Physiological responses of Lactococcus lactis ML3 to alternating conditions of growth and starvation

Abstract

Abstract.Lactococcus lact& species can survive periods of carbohydrate starvation for relatively long periods of time. In the first hours of starvation, however, the maximal glycolytic and arginine deiminase (ADI) pathway activities decline rapidly. The rate of decrease of the pathway activities diminishes as soon as the cells become depleted of energy-rich intermediates. Loss of glycolytic activity is associated with loss of glyceraldehyde 3-phosphate dehydrogenase, phosphoglycerate mutase and pyruvate kinase activities. Upon addition of sugar to starved cultures these enzymatic, and thus the glycolytic, activities can be restored to 100% values. The recovery of enzymatic activities is inhibited by chtoramphenicol, indicating that protein synthesis is involved. In contrast, restoration of ADI pathway activity does not require de novo synthesis of proteins. General protein degradation and synthesis have been studied in growing and starving cells using [35S]methionine-labeling of proteins and twodimensional gel analysis. The breakdown of bulk proteins in exponentially growing cells shows first-order rate kinetics (t~ of approximately 5 h). Following an initial breakdown of proteins with a tz ~ of 5 h during the first hour(s) of starvation, bulk proteins are degraded very slowly in starving energy-depleted cells. The breakdown of proteins during starvation appears to be (largely) nonspecific. The rate of synthesis of proteins decreases rapidly in the first hour(s) of starvation. From the onset of starvation on at least 45 proteins are no longer synthesized. During starvation relative induction of fourteen to fifteen proteins can be observed.

Di-tripeptides and oligopeptides are taken up via distinct transport mechanisms in Lactococcus lactis

“…MGAD4 (AlaT- DtpT-) was further characterized to exclude the possibility that the reduced transport activities are the result of defects in the generation of metabolic energy. The glycolytic and ADI pathway activities of these cells, estimated from the rates of product formation (8), were found to be comparable to those of wild-type cells. Furthermore, MGAD4 (AlaT-DtpT-) is capable of generating a Ap and ATP to wild-type levels (data not shown).…”

“…Protein was determined by the method of Lowry et al (11), with bovine serum albumin as the standard. The glycolytic and ADI pathway activities and the membrane potential (A+) were determined as described previously (8,19). Growth experiments were performed with enzyme-linked immunosorbent assay plates, and specific growth rates were estimated fromA660 measurements with a Thermo Max apparatus (Molecular Devices, Palo Alto, Calif.).…”

Stress Physiology of Lactic Acid Bacteria

“…Overall, the responses consist of the selection of alternative fates of pyruvate, the utilization of other carbon sources, the activation of the proteolytic system, and/or the catabolism of free amino acids (FAA) by cells. Metabolic adaptation is crucial for survival because it stimulates the production of additional energy and lowers the stress level, e.g., through alkalization of the cytosol under acidic conditions (159). The extent of metabolic perturbation and the main routes to reprogram pathways responsible for substrate catabolism in order to adapt to environmental stresses vary between LAB species (160).…”

Dynamic energy budget theory restores coherence in biology

“…stylized facts empirical evidence feeding during starvation, organisms are able to reproduce animals: Kjesbu et al (1991), Hirche & Kattner (1993) and Kirk (1997) during starvation, organisms are able to grow animals: Stromgren & Cary (1984), Russell & Wootton (1992), Roberts et al 2001, Dou et al (2002, Gallardo et al (2004) and Zheng et al (2005) during starvation, organisms are able to survive for some time animals: Stockhoff (1991) and Letcher et al (1996) bacteria: Kunji et al (1993) growth the growth of isomorphic organisms at abundant food is well described by the von Bertalanffy growth curve Putter (1920) andvon Bertalanffy (1938) animals: Frazer et al (1990), Strum (1991), Chen et al (1992), Schwartz & Hundertmark (1993), Ferreira & Russ (1994) and Ross et al (1995) for different constant food levels the inverse von Bertalanffy growth rate increases linearly with ultimate length Putter (1920) animals: Summers (1971), Galluci & Quinn (1979), Weindruch et al (1986), Hubert et al (2000) and Kooijman (2010, pp.48) many species do not stop growing after reproduction has started, i.e. they exhibit indeterminate growth Heino & Kaitala (1999) and Kozlowski (1996) animals: Shine & Iverson (1995) and Jorgensen & Fiksen (2006) holometabolic insects are an exception foetuses increase in weight approximately proportional to cubed time Huggett & Widdas (1951) animals: Huggett & Widdas (1951) and Zonneveld & Koo...…”