The Influence of pH and Lichen Metabolites (Vulpinic Acid and (+) Usnic Acid) on the Growth of the Lichen Photobiont Trebouxia 1rregularis.

1998 ◽  
Vol 30 (06) ◽  
pp. 577-582 ◽  
Author(s):  
M. Bačkor ◽  
J. Hudá ◽  
M. Repčák ◽  
W. Ziegler§ ◽  
M. Bačkorová
Keyword(s):  
Biomass Production ◽  
Culture Medium ◽  
Usnic Acid ◽  
Concentration Effect ◽  
Medium Ph ◽  
Ph Values ◽  
Lichen Metabolites ◽  
Influence Of Ph ◽  
Quantitative Response

AbstractThe quantitative response to two lichen metabolites, vulpinic acid and (+) usnic acid, on biomass production by the photobiontTrebouxia irregularis, isolated from the lichenCladina mitis, was determined experimentally. The presence of usnic acid resulted in inhibition of photobiont growth, and the effect depended on the pH of the culture medium. The concentration effect of usnic acid was observed. The application of vulpinic acid almost completely inhibited the growth ofT.irregularisand no significant differences were found among samples at different medium pH values.

The Influence of pH and Lichen Metabolites (Vulpinic Acid and (+) Usnic Acid) on the Growth of the Lichen Photobiont Trebouxia Irregularis

1992 ◽  
Vol 30 (6) ◽  
pp. 577-582 ◽  
Author(s):  
M. Bačkor ◽  
J. Hudá ◽  
M. Repčák ◽  
W. Ziegler§ ◽  
M. Bačkorová
Keyword(s):  
Biomass Production ◽  
Culture Medium ◽  
Usnic Acid ◽  
Concentration Effect ◽  
Medium Ph ◽  
Ph Values ◽  
Lichen Metabolites ◽  
Influence Of Ph ◽  
Quantitative Response

AbstractThe quantitative response to two lichen metabolites, vulpinic acid and (+) usnic acid, on biomass production by the photobiont Trebouxia irregularis, isolated from the lichen Cladina mitis, was determined experimentally. The presence of usnic acid resulted in inhibition of photobiont growth, and the effect depended on the pH of the culture medium. The concentration effect of usnic acid was observed. The application of vulpinic acid almost completely inhibited the growth of T.irregularis and no significant differences were found among samples at different medium pH values.

scholarly journals Strategies for improved rhamnolipid production by Pseudomonas aeruginosa PA1

2015 ◽  
Author(s):  
Alexandre Soares dos Santos ◽  
Nei Pereira Jr ◽  
Denise M G Freire
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Stationary Phase ◽  
Culture Medium ◽  
Fold Increase ◽  
Batch Process ◽  
Measurable Effect ◽  
Fed Batch ◽  
Batch Operation ◽  
Ph Values ◽  
Influence Of Ph

Rhamnolipids are biosurfactants with potential for diversified industrial and environmental uses. The present study evaluated three strategies to increase the production of rhamnolipid-type biosurfactants produced by Pseudomonas aeruginosa strain PA1. The influence of pH, the addition of endogenous autoinducers and the use of a fed batch process were examined. The culture medium adjusted to pH 7.0 was the most productive. Furthermore, the pH of the culture medium had a measurable effect on the ratio of mono- and dirhamnolipids synthesized. At pH values below 7.3, the proportion of monorhamnolipids decreased from 45 to 24%. Additionally, recycling 20% of the spent culture medium where P. aeruginosa was grown up to the later stationary phase was responsible for a 100% increase in rhamnolipid volumetric productivity in the new culture medium. Finally, the use of fed batch operation under conditions of limited nitrogen resulted in a 3.8-fold increase in the amount of rhamnolipids produced (1.29 g L-1 to 4.90 g L-1, as rhamnose). These results offer promising paths to optimize processes for the production of rhamnolipids.

scholarly journals Strategies for improved rhamnolipid production byPseudomonas aeruginosaPA1

