Potential of chitosan coating in delaying the postharvest anthracnose (Colletotrichum gloeosporioides Penz.) of Eksotika II papaya

The in vitro and in vivo fungicidal activity of chitosan was studied against Colletotrichum gloeosporioides, the causal agent of anthracnose in papaya fruits. Chitosan at 1.5% and 2.0% concentrations showed a fungistatic effect with 90–100% inhibition (significant at P ≤ 0.05) of the fungal mycelial growth. Changes in the conidial morphology were also observed with the higher chitosan concentrations after 7-h incubation. In vivo studies showed that 1.5% and 2.0% chitosan coatings on papaya not only controlled the fruit decay but also delayed the onset of disease symptoms by 3–4 weeks during 5 weeks storage at 12 ± 1°C and slowed down the subsequent disease development. However, when leaving the fruits to ripen at ambient temperature (28 ± 2°C), 2.0% chitosan was less effective than 1.5% in controlling the disease development. Chitosan coatings also delayed the ripening process by maintaining the firmness levels, soluble solids concentration and titratable acidity values during and after storage

EFECTO DEL QUITOSANO EN EL DESARROLLO Y MORFOLOGÍA DE ALTERNARIA ALTERNATA (FR.) KEISSL

The potential of low and medium molecular weight chitosan (LMWC, MMWC) at five concentrations (0.5, 1.0, 1.5, 2.0 and 2.5% w/v) and high molecular weight chitosan (HMWC) at four concentrations (0.5, 1.0, 1.5 and 2.0 w/v) to inhibit the fungus Alternaria alternata was evaluated. MMWC at 2.5% w/v inhibited mycelial growth of A. alternata up to 50.6%, whilst 0.5, 1.0 and 1.5% doses at the three molecular weight promoted mycelial growth. Sporulation was affected at 2.5% concentration by LMWC and MMWC. Percentage of spore germination was not affected by concentration but it was affected by molecular weight of chitosan. An inverse relationship was observed between germination and molecular weight. Mycelial dry weight was inhibited by all concentrations and type of chitosan evaluated. Observations at the scanning electron microscopy showed diverse alterations in hyphaes such as swelling, depression, and distortion by effect of chitosan.Se evaluó la capacidad in vitro del quitosano de bajo y medio peso molecular (QBPM, QMPM) a cinco concentraciones (0,5, 1,0, 1,5, 2,0 y 2,5% p/v) y alto peso molecular (QAPM) en cuatro concentraciones (0,5, 1,0, 1,5 y 2,0% p/v) para inhibir el hongo Alternaria alternata. El QMPM a la concentración de 2.5%, inhibió el crecimiento del micelio de A. alternata en un 50,6%, mientras que a las concentraciones de 0,5, 1,0 y 1,5% en sus tres pesos moleculares promovió el crecimiento del micelio. La esporulación fue afectada a concentración de 2,5% por el QBPM y el QMPM. El porcentaje de germinación de esporas no fue afectado por las concentraciones, pero sí por los pesos moleculares. Se observó una relación inversa entre la germinación y el peso molecular. El peso seco del micelio fue inhibido con todas las concentraciones y tipos de quitosano evaluados. La observación de hifas a través del Microscopio Electrónico de Barrido mostró diversos daños como hinchazón, depresiones, y distorsiones por efecto del quitosano

Microscopic study of the morphology and metabolic activity of Fusarium oxysporum f. sp. gladioli treated with Jatropha curcas oil and derivatives

AbstractThe fungus Fusarium oxysporum f. sp. gladioli is one of the main pathogenic microorganisms of the ornamental genus Gladiolus. The attack of this microorganism includes corms and different plant phenological stages. In this study, different microscopic techniques and fluorochromes were used to evaluate the effect of J. curcas oil and acylglycerides, namely trilinolein, triolein, monomyristin and dimyristin, on the morphology, membrane integrity (%), viability (%) and germination (%) of F. oxsporum f sp. gladioli. Phase-contrast optical photomicrographs and scanning microscopy showed that J. curcas oil and the triglycerides triolein and trilinolein caused the formation of numerous vacuoles, alterations in the morphology of the outer covering of the mycelium and conidia, and inhibition of membrane activity in the fungus during 24h of incubation. The fluorochromes used detected no permanent damage to the viability of the conidia. The high germination percentage of the conidia of Fusarium oxysporum f. sp. gladioli indicates that the damage caused by the application of the treatments was fungistatic rather than fungicidal and did not cause cell death

