Antifungal Mechanism of Rhodotorula mucilaginosa and Aureobasidium sp. nov. Isolated from Cerbera manghas L. against the Growth of Destructive Molds in Post Harvested Apples

Background: Apples often experience postharvest damage due to being attacked by mold organisms. Several groups of molds such as Aspergillus sp., Penicilium expansum, Botrytis cinerea, and Venturia sp. can cause a serious postharvest disease exhibited as watery regions where areas of blue-green tufts of spores develop. Current methods using fungicides to control pathogenic fungi can cause resistance if applied in the long term. An alternative procedure using yeast as a biological agent has been found. Objective: The aim of this study is to screen potential yeast, which has the ability to inhibit the growth of Aspergillus brasielensis (isolate A1) and Aspergillus flavus section flavi (isolate A17) isolated from apple fruits. Methods: Antagonism test using YMA dual culture medium using in vitro assays and ITS rDNA identification were performed. Results: The result showed that 3 out of 19 yeast isolated from Cerbera manghas L, T1, T3 and T4, demonstrated the potential ability as a biocontrol agent. ITS rDNA identification demonstrated that T1 has a similarity to Rhodotorula mucilaginosa while T3 and T4 were identified as Aureobasidium sp. nov. The 3 isolates exhibited the ability to reduce the growth of A. brasiliensis sensu lato better than dithane 0.3% with a Disease Incidence (DI) of 100% and a Disease Severity (DS) value of 45%. Only isolate T1 and T3 were able to reduce decay symptoms in apples inoculated with A. flavus sensu lato (with DO and DS were 100% and 25%, respectively) compared to dithane pesticides 0.3%. Conclusion: This study indicated that competition between nutrients occurs between pathogenic molds and under-yeast in vitro and in vivo conditions. However, further studies in the future might be able to elucidate the ‘killer’ activity and interaction with the pathogen cells and the bio-product production using Rhodotorula mucilaginosa and Aureoubasidium namibiae strains to control postharvest diseases.

Unraveling the Fungal Community Associated with Leaf Spot on Crataegus sp.

Crataegus sp. is a tree that grows in temperate zones with worldwide distribution and is commonly known in Mexico as tejocote. The use of products derived from Crataegus in traditional medicine, food, and cosmetics has increased over the last few years and the relevance of this plant has also grown. Here, we report a disease that was observed in tejocote plants that grew both in the wild and in greenhouses in Puebla (Mexico). The disease was characterized by necrotic spots on the leaf ranging from brown to reddish tones that were accompanied by structures on the back of the leaf. Furthermore, we investigated the fungal genera associated with infected leaves in wild tejocote plants, from which we recovered Alternaria sp., Aureobasidium sp., Dreschlera sp., Fusarium sp., Paecilomyces sp. and Ulocladium sp. genera. Inoculation on healthy Crataegus sp. plants with isolate UAP140 showed similar symptoms as observed in nature, while inoculation with UAP127 resulted in the development of necrotic lesions in the leaf. The identity of these isolates was further studied through the phylogenetic analysis of the ribosomal DNA internal transcribed spacer (ITS) region, where isolate UAP140 showed the highest identity with Fusarium equiseti and isolate UAP127 was similar to Alternaria arborescens. To our knowledge, this is the first report of a characteristic disease developed in Crataegus sp. plants in Mexico where the fungal community associated to the lesion was analyzed. Further studies would be necessary to determine the ecological and environmental implications of the microbiome on the appearance and development of the disease.

Chitosan Synthesis and Optimization of Root Endophytic Fungi

The cell wall component of root endophytic fungi is a main source of chitosan synthesis. This research aimed to optimize chitosan synthesis from three different isolated species of root endophytic fungi in Pulau Dua Nature Reserve, Banten Indonesia. Three species of root endophytic fungi, namely, Aspergillus niger, Aureobasidium sp., Basipetospora sp., were cultured to produce chitosan. To optimize the production of fungal chitosan, cultures were treated with different conditions such as growth medium (Oat Meal broth, Potato Dextrose Broth, CMMY Broth), pH value (4, 5, 6, 7), and temperature (25, 30, 35, 40°C). Chitosan was extracted from dried mycelium after treated on NaOH 10% at 121°C for 2 min. The degree of deacetylation (DD) of chitosan was then examined and compared with the control (shrimp chitosan). The optimum fungal chitosan condition was higher in CMMY medium, pH 5, and 30°C. The DD value of three root endophytic fungi species, Aspergillus niger, Aureobasidium sp., Basipetospora sp. were 88.5, 83.3, 80.8, respectively, which was lower than DD value resulted from control. This study indicates that Aspergillus niger was a potential endophytic fungi for chitosan synthesis.

