scholarly journals Cellular Microcystin Content in N-Limited Microcystis aeruginosa Can Be Predicted from Growth Rate

2001 ◽  
Vol 67 (1) ◽  
pp. 278-283 ◽  
Author(s):  
Benedict M. Long ◽  
Gary J. Jones ◽  
Philip T. Orr
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Cell Volume ◽  
Microcystis Aeruginosa ◽  
Specific Growth ◽  
Weight Ratio ◽  
Dry Weight ◽  
Cell Protein ◽  
Protein Ratio ◽  
Cell Quota

ABSTRACT Cell quotas of microcystin (Q MCYST; femtomoles of MCYST per cell), protein, and chlorophyll a(Chl a), cell dry weight, and cell volume were measured over a range of growth rates in N-limited chemostat cultures of the toxic cyanobacterium Microcystis aeruginosa MASH 01-A19. There was a positive linear relationship betweenQ MCYST and specific growth rate (μ), from which we propose a generalized model that enablesQ MCYST at any nutrient-limited growth rate to be predicted based on a single batch culture experiment. The model predicts Q MCYST from μ, μmax(maximum specific growth rate), Q MCYSTmax(maximum cell quota), and Q MCYSTmin (minimum cell quota). Under the conditions examined in this study, we predict aQ MCYSTmax of 0.129 fmol cell−1 at μmax and a Q MCYSTmin of 0.050 fmol cell−1 at μ = 0. Net MCYST production rate (R MCYST) asymptotes to zero at μ = 0 and reaches a maximum of 0.155 fmol cell−1 day−1at μmax. MCYST/dry weight ratio (milligrams per gram [dry weight]) increased linearly with μ, whereas the MCYST/protein ratio reached a maximum at intermediate μ. In contrast, the MCYST/Chla ratio remained constant. Cell volume correlated negatively with μ, leading to an increase in intracellular MCYST concentration at high μ. Taken together, our results show that fast-growing cells of N-limited M. aeruginosa are smaller, are of lower mass, and have a higher intracellular MCYST quota and concentration than slow-growing cells. The data also highlight the importance of determining cell MCYST quotas, as potentially confusing interpretations can arise from determining MCYST content as a ratio to other cell components.

scholarly journals Poly(3-Hydroxybutyrate) Synthesis by Recombinant Escherichia coli arcA Mutants in Microaerobiosis

2006 ◽  
Vol 72 (4) ◽  
pp. 2614-2620 ◽  
Author(s):  
Pablo I. Nikel ◽  
M. Julia Pettinari ◽  
Miguel A. Galvagno ◽  
Beatriz S. Méndez
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Specific Growth Rate ◽  
Deletion Mutant ◽  
Specific Growth ◽  
Dry Weight ◽  
Low Oxygen ◽  
Oxygen Conditions ◽  
In The Wild ◽  
Microaerobic Conditions

ABSTRACT We assessed the effects of different arcA mutations on poly(3-hydroxybutyrate) (PHB) synthesis in recombinant Escherichia coli strains carrying the pha synthesis genes from Azotobacter sp. strain FA8. The arcA mutations used were an internal deletion and the arcA2 allele, a leaky mutation for some of the characteristics of the Arc phenotype which confers high respiratory capacity. PHB synthesis was not detected in the wild-type strain in shaken flask cultures under low-oxygen conditions, while ArcA mutants gave rise to polymer accumulation of up to 24% of their cell dry weight. When grown under microaerobic conditions in a bioreactor, the arcA deletion mutant reached a PHB content of 27% ± 2%. Under the same conditions, higher biomass and PHB concentrations were observed for the strain bearing the arcA2 allele, resulting in a PHB content of 35% ± 3%. This strain grew in a simple medium at a specific growth rate of 0.69 ± 0.07 h−1, whereas the deletion mutant needed several nutritional additives and showed a specific growth rate of 0.56 ± 0.06 h−1. The results presented here suggest that arcA mutations could play a role in heterologous PHB synthesis in microaerobiosis.

