scholarly journals Over 2000-fold increased production of the leaderless bacteriocin garvicin KS by genetic engineering and optimization of culture conditions

2018 ◽  
Author(s):  
Amar A. Telke ◽  
Kirill V. Ovchinnikov ◽  
Kiira S. Vuoristo ◽  
Geir Mathiesen ◽  
Tage Thorstensen ◽  
...  
Keyword(s):  
Growth Conditions ◽  
Culture Conditions ◽  
Research Field ◽  
Bacteriocin Production ◽  
Gene Dose ◽  
Constant Ph ◽  
Wide Range ◽  
Bottle Neck ◽  
High Production ◽  
The Impact

AbstractThe leaderless bacteriocin Garvicin KS (GarKS) is a potent antimicrobial, being active against a wide range of important pathogens. GarKS production by the native producerLactococcus garvieaeKS1546 was however relatively low (80 BU/ml) under standard laboratory growth conditions (batch culture in GM17 at 30°C). To improve the production of GarKS, we systematically evaluated the impact of different media and media components on bacteriocin production. Based on the outcomes a new medium formulation was made to greatly improve bacteriocin production. The new medium composed of pasteurized milk and tryptone (PM-T), increased GarKS production about 60-fold compared to that achieved in GM17. GarKS production was increased further 4-fold (i.e., to 20,000 BU/ml) by increasing gene dose of the bacteriocin gene cluster (gak) in the native producer. Finally, a combination of the newly composed medium (PM-T), an increased gene dose and a cultivation at a constant pH 6 and a 50-60% dissolved oxygen level in growth medium, gave rise to a GarKS production of 164,000 BU/ml. This high production, which is about 2000-fold higher compared to that initially achieved in GM17, corresponds to a GarKS production of 1.2 g/L. To our knowledge, this is one of the highest bacteriocin production reported hitherto.ImportanceLow bacteriocin production is a well-known bottle-neck in developing bacteriocins into large-scaled and useful applications. The present study shows different approaches that significantly improve bacteriocin production. This is an important research field to better exploit the antimicrobial potential of bacteriocins, especially with regard to the decreasing effect of antibiotics in infection treatments due to the global emergence of antibiotic resistance.

scholarly journals Impact of culture condition modulation on the high-yield, high-specificity and cost-effective production of terpenoids from microbial sources: A review

2020 ◽  
Author(s):  
Vibha Shukla ◽  
Suresh Chandra Phulara
Keyword(s):  
Physicochemical Parameters ◽  
High Specificity ◽  
Cost Effective ◽  
Fermentation Medium ◽  
Culture Conditions ◽  
High Yield ◽  
Native Form ◽  
Yield Production ◽  
Wide Range ◽  
The Impact

Recent years have seen a remarkable increase in the non-natural production of terpenoids from microbial route. This is due to the advancements in synthetic biology tools and techniques, which have overcome the challenges associated with the non-native production of terpenoids from microbial hosts. Although, microbes in their native form have ability to grow in wide range of physicochemical parameters such as, pH, temperature, agitation, aeration etc; however, after genetic modifications, culture conditions need to be optimized in order to achieve improved titers of desired terpenoids from engineered microbes. The physicochemical parameters together with medium supplements, such as, inducer, carbon and nitrogen source, and cofactor supply not only play an important role in high-yield production of target terpenoids from engineered host, but also reduce the accumulation of undesired metabolites in fermentation medium, thus facilitate product recovery. Further, for the economic production of terpenoids, the biomass derived sugars can be utilized together with the optimized culture conditions. In the present mini-review, we have highlighted the impact of culture conditions modulation on the high-yield and high-specificity production of terpenoids from engineered microbes. Lastly, utilization of economic feedstock has also been discussed for the cost-effective and sustainable production of terpenoids.

scholarly journals Antibiotic Susceptibility of Bartonella Grown in Different Culture Conditions

Pathogens ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 718
Author(s):  
Shiva Kumar Goud Gadila ◽  
Monica E. Embers
Keyword(s):  
Antibiotic Susceptibility ◽  
Acute Infection ◽  
Standard Of Care ◽  
Growth Conditions ◽  
Culture Conditions ◽  
Intracellular Growth ◽  
Current Standard ◽  
Life Threatening Illness ◽  
Life Threatening ◽  
The Impact

