Insecticidal Activity of Ethyl Acetate Extracts from Culture Filtrates of Mangrove Fungal Endophytes

In the search for novel potent fungi-derived bioactive compounds for bioinsecticide applications, crude ethyl acetate culture filtrate extracts from 110 mangrove fungal endophytes were screened for their toxicity. Toxicity tests of all extracts against brine shrimp (Artemia salina) larvae were performed. The extracts with the highest toxicity were further examined for insecticidal activity against Spodoptera litura larvae and acetylcholinesterase (AChE) inhibition activity. The results showed that the extracts of five isolates exhibited the highest toxicity to brine shrimp at 50% lethal concentration (LC50) values of 7.45 to 10.24 ppm. These five fungal isolates that obtained from Rhizophora mucronata were identified based on sequence data analysis of the internal transcribed spacer region of rDNA as Aspergillus oryzae (strain BPPTCC 6036), Emericella nidulans (strains BPPTCC 6035 and BPPTCC 6038), A. tamarii (strain BPPTCC 6037), and A. versicolor (strain BPPTCC 6039). The mean percentage of S. litura larval mortality following topical application of the five extracts ranged from 16.7% to 43.3%. In the AChE inhibition assay, the inhibition rates of the five extracts ranged from 40.7% to 48.9%, while eserine (positive control) had an inhibition rate of 96.8%, at a concentration of 100 ppm. The extracts used were crude extracts, so their potential as sources of AChE inhibition compounds makes them likely candidates as neurotoxins. The high-performance liquid chromatography profiles of the five extracts differed, indicating variations in their chemical constituents. This study highlights the potential of culture filtrate ethyl acetate extracts of mangrove fungal endophytes as a source of new potential bioactive compounds for bioinsecticide applications.

Identification of phylloplane yeasts from paper mulberry (Broussonetia papyrifera (L.) L'Hér. ex Vent.) in Java, Indonesia

Aims: Broussonetia papyrifera (Saeh plant) has many qualities, the inner bark was the material for ‘dluwang’ papers on which Indonesian historical manuscripts were written, and the leaves have bioactive constituents of medicinal value, and antifungal activities. We investigated the diversity of yeast species associated with leaves from 6 months and 1.5 yearold plants, which is prerequisite to understand the phylloplane yeasts and plant interaction. Methodology and results: The yeasts were isolated from fresh leaves by washing and membrane filtration methods. A total of 16 leaf samples of 6 months and 1.5 year-old plants were collected from four locations in Java, Indonesia, and 2,543 yeast isolates were obtained. Based on similarity of colony morphology, 82 representative yeast isolates were selected and identified based on the sequence analyses of internal transcribed spacer (ITS) regions of rDNA. The identification result showed that they consisted of 17 genera and 32 species. Thirty six of representative yeast isolates belong to 11 genera (18 species) of the phylum Ascomycota and forty six isolates belong to 6 genera (14 species) of the phylum Basidiomycota. Phylogenetic trees showed that the yeast isolates are phylogenetically diverse and distributed in the phyla of Ascomycota (classes Saccharomycetales and Dothideomycetes) and Basidiomycota (classes Microbotryomycetes, Tremellomycetes, and Ustilaginomycetes). Conclusions, significance and impact of study: The phylloplane yeasts of B. papyrifera (Saeh plant) were taxonomically heterogeneous. This is the first report of the isolation and identification of phylloplane yeasts from B. papyrifera. Phylloplane yeasts may possess antagonistic activity to fungal plant pathogens in their natural habitats.

Screening Cellulose Activity of Yeast Isolated from Soil, Sediment and Water River from Taman Nasional Gunung Halimun, West Java, Indonesia

A total of 245 yeast isolates from Gunung Halimun National Park (GHNP) were screened for cellulolytic activity using 0.2% cellulose-azure. The results showed that 16 isolates have cellulolytic activity using cellulose-azure assay. These isolates were further screened for carboxymethyl cellulase (CMCase), avicelase and cellobiase using specific substrates (carboxymethyl cellulosa, avicel and cellobiose) with Teather and Wood method. The results showed that 7 isolates have CMCase; 6 isolates have cellobiase; 2 isolates have CMCase and cellobiase; and 1 isolate has CMCase and avicelase and cellobiase activities. Isolate S 4121 has the highest CMCase activity and identified as Trichosporon sporotrichoides (van Oorschot) van Oorschot and de Hoog UICC Y-286.