scholarly journals Manipulation of pH Shift to Enhance the Growth and Antibiotic Activity ofXenorhabdus nematophila

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Yonghong Wang ◽  
Xiangling Fang ◽  
Yongpeng Cheng ◽  
Xing Zhang
Keyword(s):  
Cell Growth ◽  
Control Strategy ◽  
Antibiotic Production ◽  
Ph Control ◽  
Antibiotic Activity ◽  
Ph Effects ◽  
Xenorhabdus Nematophila ◽  
Ph Shift ◽  
Constant Ph ◽  
Initial Ph

To evaluate the effects of pH control strategy on cell growth and the production of antibiotic (cyclo(2-Me-BABA-Gly)) byXenorhabdus nematophilaand enhance the antibiotic activity. The effects of uncontrolled- (different initial pH) and controlled-pH (different constant pH and pH-shift) operations on cell growth and antibiotic activity ofX. nematophilaYL00I were examined. Experiments showed that the optimal initial pH for cell growth and antibiotic production ofX. nematophilaYL001 occurred at 7.0. Under different constant pH, a pH level of 7.5 was found to be optimal for biomass and antibiotic activity at 23.71 g/L and 100.0 U/mL, respectively. Based on the kinetic information relating to the different constant pH effects on the fermentation ofX. nematophilaYL001, a two-stage pH control strategy in which pH 6.5 was maintained for the first 24 h, and then switched to 7.5 after 24 h, was established to improve biomass production and antibiotic activity. By applying this pH-shift strategy, the maximal antibiotic activity and productivity were significantly improved and reaching 185.0 U/mL and 4.41 U/mL/h, respectively, compared to values obtained from constant pH operation (100.0 U/mL and 1.39 U/mL/h).

Resistance to streptomycin in a producing strain of Streptomyces griseus

1975 ◽  
Vol 21 (4) ◽  
pp. 463-472 ◽  
Author(s):  
R. Cella ◽  
L. C. Vining
Keyword(s):  
Protein Synthesis ◽  
Exponential Growth ◽  
Soluble Fraction ◽  
Antibiotic Production ◽  
Streptomyces Griseus ◽  
Antibiotic Activity ◽  
Reverse Direction ◽  
Ph Effects ◽  
Phosphatase Inhibitors ◽  
Production Phase

Streptomyces griseus S 104 was sensitive to streptomycin during exponential growth in a medium which, in the subsequent stationary phase, supported production of the antibiotic in yields above 200 μg/ml. When antibiotic production began cultures developed a tolerance toward their lethal metabolite. This was not due to an increase in pH associated with antibiotic production, since pH effects on streptomycin sensitivity in S. griseus were in the reverse direction. However, the degree of tolerance was directly related to the amount of cell material present. Streptomycin production caused no change in the proportion of resistant variants in the population, nor did it cause the severe inhibition of protein synthesis observed in non-producing cultures exposed to the antibiotic. The lack of an effect on protein synthesis is attributed to the absence of streptomycin within the cytoplasm since soluble extracts from mycelium harvested in the production phase were inactive when bioassayed immediately after cell disruption. However, they developed antibacterial activity rapidly when heated, and more slowly when incubated at 25 °C. The addition of phosphatase inhibitors during incubation prevented the appearance of antibiotic activity, and it was concluded that a small amount of streptomycin phosphate is present in the mycelium during antibiotic production. Differences in (14C) streptomycin uptake suggested that the mycelium was appreciably less permeable to the antibiotic in the production phase than during exponential growth. However, a small amount was taken up and much of it was in the soluble fraction of disrupted cells. Bioassays showed that this 14C-labeled antibiotic within the cells had been partially inactivated, suggesting that conversion of streptomycin to an inactive derivative is involved in the mechanism which protects the organism from its metabolite.

Preparation of a highly active form of nisin from Streptococcus lactis

1971 ◽  
Vol 17 (1) ◽  
pp. 61-67 ◽  
Author(s):  
F. J. Bailey ◽  
A. Hurst
Keyword(s):  
Active Form ◽  
Gradient Elution ◽  
Antibiotic Activity ◽  
Complex Medium ◽  
Main Peak ◽  
Acetone Precipitation ◽  
Highly Active ◽  
Streptococcus Lactis ◽  
Constant Ph ◽  
Ph Gradient Elution

