In:
Scientific Reports, Springer Science and Business Media LLC, Vol. 10, No. 1 ( 2020-04-03)
Abstract:
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 dehydration-rehydration 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 polyethylene-glycol 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. sclerotiicarbonariu s); 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.
Type of Medium:
Online Resource
ISSN:
2045-2322
DOI:
10.1038/s41598-020-62552-4
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2020
detail.hit.zdb_id:
2615211-3
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