The impact of water and temperature interactions on lag phase, growth and potential ochratoxin A production by two new species, Aspergillus aculeatinus and A. sclerotiicarbonarius, on a green coffee-based medium

Akbar, Asya; Magan, Naresh

doi:10.1016/j.ijfoodmicro.2014.07.025

Cited by 12 publications

(8 citation statements)

References 21 publications

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“…For instance, studies of oxidative stress in S. cerevisiae BY4741 grown in batch culture found that length of lag phase is in approximate agreement with rates of exponential growth 1 20 . In the Aspergillus study by Akbar and Magan 80 , there was a strong correlation between length of lag phase and maximum growth rate for some strains, including A. aculeatinus CBS 121872 at 0.980 water activity (r 2 = 0.904) and A. aculeatinus CBS 121875 at 0.980 water activity (r 2 = 0.950) ( Fig. 7c,d).…”

Section: Lag Phase Can Sometimes Correlate With the Maximum Rates Of mentioning

confidence: 78%

“…However, over-expression of PEP3 decreased length of lag phase but did not alter the rate of subsequent growth. In a study of two Aspergillus species, food-spoilage strains were cultivated over a range of water-activity values, in glycerol-supplemented nutrient media, and incubated over a range of temperatures 80 . We analysed the relationship between lag phase and maximum rate of mycelial extension of these fungi and found that, in some cases there was inconsistency between these parameters; for A. sclerotiicarbonarius CBS 12183 at 0.950 water activity and A. aculeatinus CBS 121872 at 0.990 water activity, r 2 = 0.0002 and 0.393 respectively (Fig.…”

Section: Lag Phase Can Sometimes Vary Independently Of Maximum Rates mentioning

confidence: 99%

“…In order to determine whether the findings of the current study were applicable to mesophilic spoilage fungi and/ or for enzyme systems, extant datasets were located, analyzed, and then compared with the model systems used in the current study. For the mesophilic fungi Aspergillus aculeatinus and Aspergillus sclerotiicarbonarius, that are known to cause food-spoilage, growth data 80 were used to construct length of lag phase-versus-maximum growth-rate plots, as for B. subtilis (see above). As described by Akbar and Magan 80 , media was prepared by boiling 300 g of ground green coffee beans in 1 litre of distilled water for 30 min, then filtering through a double layer of muslin.…”

Section: Saccharomyces Cerevisiae Dehydration-rehydration Experimentsmentioning

confidence: 99%

“…For the mesophilic fungi Aspergillus aculeatinus and Aspergillus sclerotiicarbonarius, that are known to cause food-spoilage, growth data 80 were used to construct length of lag phase-versus-maximum growth-rate plots, as for B. subtilis (see above). As described by Akbar and Magan 80 , media was prepared by boiling 300 g of ground green coffee beans in 1 litre of distilled water for 30 min, then filtering through a double layer of muslin. All media contained 6% [w/v] concentrated coffee extract, agar (2% w/v) and glycerol; the latter was used to adjust water activity.…”

Section: Saccharomyces Cerevisiae Dehydration-rehydration Experimentsmentioning

confidence: 99%

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Microbial lag phase can be indicative of, or independent from, cellular stress

Hamill

Stevenson

McMullan

et al. 2020

Sci Rep

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Measures of microbial growth, used as indicators of cellular stress, are sometimes quantified at a single time-point. in reality, these measurements are compound representations of length of lag, exponential growth-rate, and other factors. Here, we investigate whether length of lag phase can act as a proxy for stress, using a number of model systems (Aspergillus penicillioides; Bacillus subtilis; Escherichia coli; Eurotium amstelodami, E. echinulatum, E. halophilicum, and e. repens; Mrakia frigida; Saccharomyces cerevisiae; Xerochrysium xerophilum; Xeromyces bisporus) exposed to mechanistically distinct types of cellular stress including low water activity, other solute-induced stresses, and dehydrationrehydration cycles. Lag phase was neither proportional to germination rate for X. bisporus (FRR3443) in glycerol-supplemented media (r 2 = 0.012), nor to exponential growth-rates for other microbes. In some cases, growth-rates varied greatly with stressor concentration even when lag remained constant. By contrast, there were strong correlations for B. subtilis in media supplemented with polyethyleneglycol 6000 or 600 (r 2 = 0.925 and 0.961), and for other microbial species. We also analysed data from independent studies of food-spoilage fungi under glycerol stress (Aspergillus aculeatinus and A. sclerotiicarbonarius); mesophilic/psychrotolerant bacteria under diverse, solute-induced stresses (Brochothrix thermosphacta, Enterococcus faecalis, Pseudomonas fluorescens, Salmonella typhimurium, Staphylococcus aureus); and fungal enzymes under acid-stress (Terfezia claveryi lipoxygenase and Agaricus bisporus tyrosinase). these datasets also exhibited diversity, with some strong-and moderate correlations between length of lag and exponential growth-rates; and sometimes none. in conclusion, lag phase is not a reliable measure of stress because length of lag and growth-rate inhibition are sometimes highly correlated, and sometimes not at all. Chemical reactions and thermodynamic and biological processes often experience a lag period prior to reaching their maximum rate. This phenomenon that can be observed at various levels; thermodynamic processes (e.g. thermal lag), chemical reactions, biochemical activities 1 , cellular physiology 2 , microbial growth kinetics, and ecosystem functions 3. The term lag, used in English since the early 14 th century, has been applied to biological processes since at least the 1680s 4. In the context of microbial growth kinetics, lag, once known as 'latency' , was studied since the 1800s, including work of Louis Pasteur 5. Despite this long pedigree of research into this phenomenon, however, some aspects of the biology and application of the lag phase are not yet resolved. Accurate assessments of microbial growth must account for the various growth processes, including: mycelial extension, cell division within planktonic populations, increases in the mass of individual cells, accumulation of compatible solutes or other endogenous reserves, cell elongation or growth, sporulation, germination,...

