Antagonistic activity of bacteria from wild honey against Colletotrichum musae, and testing of wild honey as biopesticide spray to control banana anthracnose

Anthracnose is a foliar and fruit disease caused by Colletotrichum spp. affecting a wide range of crops. Infection occurs early followed by quiescence in fruits, such as in banana, where chemical-based pesticides are used as a dependable fungal control for many years. There is an increasing need for a safe control and as implicated in the Organic Agriculture Act of 2010 (RA 10068) in the Philippines. This scenario drove the use of alternative pest control such as the use of biologicals and natural products. In this study, seven bacteria were isolated from wild honey, produced by Apis mellifera, wherein four (BC2, BC3, BC6 and BC7) were found to be an effective antagonist against Colletotrichum musae in in vitro conditions. These bacteria were identified to belong to the genus Lactobacillus spp. (BC2, BC3, BC7) and Bacillus spp. (BC6) based on sugar utilization tests, morphological and cultural growth in PDPA. For the in vivo test, different dilutions of wild honey were used and it was found out that lower concentrations were effective as biopesticide spray to prevent anthracnose infection. Lastly, we report herewith the first isolation of bacteria with biological control potential from wild honey, and to apply the raw or natural product as biopesticide in postharvest fruits.

Effectiveness Test of Trichoderma harzianum on The Development of Anthracnose Disease (Colletotrichum musae) of Ambon Banana

The decrease in the quality of bananas can be caused by the attack of the pathogen Colletotrichum musae which causes anthracnose disease. The use of the antagonist fungus Trichoderma harzianum can be relied upon to control this disease. This study aimed to obtain a more effective level of T. harzianum spore density to suppress the development of anthracnose disease in Ambon bananas. The treatment tested was T. harzianum with five levels of spore density, namely 105, 106, 107,108, and 109 spore/mL, designed using a completely randomized design with five replications. The variables observed were the incubation period and the intensity of the disease. The results showed that the spore density of 109 was effective in suppressing the development of anthracnose disease by inhibiting the incubation period to 3.85 days and suppressing the intensity of the disease to 41.4%.Keywords: Banana, Trichoderma harzianum, Anthracnose, Colletotrichum musae

Two Philippine Photorhabdus luminescens strains inhibit the in vitro growth of Lasiodiplodia theobromae, Fusarium oxysporum f. sp. lycopersici, and Colletotrichum spp.

Background Fungal phytopathogens are one of the leading causes of loss in global food production. Chemical fungicides have always been used to control the phytopathogens to mitigate losses. However, it is widely known that this approach is not sustainable. Thus, it is essential to develop alternative control methods, such as the use of biological control agents. Results This study provided a preliminary data on the efficacy of 2 local Photorhabdus strains, associated with Heterorhabditis indica BSDS and H. indica MAP, against selected post-harvest fungal phytopathogens, Fusarium oxysporum f. sp. lycopersici, Lasiodiplodia theobromae, Colletotrichum musae, and another Colletotrichum sp., by measuring their in vitro inhibitory activity. The Photorhabdus strains were isolated from the hemolymph of Ostrinia furnicalis infected with H. indica BSDS and H. indica MAP and grown selectively on NBTA media. Firstly, the bacterial endosymbionts' generic identity was confirmed through colony PCR based on a Photorhabdus Txp40 toxin-specific marker. Species identity was then elucidated through 16s marker-assisted GenBank mining as P. luminescens, sharing 99.51–99.58% similarity with P. luminescens subsp. akhurstii (Accession no. AY278643.1). Anti-fungal activity was observed by the bioassay experiments, using cell-free culture filtrates (CFCs), obtained from P. luminescens tryptic soy broth suspensions (OD600 = 2.0) amended in PDA medium (25%v/v) based on percentage growth inhibition. The CFCs of P. luminescens BSDS showed a significantly higher suppressive activity against Colletotrichum musae, Colletotrichum sp., and Lasiodiplodia theobromae, with 93.18 ± 0.46%, 74.15 ± 0.54%, and 60.51 ± 2.04% growth inhibition, respectively, while the CFC of P. luminescens MAP showed a significantly higher suppressive activity against F. oxysporum f. sp. lycopersici with 21.87 ± 0.71% growth inhibition. Conclusions The results strongly showed that these strains of Photorhabdus can be promising biological control agents against these fungal phytopathogens. Further extensive research is warranted for the development of these promising biofungicides into a practical, economically viable, and environment-friendly control strategy that can be incorporated into any integrated pest management program.

Volatile Organic Compounds (VOCs) Produced By The Rhizosphere Actinobacteria Streptomyces Sp. and Amycolatopsis Sp. Strains and Their Antifungal Activity Against Colletotrichum Musae

Herein is reported the study on the antifungal potential of VOCs produced by actinobacterial strains from the rhizosphere of Caatinga plants. Twenty strains were screened for their ability to produce VOCs with growth inhibition (GI) potential against the phytopathogen fungus Colletotrichum musae . The most active VOCs were produced by Streptomyces sp. (ACTB-77) and Amycolatopsis sp. (ACTB-290). The effect of VOCs from ACTB-77 and ACTB-290 on the morphological structure of the fungus hyphae was investigated by SEM and revealed significant deformation of the fungal cell filaments, especially in the case of ACTB-290. VOCs produced by these two actinobacteria strains and the fungus under axenic and co-culture conditions were investigated using HS-SPME-GCMS combined approaches, and all data were analyzed by statistical methods. Most of the mVOCs were identified, representing 92-100% of total peaks areas. Linalool (38.53±5.19%) and geosmin (17.25±2.55%) were the major VOCs constituents from ACTB-77, while dimethyl disulfide (48.49±3.48%) and dimethyl trisulfide (21.14±3.50%) were the major VOCs compounds produced by ACTB-290. Statistical analyses of data from co-cultures showed that the VOCs profile of the experiment involving ACTB-77 was more influenced by the fungal VOCs while the experiment with ACTB-290 was more influence by compounds from the actinobacteria.

Superior anti-infective potential of eugenol–casein nanoparticles combined with polyethylene glycol against Colletotrichum musae infections

The aim of this study was to improve the stability of eugenol–casein nanoparticles (EL–CS-NPs) through polyethylene glycol (PEG) modification.

Yeast Potential for the Biological Control of Colletotrichum musae

One of the factors that cause the greatest loss of fruit in post-harvest are diseases, especially rotting such as anthracnose. Therefore, this work aimed to test the potential of the yeasts Candida albicans, Pichia guilliermondii, Rhodotorula glutinis, Saccharomyces cerevisiae, Cryptococcus laurentii and Zygoascus hellenicus in the control of Colletotrichum musae in bananas in post-harvest period. To test the potential of these yeasts, the effect of volatile and non-volatile compounds, culture pairing and spore germination of the fungus C. musae in vitro was evaluated. In post-harvest fruits, the area below the mycelial growth curve (AACCM) and the area below the disease progress curve (AACPD) were evaluated. The yeasts C. albicans, R. glutinis, S. cerevisiae and P. guilliermondii produced volatile compounds with antifungal action, reducing the development of the fungus in vitro. The yeast R. glutinis was shown to be more efficient in reducing mycelial growth in vitro of the fungus through the production of non-volatile compounds. The yeasts C. albicans and P. guilliermondii showed the presence of an inhibition halo. All yeasts induced the germination of C. musae conidia and were not efficient in controlling anthracnose in vivo.