Low-power long-term ambulatory electrocardiography monitor of three leads with beat-to-beat heart rate measurement in real time

A low-power long-term ambulatory ECG monitor was developed for the acquisition, storage and processing of three simultaneous leads DI, aVF and V2 with a beat-to-beat heart rate measurement in real time. It provides long-term continuous ECG recordings until 84 h. The monitor uses a QRS complex detection algorithm based on the continuous wavelet transform with splines, which automatically selects the scale for the analysis of ECG records with different sampling frequencies. It includes a lead-off detection to continuously monitor the electrode connections and a real-time system of visual and acoustic alarms to alert users of abnormal conditions in its operation. The monitor presented is based in an ADS1294 analogue front end with four channels, 24-bit analog-to-digital converters and programmable gain amplifiers, a low-power dual-core ESP32 microcontroller, a microSD memory for data storage in a range of 4 GB to 32 GB and a 1.4 in thin-film transistor liquid crystal display (LCD) variant with a resolution of 128 × 128 pixels. It has programmable sampling rates of 250, 500 and 1000 Hz; a bandwidth of 0 Hz to 50% of the selected sampling rate; a CMRR of -105 dB; an input margin of ±2.4 V; a resolution of 286 nV; and a current consumption of 50 mA for an average battery life of 84 h. The ambulatory ECG monitor was evaluated with the commercial data-acquisition system BIOPAC MP36 and its module for ECG LABEL SS2LB, simultaneously comparing the morphologies of two ECG records and obtaining a correlation of 91.78%. For the QRS detection in real time, the implemented algorithm had an error less than 5%. The developed ambulatory ECG monitor can be used for the analysis of the dynamics of the heart rate variability in long-term ECG records and for the development of one’s own databases of ECG recordings of normal subjects and patients with cardiovascular and noncardiovascular diseases.This work has been funded by a scholarship from the CONAHCYT (México) to Frank Martínez Suárez (No. CVU = 736915), José Alberto García Limón (No. CVU = 924566), Jorge Enrique Baños-Bautista (No. CVU = 1003644) and the Spanish Agencia Estatal de Investigación under grant PID2020-116011RB-C21 (MCIN/AEI/10.13039/501100011033).Peer ReviewedPostprint (published version

Conservación de productos hortofrutícolas mediante el uso de nanopartículas de quitosano y agentes naturales

Actualmente se buscan nuevas alternativas amigables con el ambiente que permitan la conservación de productos agrícolas expuestos al deterioro durante la cosecha, transporte y distribución en el mercado para su venta con la subsecuente reducción de sus atributos de calidad, fisiológicos y propiedades sensoriales, aunados a la manifestación de microorganismos patógenos. En este sentido, se presenta el estado del arte del uso de recubrimientos nanoestructurados de nanopartículas de quitosano con agentes naturales, sus beneficios y un enfoque académico, industrial y gubernamental del uso de la nanoagrotecnología, así como las perspectivas de esta técnica para la conservación de frutas y hortalizas como una solución viable

Corn-Starch-Based Materials Incorporated with Cinnamon Oil Emulsion: Physico-Chemical Characterization and Biological Activity

Active packaging represents a large and diverse group of materials, with its main role being to prolong the shelf-life of food products. In this work, active biomaterials based on thermoplastic starch-containing cinnamon oil emulsions were prepared by the compression molding technique. The thermal, mechanical, and antifungal properties of obtained materials were evaluated. The results showed that the encapsulation of cinnamon oil emulsions did not influence the thermal stability of materials. Mechanical resistance to break was reduced by 27.4%, while elongation at break was increased by 44.0% by the addition of cinnamon oil emulsion. Moreover, the novel material provided a decrease in the growth rate of Botrytis cinerea by 66%, suggesting potential application in food packaging as an active biomaterial layer to hinder further contamination of fruits during the storage and transport period

in vitro response of Colletotrichum to chitosan. Effect on incidence and quality on tropical fruit. Enzymatic expression in mango

