Relative changes in incorporation rates of leucine and methionine during starvation survival of two bacteria isolated from marine waters

Abstract

Two copiotrophic Gram‐negative bacteria isolated from marine waters, S14 and Vibrio sp. DW1, were examined for changes in the rate of protein synthesis in the initial phase of energy and nutrient deprivation. The incorporation of [3H] leucine into the trichloroacetic acid (TCA)‐insoluble material was examined as a method for estimating rates of protein synthesis. The incorporation of methionine was measured and compared with the results of leucine incorporation. Protein synthesis was demonstrated throughout a period of 120 h of starvation. The incorporation rate was related to the time of starvation and decreased subsequent to an initial increase during the first few hours of dormancy. Control experiments with proteinase K and chloramphenicol demonstrated that the labelled amino acids were preferentially incorporated into proteins. It was also demonstrated that the uptake of amino acids was not a rate‐limiting step. During the first hours of starvation the ratio of the protein to the dry weight of the S14 cells increased parallel to the increase in the amino acid incorporation rate. The increased activity of the protein‐synthesising system during the first hours of nutrient and energy depletion indicates the presence of an active cellular response to the downshift conditions. Furthermore, these findings are consistent with the increased respiratory activity during the first hours of starvation, which has previously been observed for the bacteria examined in this study.

Synthesis of Membrane and Periplasmic Proteins during Starvation of a Marine Vibrio sp.

“…Increased incorporation rates of leucine and methionine (Nystrom et al, 1986), and an increase in respiration rate (MArdCn et al, 1985) during the first 3 to 4 h as compared to the onset of starvation have been demonstrated for S14.…”

“…The greatest number of changes was detected at 3 and 5 h of starvation, which may coincide with the utilization of the accumulated storage polymer poly-/?-hydroxybutyrate (PHB) (MBrdCn et al, 1985). An attempt to correlate the rate of protein synthesis (Nystrom et al, 1986), total amount of protein and utilization of PHB (Mgrdkn et al, 1985) is presented in Fig. 6.…”

“…Protein concentrations were determined by the method of Whitaker & Granum (1980). Samples were prepared according to Nystrom et al (1986).…”

Long term starvation of a marine bacterium,Alteromonas denitrificans, isolated from a Norwegian fjord

“…While short-term starvation studies ( [28] and references therein) provide essential information on the immediate responses to starvation conditions, the present study indicates that A. denitrificans does not go into a dormant state, i.e., finish its survival adaptation strategy, in a day or two. Long-term studies are needed therefore to understand the function of such bacteria in the marine microbial ecosystems.…”

Significance of Na+in the fish pathogen,Vibrio anguillarum, under energy depleted condition

“…V. angustum S14 was isolated from coastal seawater off Sydney, Australia. Both strains were cultured in VNSS [19] in the dark at 20 °C to late logarithmic phase (OD 660 =0.8) for all experiments. Before suspension or inoculation in each medium, cells were washed twice with the same medium.…”