A Specific Mutation in the Promoter Region of the Silent
            <i>cel</i>
            Cluster Accounts for the Appearance of Lactose-Utilizing Lactococcus lactis MG1363

Solopova, Ana; Bachmann, Herwig; Teusink, Bas; Neves, Ana Rute; Kuipers, Oscar P.

doi:10.1128/aem.00455-12

Cited by 35 publications

(35 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Indeed, the Pcel promoter region contains two binding sites (cre sites) for the CCR transcriptional regulator CcpA (SI Appendix, Fig. S5) (3). We deleted the ccpA gene from the chromosome of L. lactis M1gfp to examine whether population heterogeneity also occurs in the absence of CCR.…”

Section: Resultsmentioning

confidence: 99%

“…L. lactis M1 is a derivative of L. lactis MG1363, which grows well on cellobiose because of the activation of the Pcel promoter of the cellobiose uptake system IIC component CelB. An active cellobiose/lactose phosphotransferase system (PTS Cel/Lac ) consists of proteins PtcAB and CelB (3). A diauxic shift is seen when L. lactis M1 is propagated in a medium supplemented with both glucose (0.1%) and cellobiose (1%) (G-C medium; Fig.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Bet-hedging during bacterial diauxic shift

Solopova

Gestel

Weissing

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

238

245

View full text Add to dashboard Cite

When bacteria grow in a medium with two sugars, they first use the preferred sugar and only then start metabolizing the second one. After the first exponential growth phase, a short lag phase of nongrowth is observed, a period called the diauxie lag phase. It is commonly seen as a phase in which the bacteria prepare themselves to use the second sugar. Here we reveal that, in contrast to the established concept of metabolic adaptation in the lag phase, two stable cell types with alternative metabolic strategies emerge and coexist in a culture of the bacterium Lactococcus lactis. Only one of them continues to grow. The fraction of each metabolic phenotype depends on the level of catabolite repression and the metabolic state-dependent induction of stringent response, as well as on epigenetic cues. Furthermore, we show that the production of alternative metabolic phenotypes potentially entails a bet-hedging strategy. This study sheds new light on phenotypic heterogeneity during various lag phases occurring in microbiology and biotechnology and adjusts the generally accepted explanation of enzymatic adaptation proposed by Monod and shared by scientists for more than half a century.phenotypic heterogeneity | Gram-positive bacteria | metabolic fitness I n nature, bacteria are confronted with a wide range of environmental conditions that change over time. These conditions often elicit specific metabolic responses that increase the division rate of a cell. For example, when bacterial cells are exposed to multiple sugars, they do not metabolize all sugars simultaneously, but rather use the sugar that allows the highest celldivision rate. Cells switch to the less-preferred sugar when the most-preferred one (in many cases glucose) is depleted. Jacques Monod coined this phenomenon "diauxie" (1). Diauxie is characterized by two growth cycles-the first one on the preferred sugar, followed by a second one on the less-preferred sugar. Both are separated by a short period during which the population apparently does not grow. This period is known as the diauxie lag phase. It is typically assumed that cells need time to make the necessary enzymatic adaptations to switch from one substrate to another (2). However, the behavior of individual cells during the lag phase has not been studied in detail. Here, we examine the diauxic shift at the single-cell level in Lactococcus lactis using time-lapse microscopy, in addition to the traditional approach of studying population growth characteristics. Surprisingly, the lag phase at the switch from glucose to cellobiose consumption by L. lactis largely results from the heterogeneous response of cells to the environmental change, rather than the time it takes for cells to make the necessary metabolic adaptations. This result challenges Monod's view of enzymatic adaptation and asks for a revision on the interpretation of population lag phases.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Bet-hedging during bacterial diauxic shift

Solopova

Gestel

Weissing

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

238

245

View full text Add to dashboard Cite

show abstract

“…These findings are in agreement with earlier findings on sulphur-source shifts with yeast [48][49][50] . Earlier studies on different nutrient shifts have reported the existence of a subpopulation of cells that does not respond at all 2,3,5,6 or the occurrence of very dispersed response times 4,7,8 across a range of microbial species. In these cases, stochasticity in the cell population is large, mostly due to stochasticity in response times, leading either to a bimodal or very broad distribution of cell responses.…”

Section: Discussionmentioning

confidence: 99%

“…In both these cases, the lag phases of individual cells vary greatly. The fact that many different adaptation mechanisms can occur may explain the great variation in lag phase durations that have been experimentally observed, which range from minutes to days [2][3][4]7,8 .…”

mentioning

confidence: 99%

“…The general interpretation is that a lag phase results from the time that it takes for the microorganism to adapt its metabolism. Several single-cell studies indicate that the cause for the lag phase can also involve stochasticity: either only a small fraction of the population grows under the new condition [2][3][4][5][6] , and the lag phase derives from the time that it takes until those cells reach a significant fraction of the total population; or cells start to grow only after a fluctuation in gene-expression activity has occurred that is large enough to kick-start the induction of the nutrient uptake pathway [7][8][9] . In both these cases, the lag phases of individual cells vary greatly.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Single yeast cells vary in transcription activity not in delay time after a metabolic shift

Schwabe¹,

Bruggeman²

2014

Nat Commun

View full text Add to dashboard Cite

Individual cells respond very differently to changes in environmental conditions. Stochasticity causes cells to respond at different times, magnitudes or both. Here we disentangle and quantify these two sources of heterogeneity. We track the adaptation dynamics of single Saccharomyces cerevisiae cells exposed to a nutrient shift from methionine to sulphate and back. Using single-molecule RNA fluorescence in situ hybridization, we count the number of transcripts of a methionine-biosynthesis enzyme in single cells during adaptation. The variation of response times between cells is small, yet we find a high transient variability in the messenger RNA copy numbers. Surprisingly, single cells display strongly delayed transcription induction, as we could induce transcription fourfold quicker by direct activation and bypassing the cellular control circuitry. Transcription repression occurs rapidly within several minutes. This study indicates that small variability in response timing combined with high, stochastic transcription activity can cause large cell-to-cell variability in dynamic adaptation responses.

show abstract