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Section: Lag Phase Can Sometimes Correlate With the Maximum Rates Of mentioning

confidence: 78%

Section: Lag Phase Can Sometimes Vary Independently Of Maximum Rates mentioning

confidence: 99%

Section: Saccharomyces Cerevisiae Dehydration-rehydration Experimentsmentioning

confidence: 99%

Section: Saccharomyces Cerevisiae Dehydration-rehydration Experimentsmentioning

confidence: 99%

See 2 more Smart Citations

Microbial lag phase can be indicative of, or independent from, cellular stress

Hamill

Stevenson

McMullan

et al. 2020

Sci Rep

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show abstract

“…The potential effects of climate change, such as the production of mycotoxins, on the quantity and quality of some foods has aroused the interest of the scientific community (Akbar & Magan, 2014;Magan, Medina, & Aldred, 2011). According to Tirado, Clarke, Jaykus, McQuatters-Gollop, and Frank (2010), to estimate and predict the impact of climate change on mycotoxin contamination in some cultures, like coffee, it is necessary to develop models capable of predicting mycotoxin levels in relation to climatic parameters.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the effects of temperature on processed coffee beans in the presence of fungi and ochratoxin A

Sousa

Batista

Passamani

et al. 2018

Journal of Food Safety

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The coffee bean is sensitive to contamination with ocratoxigenic fungi; temperature influences the growth, and germination of these fungi, as well as the fungal toxins produced. The objectives of this study were to assess the distribution of toxigenic species, analyze the concentration of ochratoxin A (OTA) in Arabica coffee beans, and aplicate a mathematical model that considers the influence of actual temperature to predict the effects of projected temperature increase on OTA production. This toxin was, however, not detected in any of the coffee bean species analyzed here. The species with the highest incidence were Aspergillus niger and Aspergillus ochraceus. The results of the mathematical model demonstrated the influence of temperature on the production of the toxin. This information indicates the distribution of toxigenic fungal species in the regions of coffee cultivation in Minas Gerais, and thus, will assist the producers in adopting preventive measures. Practical applications Brazil is the largest coffee producer and exporter, which makes it a leader in the global coffee market; the state of Minas Gerais is responsible for 50% of this production. Following the global trend, Brazil has regulated the maximum permissible limit for ochratoxin A in coffee beans. This has led to a great interest in monitoring fungi and toxin production, mainly during the postharvest stage in the coffee cultivation regions of Brazil. Preventive measures can aid in the safe production of coffee beans, and the use of mathematical models capable of predicting the growth and production of fungal toxins are fundamental to informing the producers of the most favorable conditions in terms of temperature, as well as increases in ambient temperature, in specific regions of interest.

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Determination of potentially mycotoxigenic fungi in coffee (Coffea arabica L.) from Nayarit

Casas-Junco

Ragazzo‐Sánchez

Ascencio‐Valle

et al. 2017

Food Sci Biotechnol

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A total of fourteen roasted coffee samples were collected from different local markets in Nayarit, Mexico. Twenty-two fungi isolates were related to the genera (54.54%) and (4.5%). The strains R16 (0.33 μg/kg), 6N (1.16 μg/kg) and 11 (0.36 μg/kg) tested positive for OTA (ochratoxin A) production in PDA, the other fungi samples were not toxigenic. According to the sequence analysis of their ITS1-5.8S-ITS2 rDNA region, fungi OTA producers correspond to , and . These three strains were able to produce OTA when inoculated in roasted coffee in concentrations ranging from 75 to 90 μg/kg, after 21 days. Different production stages of roasted coffee (crop management, postharvest practices and storage) along with environmental conditions do not ensure mycotoxigenic fungi free products. This is the first report of OTA natural occurrence in roasted coffee from Nayarit.

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The impact of water and temperature interactions on lag phase, growth and potential ochratoxin A production by two new species, Aspergillus aculeatinus and A. sclerotiicarbonarius, on a green coffee-based medium

Cited by 12 publications

References 21 publications

Microbial lag phase can be indicative of, or independent from, cellular stress

Microbial lag phase can be indicative of, or independent from, cellular stress

Evaluation of the effects of temperature on processed coffee beans in the presence of fungi and ochratoxin A

Determination of potentially mycotoxigenic fungi in coffee (Coffea arabica L.) from Nayarit

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