Bartonellosis is caused by a Gram-negative intracellular bacterium with a zoonotic transmission. The disease, caused by any of several genospecies of Bartonella can range from a benign, self-limited condition to a highly morbid and life-threatening illness. The current standard of care antibiotics are generally effective in acute infection; these include azithromycin or erythromycin, doxycycline, gentamicin, rifampin, and ciprofloxacin. However, treatment of chronic infection remains problematic. We tested six different antibiotics for their ability to stop the growth of Bartonella sp. in the standard insect media and in an enrichment media. All antibiotics (ceftriaxone, doxycycline, gentamycin, azithromycin, ampicillin, and azlocillin) had minimum inhibitory concentrations (MICs) below 0.5 µg/mL in the BAPGM enrichment media but were ineffective at inhibiting growth when the standard insect media was used. Azlocillin was the most potent, with a MIC of 0.01 µg/mL. When Bartonella was tested under intracellular growth conditions, none of the antibiotics were efficacious singly. However, growth inhibition was observed when azlocillin and azithromycin were combined. These studies illustrate the impact of growth medium and intracellular environment on antibiotic susceptibility testing and indicate that azlocillin combined with azithromycin may be an effective drug combination for the treatment of Bartonellosis.

scholarly journals In VitroCulture Conditions for Maintaining a Complex Population of Human Gastrointestinal Tract Microbiota

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Bong-Soo Kim ◽  
Jong Nam Kim ◽  
Carl E. Cerniglia
Keyword(s):  
Gastrointestinal Tract ◽  
Bacterial Community ◽  
Intestinal Microbiota ◽  
Brain Heart Infusion ◽  
Culture Conditions ◽  
Human Gastrointestinal Tract ◽  
Gastrointestinal Microbiota ◽  
Wide Range ◽  
The Impact

A stable intestinal microbiota is important in maintaining human physiology and health. Although there have been a number of studies usingin vitroandin vivoapproaches to determine the impact of diet and xenobiotics on intestinal microbiota, there is no consensus for the bestin vitroculture conditions for growth of the human gastrointestinal microbiota. To investigate the dynamics and activities of intestinal microbiota, it is important for the culture conditions to support the growth of a wide range of intestinal bacteria and maintain a complex microbial community representative of the human gastrointestinal tract. Here, we compared the bacterial community in three culture media: brain heart infusion broth and high- and low-carbohydrate medium with different growth supplements. The bacterial community was analyzed using denaturing gradient gel electrophoresis (DGGE), pyrosequencing and real-time PCR. Based on the molecular analysis, this study indicated that the 3% fecal inoculum in low-concentration carbohydrate medium with 1% autoclaved fecal supernatant provided enhanced growth conditions to conductin vitrostudies representative of the human intestinal microbiota.

Philosophical Framing and Its Impact on Research

Crowdsourcing ◽  
2019 ◽  
pp. 1451-1468
Author(s):  
Eileen M. Trauth ◽  
Lee B. Erickson
Keyword(s):  
Academic Research ◽  
Research Process ◽  
Research Field ◽  
Clear Understanding ◽  
Wide Range ◽  
Stakeholder Perspective ◽  
Alternative Research ◽  
Key Dimensions ◽  
Use Of Social Media ◽  
The Impact

The variety of lenses and openness that is brought to the research process shapes both academic research and the application of knowledge to real-world settings. Researchers who endeavor to contribute both rigor and relevance require a wide range of methodological tools and a clear understanding of how such tools frame the questions to be answered, as well as the methods used and potential outcomes. It is important that both researchers and publication gatekeepers clearly understand the impact of philosophical framing on research methods and findings. Drawing on research related to the use of social media to facilitate product innovation “crowdsourcing,” the authors consider the implications of alternative research scenarios on five key dimensions of research: epistemology, theory, review of literature, stakeholder perspective, and rigor-relevance. Examples of existing and emergent topics within the research field of crowdsourcing are provided to illustrate methodological pluralism.

