Screening and isolation of antibacterial activities of the fermentative extracts of freshwater fungi from Yunnan Province, China

Abstract

The EtOAc extracts of cultural filtrates of 30 freshwater fungi were assayed for the in vitro antibacterial activity against Bacillus cereus YMF 3.19, Brevibacillus laterosporus YMF 3.08, Escherichia coli YMF 3.16, Staphylococcus aureus YMF 3.17 using the disc diffusion method. A total of 14 fungal strains displayed active against all of the bacteria tested and the strongest antibacterial activity was recorded in Camposporium quercicola YMF1.01300 isolate. Extraction of fermentation broth of C. quercicola YMF1.01300 and various separation and purification steps led to isolation of three pure active molecules. The chemical structures of these three compounds, a new diphenyl ether, named as quercilolin (compound 1), as well as two previously known compounds, tenellic acid A (compound 2), and 2',4'-dihydroxyacetophenone (compound 3), were established by analysis of NMR and MS data, and by comparison with reference data from the literature. These results indicate that some freshwater fungi could be a potential source of antibacterial agents.

Antimicrobial activities of endophytic fungi of the Sri Lankan aquatic plantNymphaea nouchaliand chaetoglobosin A and C, produced by the endophytic fungusChaetomium globosum

“…Aquatic plants or hydrophytes are highly adapted to their environment with unique morphological and physiological features (Yakandawala 2012) and these features are likely to make the aquatic plants unique habitats for the growth of potentially distinctive endophytic fungi. Compared to their terrestrial counterparts endophytic fungi of aquatic plants are far less investigated with respect to secondary metabolite production and their biological activities (Shearer et al 2007; Wang et al 2008) and more of such studies are needed to evaluate their true potential in this respect. Nymphaea nouchali (Nil Manel in Sinhalese) is a vulnerable aquatic plant native to Sri Lanka (MOE 2012), found in the inland freshwater bodies, rooted at the bottom, with leaves floating at the surface.…”

Multifaceted Defense against Antagonistic Microbes in Developing Offspring of the Parasitoid Wasp Ampulex compressa (Hymenoptera, Ampulicidae)

“…The second compound, resacetophenone, was present on both parasitized cockroaches and cocoons. Resacetophenone isolated from a freshwater fungus was shown to have antibacterial activity [60] . Notably, both nerolic acid and resacetophenone have previously been found in conjunction with mellein in ants [49] , [61] .…”

Antimicrobial activity of some saprobic fungi isolated fromMagnolia liliiferaandCinnamomum inersleaves

“…A modified paper disk method was used for antimicrobial activities assay (Wang et al 2008;Gu 2009). Bacteria were grown in nutrient broth at 37 • C for 18 h and yeast was grown in potato dextrose broth at 30 • C for 18 h. After that, they were adjusted to approximately 10 8 colony-forming units per milliliter (CFU/ml).…”

“…The investigation of fungi isolated from plant debris or dead plant materials is also an interesting alternative for finding novel bioactive compounds because these fungi can degrade organic materials in decaying process and might secrete secondary metabolites for promoting of their growth (Duong et al 2004). There have been a few studies about screening bioactive compounds from saprobic fungi (Wang et al 2008). Some examples of these bioactive compounds which are derived from freshwater fungi are two new eudesmane sesquiterpenes (rhombidiol and rhombitriol) isolated from Beltrania rhombica (Rukachaisirikul et al 2005) and ophiocerins A-D, ophioceric acid, an africane sesquiterpenoid isolated from *Corresponding author.…”