Molecular Identification and Diversity of Pestalotiopsis, Neopestalotiopsis and Pseudopestalotiopsis Species from Four Host Plants in Sarawak, Borneo Island (Malaysia)

Until recently, Pestalotiopsis species have been identified based on host relationship and conidial dimensions. Pestalotiopsis species occur as endophytes, saprobes and also pathogens of many plant hosts. This study used molecular phylogenetic relationships based on ITS sequence data to identify Pestalotiopsis, Neopestalotiopsis and Pseudopestalotiopsis species in addition to their conidial pigmentation from four host plants namely Macaranga triloba, Macaranga sp., Shorea macrophylla and Syzygium sp. Based on the molecular phylogenetic analysis of 18 Pestalotiopsis-like isolates from the four different host plants, the isolates clustered separately into three clades corresponding to their conidial morphology and conidial median cell pigmentation as Neopestalotiopsis, Pestalotiopsis, and Pseudopestalotiopsis irrespective of their host plant association. Among the four host plants studied, S. macrophylla hosts the highest diversity of Pestalotiopsis-like species while Syzygium sp. had the lowest diversity. This is the first report on the molecular phylogenetics and diversity of Pestalotiopsis, Neopestalotiopsis and Pseudopestalotiopsis species from Sarawak, Malaysia in line with recent re-classification in the genus. New records of Pestalotiopsis-like species were also recorded on new host plants

Effects of modified atmosphere storage on banana postharvest diseases and the control of bunch main-stalk rot

Banana (Musa, AAA) bunch-sections consisting of one hand attached to a short section of main-stalk were wound-inoculated with cultures of fungi isolated from diseased fingers, crowns, or main-stalks and stored in sealed polyethylene bags containing 3–7% oxygen, 10–13% carbon dioxide and <0.1 μl l−1 ethylene for 40 days at 20°C, then ripened with ethylene in air for nine days. Colletotrichum musae, Fusarium moniliforme var. subglutinans and Nattrassia mangiferae caused high infection incidence in unripe fingers during storage. These fungi also caused crown rot, but only F. moniliforme var. subglutinans caused main-stalk rot. Alternaria alternata and F. pallidoroseum both caused some infection in unripe fingers during storage, and both subsequently caused crown rot. A. alternata also infected main-stalks. Lasiodiplodia theobromae and Phomopsis musicola infected only ripening fingers, and F. culmorum infected only crowns and main-stalks. The pathogenicity of some isolates was changed by interposing storage between inoculation and ripening. C. acutatum and C. gloeosporioides became unable to cause disease and F. culmorum caused less disease. In contrast, A. alternata and F. pallidoroseum became pathogenic to fingers, crowns and, in the case of A. alternata, to bunch main-stalks. Benomyl and prochloraz (500 mg l−1) controlled most diseases at inoculation sites, and naturally-occurring main-stalk rot. Prochloraz controlled more diseases than benomyl, and this control was usually more effective

Description of Pseudopestalotiopsis kubahensis sp. nov., a new species of microfungi from Kubah National Park, Sarawak, Malaysia

A survey on the diversity and distribution of microfungi was carried out, during which a distinct Pestalotiopsis-like taxa was isolated from green leaves of Macaranga sp. from Kubah National Park, Sarawak. The phylogenetic analysis of DNA sequences from the internal transcribed spacer gene region (ITS1, 5.8S and ITS2) of the rDNA shows this species to form a distinct clade from the Pestalotiopsis, and cluster with the genus Pseudopestalotiopsis, a new genus which was recently carved out from the Pestalotiopsis. This species differs from closely related Pseudopestalotiopsis species such as Ps. cocos, Ps. indica and Ps. theae by its conidial characters such as its unknobbed apical appendages and shorter basal appendages. The new microfungal species, Ps. kubahensis is hereby described based on morphological and molecular data as the fifth species in the genus Pseudopestalotiopsis

Nutrient and Physiological Requirements for Biomass Production of Pestalotiopsis sp. UMAS P14 and Pseudopestalotiopsis sp. UMAS P2005/2592

Fungi are important decomposers in our ecosystem and are useful in metabolite production, bio-degradation and bio-sorption of different substrates and wastes through their mycelial biomass. Fungal species are known to have different preferences for their growth requirements. Two fungal species Pestalotiopsis and Pseudopestalotiopsis useful in many biotechnological applications were studied. Nutrient and physiological requirements for mycelial biomass production such as carbon and nitrogen, pH, light and temperature were investigated. Both fungal isolates were grown in liquid basal medium supplemented separately with various carbon and nitrogen source and incubated under different light, pH and temperature conditions for 15 days. In general, Pestalotiopsis sp. and Pseudopestalotiopsis sp. showed significant preferences for monosaccharide and disaccharide carbon source as compared to sugar alcohols and polysaccharides, whereas ammonium tartrate was more preferred as a nitrogen source compared to ammonium nitrate, ammonium sulphate and other ammonium salts. These two fungal species were able to grow and produce good mycelial biomass (223.33 mg for Pseudopestalotiopsis and 136.67 mg for Pestalotiopsis) at temperature range of 15°C to 30°C and (290.00 mg for Pseudopestalotiopsis and 256.67 mg for Pestalotiopsis) on media pH of slightly acidic to slightly alkaline. However, they showed no significant preferences between constant light, total darkness and alternate light conditions. The results from this study will be very useful for the mycelial biomass production of Pestalotiopsis sp. and Pseudopestalotiopsis sp. for their biotechnological applications

Effect of Yeast Species on Total Soluble Solids, Total Polyphenol Content and Fermentation Index during Simulation Study of Cocoa Fermentation

The polyphenols has potential of health beneficial and its changes in cocoa are related to fermentation index. However, relationship of yeast species to total soluble solids, total polyphenols and fermentation index changes during cocoa fermentation is still unclear. This study focused on effect of yeast as starter culture during cocoa fermentation towards those parameters. Sixteen species of yeast were used as starter cultures during simulation study of cacao fermentation in the laboratory. Study revealed that Candida ethanolica give the highest correlation with fermentation index whereas Candida jaroonii is the lowest correlation. None of the yeast species showed high correlation with total polyphenols content compared to the control. Conversely, all of the yeasts especially Pichia kudriavzevii showed higher correlation with total soluble solids compared to control. The study also exhibited that cacao simulation media method can be useful to predict yeast performance during cacao fermentation prior to field application