Protection of Citrus Fruits from Postharvest Infection with Penicillium digitatum and Degradation of Patulin by Biocontrol Yeast Clavispora lusitaniae 146

Abstract

Fungal rots are one of the main causes of large economic losses and deterioration in the quality and nutrient composition of fruits during the postharvest stage. The yeast Clavispora lusitaniae 146 has previously been shown to efficiently protect lemons from green mold caused by Penicillium digitatum. In this work, the effect of yeast concentration and exposure time on biocontrol efficiency was assessed; the protection of various citrus fruits against P. digitatum by C. lusitaniae 146 was evaluated; the ability of strain 146 to degrade mycotoxin patulin was tested; and the effect of the treatment on the sensory properties of fruits was determined. An efficient protection of lemons was achieved after minimum exposure to a relatively low yeast cell concentration. Apart from lemons, the yeast prevented green mold in grapefruits, mandarins, oranges, and tangerines, implying that it can be used as a broad-range biocontrol agent in citrus. The ability to degrade patulin indicated that strain 146 may be suitable for the control of further Penicillium species. Yeast treatment did not alter the sensory perception of the aroma of fruits. These results corroborate the potential of C. lusitaniae 146 for the control of postharvest diseases of citrus fruits and indicate its suitability for industrial-scale fruit processing.

Keywords: Clavispora lusitaniae; Penicillium; biocontrol spectrum; citrus; patulin; postharvest disease; sensorial analysis.

Figure 1

Efficiency of Clavispora lusitaniae 146 to protect lemon wounds against Penicillium digitatum according to the yeast concentration (A) and dipping time (B). (A) The values on the horizontal axis indicate the percentage of the dilution prepared from an initial concentration (100%) of 3.06 × 10⁸ colony forming units (CFU) mL⁻¹. (B) Dipping times from 15 s to 2.5 min were tested. Significant differences in the efficiency are indicated by asterisks according to Tukey’s test (* indicates p < 0.05, n = 4).

Figure 2

Biocontrol efficiency of C. lusitaniae 146 against P. digitatum in lemons according to yeast growth phase. Box plots represent the efficiency of protection against P. digitatum. Line graph indicates the cell density of C. lusitaniae 146. Significant differences in the efficiency are indicated by asterisks according to Tukey’s test (* indicates p < 0.05, n = 4).

Figure 3

Efficiency of C. lusitaniae 146 in the protection of wounds against P. digitatum on four citrus varieties. The upper panel shows in vivo results on the control of green mold by C. lusitaniae 146 after 5 days of incubation at 25 °C. From top left to bottom right: oranges (A), tangerines (B), mandarins (C), and grapefruits (D). The bottom panel shows the protection efficiency graphically (n = 4).

Figure 3

Efficiency of C. lusitaniae 146 in the protection of wounds against P. digitatum on four citrus varieties. The upper panel shows in vivo results on the control of green mold by C. lusitaniae 146 after 5 days of incubation at 25 °C. From top left to bottom right: oranges (A), tangerines (B), mandarins (C), and grapefruits (D). The bottom panel shows the protection efficiency graphically (n = 4).

Figure 4

Removal of patulin from solution by C. lusitaniae, Rhodosporidium paludigenum, and Saccharomyces cerevisiae. Cells of the yeasts, native and heat-inactivated, were incubated in phosphate buffer with patulin for 48 h and the patulin concentration in the supernatant was determined. The significance of differences between means was determined by an unpaired t-test with Welch’s correction (n = 5) with *** indicating p < 0.0001 and ** indicating p < 0.001.