Antifungal activity and molecular identification of endophytic fungi from the angiosperm Rhodomyrtus tomentosa

Problems associated with fungal resistance to antifungal agents are increasing worldwide. There is need to find sources of novel antifungal drugs and endophytic fungi could be another interesting source. In this study, 213 culturable endophytic fungi isolated from leaves and branches of Rhodomyrtus tomentosa from Thailand were screened for their ability to produce antifungal agents. Crude extracts from 177 out of 213 fungal isolates exhibited inhibitory activity against human pathogenic fungi, evaluated by a microbroth dilution method. Of the 349 active extracts out of 617 extracts tested, 43.5% inhibited Penicillium marneffei; 16.5 to 20.8% inhibited two strains of Cryptococcus neoformans; 6.0% Microsporum gypseum; 5.0% Candida albicans, with minimal inhibitory concentrations (MIC) of 1 to 200 μg/ml. 22 endophytic fungi showing strong antifungal activity (MICs of 1 to 8 μg/ml) were identified by morphological and molecular methods. They mainly belonged to the genera Colletotrichum, Diaporthe, Guignardia and Phomopsis. The results of this work indicate that endophytic fungi from R. tomentosa can be a good source of potential antifungal natural products.Keywords: Rhodomyrtus tomentosa, antifungal activity, endophytic fungi, molecular identificatio

Effects of mangosteen wood vinegar as a potential additive on nutrient digestibility in growing pigs

The aim of the experiment was to determine the effects of mangosteen wood vinegar as a potential additive on nutrient digestibility in growing pigs. A 4x4 Latin square design was used in this study. Four crossbred (Duroc x Landrace x Large White) barrows averaging 19.41±0.81 kg in body weight were allotted 4 diets, mixed with mangosteen wood vinegar at levels of 0, 0.2, 0.4, and 0.8%, respectively. The pigs were raised in individual metabolism crates. Feces and urine samples were collected 4 times a day for 5 days for data collection. The results showed that the apparent nutrient digestibility of dry matter, ether extract, crude fiber, ash, nitrogen-free extract, apparent biological value, and digestible energy were not significantly different (P>0.05) in pigs fed with different diets. However, pigs fed with the diets mixed with mangosteen wood vinegar at levels of 0.2, 0.4, and 0.8%, respectively had significantly (P<0.05) higher digestible crude protein than pigs fed with the control diet and pigs fed with the diets mixed with mangosteen wood vinegar at levels 0.4 and 0.8% had significantly (P<0.05) higher metabolizable energy than pigs fed with the control diet. Moreover, Pearson’s correlation coefficients with increasing levels of mangosteen wood vinegar showed a positive correlation at their apparent nutrient, energy digestibility, and protein quality evaluation. In conclusion, our results suggest that mangosteen wood vinegar could be used as a potential additive in increasing digestibility efficiency in growing pigs

Role of acuK in Control of Iron Acquisition and Gluconeogenesis in Talaromyces marneffei

Talaromyces marneffei is a dimorphic pathogenic fungus causing opportunistic infection in immunocompromised patients. It is a facultative intracellular pathogen and is usually found inside the host macrophages during infection. Alternative carbons and iron are the important nutrients associated with intracellular survival and pathogenesis of T. marneffei. This study reported the importance of the transcription factor AcuK in control of gluconeogenesis and iron acquisition in T. marneffei. Deletion of acuK gene in T. marneffei resulted in retardation of growth and germination in both mold and yeast phases. Microscopically, ΔacuK showed double nuclei hyphae. However, the yeast cells showed normal morphology. The ΔacuK failed to grow in iron-limiting conditions. Additionally, it could not grow in a medium containing gluconeogenic carbon sources. Moreover, ΔacuK showed higher susceptibility to macrophage killing than the wild type. These results demonstrated that AcuK controlled both iron acquisition and gluconeogenesis, and it could contribute to the pathogenicity of this fungus

Antifungal activity of protein hydrolysates from Thai Phatthalung Sangyod rice (Oryza sativa L.) seeds

Background and Aim: Fungal zoonoses are an economic and public health concern because they can cause various degrees of morbidity and mortality in animals and humans. To combat this issue, alternative natural antifungals, such as products derived from rice protein hydrolysates or rice antifungal protein/peptide are being considered because they are highly bioactive and exhibit various functional properties. Thailand is a leading rice producer and exporter. Among the various cultivated rice varieties, Sangyod rice (Oryza sativa L.) is exclusively indigenous to Thailand’s Phatthalung province; it has a Thai geographical indication tag. Here, we investigated whether the Phatthalung Sangyod rice seeds have bioactive antifungal peptides. Materials and Methods: Antifungal activity in four Sangyod rice seed extracts (SYPs) – namely, (1) the crude lysate, SYP1; (2) the heat-treated lysate, SYP2; (3) the heat- and pepsin digested lysate, SYP3; and (4) the heat- and proteinase K-digested lysate, SYP4 – was analyzed. Protein concentrations in these SYPs were determined using the Bradford assay. The total phenolic compound content was determined using the modified Folin–Ciocalteu method in a 96-well microplate. Then, the SYP protein pattern was determined using the sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Subsequently, using the agar well diffusion method, the antifungal properties of these SYPs were tested against ten medically important pathogenic fungi. The minimal inhibitory concentration (MIC) and minimal fungicidal concentration values were determined for the active SYPs – SYP2-4. Finally, the clinical safety of SYP4 was determined using a hemolytic assay (using canine red blood cells [RBCs]). Results: The crude lysate SYP1 did not show antifungal activity against any of the ten tested pathogenic fungi. Surprisingly, hydrolysates SYP2, SYP3, and SYP4 displayed antifungal properties against the ten tested pathogenic fungi. Thus, heat and enzymatic hydrolysis seem to transform the bioactivity of the crude protein extract – SYP1. Further, SYP4 shows the most effective antifungal activity. It completely inhibited Cryptococcus neoformans, Talaromyces marneffei yeast phase, Trichophyton mentagrophytes, and Trichophyton rubrum. A partial inhibitory action on Candida albicans and Microsporum gypseum was possessed while showing the least activity to C. neoformans. SYP4 was nontoxic to canine RBCs. Hemolysis of canine RBCs was undetectable at 1 × MIC and 2 × MIC concentrations; therefore, it can be safely used in further applications. Conclusion: These results indicate that heat and proteinase K hydrolyzed SYP is a very potent antifungal preparation against animal and human fungal pathogens and it can be used in future pharmaceuticals and functional foods