Influence of Oxidative Stress on Biocontrol Activity of Cryptococcus laurentii against Blue Mold on Peach Fruit

Abstract

The limitations of chemical fungicides for the control of postharvest diseases have recently become more apparent. The utilization of antagonistic microorganisms is a promising alternative to that of fungicides to control postharvest decay. In previous studies, the antagonistic yeast Cryptococcus laurentii has shown excellent effects of biocontrol and great potential for practical application. Adverse conditions, such as oxidative stress, limit the practical application of antagonistic yeast. In this study, we investigated the oxidative stress tolerance of C. laurentii and the associated mechanisms. The results indicated that exogenous oxidative stress has a significant effect on the viability and biocontrol efficiency of C. laurentii. H2O2-induced oxidative stress led to the accumulation of reactive oxygen species. The results of flow cytometric analysis suggested that apoptosis is responsible for the reduced survival rate of C. laurentii under oxidative stress. Using tests of antioxidant activity, we found that C. laurentii could employ enzymatic systems to resist exogenous oxidative stress. The addition of exogenous glutathione, a non-enzymatic antioxidant, to the media can significantly enhance oxidative tolerance and biocontrol efficiency of C. laurentii.

Proline Increases Pigment Production to Improve Oxidative Stress Tolerance and Biocontrol Ability of Metschnikowia citriensis

“…The oxidative stress tolerance of M . citriensis was investigated according to the method of Zhang et al (2017) with slight modification. The mid-log phase yeast cells were harvested by centrifugation (8,000 × g , 5 min) and then washed twice with SDW.…”

“…The effect of proline on cell viability of M . citriensis after exposure to H 2 O 2 was determined according to the method of Zhang et al (2017), with some modification. The yeast cells were incubated in NYDB medium and NYDB medium containing (1) 1 mM proline and (2) 10 μM tropolone, and the cell concentration was adjusted to 1 × 10 5 cells/ml.…”

“…Yeast cells (untreated and proline-treated) at mid-log phase were harvested by centrifugation as described above and then exposed to 40 mM H 2 O 2 . Extracts of enzymes of CAT and SOD were prepared according to the method of Zhang et al (2017), with some modification. The yeast cells were collected by centrifugation (8,000 × g , 5 min) at specific intervals (0, 30, 60, and 90 min) after being treated with 40 mM H 2 O 2 , and then washed twice with SDW.…”

“…Proline treatment can diminish ROS levels in fungi and thus inhibits ROS-induced apoptosis (Chen and Dickman, 2005). Under oxidative stress, apoptosis has been reported as a major cause of loss of cell viability for biocontrol yeasts (Chen et al, 2015; Zhang et al, 2017). In addition to its antioxidant feature, proline can also stabilize cellular homeostasis during stress through proline metabolism (Szabados and Savoure, 2010).…”

Pseudomonas graminis strain CPA-7 differentially modulates the oxidative response in fresh-cut ‘Golden delicious’ apple depending on the storage conditions

“…Rhodotorula glutinis LS-11) inoculated in wounded apple and peach fruits has been 411 associated with enhanced antagonistic activity against Botrytis cinerea and Penicilium 412 expansum (Castoria et al, 2003;Zhang et al, 2017). 413…”