Phytopathogenicity of avian mycoplasma Mycoplasma gallisepticum S6: Morphologic and ultracytostructural changes in plants infected with the vegetative forms and the viable but nonculturable forms of the bacterium

Recent studies show that mycoplasmas have various programs of life. This means that changes in morphology and genome expression may occur once the environment of these microorganisms becomes extremely altered. In this article, we report on changes in the DNA molecule obtained from the vegetative forms and the viable but nonculturable (VBNC) forms ofMycoplasma gallisepticumS6. Atomic force microscopy studies show that the above-mentioned forms of the mycoplasma have different values of DNA parameters (height: 0.461 ± 0.141 and 0.236 ± 0.069 nm; width: 2.221 ± 0.286 and 1.291 ± 0.705 nm for the vegetative and the VBNC forms, respectively). We suppose that the observed phenomenon may be connected with the process of adaptation of these bacteria to severe environments.

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Exemplar Abstract for Mycoplasma gallisepticum Edward and Kanarek 1960 (Approved Lists 1980).

The NamesforLife Abstracts ◽

10.1601/ex.18002 ◽

2003 ◽

Author(s):

Charles Thomas Parker ◽

Dorothea Taylor ◽

George M Garrity

Keyword(s):

Mycoplasma Gallisepticum

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Evidence for Environmental Factors, Including Presence of Heavy Metals, Involved in Converting Potential Pathogens to a Viable But Nonculturable State in River and Estuarine Water

10.21236/ada237512 ◽

1991 ◽

Author(s):

Jafrul A. Hasan ◽

Anwarul Huq ◽

Rita R. Colwell

Keyword(s):

Heavy Metals ◽

Environmental Factors ◽

Estuarine Water ◽

Viable But Nonculturable ◽

Nonculturable State ◽

Viable But Nonculturable State

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GAA Trinucleotide Repeat Region Regulates M9/pMGA Gene Expression in Mycoplasma gallisepticum

Infection and Immunity ◽

10.1128/iai.68.2.871-876.2000 ◽

2000 ◽

Vol 68 (2) ◽

pp. 871-876 ◽

Cited By ~ 34

Author(s):

Li Liu ◽

Kevin Dybvig ◽

Victor S. Panangala ◽

Vicky L. van Santen ◽

Christopher T. French

Keyword(s):

Gene Expression ◽

Trinucleotide Repeat ◽

Mycoplasma Gallisepticum ◽

Avian Host ◽

Phase Variable ◽

Repeat Region ◽

Chromosomal Dna ◽

Promoter Regions ◽

Variable Expression ◽

Gaa Repeats

ABSTRACT Mycoplasma gallisepticum, the cause of chronic respiratory infections in the avian host, possesses a family of M9/pMGA genes encoding an adhesin(s) associated with hemagglutination. Nucleotide sequences of M9/pMGA gene family members indicate extensive sequence similarity in the promoter regions of both the transcribed and silent genes. The mechanism that regulates M9/pMGA gene expression is unknown, but studies have revealed an apparent correlation between gene expression and the number of tandem GAA repeat motifs located upstream of the putative promoter. In this study, transposon Tn4001was used as a vector with the Escherichia coli lacZ gene as the reporter system to examine the role of the GAA repeats in M9/pMGA gene expression in M. gallisepticum. A 336-bp M9 gene fragment (containing the GAA repeat region, the promoter, and the translation start codon) was amplified by PCR, ligated with alacZ gene from E. coli, and inserted into the Tn4001-containing plasmid pISM2062. This construct was transformed into M. gallisepticum PG31. Transformants were filter cloned on agar supplemented with 5-bromo-4-chloro-3-indolyl-β-d-galactopyranoside (X-Gal) to monitor lacZ gene expression on the basis of blue/white color selection. Several cycles of filter cloning resulted in cell lineages in which lacZ gene expression alternated between the On and Off states in successive generations of progeny clones. The promoter regions of the M9-lacZ hybrid genes of individual progeny clones were amplified by PCR and sequenced. The only differences between the promoter regions of the blue and white colonies were in the number of GAA repeats. Clones that expressedlacZ had exactly 12 tandem copies of the GAA repeat. Clones that did not express lacZ invariably had either more than 12 (14 to 16) or fewer than 12 (5 to 11) GAA repeats. Southern analysis of M. gallisepticum chromosomal DNA confirmed that the phase-variable expression of the lacZ reporter gene was not caused by Tn4001 transposition. These data strongly indicate that changes in the length of the GAA repeat region are responsible for regulating M9/pMGA gene expression.

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Induction and Resuscitation of Viable but Nonculturable Corynebacterium diphtheriae

Microorganisms ◽

10.3390/microorganisms9050927 ◽

2021 ◽

Vol 9 (5) ◽

pp. 927

Author(s):

Takashi Hamabata ◽

Mitsutoshi Senoh ◽

Masaaki Iwaki ◽

Ayae Nishiyama ◽

Akihiko Yamamoto ◽

...

Keyword(s):

Low Temperatures ◽

Diphtheria Toxin ◽

Pathogenic Bacteria ◽

Corynebacterium Diphtheriae ◽

Human Pathogen ◽

Vbnc State ◽

Viable But Nonculturable ◽

Environmental Survival ◽

Reverse Transcription Quantitative Pcr ◽

Morphological Differences

Many pathogenic bacteria, including Escherichia coli and Vibrio cholerae, can become viable but nonculturable (VBNC) following exposure to specific stress conditions. Corynebacterium diphtheriae, a known human pathogen causing diphtheria, has not previously been shown to enter the VBNC state. Here, we report that C. diphtheriae can become VBNC when exposed to low temperatures. Morphological differences in culturable and VBNC C. diphtheriae were examined using scanning electron microscopy. Culturable cells presented with a typical rod-shape, whereas VBNC cells showed a distorted shape with an expanded center. Cells could be transitioned from VBNC to culturable following treatment with catalase. This was further evaluated via RNA sequence-based transcriptomic analysis and reverse-transcription quantitative PCR of culturable, VBNC, and resuscitated VBNC cells following catalase treatment. As expected, many genes showed different behavior by resuscitation. The expression of both the diphtheria toxin and the repressor of diphtheria toxin genes remained largely unchanged under all four conditions (culturable, VBNC, VBNC after the addition of catalase, and resuscitated cells). This is the first study to demonstrate that C. diphtheriae can enter a VBNC state and that it can be rescued from this state via the addition of catalase. This study helps to expand our general understanding of VBNC, the pathogenicity of VBNC C. diphtheriae, and its environmental survival strategy.

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