose, is made available to the parasite for assimilation. Subsequent action of the enzyme on both sucrose and the oligofructoside leads to the release of more glucose and the formation of additional oligosaccharides. The structures of the main oligosaccharides formed have been elucidated and the interactions of each compound studied. In experiments with purified enzyme in vitro the interaction of the oligosaccharides is rapid but in culture they are assimilated only slowly; in each case some free fructose is liberated. Free fructose is not assimilated in the presence of glucose and, further, inhibits growth at concentrations which might be expected to occur in the parasitic condition. A dual role has been suggested for the enzyme, with sucrose as substrate, in which glucose is made available to the growing parasite, while at the same time transfer of the fructose to form oligosaccharides prevents it from accumulating at inhibitory concentrations. Ultimately, when glucose becomes limiting, the fungus will adapt to fructose assimilation.

scholarly journals Influence of thermal treatment and combustible additives on properties of Latvian clay ceramics pellets

2013 ◽  
Vol 7 (4) ◽  
pp. 175-180 ◽  
Author(s):  
Liga Dabare ◽  
Ruta Svinka
Keyword(s):  
Surface Area ◽  
Ph Value ◽  
Water Solution ◽  
Porous Ceramic ◽  
Mercury Porosimetry ◽  
Environmental Application ◽  
Wide Range ◽  
Different Temperatures ◽  
Ph Level ◽  
Clay Ceramics

Porous ceramic pellets for possible environmental application were produced from different Latvian clays by sintering at different temperatures. Their characteristics and influence of additives were analysed using X-ray diffraction, mercury porosimetry and BET tests. The obtained ceramic pellets from calcareous clays after immersion in distilled water change its pH value, which affects their capability to adsorb ions or molecules on the surface. The sorption capabilities are dependent on the pH level of water solution, composition of clays, and used adsorbate. Porosity of the produced pellets is mostly within range from 15 to 25 % throughout all sintering temperatures with a slight decrease at 1050 ?C. The specific surface area has a wide range up to 30 m2/g. The highest surface area has pellets sintered at lower temperatures. The adsorption capability of pellets was evaluated using water solutions with different ions. The most promising results were obtained with iodine sorption. For most pellets the sorption capacity was 12.7 mg/g, although for the pellets sintered at 1050 ?C it was lower.

scholarly journals Changes in Oxygen Availability during Glucose-Limited Chemostat Cultivations of Penicillium chrysogenum Lead to Rapid Metabolite, Flux and Productivity Responses

Metabolites ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 45
Author(s):  
Qi Yang ◽  
Wenli Lin ◽  
Jiawei Xu ◽  
Nan Guo ◽  
Jiachen Zhao ◽  
...  
Keyword(s):  
Steady State ◽  
Dissolved Oxygen ◽  
Penicillium Chrysogenum ◽  
Large Scale ◽  
Scale Up ◽  
Redox Status ◽  
Oxygen Availability ◽  
Industrial Scale ◽  
Cell Factory ◽  
Microbial Cell Factory

Bioreactor scale-up from the laboratory scale to the industrial scale has always been a pivotal step in bioprocess development. However, the transition of a bioeconomy from innovation to commercialization is often hampered by performance loss in titer, rate and yield. These are often ascribed to temporal variations of substrate and dissolved oxygen (for instance) in the environment, experienced by microorganisms at the industrial scale. Oscillations in dissolved oxygen (DO) concentration are not uncommon. Furthermore, these fluctuations can be exacerbated with poor mixing and mass transfer limitations, especially in fermentations with filamentous fungus as the microbial cell factory. In this work, the response of glucose-limited chemostat cultures of an industrial Penicillium chrysogenum strain to different dissolved oxygen levels was assessed under both DO shift-down (60% → 20%, 10% and 5%) and DO ramp-down (60% → 0% in 24 h) conditions. Collectively, the results revealed that the penicillin productivity decreased as the DO level dropped down below 20%, while the byproducts, e.g., 6-oxopiperidine-2-carboxylic acid (OPC) and 6-aminopenicillanic acid (6APA), accumulated. Following DO ramp-down, penicillin productivity under DO shift-up experiments returned to its maximum value in 60 h when the DO was reset to 60%. The result showed that a higher cytosolic redox status, indicated by NADH/NAD+, was observed in the presence of insufficient oxygen supply. Consistent with this, flux balance analysis indicated that the flux through the glyoxylate shunt was increased by a factor of 50 at a DO value of 5% compared to the reference control, favoring the maintenance of redox status. Interestingly, it was observed that, in comparison with the reference control, the penicillin productivity was reduced by 25% at a DO value of 5% under steady state conditions. Only a 14% reduction in penicillin productivity was observed as the DO level was ramped down to 0. Furthermore, intracellular levels of amino acids were less sensitive to DO levels at DO shift-down relative to DO ramp-down conditions; this difference could be caused by different timescales between turnover rates of amino acid pools (tens of seconds to minutes) and DO switches (hours to days at steady state and minutes to hours at ramp-down). In summary, this study showed that changes in oxygen availability can lead to rapid metabolite, flux and productivity responses, and dynamic DO perturbations could provide insight into understanding of metabolic responses in large-scale bioreactors.