Colletotrichum is considered one of the fungal genera with the greatest diversity of species of phytopathogenic fungi and with a wide range of hosts including tropical fruits. In this study, the concentration of chitosan applied was a key factor in the in vitro inhibition of the three Colletotrichum isolates with the most sensitive being the one from banana. Germination was the development stage most affected by the application of this polymer. At the end of 10 days of storage, control of anthracnose in soursop, mango and banana fruit was considerable with the application of 1 % chitosan, with 80 to 100 % inhibition. Likewise, the ripening process of fruit with and without chitosan was generally similar. Activity of the peroxidase (POD) and polyphenol oxidase (PPO) enzymes was observed only in fruit of mango cv. 'Tommy Atkins,' inoculated and non-inoculated with C. gloeosporioides, the activity of both enzymes was higher in the chitosan treatments and the 1.0 % concentration was able to induce gene expression of POD and PPO, occurring until 24 h

Physical-Chemical Evaluation of Active Food Packaging Material Based on Thermoplastic Starch Loaded with Grape cane Extract

The aim of this paper is to evaluate the physicochemical and microbiological properties of active thermoplastic starch-based materials. The extract obtained from grape cane waste was used as a source of stilbene bioactive components to enhance the functional properties of thermoplastic starch (TPS). The biomaterials were prepared by the compression molding technique and subjected to mechanical, thermal, antioxidant, and microbiological tests. The results showed that the addition of grape cane extract up to 15 wt% (TPS/WE15) did not significantly influence the thermal stability of obtained biomaterials, whereas mechanical resistance decreased. On the other side, among all tested pathogens, thermoplastic starch based materials showed antifungal activity toward Botrytis cinerea and antimicrobial activity toward Staphylococcus aureus, suggesting potential application in food packaging as an active biomaterial layer

Infection Strategies Deployed by Botrytis cinerea, Fusarium acuminatum, and Rhizopus stolonifer as a Function of Tomato Fruit Ripening Stage

Worldwide, 20–25% of all harvested fruit and vegetables are lost annually in the field and throughout the postharvest supply chain due to rotting by fungal pathogens. Most postharvest pathogens exhibit necrotrophic or saprotrophic lifestyles, resulting in decomposition of the host tissues and loss of marketable commodities. Necrotrophic fungi can readily infect ripe fruit leading to the rapid establishment of disease symptoms. However, these pathogens generally fail to infect unripe fruit or remain quiescent until host conditions stimulate a successful infection. Previous research on infections of fruit has mainly been focused on the host’s genetic and physicochemical factors that inhibit or promote disease. Here, we investigated if fruit pathogens can modify their own infection strategies in response to the ripening stage of the host. To test this hypothesis, we profiled global gene expression of three fungal pathogens that display necrotrophic behavior—Botrytis cinerea, Fusarium acuminatum, and Rhizopus stolonifer—during interactions with unripe and ripe tomato fruit. We assembled and functionally annotated the transcriptomes of F. acuminatum and R. stolonifer as no genomic resources were available. Then, we conducted differential gene expression analysis to compare each pathogen during inoculations versus in vitro conditions. Through characterizing patterns of overrepresented pathogenicity and virulence functions (e.g., phytotoxin production, cell wall degradation, and proteolysis) among the differentially expressed genes, we were able to determine shared strategies among the three fungi during infections of compatible (ripe) and incompatible (unripe) fruit tissues. Though each pathogen’s strategy differed in the details, interactions with unripe fruit were commonly characterized by an emphasis on the degradation of cell wall components, particularly pectin, while colonization of ripe fruit featured more heavily redox processes, proteolysis, metabolism of simple sugars, and chitin biosynthesis. Furthermore, we determined that the three fungi were unable to infect fruit from the non-ripening (nor) tomato mutant, confirming that to cause disease, these pathogens require the host tissues to undergo specific ripening processes. By enabling a better understanding of fungal necrotrophic infection strategies, we move closer to generating accurate models of fruit diseases and the development of early detection tools and effective management strategies