Oxygen requirements of strains of Pseudomonas and Achromobacter

1972 ◽  
Vol 18 (3) ◽  
pp. 321-326 ◽  
Author(s):  
D. S. Clark ◽  
T. Burki
Keyword(s):  
Growth Rate ◽  
Stationary Phase ◽  
Oxygen Concentration ◽  
Generation Time ◽  
Logarithmic Phase ◽  
Nutrient Media ◽  
Meat Spoilage ◽  
Oxygen Oxygen ◽  
Lag Period ◽  
Oxygen Requirements

Studies on the oxygen requirements of aerobic psychrotolerant bacteria showed that the oxygen concentration of the atmosphere can be lowered to 2% without noticeably inhibiting growth rate. Tests were made with meat-spoilage strains of Achromobacter and Pseudomonas in nutrient media sparged with gases containing from 0.1 to 100% oxygen. Reduction of overall growth rate with reduction in oxygen concentration below 2% was mainly the result of an increase in the lag period. At an oxygen concentration of 0.5% or lower, however, cell generation time during the logarithmic phase was increased and cell yield at the stationary phase was reduced. The increased lag period could be eliminated by using an inoculum adapted to the oxygen concentration under test. Growth did not occur in the absence of oxygen. Oxygen concentrations greater than 21% (air) had a negligible effect on Pseudomonas, but inhibited the growth rate of Achromobacter. The results indicate that insufficient oxygen is not a major cause of the failure of these bacteria to grow rapidly in vacuum packaged meats.

Axenic culture of myxamoebae of the myxomycete Echinostelium minutum

1970 ◽  
Vol 48 (3) ◽  
pp. 663-664 ◽  
Author(s):  
Edward F. Haskins
Keyword(s):  
Stationary Phase ◽  
Generation Time ◽  
Axenic Culture ◽  
Serial Passage ◽  
Logarithmic Phase ◽  
First Time ◽  
Axenic Cultivation ◽  
Average Generation Time

Axenic cultivation of the myxomycete Echinostelium minutum De Bary (Echinosteliales) is reported for the first time. After more than a year of serial passage the average generation time of amoebae during the logarithmic phase is 18 h and a stationary phase yield of over 2 × 106 cells/ml is typical.

scholarly journals KOMPONEN METABOLIT SEKUNDER DAN AKTIVITAS ANTIOKSIDAN Spirulina fusiformis YANG DIKULTUR PADA MEDIA CAMPURAN (PUPUK R1, UREA DAN KATALIS)

2018 ◽  
Vol 5 (2) ◽  
pp. 161
Author(s):  
Nabila Ukhty
Keyword(s):  
Growth Rate ◽  
Antioxidant Activity ◽  
Stationary Phase ◽  
Secondary Metabolite ◽  
Mixed Media ◽  
Logarithmic Phase ◽  
Stages Of Growth ◽  
Death Phase ◽  
Microalgae Growth

Spirulina fusiformis is one of blue algae which can produce phycocyanin pigments. In this study used a mixed media consists of fertilizer R1, urea and catalyst as a medium for microalgae growth. This study aims to determine the growth rate, secondary metabolite component and antioxidant activity of S. fusiformis which was cultivated in a mixture media cnsists of fetilizer R1, urea and catalysts. S. fusiformis was cultured for 21 days. Based on the results of the study, it is known that S. fusiformis culture experienced five stages of growth. The logarithmic phase occurs on the 3rd day until the 10th day, the stationary phase occurs on the 10th day to the 15th day, and the death phase occurs on the 20th day. S. fusiformis biomass harvested on the 12th day contained alkaloids, flavonoids, saponins and steroids. The biomass antioxidant activity of S. fusiformis harvested on the 12th day had IC50 tilapia of 1937.41 ppm.

scholarly journals LAJU PERTUMBUHAN DAN KEPADATAN MIKROALGA Dunaliella sp. PADA PEMBERIAN TIMBAL ASETAT DENGAN KONSENTRASI YANG BERBEDA