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2078 ◽  
Author(s):  
Alexandre Soares dos Santos ◽  
Nei Pereira Jr ◽  
Denise M.G. Freire
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Stationary Phase ◽  
Culture Medium ◽  
Fold Increase ◽  
Batch Process ◽  
Measurable Effect ◽  
Fed Batch ◽  
Batch Operation ◽  
Ph Values ◽  
Influence Of Ph

Rhamnolipids are biosurfactants with potential for diversified industrial and environmental uses. The present study evaluated three strategies for increasing the production of rhamnolipid-type biosurfactants produced byPseudomonas aeruginosastrain PA1. The influence of pH, the addition ofP. aeruginosaspent culture medium and the use of a fed-batch process were examined. The culture medium adjusted to pH 7.0 was the most productive. Furthermore, the pH of the culture medium had a measurable effect on the ratio of synthesized mono- and dirhamnolipids. At pH values below 7.3, the proportion of monorhamnolipids decreased from 45 to 24%. The recycling of 20% of the spent culture medium in whereP. aeruginosawas grown up to the later stationary phase was responsible for a 100% increase in rhamnolipid volumetric productivity in the new culture medium. Finally, the use of fed-batch operation under conditions of limited nitrogen resulted in a 3.8-fold increase in the amount of rhamnolipids produced (2.9 g L−1–10.9 g L−1). These results offer promising pathways for the optimization of processes for the production of rhamnolipids.

scholarly journals Strategies for improved rhamnolipid production by Pseudomonas aeruginosa PA1

2015 ◽  
Author(s):  
Alexandre Soares dos Santos ◽  
Nei Pereira Jr ◽  
Denise M G Freire
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Stationary Phase ◽  
Culture Medium ◽  
Fold Increase ◽  
Batch Process ◽  
Measurable Effect ◽  
Fed Batch ◽  
Batch Operation ◽  
Ph Values ◽  
Influence Of Ph

Rhamnolipids are biosurfactants with potential for diversified industrial and environmental uses. The present study evaluated three strategies to increase the production of rhamnolipid-type biosurfactants produced by Pseudomonas aeruginosa strain PA1. The influence of pH, the addition of endogenous autoinducers and the use of a fed batch process were examined. The culture medium adjusted to pH 7.0 was the most productive. Furthermore, the pH of the culture medium had a measurable effect on the ratio of mono- and dirhamnolipids synthesized. At pH values below 7.3, the proportion of monorhamnolipids decreased from 45 to 24%. Additionally, recycling 20% of the spent culture medium where P. aeruginosa was grown up to the later stationary phase was responsible for a 100% increase in rhamnolipid volumetric productivity in the new culture medium. Finally, the use of fed batch operation under conditions of limited nitrogen resulted in a 3.8-fold increase in the amount of rhamnolipids produced (1.29 g L-1 to 4.90 g L-1, as rhamnose). These results offer promising paths to optimize processes for the production of rhamnolipids.

scholarly journals Production and Optimization of Xylanase and α-Amylase from Non-Saccharomyces Yeasts (Pichia membranifaciens)

2021 ◽  
pp. 452-461
Author(s):  
Hala A. Salah ◽  
Hanan A. Temerk ◽  
Nivin A. Salah ◽  
Saeed Rafa Zara Alshehri ◽  
Jazi A. Al-Harbi ◽  
...  
Keyword(s):  
Culture Medium ◽  
Potato Starch ◽  
Pcr Amplification ◽  
Soluble Starch ◽  
Relative Activity ◽  
Rrna Gene ◽  
Pichia Membranifaciens ◽  
Ph Values ◽  
26S Rrna ◽  
Saccharomyces Yeasts