THE KINETICS OF METABOLISM OF GIBBERELLA FUJIKUROI IN STIRRED CULTURE

1964 ◽  
Vol 10 (3) ◽  
pp. 407-444 ◽  
Author(s):  
A. Borrow ◽  
Sheila Brown ◽  
E. G. Jefferys ◽  
R. H. J. Kessell ◽  
Eithne C. Lloyd ◽  
...  
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Nitrogen Uptake ◽  
Exponential Growth ◽  
Ammonium Acetate ◽  
Specific Growth ◽  
Dry Weight ◽  
Gibberella Fujikuroi ◽  
Ammonium Tartrate ◽  
Kinetics Of

Some aspects are described of the kinetics of the growth of Gibberella fujikuroi in nitrogen-limited media containing either ammonium nitrate, ammonium acetate, ammonium tartrate, urea, or glycine. Also varied were inoculum size, agitation rate, pH, and initial concentrations of glucose and nitrogen source. The significance of kinetic parameters used in this, and published studies, is discussed.A lag phase was only found on ammonium acetate media or when high concentrations of glucose were present. Early growth was exponential on all nitrogen sources. On ammonium acetate the specific growth rate decreased at a dry weight of ca. 1 mg/g WS (Whole unfiltered Sample). On ammonium nitrate, early exponential growth utilized more NH3-nitrogen than NO3-nitrogen with a concomitant decrease in pH. In the range pH 3.0–2.8 NH3-nitrogen uptake and dry weight increase ceased, but NO3-nitrogen uptake continued, and the pH increased until growth and NH3-nitrogen uptake restarted. This pattern could be repeated. Finally, exponential growth was resumed at a low specific growth rate. On glycine, urea, and ammonium tartrate media, exponential growth continued to a dry weight of about 7 mg/g WS. During this period the uptakes relative to dry weight (contributions) of glucose, nitrogen, phosphate, and magnesium remained constant and were unaffected by the rate of agitation, as also was the specific growth rate, but the latter decreased with increasing glucose concentration.A period of linear growth could follow the exponential period. The contribution of glucose was greater, and that of phosphate and magnesium less, than during exponential growth. The dry weight at which exponential growth changed to linear growth was greater the higher the rate of agitation, and this change may be a response to oxygen restriction.After nitrogen exhaustion, fat and carbohydrate accumulation in the cells largely accounted for the increase in dry weight. The specific rates of dry weight increase and glucose uptake remained constant over the lower range of initial nitrogen concentrations. Both rates decreased with increasing nitrogen over the higher range.Gibberellic acid production began at, or soon after, nitrogen exhaustion. The amount present increased linearly with time. The productivity decreased with increasing glucose concentration, and first increased and then decreased with increasing initial nitrogen. The maximum amount produced was proportional to the initial nitrogen provided. Some published results are discussed in the light of these relations.

scholarly journals Effect of soil extracts concentration on specific growth rate and lipid content of chlorella vulgaris in bolds basal medium

2014 ◽  
Vol 10 (2) ◽  
Author(s):  
Ani Idris ◽  
M. Atta ◽  
A. Bukhari
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Chlorella Vulgaris ◽  
Mass Culture ◽  
Specific Growth ◽  
Basal Medium ◽  
Dry Weight ◽  
Soil Extract ◽  
Soil Extracts ◽  
Key Factor

Effective nutrient medium is the key factor that significantly influences the specific growth rate and the final concentration of microalgae. The main objective of this study was to optimize the microalgal growth in mass culture system under the effect of soil extract in modified Bolds Basal medium. Chlorella vulgaris was grown aseptically for 10 days at five different concentrations of soil extract (10, 20, 30, 40, 50ml/L) at 25°C cultivation temperature. After 10 days of cultivation, Chlorella vulgaris showed maximum cell concentration of 5x107/ml at 30ml/L of soil extract concentration which corresponds to the maximum specific growth rate 1.56μd-1 with the doubling rate of 2.25d-1   andlipid yield of 22.74 % of dry weight.________________________________________GRAPHICAL ABSTRACT

The Effect of De-Oiled Rice Bran for Single Cell Protein Production Using Fungal Cultures under Solid State Fermentation

