Effects of alcohols on the respiration and fermentation of aerated suspensions of baker's yeast

Carlsen, Helle N.; Degn, Hans; Lloyd, David

doi:10.1099/00221287-137-12-2879

Cited by 49 publications

(29 citation statements)

References 17 publications

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“…M. albus produces short-chain alcohols that could have this activity. These shortchain, branched alcohols are known to have toxic effects on E. coli due to increased permeability when present at high concentrations (15,35). In our screen, the knockout of 44 genes functioning as or in association with membrane proteins rendered the E. coli strain highly sensitive to M. albus VOCs.…”

Section: Discussionmentioning

confidence: 80%

Mycofumigation by the Volatile Organic Compound-Producing Fungus Muscodor albus Induces Bacterial Cell Death through DNA Damage

Alpha

Campos

Jacobs‐Wagner

et al. 2015

Appl Environ Microbiol

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bMuscodor albus belongs to a genus of endophytic fungi that inhibit and kill other fungi, bacteria, and insects through production of a complex mixture of volatile organic compounds (VOCs). This process of mycofumigation has found commercial application for control of human and plant pathogens, but the mechanism of the VOC toxicity is unknown. Here, the mode of action of these volatiles was investigated through a series of genetic screens and biochemical assays. A single-gene knockout screen revealed high sensitivity for Escherichia coli lacking enzymes in the pathways of DNA repair, DNA metabolic process, and response to stress when exposed to the VOCs of M. albus. Furthermore, the sensitivity of knockouts involved in the repair of specific DNA alkyl adducts suggests that the VOCs may induce alkylation. Evidence of DNA damage suggests that these adducts lead to breaks during DNA replication or transcription if not properly repaired. Additional cytotoxicity profiling indicated that during VOC exposure, E. coli became filamentous and demonstrated an increase in cellular membrane fluidity. The volatile nature of the toxic compounds produced by M. albus and their broad range of inhibition make this fungus an attractive biological agent. Understanding the antimicrobial effects and the VOC mode of action will inform the utility and safety of potential mycofumigation applications for M. albus. T he endophytic fungusMuscodor albus (CZ-620) inhibits growth of a broad range of pathogenic fungi and bacteria, as well as some nematode and arthropod species (1-6). The inhibition is achieved exclusively through a complex mixture of volatile organic compounds (VOCs) that M. albus secretes into the headspace of the culture. The volatile compounds emitted by M. albus and other closely related organisms in the genus consist of a combination of short-chain alcohols, organic acids, esters, ketones, and several aromatic hydrocarbons as monitored by gas chromatography-mass spectrometry (GC-MS) (6). The compounds range from two to nine carbons and include both straight and branched-chain varieties. The larger aromatic products are predicted to be sesquiterpenes and derivatives of naphthalene and azulene but have not been confirmed by comparison to standards. Although many fungal species have been reported to produce VOCs, none have demonstrated the wide-ranging bioactivity seen with isolates of M. albus (7,8).The biological function of the toxic compound production by M. albus is unknown. M. albus was first identified as an endophyte, an organism that lives within the inner tissues of plants (9). Although endophytic interactions between fungi and host plants are typically asymptomatic for part, or all, of their life cycle, these can also be commensal relationships. There are examples where fungi improve the host plant's growth, fitness, or response to stress response (10-12). In the case of M. albus, its VOC emissions may serve as a defense mechanism for the host plant against insects or potential pathogens, and these same products ha...

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Section: Discussionmentioning

confidence: 80%

Mycofumigation by the Volatile Organic Compound-Producing Fungus Muscodor albus Induces Bacterial Cell Death through DNA Damage

Alpha

Campos

Jacobs‐Wagner

et al. 2015

Appl Environ Microbiol

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“…The ethanol released from seeds might accelerate respiration of the yeast in the RR, which would result in the reduction of resazurin and a color change. Carlsen et al (1991) reported that low concentrations (e.g. 10%) of ethanol were a respiratory substrate in aerated yeast (Saccharomyces cerevisiae, baker's yeast) suspension without glucose.…”

Section: Discussionmentioning

confidence: 99%

Detection of ethanol released from aged radish (Raphanus sativus L.) seeds using resazurin

Min

2012

Hortic. Environ. Biotechnol.