Engineering the CBB cycle and hydrogen utilization pathway of Ralstonia eutropha H16 for improved autotrophic growth and PHB production

2020 ◽  
Author(s):  
Zhongkang Li ◽  
Muzi Hu ◽  
Bin Xiong ◽  
Dongdong Zhao ◽  
Chunzhi Zhang ◽  
...  
Keyword(s):  
Carbon Fixation ◽  
Ralstonia Eutropha ◽  
Biological Research ◽  
Industrial Biotechnology ◽  
Cell Factory ◽  
Autotrophic Growth ◽  
Microbial Cell Factory ◽  
Knock Out ◽  
Ralstonia Eutropha H16 ◽  
Living Organisms

Abstract CO 2 is fixed by all living organisms with an autotrophic metabolism, among which the Calvin-Benson-Bassham ( CBB) cycle is the most important and widespread carbon fixation pathway. Thus, studying and engineering the CBB cycle with the associated energy providing pathways to increase the CO 2 fixation efficiency of cells is an important subject of biological research with significant application potential. In this work, the autotrophic microbe Ralstonia eutropha H16 was selected as a research platform for CBB cycle optimization engineering. By knocking out either CBB operon genes on the operon or mega-plasmid of R. eutropha , we found that both CBB operons were active and contributed almost equally to the carbon fixation process. With similar knock-out experiments, we found while both soluble and membrane-bound hydrogenases (SH and MBH), belonging to the energy providing hydrogenase module, were f unctional d uring autotrophic growth of R. eutropha. And SH played a more significant role. By introducing a heterologous cyanobacterial RuBisCO with the endogenous GroES/EL chaperone system and RbcX, the culture OD 600 of engineered strain increased 89.15% after 72 hours of autotrophic growth, indicating cyanobacterial RuBisCO with a higher activity was functional in R. eutropha and improved upon original CBB pathway. Meanwhile, expression of hydrogenases were optimized by modulating the expression of MBH and SH, which could further increase the R. eutropha H16 culture OD 600 to 93.4% at 72 hours. Moreover, the autotrophic yield of its major industrially relevant product, polyhydroxybutyrate (PHB), was increased by 99.71%. To our best knowledge, this is the first report of successfully engineering the CBB pathway of R. eutropha for improved activity , and is one of only a few cases where the efficiency of CO 2 assimilation pathway was improved. Our work demonstrates that R. eutropha is an extremely useful platform for studying and engineering the CBB for applications in more important organisms, such as agricultural crops, and a potential microbial cell factory to develop industrial biotechnology for sequestrating CO 2 .

Soil: Microbial Cell Factory for Assortment with Beneficial Role in Agriculture

2019 ◽  
pp. 63-92 ◽  
Author(s):  
Pratiksha Singh ◽  
Rajesh Kumar Singh ◽  
Mohini Prabha Singh ◽  
Qi Qi Song ◽  
Manoj K. Solanki ◽  
...  
Keyword(s):  
Microbial Cell ◽  
Cell Factory ◽  
Microbial Cell Factory ◽  
Soil Microbial ◽  
Beneficial Role
Sign in / Sign up

Export Citation Format

Share Document