2009 ◽  
Vol 5 (2) ◽  
Author(s):  
Ravindra Pogaku ◽  
Ravinder Rudravaram ◽  
Anuj Kumar Chandel ◽  
Venkateshwara Rao Linga ◽  
Zhi Hui Yim
Keyword(s):  
Growth Rate ◽  
Solid State ◽  
Specific Growth Rate ◽  
Rice Bran ◽  
Solid State Fermentation ◽  
Specific Growth ◽  
Trichoderma Viride ◽  
Single Cell Protein ◽  
Major Constituent ◽  
Cell Protein

In the present work, de-oiled rice bran (DOB) was exploited for SCP production using three different fungi, namely, Aspergillus oryzae MTCC 1846, Trichoderma viride NRRL 1186 and Aspergillus niger MTCC 1842 under solid state fermentation. DOB was found to contain 9% protein, 39% cellulose, 28% hemicellulose and 24% lignin. All the three cultures have shown more specific growth rate when grown on glucose in comparison to maltose and cellulose. The specific growth rates on glucose were 0.203, 0.201 and 0.196 h-1 and on maltose were 0.173, 0.171, 0.169 h-1 for A. oryzae MTCC 1846, T. viride NRRL 1186 and A. niger MTCC 1842, respectively. All the three microorganisms showed lowest specific growth rate on cellulose 0.119, 0.117, 0.114 h-1 for A. oryzae MTCC 1846, T. viride NRRL 1186 and A. niger MTCC 1842, respectively. The major constituent of dried fungi is crude protein, which contributes to 43% in A. oryzae MTCC 1846, 44% in T. viride NRRL 1186 and 39.2% in A. niger MTCC 1842 on dry basis. Among the three fungi A. oryzae MTCC 1846 shows minimum content of nucleic acids (5.3%) while A. niger MTCC 1842 and T. viride NRRL 1186 showed (6.1%) and (7.2%), respectively.

On-line viable biomass measurement and estimation of the specific growth rate of activated sludge from municipal wastewater treatment

2001 ◽  
Vol 43 (7) ◽  
pp. 97-102 ◽  
Author(s):  
E. J. November ◽  
J. F. Van Impe
Keyword(s):  
Growth Rate ◽  
Activated Sludge ◽  
Specific Growth Rate ◽  
Municipal Wastewater ◽  
Specific Growth ◽  
Dry Weight ◽  
Municipal Wastewater Treatment ◽  
Experimental Conditions ◽  
On Line ◽  
Viable Biomass

In order to control wastewater processes, on-line measurements of important process variables are crucial. This contribution focuses on the applicability of the Biomass Monitor for on-line viable biomass measurement of activated sludge from a municipal wastewater plant. In addition, the specific growth rate of the sludge is estimated on-line, based on the information derived from the device under study. Compared to dry weight measurements, the Biomass Monitor hardware offers the advantage of a biologically more appropriate observation of the biomass by only taking into account the viable cells in the population. The optimal measurement frequency of the biomass monitoring device for the given experimental conditions has been determined. Furthermore, the capacitance readings have been correlated with off-line analyses of dry weight of the sludge during the experimental phase in which no death of cells occurred. Finally, an evaluation of the estimator of the specific growth rate including its tuning is presented.

scholarly journals Influence of Carbon Source on Nitrate Removal by Nitrate-TolerantKlebsiella oxytoca CECT 4460 in Batch and Chemostat Cultures

1998 ◽  
Vol 64 (8) ◽  
pp. 2970-2976 ◽  
Author(s):  
Guadalupe Piñar ◽  
Karin Kovárová ◽  
Thomas Egli ◽  
Juan L. Ramos
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Specific Growth ◽  
Nitrate Removal ◽  
Dry Weight ◽  
Specific Rate ◽  
Continuous Cultures ◽  
Batch Cultures ◽  
Chemostat Cultures ◽  
C And N