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The release of volatiles from aged radish (Raphanus sativus L., var. Yechanmoo) seeds and from ethanol was evaluated using the resazurin reagent (RR, solution of resazurin and yeast mixture). The primary volatile released from the aged radish seeds was identified as ethanol, but no volatiles from non-aged seeds were detected by solid phase microextraction (SPME) followed by GC-MS analysis and ethanol standard confirmation. The volatiles from aged radish seeds and from ethanol changed the color of the RR from blue to pink after 8-10 hours of incubation at 35 , and the absorbance of the RR was read at 570 nm. When ethanol was diluted with the RR at concentrations ranging from 0 to 10,000 ppm, the absorbance and ethanol concentrations were found to be negatively correlated in the linear regression analysis with r 2 = 0.91. For the seed test, the aged and non-aged radish seeds were soaked individually in the RR using a 96-well plate and incubated at 35 for 4 hours. The absorbance of the RR soaked non-aged seeds did not change; however, the absorbance of the aged seeds rapidly decreased with incubation time. Also, the visual color of the RR soaked aged seeds visibly changed from blue to pink after two hour of incubation and was colorless after four hours of incubation. The color changes of the RR could be attributed to the fact that ethanol accelerated respiration of the yeast and resorufin was produced through the reduction of resazurin. In conclusion, RR was shown to be a highly sensitive reagent for the detection of volatiles (mainly ethanol) released from aged radish seeds and could be used to simply, rapidly and nondestructively classify the viable and non-viable seeds.Additional key words: resazurin reagent, seed quality, solid phase microextraction (SPME), volatile, yeast Hort. Environ. Biotechnol. 53(1):66-71. 2012.

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“…The addition of ethanol to yeast cultures is known to limit the rate of yeast fermentation (3). To determine whether Baxexpressing yeasts are more reliant on fermentation for ATP synthesis than control yeast, ethanol was added to normalized cultures of Bax-expressing and control cells and growth was measured after 24 h. The difference in growth between Baxexpressing and control cells became progressively greater as an increasing amount of ethanol was added to the cultures (Fig.…”

Section: Resultsmentioning

confidence: 99%

Role of Oxidative Phosphorylation in Bax Toxicity

Harris

Heiden²,

Kron

et al. 2000

Molecular and Cellular Biology

119

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The Bcl-2-related protein Bax is toxic when expressed either in yeast or in mammalian cells. Although the mechanism of this toxicity is unknown, it appears to be similar in both cell types and dependent on the localization of Bax to the outer mitochondrial membrane. To investigate the role of mitochondrial respiration in Bax-mediated toxicity, a series of yeast mutant strains was created, each carrying a disruption in either a component of the mitochondrial electron transport chain, a component of the mitochondrial ATP synthesis machinery, or a protein involved in mitochondrial adenine nucleotide exchange. Bax toxicity was reduced in strains lacking the ability to perform oxidative phosphorylation. In contrast, a respiratory-competent strain that lacked the outer mitochondrial membrane Por1 protein showed increased sensitivity to Bax expression. Deficiencies in other mitochondrial proteins did not affect Bax toxicity as long as the ability to perform oxidative phosphorylation was maintained. Characterization of Bax-induced toxicity in wild-type yeast demonstrated a growth inhibition that preceded cell death. This growth inhibition was associated with a decreased ability to carry out oxidative phosphorylation following Bax induction. Furthermore, cells recovered following Bax-induced growth arrest were enriched for a petite phenotype and were no longer able to grow on a nonfermentable carbon source. These results suggest that Bax expression leads to an impairment of mitochondrial respiration, inducing toxicity in cells dependent on oxidative phosphorylation for survival. Furthermore, Bax toxicity is enhanced in yeast deficient in the ability to exchange metabolites across the outer mitochondrial membrane.

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Effects of alcohols on the respiration and fermentation of aerated suspensions of baker's yeast

Cited by 49 publications

References 17 publications

Mycofumigation by the Volatile Organic Compound-Producing Fungus Muscodor albus Induces Bacterial Cell Death through DNA Damage

Mycofumigation by the Volatile Organic Compound-Producing Fungus Muscodor albus Induces Bacterial Cell Death through DNA Damage

Detection of ethanol released from aged radish (Raphanus sativus L.) seeds using resazurin

Role of Oxidative Phosphorylation in Bax Toxicity

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