This study aimed to investigate the fungicidal effects of essential oils (EO) from Ocimum sp. on Colletotrichum musae. The fungus was isolated from bananas that showed typical symptoms of anthracnose followed by molecular identification. Oils were obtained by hydro-distillation, and the chemical constituents were analysed using gas chromatography. The antifungal activity of the oils was tested in vitro against mycelia growth and conidia germination. In situ tests were carried out by spraying the oil on healthy bananas followed by the inoculation with C. musae conidia and the assessment of the necrosis symptoms. The obtained results revealed that the yield of the oil extracted from Ocimum basilicum and Ocimum gratissimum were 0.17% and 0.40%, respectively. Thujanol (24.38%), eugenol (23.78%) and (Z)-ß-ocimene (16.59%) were the main components found in O. basilicum while thymol (42.65%), trans-sabinene hydrate (21.63%) and limonene (8.68%) were the major components found in O. gratissimum. The total reduction in the C. musae mycelial growth was observed at 800 and 275 µl/L, for the O. basilicum and O. gratissimum oils, respectively.These oils also inhibited completely the conidia germination at 400 and 185 µl/L. In situ tests showed the necrosis reduction bananas anthracnose. The minimum inhibitory concentration (MIC) for the preventive and curative test after the application of O. basilicum oil was 6,000 and 4,000 µl/L, respectively, whereas for the O. gratissimum oil, the MIC was 3,000 and 1,000 µl/L, jointly. Positive correlations were identified between the oil concentration and the reduction in bananas necrosis. These results indicated that the O. gratissimum EOs might be used as a biocide for the control of bananas anthracnose disease. K E Y W O R D S anthracnose, antifungal activity, essential oil, Ocimum sp., ripe banana How to cite this article: Madjouko MA, Nguemezi Tchameni S, Sonwa Tchinda E, et al. Inhibitory effects of essential oils from Ocimum basilicum and Ocimum gratissimum on Colletotrichum musae: The causal agent of bananas anthracnose. J Phytopathol. 2019;167:257-264. https://doi.

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Aim: The aim of this study was to evaluate the sanitary quality of smoked fish by determining their mycotoxin content, and also the chemical composition, antifungal activity of Cymbopogon citratus and Ocimum basilicum essential oils from Cameroon against some mycotoxigenic fungal strains responsible of the smoked fish biodegradation. Place and Duration of Study: Laboratory of Food Microbiology and Biotechnology, National School of Agro-Industrial Sciences, University of Ngaoundere, Cameroon, from August 2019 to April 2020. Methodology: Fifteen samples of smoked fishes have been collected in August 2019 from “petit marché” market (Ngaoundere, Cameroon). Physico-chemical parameters of smoked fishes were evaluated. Mycotoxin (AFB1, CIT, and OTA) contents have been determined with HPLC. Isolation and identification of molds were done using their macroscopic and microscopic characteristics, and the identity of the strains was done by PCR sequencing methods. For plants, 15 kg of Cymbopogon citratus leaves and 5 kg of Ocimum basilicum leaves have been harvested on 10 September 2019 in Ngaoundere and used for the essential oil’s extraction. Essential oil extraction has been done through hydrodistillation and the determination of its chemical composition done with GC/MS. Results: Major part of samples contains at least one mycotoxin, in quantities which are beyond the safe dose. Eleven species of molds have been identified: Aspergillus spp., Penicillium citrinum, and Mucor hiemalis. Amongst the isolated species, those which can produce mycotoxins are: Penicillium citrinum, Aspergillus versicolor, Aspergillus fumigatus, Aspergillus carbonarius, Aspergillus niger, and Fusarium moniliforme. Geranial (42.4%), Neral (33.5%) and Myrcene (10.8%) are major compounds found in the essential oil of C. citratus while monoterpens (60.8%), Eugenol (30.7%), Linalol (29.4%) and 1,8-Cineol (14.3%) are the major compounds found in the essential oil of O. basilicum.  Conclusion: Essential oils of C. citratus and O. basilicum are efficient against isolated toxigenic species. C. citratus being more efficient than O. basilicum.

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With a view to finding alternative compounds to the synthetic chemicals used in food preservation, a study was initiated to evaluate the antifungal activity of C. citratus essential oil on toxigenic molds isolated from Cameroonian rice. To this end, 12 rice samples of one kilogram each was taken in October 2019 in four cities in Cameroon: Tonga, Ndop, Yagua and Maga. Water activity in the rice samples collected was measured using an electronic hygrometer; mycotoxins were determined by HPLC. The isolation and identification of fungal strains were done on the basis of macroscopic and microscopic characteristics, and the identity of the strains was confirmed by PCR-sequencing. The extraction of the essential oil was done using a Clevenger by hydrodistillation, and the analysis of its chemical composition by GC/MS. From these analyses, it appears that all samples tested are contaminated with at least one mycotoxin, and that the three mycotoxins tested (AFB1, CIT and OTA) are indeed present in our rice samples, but at values not exceeding the limits set by European Commission Regulation N0 1881/2006. Seven cases of co-contamination have been identified. On the other hand, 9 fungal genera have been identified and the dominant genera being Aspergillus, Penicillium and Fusarium, all of which are involved in the synthesis and excretion of mycotoxins in cereals. The essential oil of C. citratus has been shown to be effective in inhibiting the growth of A. carbonarius, A. versicolor, F. graminaerum, F. moniliform and P. citrinum; and the main compounds of this oil are geranial (42.4%), neral (33.5%) and myrcene (10.8). A. carbonarius was the most sensitive strain to the essential oil, and F. moniliform was the most resistant strain.