ABSTRACT The nitrate-tolerant organism Klebsiella oxytoca CECT 4460 tolerates nitrate at concentrations up to 1 M and is used to treat wastewater with high nitrate loads in industrial wastewater treatment plants. We studied the influence of the C source (glycerol or sucrose or both) on the growth rate and the efficiency of nitrate removal under laboratory conditions. With sucrose as the sole C source the maximum specific growth rate was 0.3 h−1, whereas with glycerol it was 0.45 h−1. In batch cultures K. oxytocacells grown on sucrose or glycerol were able to immediately use sucrose as a sole C source, suggesting that sucrose uptake and metabolism were constitutive. In contrast, glycerol uptake occurred preferentially in glycerol-grown cells. Independent of the preculture conditions, when sucrose and glycerol were added simultaneously to batch cultures, the sucrose was used first, and once the supply of sucrose was exhausted, the glycerol was consumed. Utilization of nitrate as an N source occurred without nitrite or ammonium accumulation when glycerol was used, but nitrite accumulated when sucrose was used. In chemostat cultures K. oxytoca CECT 4460 efficiently removed nitrate without accumulation of nitrate or ammonium when sucrose, glycerol, or mixtures of these two C sources were used. The growth yields and the efficiencies of C and N utilization were determined at different growth rates in chemostat cultures. Regardless of the C source, yield carbon (YC) ranged between 1.3 and 1.0 g (dry weight) per g of sucrose C or glycerol C consumed. Regardless of the specific growth rate and the C source, yield nitrogen (YN) ranged from 17.2 to 12.5 g (dry weight) per g of nitrate N consumed. In contrast to batch cultures, in continuous cultures glycerol and sucrose were utilized simultaneously, although the specific rate of sucrose consumption was higher than the specific rate of glycerol consumption. In continuous cultures double-nutrient-limited growth appeared with respect to the C/N ratio of the feed medium and the dilution rate, so that for a C/N ratio between 10 and 30 and a growth rate of 0.1 h−1 the process led to simultaneous and efficient removal of the C and N sources used. At a growth rate of 0.2 h−1the zone of double limitation was between 8 and 11. This suggests that the regimen of double limitation is influenced by the C/N ratio and the growth rate. The results of these experiments were validated by pulse assays.

scholarly journals Copper-Induced Inhibition of Growth of Desulfovibrio desulfuricans G20: Assessment of Its Toxicity and Correlation with Those of Zinc and Lead

2001 ◽  
Vol 67 (10) ◽  
pp. 4765-4772 ◽  
Author(s):  
Rajesh Kumar Sani ◽  
Brent M. Peyton ◽  
Laura T. Brown
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Specific Growth ◽  
Membrane Integrity ◽  
Desulfovibrio Desulfuricans ◽  
Maximum Specific Growth Rate ◽  
Cell Protein ◽  
Prolonged Incubation ◽  
Lag Times ◽  
Measurable Growth

ABSTRACT The toxicity of copper [Cu(II)] to sulfate-reducing bacteria (SRB) was studied by using Desulfovibrio desulfuricansG20 in a medium (MTM) developed specifically to test metal toxicity to SRB (R. K. Sani, G. Geesey, and B. M. Peyton, Adv. Environ. Res. 5:269–276, 2001). The effects of Cu(II) toxicity were observed in terms of inhibition in total cell protein, longer lag times, lower specific growth rates, and in some cases no measurable growth. At only 6 μM, Cu(II) reduced the maximum specific growth rate by 25% and the final cell protein concentration by 18% compared to the copper-free control. Inhibition by Cu(II) of cell yield and maximum specific growth rate increased with increasing concentrations. The Cu(II) concentration causing 50% inhibition in final cell protein was evaluated to be 16 μM. A Cu(II) concentration of 13.3 μM showed 50% inhibition in maximum specific growth rate. These results clearly show significant Cu(II) toxicity to SRB at concentrations that are 100 times lower than previously reported. No measurable growth was observed at 30 μM Cu(II) even after a prolonged incubation of 384 h. In contrast, Zn(II) and Pb(II), at 16 and 5 μM, increased lag times by 48 and 72 h, respectively, but yielded final cell protein concentrations equivalent to those of the zinc- and lead-free controls. Live/dead staining, based on membrane integrity, indicated that while Cu(II), Zn(II), and Pb(II) inhibited growth, these metals did not cause a loss of D. desulfuricans membrane integrity. The results show that D. desulfuricans in the presence of Cu(II) follows a growth pattern clearly different from the pattern followed in the presence of Zn(II) or Pb(II). It is therefore likely that Cu(II) toxicity proceeds by a mechanism different from that of Zn(II) or Pb(II) toxicity.

Sign in / Sign up

Export Citation Format

Share Document