Philosophical Framing and Its Impact on Research

2012 ◽  
pp. 1-17
Author(s):  
Eileen M. Trauth ◽  
Lee B. Erickson
Keyword(s):  
Academic Research ◽  
Research Process ◽  
Research Field ◽  
Clear Understanding ◽  
Wide Range ◽  
Stakeholder Perspective ◽  
Alternative Research ◽  
Key Dimensions ◽  
Use Of Social Media ◽  
The Impact

The variety of lenses and openness that is brought to the research process shapes both academic research and the application of knowledge to real-world settings. Researchers who endeavor to contribute both rigor and relevance require a wide range of methodological tools and a clear understanding of how such tools frame the questions to be answered, as well as the methods used and potential outcomes. It is important that both researchers and publication gatekeepers clearly understand the impact of philosophical framing on research methods and findings. Drawing on research related to the use of social media to facilitate product innovation “crowdsourcing,” the authors consider the implications of alternative research scenarios on five key dimensions of research: epistemology, theory, review of literature, stakeholder perspective, and rigor-relevance. Examples of existing and emergent topics within the research field of crowdsourcing are provided to illustrate methodological pluralism.

scholarly journals Pre-Growth Culture Conditions Affect Type 1 Fimbriae-Dependent Adhesion of Salmonella

2020 ◽  
Vol 21 (12) ◽  
pp. 4206 ◽  
Author(s):  
Beata Klasa ◽  
Anna Ewa Kędzierska ◽  
Krzysztof Grzymajło
Keyword(s):  
Growth Conditions ◽  
Culture Conditions ◽  
Infection Process ◽  
Intestinal Epithelial ◽  
Exact Role ◽  
Type 1 Fimbriae ◽  
Wide Range ◽  
Host Cell Interactions ◽  
Host Tissues

Among various fimbrial structures used by Salmonella enterica to colonize host tissues, type 1 fimbriae (T1F) are among the most extensively studied. Although some experiments have shown the importance of T1F in the initial stages of Salmonella infection, their exact role in the infection process is not fully known. We suggested that different outcomes of T1F investigations were due to the use of different pre-infection growth conditions for the induction of the T1F. We utilized qPCR, flow cytometry, and a wide range of adhesion assays to investigate Salmonella Choleraesuis and Salmonella Typhimurium adhesion in the context of T1F expression. We demonstrated that T1F expression was highly dependent on the pre-infection growth conditions. These growth conditions yielded T1F+ and T1F- populations of Salmonella and, therefore, could be a factor influencing Salmonella-host cell interactions. We supported this conclusion by showing that increased levels of T1F expression directly correlated with higher levels of Salmonella adherence to the intestinal epithelial IPEC-J2 cell line.

scholarly journals Growth Culture Conditions and Nutrient Signaling Modulating Yeast Chronological Longevity

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Júlia Santos ◽  
Cecília Leão ◽  
Maria João Sousa
Keyword(s):  
Signaling Pathways ◽  
Culture Medium ◽  
Culture Media ◽  
Growth Conditions ◽  
Culture Conditions ◽  
Induce Cell Death ◽  
Yeast Aging ◽  
Nutrient Signaling ◽  
Multicellular Organisms ◽  
The Impact

The manipulation of nutrient-signaling pathways in yeast has uncovered the impact of environmental growth conditions in longevity. Studies using calorie restriction show that reducing glucose concentration of the culture media is sufficient to increase replicative and chronological lifespan (CLS). Other components of the culture media and factors such as the products of fermentation have also been implicated in the regulation of CLS. Acidification of the culture media mainly due to acetic acid and other organic acids production negatively impacts CLS. Ethanol is another fermentative metabolite capable of inducing CLS reduction in aged cells by yet unknown mechanisms. Recently, ammonium was reported to induce cell death associated with shortening of CLS. This effect is correlated to the concentration ofNH4+added to the culture medium and is particularly evident in cells starved for auxotrophy-complementing amino acids. Studies on the nutrient-signaling pathways regulating yeast aging had a significant impact on aging-related research, providing key insights into mechanisms that modulate aging and establishing the yeast as a powerful system to extend knowledge on longevity regulation in multicellular organisms.

