Mycotoxigenic fungi contamination of grains and peanuts from open markets in Kelantan, Malaysia

The warm weather and high relative humidity in Malaysia are ideal for the survival and proliferation of mycotoxigenic fungi leading to a high rate of stored product contamination. This study was conducted to enumerate and characterise the mycotoxigenic fungi associated with commonly consumed food grains in Kelantan, Malaysia. The fungal bioburden and fungal identification from forty-four composite food samples comprising 11 samples each of maize, wheat, rice, and peanuts from open markets in Kelantan, Malaysia, were determined using standard mycological techniques. A total of 115 mould fungal isolates belonging to 12 species were isolated, of which Aspergillus flavus (17.39%), A. versicolor (13.04%), A. felis (12.17%), Neoscytalidium dimidiatum (11.3%), Penicillium cheresanum (11.3%) and P. chrysogenum (8.7%), were predominant. Peanuts were the most contaminated (9.7×105 ± 1.5×105 CFU/g) followed by maize (7.5×105 ± 1.8×106 CFU/g), wheat (1.9×105 ± 2.6×105 CFU/g), and rice (9.9×104 ± 1.5×105 CFU/g). The levels of the mycotoxigenic fungi in peanut, maize, and wheat were above the permissible limit of 102 CFU/g set by the Malaysian Ministry of Health and 102 to 105 CFU/g set by the International Commission for Microbiological Specification for Foods, signifying that they are unsafe for use as food or feed ingredients. Hence, there is a need for more stringent control measures.

Fungal canker agents in apple production hubs of Iran

To identify apple canker casual agents and evaluate their pathogenicity and virulence in apple production hubs including West Azarbaijan, Isfahan and Tehran provinces; samples were collected from symptomatic apple trees. Pathogenic isolates on the detached branches were identified as Cytospora cincta, Diplodia bulgarica, Neoscytalidium dimidiatum and Eutypa cf. lata. E. cf. lata was reported as a potential apple canker causal agent in Iran for the first time based on the pathogenicity test on the detached branches, whereas it caused no canker symptoms in apple trees until 6 months after inoculation. Currently, E. cf. lata seems to be adapted to a single city. C. cincta, D. bulgarica and N. dimidiatum caused canker symptoms in apple trees. “C. cincta” and also “C. cincta and N. dimidiatum” were the most widespread and aggressive apple canker species, respectively, associated with apple canker in Iran. Therefore, they are considered to be the main threat to apple production in Iran and should be carefully monitored. Disease progress curve, area under the disease progress curve and optimum temperatures were determined for mentioned species. It is concluded that the establishment of each species occurs in appropriate areas and times in terms of the optimum temperature for their growth.

Effectiveness of Augmentative Biological Control of Streptomyces griseorubens UAE2 Depends on 1-Aminocyclopropane-1-Carboxylic Acid Deaminase Activity against Neoscytalidium dimidiatum

To manage stem canker disease on royal poinciana, actinobacterial isolates were used as biological control agents (BCAs) based on their strong in vitro inhibitory effects against Neoscytalidium dimidiatum. Streptomyces griseorubens UAE2 and Streptomyces wuyuanensis UAE1 had the ability to produce antifungal compounds and cell-wall-degrading enzymes (CWDEs). Only S. griseorubens, however, restored the activity of 1-aminocyclopropane-1-carboxylate (ACC) deaminase (ACCD). In vivo apple fruit bioassay showed that lesion development was successfully constrained by either isolates on fruits inoculated with N. dimidiatum. In our greenhouse and container nursery experiments, S. griseorubens showed almost complete suppression of disease symptoms. This was evident when the preventive treatment of S. griseorubens significantly (p < 0.05) reduced the numbers of conidia of N. dimidiatum and defoliated leaves of royal poinciana seedlings to lesser levels than when S. wuyuanensis was applied, but comparable to control treatments (no pathogen). The disease management of stem canker was also associated with significant (p < 0.05) decreases in ACC levels in royal poinciana stems when S. griseorubens was applied compared to the non-ACCD-producing S. wuyuanensis. This study is the first to report the superiority of antagonistic actinobacteria to enhance their effectiveness as BCAs not only for producing antifungal metabolites and CWDEs but also for secreting ACCD.

Ocimum basilicum L. associated bacteria with antifungal activity

The presence of pathogens, like fungi, is one of the most important causes of basil crop loss around the world; however, many microorganisms have a crucial role on plant development including protection against pathogenic ones. In the present study, basil associated bacteria were isolated, quantified and preserved. Characterization of isolated bacteria showed 165 Gram positive strains, 152 with bacillary and 13 with coccoid morphology. Later, in vitro antagonism assays were performed, first against Aspergillus spp. and then against Neoscytalidium dimidiatum, Alternaria spp. and Aspergillus spp. Finally, the effect of the isolated bacteria on basil seed germination and first stages of development were carried out. Sampled basil plants, produced around La Paz, Baja California Sur, Mexico, were colonized by known antagonistic bacteria of the Bacillus genus. Bacillus amyloliquefaciens strains were the prevailing species with antifungal activity. Moreover, strains ALMH42, ALMR73 and ALAH91 did not show any deleterious effect on basil seedling development. Biotechnological potential exploration of these isolated strains from healthy basil plants is of great interest for future applications on this and other crops.

Secondary Metabolite Ceiba pentandra Gaertn. as Biological Control to Canker Disease on Dragon Fruit

Canker diseases caused by Neoscytalidium dimidiatum are a serious threat for dragon fruit production. Comprehensive and environmentally friendly control efforts are needed to reduce yield losses due to this disease. Cottonwood (Ceiba pentandra) is one of the plants that contain complex phytochemicals that can control phyto-pathogens. This study aimed to examine the potential of secondary metabolites produced from the leaves and bark of the C. pentandara as botanical fungicides. Parts of dragon fruit that are attacked by canker are isolated on Potatoes Dextrose Agar media. Observation of conidia and fungal spores using a binocular microscope with a magnification of 100×. The hyphal form of the N. dimidiatum is rectangular and clear. As botanical fungicides, the leaves and the bark of the C. pentandara are dried for 14 days. The extract solution then analyzed for it’s secondary metabolites. The results of the qualitative analysis showed that each leaf extract and bark (+) compound of flavonoids, alkaloids, tannins, and saponins. The quantitative results of secondary metabolites detected 304.3 mg.kg-1, Flavonoids and Tannins of 1.6 mg.kg-1. Secondary metabolites obtained were tested on the fungus N. dimidiatum with inhibitory parameters in vitro and in vivo. This study followed a factorial completely randomized design consisting of concentration factors and types of extract parts. The data obtained were then analyzed by ANOVA and significant treatments were further tested by Duncan Multiple Range Test (DMRT) at α = 5%. The combination treatment with a concentration of 40 mg ml-1 is more effective in controlling canker in indicators of inhibitory, the extent of the attack, and intensity of disease severity.