2021 ◽  
Vol 9 (1) ◽  
pp. 30
Author(s):  
Fitly Tewal ◽  
Kurniati Kemer ◽  
Joice R.T.S.L. Rimper ◽  
Desy M.H. Mantiri ◽  
Wilmy E Pelle ◽  
...  
Keyword(s):  
Growth Rate ◽  
Stationary Phase ◽  
Green Algae ◽  
Lead Acetate ◽  
Exponential Phase ◽  
Lag Phase ◽  
Logarithmic Phase ◽  
Good Source ◽  
Acetate Concentration ◽  
Living Things

Microalgae are organisms that contain chlorophyll and other pigments so they can carry out photosynthesis. Microalgae are widespread in nature and can be found in any environment exposed to sunlight. Microalgae are micro-sized biota with a diameter of less than 2 µm. The benefits of microalgae for other living things, especially humans, are numerous, including as a source of food and ingredients in the manufacture of medicines. Dunaliella sp. is a group of green algae that contains protein, fat and carbohydrates as a good source of food. Growth rate and density of microalgae Dunaliella sp. and the effect of lead acetate with different concentrations was observed using a microscope, starting from the lag phase, the logarithmic phase, the stationary phase and the declination phase. Dunaliella sp. Experiencing an exponential phase in the observation before treatment, namely on the 9th day and then doing the treatment. Treatment with lead acetate with concentrations of 10 ppm, 50 ppm and 80 ppm is very influential in the growth of microalgae. The result is that lead acetate contains toxins that can kill microalgae cells in both low and high concentrations.Keywords: Microalgae, Dunaliella sp., Lead Acetate, Concentration

scholarly journals Effects of cofD gene knock-out on the methanogenesis of Methanobrevibacter ruminantium

AMB Express ◽  
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jian Ma ◽  
Xueying Wang ◽  
Ting Zhou ◽  
Rui Hu ◽  
Huawei Zou ◽  
...  
Keyword(s):  
Growth Rate ◽  
Specific Growth ◽  
Production Capacity ◽  
Maximum Amount ◽  
Logarithmic Phase ◽  
Wild Type ◽  
Knock Out ◽  
Maximum Biomass ◽  
Reproductive Ability ◽  
Methanobrevibacter Ruminantium

AbstractThis study aimed to investigate the effects of cofD gene knock-out on the synthesis of coenzyme F420 and production of methane in Methanobrevibacter ruminantium (M. ruminantium). The experiment successfully constructed a cofD gene knock-out M. ruminantium via homologous recombination technology. The results showed that the logarithmic phase of mutant M. ruminantium (12 h) was lower than the wild-type (24 h). The maximum biomass and specific growth rate of mutant M. ruminantium were significantly lower (P < 0.05) than those of wild-type, and the maximum biomass of mutant M. ruminantium was approximately half of the wild-type; meanwhile, the proliferation was reduced. The synthesis amount of coenzyme F420 of M. ruminantium was significantly decreased (P < 0.05) after the cofD gene knock-out. Moreover, the maximum amount of H2 consumed and CH4 produced by mutant were 14 and 2% of wild-type M. ruminantium respectively. In conclusion, cofD gene knock-out induced the decreased growth rate and reproductive ability of M. ruminantium. Subsequently, the synthesis of coenzyme F420 was decreased. Ultimately, the production capacity of CH4 in M. ruminantium was reduced. Our research provides evidence that cofD gene plays an indispensable role in the regulation of coenzyme F420 synthesis and CH4 production in M. ruminantium.

scholarly journals The ameliorative effect of selenium on Azolla caroliniana grown under UV-B stress

2015 ◽  
Vol 95 (1) ◽  
pp. 20-26 ◽  
Author(s):  
E.M. Mostafa ◽  
A.M.A. Hassan
Keyword(s):  
Growth Rate ◽  
Protein Content ◽  
Doubling Time ◽  
The Other ◽  
Total Glutathione ◽  
Nutrient Media ◽  
Relative Growth ◽  
Other Hand ◽  
Ameliorative Effect ◽  
Glutathione Redox

