Microbial maximal specific growth rate as a square-root function of biomass yield and two kinetic parameters

Thermophiles are challenging to be studied for ethanol production using agricultural waste containing lignocellulosic materials rich in hexose and pentose. These bacteria have many advantages such as utilizing a wide range of substrates, including pentose (C5) and hexose (C6). In ethanol production, it is important to use ethanol tolerant strain capable in converting lignocellulosic hydrolysate. This study was aimed to investigate the growth profile of ethanol-tolerant thermophile Geobacillus thermoglucosidasius M10EXG using a defined growth medium consisted of single carbon glucose (TGTV), xylose (TXTV), and a mixture of glucose and xylose (TGXTV), together with the effect of yeast extract addition<br />to the media. The experiments were conducted at the School of Biotechnology and Biomolecular Sciences of The University of New South Wales, Australia on a shake flask fermentation at 60°C in duplicate experiment. Cultures were sampled every two hours and analised for their kinetic parameters including the maximum specific growth rate (µmax), biomass yield (Yx/s), ethanol and by-product yields (acetate and L-lactate) (Yp/s), and the doubling time (Td). Results showed that this strain was capable of growing on minimal medium containing glucose or xylose as a single carbon source. This strain utilized glucose and xylose simultaneously (co-fermentation), although there was glucose repression of xylose at relatively low glucose concentration (0.5% w/v), particularly when yeast extract (0.2% w/v) was added to the medium. The highest biomass yield was obtained at 0.5 g l-1 on glucose medium; the yield increased when yeast extract was added (at 0.59 g l-1). The highest specific growth rate of 0.25 was obtained in the phase I growth when the strain was grown on a mixture of glucose and xylose (0.5% : 0.5% w/v) medium. Diauxic growth was shown on the mixture of glucose, xylose, and yeast extract. The strain produced low level of ethanol (0.1 g l-1), as well as low level (0.2 g l-1) of by-products (L-lactate and acetate) after 15 hours. The results suggests its potential application for fermenting lignocellulosic agricultural wastes for ethanol production.

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Microbial Interactions between Amylolytic and Non-Amylolytic Lactic Acid Bacteria Strains Isolated during the Fermentation of Pozol

10.20944/preprints202108.0280.v1 ◽

2021 ◽

Author(s):

Sandra Bolaños-Nuñez ◽

Jorge A. Santiago-Urbina ◽

Jean-Pierre Guyot ◽

Gloria Díaz-Ruiz ◽

Carmen Wacher

Keyword(s):

Growth Rate ◽

Lactic Acid ◽

Specific Growth Rate ◽

Kinetic Parameters ◽

Acid Production ◽

Specific Growth ◽

Lactic Acid Production ◽

Amylolytic Activity ◽

Specific Rate ◽

Acid Yield

Pozol is a Mexican beverage prepared from fermented nixtamalized maize dough. To contribute to understanding its complex microbial ecology, the effect of inoculating on MRS-starch pure and mixed cultures of amylolytic Sii-25124 and non-amylolytic W. confusa 17, isolated from pozol, were studied on their interactions and fermentation parameters. These were compared with L. plantarum A6, an amylolytic strain isolated from cassava. Microbial growth, kinetic parameters, amylolytic activity, lactic acid production, and hydrolysis products from starch fermentation were measured. The population dynamics were followed by qPCR. L. plantarum A6 showed higher enzymatic activity, lactic acid, biomass production, and kinetic parameters than pozol LAB in pure cultures. Mixed culture of each pozol LAB with L. plantarum A6 showed a significant decrease in amylolytic activity, lactic acid yield, specific growth rate, and specific rate of amylase production. The interaction between Sii-25124 and W. confusa 17 increased the global maximum specific growth rate (µ), the lactic acid yield from starch (Ylac/s), lactic acid yield from biomass (Ylac/x), and specific rate of lactic acid production (qlac) by 15, 30, 30, and 40%, respectively compared with the pure culture of Sii-25124. Interactions between the two strains are essential for this fermentation.

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Influence of specific growth rate on biomass yield, productivity, and compostion of Candida utilis in batch and continuous culture.

Applied and Environmental Microbiology ◽

10.1128/aem.31.4.487-491.1976 ◽

1976 ◽

Vol 31 (4) ◽

pp. 487-491 ◽

Cited By ~ 23

Author(s):

O Paredes-López ◽

E Camargo-Rubio ◽

A Ornelas-Vale

Keyword(s):

Growth Rate ◽

Specific Growth Rate ◽

Continuous Culture ◽

Candida Utilis ◽

Biomass Yield ◽

Specific Growth

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Kinetic Study of an Industrial Waste Containing a Non-Biodegradable Fraction

Water Quality Research Journal ◽

10.2166/wqrj.1972.005 ◽

1972 ◽

Vol 7 (1) ◽

pp. 21-30

Author(s):

E. Davis ◽

G. Goos

Keyword(s):

