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Inventory of aquatic microfungi diversity needs to be done as a new information about specific types found in certain waters. The objective of this study was to determine the diversity of aquatic microfungi in Madong waters, Tanjungpinang City, Riau Islands. Research on diversity of microfungi was carried out through survey methods at three stations (mangrove areas, fishing settlements and floating net cages, and coastal of Madong villages). Samples were collected by taking litters from the waters (roots, leaves, and branches of mangrove, and also seaweed). Isolation and culture process of aquatic microfungi were carried out in the laboratory. Microfungi isolates that were grown and were successfully identified were: Aspergillus sp., Epicoccum sp., Colletotrichum sp., Penicillium sp., and Stemphylium sp. Key words: aquatic microfungi, consortium, inventory, isolates, Tanjungpinang

Leaf spots on spinach were found in three greenhouses in Hokkaido and Iwate, Japan, in 2011–2012. Three isolates obtained from the lesions were classified into Stemphylium sp. Subgroups C2 and E3, based on morphology and molecular analyses. We compared the three isolates with two reference isolates belonging to Subgroup C2 from Welsh onion and leek in terms of pathogenicity. All five isolates caused leaf spot symptoms on spinach and leaf blight on Welsh onion in inoculation tests. This is the first report of spinach leaf spot caused by Stemphylium sp. Subgroups C2 and E3.

Three new methylated Δ8-pregnene steroids, stemphylisteroids A–C (1–3) were isolated from the medicinal plant Polyalthia laui-derived fungus Stemphylium sp. AZGP4-2. Their structures were elucidated by the detailed analysis of comprehensive spectroscopic data. The absolute configuration of 1 was determined by X-ray crystallographic analysis. Compound 1 show antibacterial activity against Escherichia coli with the MIC value of 6.25 μg/mL, and 2 exhibited a broad spectrum of antibacterial activities against six pathogenic bacteria with the MIC values ranging from 12.5 to 50 μg/mL. The discovery of three methylated Δ8-pregnene steroids 1–3 are a further addition to diverse and complex array of methylated steroids.

Two new stemphol sulfates, stemphol A (1) and stemphol B (2), along with known compound stemphol (3) were isolated from the EtOAc extract of the fermentation of an endophytic Stemphylium sp. 33231. The structures of these compounds were elucidated on the basis of spectroscopic analysis. The isolated compounds exhibited potent antibacterial activities against six terrestrial pathogenic bacteria with MIC values of 0.6-10 μg ml(-1). The inhibitory activities of all compounds against five cancer cell lines were evaluated.