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  • M. luteus  (1)
  • antibacterial factor  (1)
  • 1
    ISSN: 1572-9699
    Keywords: dormancy ; resuscitation ; cryptobiosis ; anabiosis ; M. luteus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It has been found previously that a significant number of Micrococcus luteus cells starved in a prolonged stationary phase (up to 2 months) and then held on the bench at room temperature without agitation for periods of up to a further 2–7 months can be resuscitated in liquid media which contained (statistically) no initially-viable (colony-forming) cells but which were fortified with sterile supernatant from the late logarithmic phase of batch growth. Here it was found that such resuscitation can be done only within a defined time period after taking the first sample from such cultures, necessarily involving agitation of the cells. The duration of this period depends on the age of the starved culture: cells kept on the bench for 3 months possess a 2 month period of resuscitability while cells starved for 6 months can be resuscitated only within 10 days after the beginning of sampling. It is suggested that the input of oxygen to the starved cultures while they are agitated may exert a negative influence on the cells, since cultures stored in anaerobic conditions (under nitrogen) had a more prolonged ’survival' time. The cells which experienced between 10 and 60 days of starvation on the bench could be resuscitated, although the number of resuscitable cells depended strongly on the concentration of yeast extract in the resuscitation medium. This concentration for cells stored on the bench for more than 2 months was 0.05% while ’1-month-old‘ cells displayed a maximum resuscitability in the presence of 0.01% of yeast extract. Application of the fluorescent probe propidium iodide revealed the formation of cells with a damaged permeability barrier if resuscitation was performed by using concentrations of yeast extract of 0.1% and above. Thus the successful resuscitation of bacterial cultures under laboratory conditions may need rather strictly defined parameters if it is to be successfully performed for the majority of cells in a population.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-9699
    Keywords: antibacterial factor ; dormancy ; Micrococcus luteus ; resuscitation ; stationary phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A high proportion ofMicrococcus luteus cells in cultures starved for 3–6 months in spent medium following growth to stationary phase in batch culture lost the ability to grow and form colonies on agar plates, but could be resuscitated from dormancy by incubation in liquid medium containing supernatant taken from the late log phase of viable cultures of the same organism (Kaprelyants et al. 1994). In the present work, we found that during the first 50–70 h of such resuscitation the dormant cells actually divide for 10–17 generations in lactate minimal medium containing yeast extract whilst remaining nonculturable on agar plates. Further incubation results in a decrease in the total cell number in liquid medium. The addition of viable (culturable)Micrococcus luteus cells in concentrations of up to 104 ml−1 to test tubes containing either resuscitating cells or supernatant from these cultures revealed the excretion of a factor or factors which inhibited the proliferation of otherwise viable cells. The maximum production of this factor took place after some 96 h of incubation of starved cells in resuscitation medium. Supernatant from late logarithmic phase batch cultures ofM. luteus abolished the antibacterial effect of starved cultures incubated in resuscitation medium. It is concluded that the stimulating effect of viable cells, and of supernatant taken from batch cultures, on the resuscitation of dormant cells might be connected in part with overcoming the activity of an antibacterial factor causing self-poisoning of dormant cells during their resuscitation.
    Type of Medium: Electronic Resource
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