Exposure ofAzollaplants to UV-B radiation for 6 h resulted in a decrease in biomass and relative growth rate (RGR), which coincided with an increase in doubling time (DT) as compared with the control. Also, the protein content decreased. On the other hand, hydrogen peroxyde (H2O2) and malondialdehyde (MDA) accumulated significantly in UV-treatedAzollaplants. Conversely, the addition of selenium (Se) at 1 ppm resulted in a significant increase in biomass and protein content of untreated and UV-treatedAzollaplants, and a significant reduction in both H2O2and MDA. Moreover, the addition of Se to UV-treated and untreatedAzollaplants resulted in a significant increase in total ascorbate and total glutathione (GSH) contents compared with the control and UV-stressedAzollaplants. Also, glutathione redox potential (GSH/TG) increased significantly in UV-treatedAzollaplants in the presence of Se. There also was a significant increase (38%) in ascorbate peroxidase (APX) activity in UV-treated plants compared with the control. APX activity in the presence of Se did not change significantly compared with the control. Glutathione reductase (GR) activity increased significantly in UV-treatedAzolla, while glutathione peroxidase (GSH-PX) activity did not. On the other hand, both GSH-PX and GR activity in untreated and UV-treatedAzollaplants were significantly enhanced by the application of Se to the nutrient media at a concentration of 1 ppm. Therefore, we can conclude that Se protectsAzollaplants from UV-B stress.

Validation and Analysis of Modeled Predictions of Growth of Bacillus cereus Spores in Boiled Rice

2000 ◽  
Vol 63 (2) ◽  
pp. 268-272 ◽  
Author(s):  
DANA M. McELROY ◽  
LEE-ANN JAYKUS ◽  
PEGGY M. FOEGEDING
Keyword(s):  
Growth Rate ◽  
Bacillus Cereus ◽  
Exponential Growth ◽  
Generation Time ◽  
Time Lag ◽  
Lag Phase ◽  
Exponential Growth Rate ◽  
Phase Duration ◽  
Margin Of Safety ◽  
Fail Safe

The growth of psychrotrophic Bacillus cereus 404 from spores in boiled rice was examined experimentally at 15, 20, and 30°C. Using the Gompertz function, observed growth was modeled, and these kinetic values were compared with kinetic values for the growth of mesophilic vegetative cells as predicted by the U.S. Department of Agriculture's Pathogen Modeling Program, version 5.1. An analysis of variance indicated no statistically significant difference between observed and predicted values. A graphical comparison of kinetic values demonstrated that modeled predictions were “fail safe” for generation time and exponential growth rate at all temperatures. The model also was fail safe for lag-phase duration at 20 and 30°C but not at l5°C. Bias factors of 0.55, 0.82, and 1.82 for generation time, lag-phase duration, and exponential growth rate, respectively, indicated that the model generally was fail safe and hence provided a margin of safety in its growth predictions. Accuracy factors of 1.82, 1.60, and 1.82 for generation time, lag-phase duration, and exponential growth rate, respectively, quantitatively demonstrated the degree of difference between predicted and observed values. Although the Pathogen Modeling Program produced reasonably accurate predictions of the growth of psychrotrophic B. cereus from spores in boiled rice, the margin of safety provided by the model may be more conservative than desired for some applications. It is recommended that if microbial growth modeling is to be applied to any food safety or processing situation, it is best to validate the model before use. Once experimental data are gathered, graphical and quantitative methods of analysis can be useful tools for evaluating specific trends in model prediction and identifying important deviations between predicted and observed data.

scholarly journals Induction of the synthesis of an additional family of long-chain dolichols in the yeast Saccharomyces cerevisiae. Effect of starvation and ageing.

2002 ◽  
Vol 49 (3) ◽  
pp. 781-787 ◽  
Author(s):  
Anna Szkopinska ◽  
Ewa Swiezewska ◽  
Joanna Rytka
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Stationary Phase ◽  
Yeast Cells ◽  
Logarithmic Phase ◽  
Cellular Membranes ◽  
Yeast Saccharomyces Cerevisiae ◽  
Chemical Changes ◽  
Physico Chemical ◽  
Long Chain

The yeast Saccharomyces cerevisiae strain W303 synthesizes in the early logarithmic phase of growth dolichols of 14-18 isoprene residues. The analysis of the polyisoprenoids present in the stationary phase revealed an additional family which proved to be also dolichols but of 19-24 isoprene residues, constituting 39% of the total dolichols. The transfer of early logarithmic phase cells to a starvation medium lacking glucose or nitrogen resulted in the synthesis of the longer chain dolichols. The additional family of dolichols represented 13.8% and 10.3% of total dolichols in the glucose and nitrogen deficient media, respectively. The level of dolichols in yeast cells increased with the age of the cultures. Since both families of dolichols are present in stationary phase cells we postulate that the longer chain dolichols may be responsible for the physico-chemical changes in cellular membranes allowing yeast cells to adapt to nutrient deficient conditions to maintain long-term viability.