Growth Rate ◽

Specific Growth Rate ◽

Kinetic Parameters ◽

Industrial Waste ◽

Specific Growth ◽

Removal Rate ◽

Forest Products ◽

First Order ◽

Substrate Removal ◽

Organism Growth

Abstract A study was undertaken which was primarily concerned with the use of batch tests to investigate the kinetic behaviour of a high strength industrial waste which contained a non-biodegradable fraction and to determine the kinetic parameters, maximum specific growth rate, umax, saturation constant, Ks, and cell yield, Y. Substrate for the experiments was obtained from the effluent of a forest products industry manufacturing millboard. Bacterial cells were obtained from a heterogeneous culture of organisms acclimatized to this substrate. Samples were withdrawn periodically and analysed, using organic carbon as a parameter, to study the organism growth and substrate removal patterns. Data analysis based on the Monod equation, u = umax S/(Ks + S), performed after values of specific growth rate, u, specific decay rate, kd, organism growth rate, dX/dt, and substrate removal rate, dS/dt, were obtained and the initial substrate concentrations were corrected for the ultimate non-biodegradable fraction, produced values for the desired kinetic parameters. The activation energy, E, calculated from the van’t Hoff-Arrhenius relationship was found to be 15,160 calories per mole. The corresponding Streeter-Phelps coefficient, Θ, was found to be 1.095. Observations indicated that the organic matter in the substrate was removed initially by adsorption, and then a first-order removal rate. At the higher temperatures the initial first-order removal rate was ultimately replaced by a second and slower first-order removal rate. This overall condition could be approximated by the use of a single second-order removal rate. This investigation indicated that relatively simple and economical batch shaker flask studies can be successfully used to determine kinetic parameters for a complex industrial waste undergoing biological degradation by a heterogeneous population of organisms.

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KINETIC EVALUATION OF ETHANOL-TOLERANT THERMOPHILE Geobacillus thermoglucosidasius M10EXG FOR ETHANOL PRODUCTION

Indonesian Journal of Agricultural Science ◽

10.21082/ijas.v10n1.2009.24-41 ◽

2016 ◽

Vol 10 (1) ◽

pp. 24

Author(s):

Eny Ida Riyanti ◽

Peter L. Rogers

Keyword(s):

Growth Rate ◽

Specific Growth Rate ◽

Ethanol Production ◽

Yeast Extract ◽

Biomass Yield ◽

Specific Growth ◽

Kinetic Evaluation ◽

Geobacillus Thermoglucosidasius ◽

Low Level ◽

Wide Range

Thermophiles are challenging to be studied for ethanol production using agricultural waste containing lignocellulosic materials rich in hexose and pentose. These bacteria have many advantages such as utilizing a wide range of substrates, including pentose (C5) and hexose (C6). In ethanol production, it is important to use ethanol tolerant strain capable in converting lignocellulosic hydrolysate. This study was aimed to investigate the growth profile of ethanol-tolerant thermophile Geobacillus thermoglucosidasius M10EXG using a defined growth medium consisted of single carbon glucose (TGTV), xylose (TXTV), and a mixture of glucose and xylose (TGXTV), together with the effect of yeast extract addition<br />to the media. The experiments were conducted at the School of Biotechnology and Biomolecular Sciences of The University of New South Wales, Australia on a shake flask fermentation at 60°C in duplicate experiment. Cultures were sampled every two hours and analised for their kinetic parameters including the maximum specific growth rate (µmax), biomass yield (Yx/s), ethanol and by-product yields (acetate and L-lactate) (Yp/s), and the doubling time (Td). Results showed that this strain was capable of growing on minimal medium containing glucose or xylose as a single carbon source. This strain utilized glucose and xylose simultaneously (co-fermentation), although there was glucose repression of xylose at relatively low glucose concentration (0.5% w/v), particularly when yeast extract (0.2% w/v) was added to the medium. The highest biomass yield was obtained at 0.5 g l-1 on glucose medium; the yield increased when yeast extract was added (at 0.59 g l-1). The highest specific growth rate of 0.25 was obtained in the phase I growth when the strain was grown on a mixture of glucose and xylose (0.5% : 0.5% w/v) medium. Diauxic growth was shown on the mixture of glucose, xylose, and yeast extract. The strain produced low level of ethanol (0.1 g l-1), as well as low level (0.2 g l-1) of by-products (L-lactate and acetate) after 15 hours. The results suggests its potential application for fermenting lignocellulosic agricultural wastes for ethanol production.

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Protein turnover forms one of the highest maintenance costs in Lactococcus lactis

Microbiology ◽

10.1099/mic.0.078089-0 ◽

2014 ◽

Vol 160 (7) ◽

pp. 1501-1512 ◽

Cited By ~ 22

Author(s):

Petri-Jaan Lahtvee ◽

Andrus Seiman ◽

Liisa Arike ◽

Kaarel Adamberg ◽

Raivo Vilu

Keyword(s):

Growth Rate ◽

Total Energy ◽

Specific Growth Rate ◽

Lactococcus Lactis ◽

Protein Turnover ◽

Biomass Yield ◽

Specific Growth ◽

High Energy ◽

Turnover Rates ◽

Maintenance Costs

Protein turnover plays an important role in cell metabolism by regulating metabolic fluxes. Furthermore, the energy costs for protein turnover have been estimated to account for up to a third of the total energy production during cell replication and hence may represent a major limiting factor in achieving either higher biomass or production yields. This work aimed to measure the specific growth rate (μ)-dependent abundance and turnover rate of individual proteins, estimate the ATP cost for protein production and turnover, and compare this with the total energy balance and other maintenance costs. The lactic acid bacteria model organism Lactococcus lactis was used to measure protein turnover rates at μ = 0.1 and 0.5 h−1 in chemostat experiments. Individual turnover rates were measured for ~75 % of the total proteome. On average, protein turnover increased by sevenfold with a fivefold increase in growth rate, whilst biomass yield increased by 35 %. The median turnover rates found were higher than the specific growth rate of the bacterium, which suggests relatively high energy consumption for protein turnover. We found that protein turnover costs alone account for 38 and 47 % of the total energy produced at μ = 0.1 and 0.5 h−1, respectively, and gene ontology groups Energy metabolism and Translation dominated synthesis costs at both growth rates studied. These results reflect the complexity of metabolic changes that occur in response to changes in environmental conditions, and signify the trade-off between biomass yield and the need to produce ATP for maintenance processes.

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