Isolation of nonlysogenic bacteria from λ-lysogenized strains using antibiotic-resistant phage

1984 ◽  
Vol 30 (1) ◽  
pp. 74-76 ◽  
Author(s):  
V. A. Kordyum ◽  
S. I. Chernykh ◽  
I. Y. Medvedeva
Keyword(s):  
Efficient Method ◽  
Selective Medium ◽  
Antibiotic Resistant ◽  
Lysogenic Culture

A simple and efficient method for obtaining nonlysogenic bacteria from λ-lysogenized strains using phage with an inserted antibiotic-resistant plasmid is described. When the lysogenic culture is infected with antibiotic-resistant phage, single non-lysogenic cells are lysogenized, isolated on selective medium, and cured of phage during incubation at 37 °C.

scholarly journals ON THE ORIGIN OF MITOCHONDRIAL MUTANTS: EVIDENCE FOR INTRACELLULAR SELECTION OF MITOCHONDRIA IN THE ORIGIN OF ANTIBIOTIC-RESISTANT CELLS IN YEAST

Genetics ◽  
1973 ◽  
Vol 74 (3) ◽  
pp. 421-432
Author(s):  
C W Birky
Keyword(s):  
Selective Medium ◽  
Wild Type ◽  
Respiratory Enzymes ◽  
Antibiotic Resistant ◽  
Homogeneous Population ◽  
Chloramphenicol Resistance ◽  
Mitochondrial Ribosomes ◽  
Constant Rate ◽  
A Cell ◽  
Mutant Cells

ABSTRACT In wild-type Sacchromyces cerevisiae, erythromycin and certain other antibacterial antibiotics inhibit the formation of respiratory enzymes in mitochondria by inhibiting translation on mitochondrial ribosomes. This paper is concerned with the origin of mutant cells, resistant to erythromycin by virtue of having a homogeneous population of mutant mitochondrial DNA molecules. Such mutant cells are obtained by plating wild-type (sensitive) cells on a nonfermentable substrate plus the antibiotic. Colonies of mutant cells appear first about four days after the time of appearance of established mutant cells; new colonies continue to appear, often at a constant rate, for many days. Application of the NEWCOMBrEes preading experiment demonstrates that most or all of the mutant cells which form the resistant colonies on selective medium arise only after exposure of the population to erythromycin. It is suggested that this result is most probably due to intracellular selection for mitochondrial genomes. Resistant mitochondria arising from spontaneous mutatLon are postulated to be at a selective disadvantage in the absence of erythromycin; reproducing more slowly than wild-type sensitive mitochondria, they cannot easily accumulate in sufficient numbers in a cell to render it resistant as a whole. In the presence of erythromycin, resistant mitochondria can continue to reproduce while sensitive mitochondria cannot, until there is a sufficient number to make the cell resistant, i.e. to permit normal cell growth. The same phenomenon is seen with respect to chloramphenicol resistance. Intracellular selection is considered more likely than direct induction of mutation by the antibiotic, since mutant cells do not accumulate in the presence of erythromycin if the mitochondrial genome is rendered nonessential by growth on glucose or nontranslatable by chloramphenicol. Intracellular selection provides a mechanism for direct adaptation at the cell level, compatible with currently acceptable ideas of spontaneous miitation and selection at the organelle level.

scholarly journals Selective antibiofilm properties and biocompatibility of nano-ZnO and nano-ZnO/Ag coated surfaces

2020 ◽  
Author(s):  
M. Rosenberg ◽  
M. Visnapuu ◽  
H. Vija ◽  
V. Kisand ◽  
K. Kasemets ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Human Keratinocytes ◽  
Selective Medium ◽  
Resistant Bacteria ◽  
Antibiofilm Activity ◽  
Nano Zno ◽  
Antibiotic Resistant ◽  
Surface Development ◽  
Coated Surfaces ◽  
Selective Enhancement

ABSTRACTSpread of pathogenic microbes and antibiotic-resistant bacteria in health-care settings and public spaces is a serious public health challenge. Materials that prevent solid surface colonization or impede touch-transfer of viable microbes could provide means to decrease pathogen transfer from high-touch surfaces in critical applications. ZnO and Ag nanoparticles have shown great potential in antimicrobial applications. Less is known about nano-enabled surfaces. Here we demonstrate that surfaces coated with nano-ZnO or nano-ZnO/Ag composites are not cytotoxic to human keratinocytes and possess species-selective medium-dependent antibiofilm activity against Escherichia coli, Staphylococcus aureus and Candida albicans. Colonization of nano-ZnO and nano-ZnO/Ag surfaces by E. coli and S. aureus was decreased in static oligotrophic conditions (no planktonic growth). Moderate to no effect was observed for bacterial biofilms in growth medium (supporting exponential growth). Inversely, nano-ZnO surfaces enhanced biofilm formation by C. albicans in oligotrophic conditions. However, enhanced C. albicans biofilm formation on nano-ZnO surfaces was effectively counteracted by the addition of Ag. Possible selective enhancement of biofilm formation by the yeast C. albicans on Zn-enabled surfaces should be taken into account in antimicrobial surface development. Our results also indicated the importance of the use of application-appropriate test conditions and exposure medium in antimicrobial surface testing.

Morphological Characterization of Mycobacteriophage R1

1974 ◽  
Vol 32 ◽  
pp. 254-255
Author(s):  
B. L. Soloff ◽  
T. A. Rado
Keyword(s):  
Carbon Source ◽  
Stationary Phase ◽  
Growth Phase ◽  
Minimal Medium ◽  
Morphological Characterization ◽  
Logarithmic Growth Phase ◽  
Complete Lysis ◽  
Lysogenic Culture ◽  
Logarithmic Growth

Mycobacteriophage R1 was originally isolated from a lysogenic culture of M. butyricum. The virus was propagated on a leucine-requiring derivative of M. smegmatis, 607 leu−, isolated by nitrosoguanidine mutagenesis of typestrain ATCC 607. Growth was accomplished in a minimal medium containing glycerol and glucose as carbon source and enriched by the addition of 80 μg/ ml L-leucine. Bacteria in early logarithmic growth phase were infected with virus at a multiplicity of 5, and incubated with aeration for 8 hours. The partially lysed suspension was diluted 1:10 in growth medium and incubated for a further 8 hours. This permitted stationary phase cells to re-enter logarithmic growth and resulted in complete lysis of the culture.

THE BACTERIAL MULTIPLE ANTIBIOTIC RESISTANT (MAR) PHENOTYPE LEADS TO INCREASED TOLERANCE TO TEA TREE OIL

Pathology ◽  
2001 ◽  
Vol 33 (2) ◽  
pp. 211-215 ◽  
Author(s):  
John E. Gustafson ◽  
Sean D. Cox ◽  
Yoon C. Liew ◽  
S. Grant Wyllie ◽  
John R. Warmington
Keyword(s):  
Tea Tree Oil ◽  
Antibiotic Resistant ◽  
Tea Tree
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