Cells of Streptococcus lactis (354/07) synthesized and retained nisin when grown in a complex medium with 2.5% glucose at a constant pH of 6.7. Nisin was extracted from cells by a previously used method with hot 0.05 N HCl but milder methods of extraction from whole and broken cells using a variety of solvents were also tested. In the preferred method broken cells were extracted with 0.05 N HCl at 2 °C. The Cl− ions of the extract were exchanged for acetate on columns of the resin Amberlite CG 4B and the eluate was concentrated by acetone precipitation at −19 °C. The nisin was finally purified by pH gradient elution from CM cellulose columns. Three peaks with antibiotic activity were found, two of the peaks were minor and represented less than 5% of the nisin. The main peak gave a single band on electrophoresis. Electrophoresis of the material from the CM cellulose peaks revealed about 44 bands of basic proteins. Nisin made by the hot or cold HCl extraction behaved similarly in electrophoresis and CM cellulose chromatography but the antibiotic activity of the material isolated from the cold extract was nine times greater than that of the material isolated from the hot extract.

Acetone–butanol–ethanol production using pH control strategy and immobilized cells in an integrated fermentation–pervaporation process

2015 ◽  
Vol 50 (4) ◽  
pp. 614-622 ◽  
Author(s):  
Hao Wu ◽  
Ai-yong He ◽  
Xiang-ping Kong ◽  
Min Jiang ◽  
Xiao-peng Chen ◽  
...  
Keyword(s):  
Ethanol Production ◽  
Control Strategy ◽  
Immobilized Cells ◽  
Ph Control ◽  
Acetone Butanol Ethanol

scholarly journals Proliferation of Antibiotic-Producing Bacteria and Concomitant Antibiotic Production as the Basis for the Antibiotic Activity of Jordan's Red Soils

2009 ◽  
Vol 75 (9) ◽  
pp. 2735-2741 ◽  
Author(s):  
Joseph O. Falkinham ◽  
Thomas E. Wall ◽  
Justin R. Tanner ◽  
Khaled Tawaha ◽  
Feras Q. Alali ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Activity ◽  
Incubation Period ◽  
Micrococcus Luteus ◽  
Antibiotic Production ◽  
Antibiotic Activity ◽  
Skin Infections ◽  
High Antimicrobial Activity ◽  
Methanol Extracts ◽  
Red Soils

ABSTRACT Anecdotes, both historical and recent, recount the curing of skin infections, including diaper rash, by using red soils from the Hashemite Kingdom of Jordan. Following inoculation of red soils isolated from geographically separate areas of Jordan, Micrococcus luteus and Staphylococcus aureus were rapidly killed. Over the 3-week incubation period, the number of specific types of antibiotic-producing bacteria increased, and high antimicrobial activity (MIC, ∼10 μg/ml) was observed in methanol extracts of the inoculated red soils. Antibiotic-producing microorganisms whose numbers increased during incubation included actinomycetes, Lysobacter spp., and Bacillus spp. The actinomycetes produced actinomycin C2 and actinomycin C3. No myxobacteria or lytic bacteriophages with activity against either M. luteus or S. aureus were detected in either soil before or after inoculation and incubation. Although protozoa and amoebae were detected in the soils, the numbers were low and did not increase over the incubation period. These results suggest that the antibiotic activity of Jordan's red soils is due to the proliferation of antibiotic-producing bacteria.

scholarly journals Multiple strain analysis of Streptomyces species from Philippine marine sediments reveals intraspecies heterogeneity in antibiotic activities

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chuckcris P. Tenebro ◽  
Dana Joanne Von L. Trono ◽  
Carmela Vannette B. Vicera ◽  
Edna M. Sabido ◽  
Jovito A. Ysulat ◽  
...  
Keyword(s):  
16S Rrna ◽  
Marine Sediments ◽  
Marine Sediment ◽  
Antibiotic Production ◽  
Marine Ecosystem ◽  
Strain Analysis ◽  
Antibacterial Activities ◽  
Antibiotic Activity ◽  
Ecological Niches ◽  
Streptomyces Species

AbstractThe marine ecosystem has become the hotspot for finding antibiotic-producing actinomycetes across the globe. Although marine-derived actinomycetes display strain-level genomic and chemodiversity, it is unclear whether functional traits, i.e., antibiotic activity, vary in near-identical Streptomyces species. Here, we report culture-dependent isolation, antibiotic activity, phylogeny, biodiversity, abundance, and distribution of Streptomyces isolated from marine sediments across the west-central Philippines. Out of 2212 marine sediment-derived actinomycete strains isolated from 11 geographical sites, 92 strains exhibited antibacterial activities against multidrug-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. The 16S rRNA and rpoB gene sequence analyses confirmed that antibiotic-producing strains belong to the genus Streptomyces, highlighting Streptomyces parvulus as the most dominant species and three possible new species. Antibiotic-producing Streptomyces strains were highly diverse in Southern Antique, and species diversity increase with marine sediment depth. Multiple strains with near-identical 16S rRNA and rpoB gene sequences displayed varying strength of antibiotic activities. The genotyping of PKS and NRPS genes revealed that closely related antibiotic-producing strains have similar BGC domains supported by their close phylogenetic proximity. These findings collectively suggest Streptomyces' intraspecies adaptive characteristics in distinct ecological niches that resulted in outcompeting other bacteria through differential antibiotic production.