THE IMPACT OF LEADERSHIP PRACTICES TO TEAM MEMBERS’ SATISFACTION

2009 ◽  
Vol 8 (1) ◽  
Author(s):  
Chalimah .
Keyword(s):  
Conflict Resolution ◽  
Leadership Practices ◽  
Hotel Industry ◽  
Leader Behavior ◽  
Team Leader ◽  
Shop Floor ◽  
Team Members ◽  
Top Executives ◽  
Wide Range ◽  
The Impact

eamwork is becoming increasingly important to wide range of operations. It applies to all levels of the company. It is just as important for top executives as it is to middle management, supervisors and shop floor workers. Poor teamwork at any level or between levels can seriously damage organizational effectiveness. The focus of this paper was therefore to examine whether leadership practices consist of team leader behavior, conflict resolution style and openness in communication significantly influenced the team member’s satisfaction in hotel industry. Result indicates that team leader behavior and the conflict resolution style significantly influenced team member satisfaction. It was surprising that openness in communication did not affect significantly to the team members’ satisfaction.

Constant pH Molecular Dynamics Reveals How Proton Release Drives the Conformational Transition of a Transmembrane Efflux Pump

2017 ◽  
Author(s):  
Jana Shen ◽  
Zhi Yue ◽  
Helen Zgurskaya ◽  
Wei Chen
Keyword(s):  
Molecular Dynamics ◽  
Conformational Changes ◽  
Transmembrane Domain ◽  
Conformational Transition ◽  
Conformational Dynamics ◽  
Proton Release ◽  
Intrinsic Resistance ◽  
Constant Ph ◽  
Wide Range ◽  
Constant Ph Molecular Dynamics

AcrB is the inner-membrane transporter of E. coli AcrAB-TolC tripartite efflux complex, which plays a major role in the intrinsic resistance to clinically important antibiotics. AcrB pumps a wide range of toxic substrates by utilizing the proton gradient between periplasm and cytoplasm. Crystal structures of AcrB revealed three distinct conformational states of the transport cycle, substrate access, binding and extrusion, or loose (L), tight (T) and open (O) states. However, the specific residue(s) responsible for proton binding/release and the mechanism of proton-coupled conformational cycling remain controversial. Here we use the newly developed membrane hybrid-solvent continuous constant pH molecular dynamics technique to explore the protonation states and conformational dynamics of the transmembrane domain of AcrB. Simulations show that both Asp407 and Asp408 are deprotonated in the L/T states, while only Asp408 is protonated in the O state. Remarkably, release of a proton from Asp408 in the O state results in large conformational changes, such as the lateral and vertical movement of transmembrane helices as well as the salt-bridge formation between Asp408 and Lys940 and other sidechain rearrangements among essential residues.Consistent with the crystallographic differences between the O and L protomers, simulations offer dynamic details of how proton release drives the O-to-L transition in AcrB and address the controversy regarding the proton/drug stoichiometry. This work offers a significant step towards characterizing the complete cycle of proton-coupled drug transport in AcrB and further validates the membrane hybrid-solvent CpHMD technique for studies of proton-coupled transmembrane proteins which are currently poorly understood. <p><br></p>

Stress, anxiety, depression and burnout in frontline health care workers during COVID-19 pandemic: a brief systematic review and new data from Russia

2021 ◽  
Author(s):  
Ekaterina Mosolova ◽  
Dmitry Sosin ◽  
Sergey Mosolov
Keyword(s):  
Risk Factors ◽  
Systematic Review ◽  
Female Gender ◽  
Assessment Tools ◽  
Care Workers ◽  
Younger Age ◽  
Wide Range ◽  
Associated Risk Factors ◽  
Anxiety Depression ◽  
The Impact

During the COVID-19 pandemic, healthcare workers (HCWs) have been subject to increased workload while also exposed to many psychosocial stressors. In a systematic review we analyze the impact that the pandemic has had on HCWs mental state and associated risk factors. Most studies reported high levels of depression and anxiety among HCWs worldwide, however, due to a wide range of assessment tools, cut-off scores, and number of frontline participants in the studies, results were difficult to compare. Our study is based on two online surveys of 2195 HCWs from different regions of Russia during spring and autumn epidemic outbreaks revealed the rates of anxiety, stress, depression, emotional exhaustion and depersonalization and perceived stress as 32.3%, 31.1%, 45.5%, 74.2%, 37.7% ,67.8%, respectively. Moreover, 2.4% of HCWs reported suicidal thoughts. The most common risk factors include: female gender, nurse as an occupation, younger age, working for over 6 months, chronic diseases, smoking, high working demands, lack of personal protective equipment, low salary, lack of social support, isolation from families, the fear of relatives getting infected. These results demonstrate the need for urgent supportive programs for HCWs fighting COVID-19 that fall into higher risk factors groups.

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