Antifungal Activity of Squid Pen Chitosan Nanoparticles against Three Fungal Pathogens in Various Citrus Fruits In Vitro and In Vivo

Hoang Ngoc Cuong,Nguyen Van Hieu,Nguyen Cong Minh,Dang Ha Giang,Nguyen Van Hoa,Pham Viet Nam

doi:10.3390/coatings12020235

Hoang Ngoc Cuong, Nguyen Van Hieu + Show 4 more

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https://doi.org/10.3390/coatings12020235

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Abstract

Fungal infections have been considered a primary cause of the postharvest losses of citrus fruits. Therefore, it is necessary to find low-cost and high antifungal activity materials for preventing the decay of citrus fruits after harvest. In this study, squid chitosan nanoparticles (SCNs) were prepared from squid pen chitosan and used as a biofungicide against three citrus fungal pathogens in both in vitro and in vivo evaluations. The prepared SCNs had a mean size of ca. 56 nm and a high zeta potential of +98.7 eV with a narrow size distribution. At a range of 50–250 ppm, the SCN concentration of 200 ppm exhibited the highest activity in totally inhibiting the growth of Lasiodiplodia pseudotheobromae, Alternaria alternate, and Penicillium digitatum in in vitro tests where these fungi were isolated from symptomatic fruits and identified. Furthermore, after 12 days of incubation at 30 ± 0.2 °C and high relative humidity in in vivo studies, the infection area of the sample treated at 250 ppm completely suppressed fruit disease symptoms. The results demonstrate that prepared SCNs efficiently control postharvest citrus fruit diseases. These findings recommend applying SCNs as a potential candidate for citrus fruit storage.

Highlights

Citrus is an important fruit with a world production estimated at over 100 million tons per year [1]
No investigations on the antifungal activity of squid chitosan nanoparticles against the fungal pathogens in citrus fruits have been reported. Based on these above considerations, the present study aims to determine the antifungal activity of squid chitosan nanoparticles against Lasiodiplodia pseudotheobromae, Alternaria alternate, and Penicillium digitatum caused by the decay of postharvest citrus fruits; the fungi were isolated from symptomatic fruits and identified
After 12 days of incubation, the colonies of Lasiodiplodia pseudotheobromae on the potato dextrose agar (PDA) medium were turquoise in color (Figure 2a), while the color of the Alternaria alternate and Penicillium digitatum colonies was dark brown (Figures 3a and 4a)

Summary

Introduction

Citrus is an important fruit with a world production estimated at over 100 million tons per year [1]. In Vietnam, citrus is widely grown as a high economic fruit in the Northern and Southern provinces. Citrus fruits have a low pH value, high moisture content, and many nutrients making them very susceptible to attack by pathogenic fungi [2]. The postharvest losses usually are high during the storage stage, and the loss rate is about 15–35% of the total output, which causes severe economic losses after harvest. It was reported that Lasiodiplodia pseudotheobromae, Alternaria alternate, and Penicillium digitatum were the main disease problems with blue mold, green mold, and watery rot and unexpected flavor during postharvest storage [3,4]. It is necessary to create safe alternatives for controlling postharvest rots [6]

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