scholarly journals A Theoretical and Experimental Study of Electrochemical pH Control at Gold Interdigitated Microband Arrays

2021 ◽  
Author(s):  
Bernardo Patella ◽  
Robert Daly ◽  
Ian Seymour ◽  
Pierre Lovera ◽  
James Rohan ◽  
...  
Keyword(s):  
Electrode Array ◽  
Ph Control ◽  
Reduction Peak ◽  
Solution Ph ◽  
Ph Indicator ◽  
Ph Change ◽  
Initial Ph ◽  
The Impact ◽  
Strong Acids

In electroanalysis, solution pH is a critical parameter that often needs to be adjusted and controlled for the detection of particular analytes. This is most commonly performed by the addition of chemicals, such as strong acids or bases. Electrochemical in-situ pH control offers the possibility for the local adjustment of pH at the point of detection, without additional reagents. FEA simulations have been performed to guide experimental design for both electroanalysis and in-situ control of solution pH. No previous model exists that describes the generation of protons at an interdigitated electrode array in buffered solution with one comb acting as a protonator, and the other as the sensor. In this work, FEA models are developed to provide insight into the optimum conditions necessary for electrochemical pH control. The magnitude of applied galvanostatic current has a direct relation to the flux of protons generated and subsequent change in pH. Increasing the separation between the electrodes increases the time taken for protons to diffuse across the gap. The final pH achieved at both, protonators and sensor electrodes, after 1 second, was shown to be largely uninfluenced by the initial pH of the solution. The impact of buffer concentration was modelled and investigated. In practice, the pH at the electrode surface was probed by means of cyclic voltammetry, i.e., by cycling a gold electrode in solution and identifying the potential of the gold oxide reduction peak. A pH indicator, methyl red, was used to visualise the solution pH change at the electrodes, comparing well with the model’s prediction

Temperature and pH effects on Ca2+ sensitivity of cardiac myofibrils: a comparison of trout with mammals

1994 ◽  
Vol 267 (1) ◽  
pp. R62-R70 ◽  
Author(s):  
C. S. Churcott ◽  
C. D. Moyes ◽  
B. H. Bressler ◽  
K. M. Baldwin ◽  
G. F. Tibbits
Keyword(s):  
Mammalian Species ◽  
Contractile Element ◽  
Ph Effects ◽  
Myofibrillar Atpase ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Constant Ph ◽  
Calcium Affinity ◽  
Effects Of Temperature ◽  
Lower Temperature ◽  
Induced Changes

Active salmonids maintain myocardial contractility at temperatures that are cardioplegic for mammals. We postulated that myofibrillar Ca2+ sensitivity in the trout heart might 1) exhibit lower temperature dependence and/or 2) be greater over the range of physiological temperatures. Temperature-induced changes in intracellular pH may also play a role as alkalosis typically increases calcium affinity of myofibrillar adenosinetriphosphatase (ATPase). Ca2+ sensitivities of ventricular myofibrillar ATPase were determined in rats and in rainbow trout (Oncorhynchus mykiss) over a physiological range of pH and temperatures. Maximal myofibrillar ATPase activities of each species were similar and equally affected by temperature. Trout myofibrillar ATPase lost Ca2+ dependence at 37 degrees C. At constant pH, reduced temperature decreased calcium affinity more in trout (0.35 pCa/10 degrees C) than in rat (0.08-0.16 pCa/10 degrees C). Under alpha-stat conditions, the effects of temperature were reduced in both trout (0.2 pCa/10 degrees C) and rat (no significant effect). Over trout physiological temperatures, Ca2+ sensitivity was greater than rat at 37 degrees C. Qualitatively similar results were observed in studies measuring tension in skinned trout ventricular fibers. One mechanism by which the trout heart is able to maintain contractility at low temperatures is through the inherent higher Ca2+ sensitivity of the contractile element compared with mammalian species.

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