Factors Influencing the Rate and Duration of Grain Filling in Wheat

1977 ◽  
Vol 4 (5) ◽  
pp. 785 ◽  
Author(s):  
I Sofield ◽  
LT Evans ◽  
MG Cook ◽  
IF Wardlaw
Keyword(s):  
Growth Rate ◽  
Grain Yield ◽  
Grain Growth ◽  
Dry Weight ◽  
Grain Filling ◽  
Close Relation ◽  
Grain Number ◽  
Lag Period ◽  
The Difference ◽  
Leaf Photosynthetic Rate

Controlled-environment conditions were used to examine the effects of cultivar and of temperature and illuminance after anthesis on grain setting and on the duration and rate of grain growth. After an initial lag period, which did not differ greatly between cultivars, grain dry weight increased linearly under most conditions until final grain weight was approached. Growth rate per grain depended on floret position within the ear, varied between cultivars (those with larger grains at maturity having a faster rate), and increased with rise in temperature. With cultivars in which grain number per ear was markedly affected by illuminance, light had relatively little effect on growth rate per grain. With those in which grain number was less affected by illuminance, growth rate per grain was highly responsive to it, especially in the more distal florets. In both cases there was a close relation between leaf photosynthetic rate as influenced by illuminance, the rate of grain growth per ear, and final grain yield per ear. The duration of linear grain growth, on the other hand, was scarcely influenced by illuminance, but was greatly reduced as temperature rose, with pronounced effects on grain yield per ear. Cultivars differed to some extent in their duration of linear growth, but these differences accounted for less of the difference in final weight per grain than did those in rate of grain growth. Under most conditions the cessation of grain growth did not appear to be due to lack of assimilates.

Growth Kinetics of Salmonella Isolates in a Laboratory Medium as Affected by Isolate and Holding Temperature†

1998 ◽  
Vol 61 (8) ◽  
pp. 964-968 ◽  
Author(s):  
THOMAS P. OSCAR
Keyword(s):  
Growth Rate ◽  
Stationary Phase ◽  
Growth Kinetics ◽  
Brain Heart Infusion ◽  
Lag Time ◽  
Culture Collection ◽  
Subsequent Growth ◽  
Laboratory Medium ◽  
Different Temperatures ◽  
Holding Temperature

Salmonella isolates were surveyed for their growth kinetics in a laboratory medium for the purpose of identifying isolates suitable for modeling experiments. In addition, the effect of holding stationary phase Salmonella cultures at different temperatures on their subsequent growth kinetics was evaluated for the purpose of developing a protocol to prevent the need for midnight sampling in modeling experiments. In Experiment 1, 16 isolates of Salmonella, 2 from the American Type Culture Collection (ATCC) and 14 from broiler operations, were surveyed for their growth kinetics in brain heart infusion (BHI) broth at 40°C. Lag time (P = 0.005) and growth rate (P = 0.022) were affected by identity of the isolate. Lag time ranged from 0.73 to 1.38 h, whereas growth rate ranged from 0.78 to 0.94 log10 CFU/ml/h. Overall, isolate S1 (Salmonella infantis from ATCC) was the fastest growing. In Experiment 2, 4 isolates of Salmonella, 1 from ATCC and 3 from broiler operations, were used to determine whether holding temperature influences subsequent growth kinetics. Salmonella isolates were grown to stationary phase at 37°C in BHI and then held for 24 h at 5, 22, or 37°C before dilution and reinitiation of growth in BHI at 37°C. Holding temperature did not alter or interact with identity of the isolate to alter subsequent growth kinetics. From the latter finding, a protocol was devised in which a dual-flask system is used to prevent the need for midnight sampling in modeling experiments. Similar to the results obtained in Experiment 1, identity of the isolate had only minor effects on growth kinetics in Experiment 2 indicating that all isolates examined were suitable for modeling experiments.

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