The xylanolytic and amylolytic yeasts were qualitatively determined by Cong red xylan agar and soluble starch agar plates, respectively. The most xylanase and α-amylase inducible strain (AUN-02) was selected and identified using PCR amplification of 26S rRNA gene and sequence analysis. The comparison of the alignment results and phylogenetic analysis of the sequences of the isolated yeast to published rRNA gene sequences in GenBank, confirmed the identification of the isolate as Pichia membranifaciens. Xylanase and α-amylase production by isolated P. membranifaciens were investigated at different pH values (4-8), temperature degrees (20-45°C), incubation time (1-7 days) and various substrates.A higher production of xylanase (38.8 U/mL) and a-amylase (28.7 U/mL) was obtained after 4 days of fermentation of P. membranifaciens. Higher activity of xylanase (36.83 U/mL) and a-amylase (27.7 U/mL) was obtained in the fermentation of P. membranifaciens in a culture medium adjusted to pH 7.0. The optimum temperature showed maximum xylanase and a-amylase activity (42.6 and 32.5 units/mL, respectively) was estimated at 35 °C. The xylanase and a-amylase activities of P. membranifaciens were estimated and compared for the different substrates tested. The strain revealed 100% relative activity of xylanase and a-amylase on beechwood and potato starch, respectively. The affinity of enzymes towards substrate was estimated using Km values. The Km values of xylanase and α-amylase increased in the order of pH’s 7.0, 6.0 and 4.5 (0.85, 1.6 and 3.4 mg xylan/mL and 0.22, 0.43 and 2.8 mg starch/mL, respectively). the yeast P. membranifaciensis is suitable for produce neutral xylanase and α-amylase enzymes. So, it could be used as a promising strain for production of these enzymes in industrial field.

scholarly journals The Influence of pH Values on the Crystallite Size of ZnO by Solvothermal Synthesis

2017 ◽  
Vol 2 (2) ◽  
pp. 118 ◽  
Author(s):  
Ahmadi Jaya Permana ◽  
Dian Wulandari ◽  
Hartati Hartati ◽  
Harsasi Setyawati ◽  
Mochammad Zakki Fahmi
Keyword(s):  
Heat Treatment ◽  
Zinc Oxide ◽  
Crystallite Size ◽  
Solvothermal Synthesis ◽  
Solvothermal Method ◽  
Ph Value ◽  
Semiconductor Material ◽  
X Ray ◽  
Ph Values ◽  
Influence Of Ph

 Zinc oxide (ZnO) is a semiconductor material that widely used in various applications due to its unique properties. Synthesis of ZnO by solvothermal method has been conducted with controlled pH values. The variations of pH value were 10, 11 and 12 by adjusting NaOH content. Crystall structure of the synthesis products after heat treatment at 110oC and 600oC has characterised by X-ray Diffratometer (XRD). Crystallite size of ZnO was measured by Scherrer equation. Crystall phase of ZnO has been observed on all pH value variations at 110 oC with 22,98-37,06 nm of crystallite size, whereas ZnO has been observed on all pH value variations at 600 oC with 41,39-71,77 nm of crystallite size.Keywords: ZnO, pH values, crystallite size, solvothermal

Proteolysis of αs1-casein by chymosin: influence of pH and urea

1977 ◽  
Vol 44 (3) ◽  
pp. 533-540 ◽  
Author(s):  
D. M. Mulvihill ◽  
P. F. Fox
Keyword(s):  
Aqueous Solution ◽  
The State ◽  
Ph Values ◽  
Influence Of Ph ◽  
Hydrolysis Of

SummaryThe specificity of chymosin on αs1-casein was shown to be dependent on the reaction pH and on the state of aggregation of the substrate. In aqueous solution αs1-casein was optimally hydrolysed to αs1-I at pH 5·8; if the casein was solubilized in the isoelectric region by the use of 5 M-urea, optimum proteolysis occurred at pH 2·8. Hydrolysis of αs1-I to yield αs1-II, αs1-III and αs1-IV occurred at pH values > 5·8 in the presence or absence of urea. In the isoelectric region αs1-II, αs1-III and αs1-IV were not formed in the absence of urea where the substrate was aggregated: instead a peptide αs1-V was produced; at the same pH and using urea as a solubilizing agent αs1-II, αs1-III and αs1-IV were formed together with a further peptide αs1-VI.

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