Immobilization of Fructofuranosidase from Aureobasidium sp. Onto TiO2 and Its Encapsulation on Gellan Gum for FOS Production

Fructofuranosidase (EC 3.2.1.26) from Aureobasidium sp. ATCC 20524, recovered from 5 L fermented medium, purified by two simple steps with a yield of 65 % and a purification factor of 16, was immobilized by adsorption onto titanium dioxide (FTIO). The enzyme was also covalently immobilized onto TiO2 coated with polyethyleneimine (FTIOP) and encapsulated in gellan gum (FTIOPG). FTIO and FTIOP recorded an activity of 903 U g−1 and 9212 U g−1, respectively. The immobilized enzyme showed high activity and stability at pH levels ranging from 4.0 to 8.0 and there were no changes in the temperature profile for either methodology when compared with free fructofuranosidase. The immobilized biocatalysts were reused 7 times for FOS production without significant activity loss, except FTIO at pH 5.0. Gellan gum was used for FTIOP encapsulation. FOS production was performed in a batch and a continuous reactor using FTIOPG as a biocatalyst. Batch conversion (gFOS/ginitial sucrose) was around 60 % for initial sucrose concentrations of 100, 300 and 600 g L−1, at a time of maximum conversion. Fixed-bed reactor operational stability was remarkable, providing a constant FOS production in the outlet of the column during 720 h.

ISOLASI DAN KARAKTERISASI JAMUR LIGNINOLITIK SERTA PERBANDINGAN KEMAMPUANNYA DALAM BIODELIGNIFIKASI

Fungi can survive in various environments on different media including wood. Lignin in timber is hard to degrade efficiently because of its polymer form, and only a few of it can be hydrolyzed because of its composite and complex structure. Ligninolytic fungi produce an extracellular enzyme to withstand to toxic or mutagenic chemicals exposure and known to degrade different types of pollutant compounds. Lignin decomposers were also known to play a significant role in the pulping process of paper mills, used in waste treatment such as textile and hydrocarbon wastes. This study was conducted to obtain fungal isolates that have de-lignification capability and to compare the ability of fungal isolates to degrade lignin. The research isolated samples from rotten wood and soil using selective lignin medium with tannic acid as sole C source. This study characterized the isolates by its morphology and identified using the Morphology and Taxonomy of Fungi book by Bessey (1950) as a reference. This study compared the ligninolytic capability by measuring the transparent zone formed on selective lignin media. This research found 14 isolates of fungi and all of them had a ligninolytic capability. Aspergillus niger isolate has the highest ligninolytic capability by producing 6.45 cm clear zone diameter on the 7th day. Aureobasidium sp has the smallest clear zone diameter of 1.9 cm within the same period.

Removal and recovery of lead (Pb2+) from industrial effluent using indigenous and tailor-made Aureobasidium sp. RBSS-303

The objective of this study was to assess the removal and recovery of Pb-II from industrial wastewater using a locally isolated strain of Aureobasidium sp. RBSS-303. The initial Pb2+ concentration of 600 mg/L resulted in maximum uptake capacity (Qmax 235.1 ± 0.3 mg/g). The biosorbent revival was attained by contacting with HCl (0.01 M), with 75.3% recovery of Pb2+. The Freundlich isotherm best explains the Pb2+ sorption performances. Maximum adsorption distribution coefficient of 1,309.6 mg metal/mL was observed at initial Pb2+ concentration value of 100 mg/L. Evaluation of nine kinetic models showed the removal rate of Pb2+ was reliant on diffusion control pseudo-second-order and saturation-mixed-order kinetic models with a high correlation coefficient value (R = 0.99). Fourier transform infrared spectroscopy analysis showed the major contribution of –NH2 and –CN ligands of Aureobasidium sp. RBSS-303 in the sorption phenomenon of Pb2+. The biosorption assays carried out with effluent of the paint industry showed 76.8% efficiency for Pb2+ removal by the candidate biosorbent, regardless of the complex composition of the industrial effluent.