Indolediketopiperazine Alkaloids from Eurotium cristatum EN-220, an Endophytic Fungus Isolated from the Marine Alga Sargassum thunbergii

Current Status and Future Prospects of Marine Natural Products (MNPs) as Antimicrobials

The marine environment is a rich source of chemically diverse, biologically active natural products, and serves as an invaluable resource in the ongoing search for novel antimicrobial compounds. Recent advances in extraction and isolation techniques, and in state-of-the-art technologies involved in organic synthesis and chemical structure elucidation, have accelerated the numbers of antimicrobial molecules originating from the ocean moving into clinical trials. The chemical diversity associated with these marine-derived molecules is immense, varying from simple linear peptides and fatty acids to complex alkaloids, terpenes and polyketides, etc. Such an array of structurally distinct molecules performs functionally diverse biological activities against many pathogenic bacteria and fungi, making marine-derived natural products valuable commodities, particularly in the current age of antimicrobial resistance. In this review, we have highlighted several marine-derived natural products (and their synthetic derivatives), which have gained recognition as effective antimicrobial agents over the past five years (2012–2017). These natural products have been categorized based on their chemical structures and the structure-activity mediated relationships of some of these bioactive molecules have been discussed. Finally, we have provided an insight into how genome mining efforts are likely to expedite the discovery of novel antimicrobial compounds.

Fungal community succession and major components change during manufacturing process of Fu brick tea

Fu brick tea is a unique post-fermented tea product which is fermented with microorganism during the manufacturing process. Metabolic analysis showed that most metabolites content were decreased during the manufacturing process of Fu brick tea, except GA (gallic acid). Illumina MiSeq sequencing of ITS gene amplicons was applied to analyze the fungal community succession. The genera Aspergillus, Cyberlindnera and Candida were predominant at the early stage of manufacturing process (from "primary dark tea" to "fermentation for 3 days"), but after the stage of "fermentation for 3 days" only Aspergillus was still dominated, and maintain a relatively constant until to the end of manufacturing process. The effects of metabolites on the structure of the fungal community were analyzed by redundancy analysis (RDA) and variation partitioning analysis (VPA). The results indicated that GCG (gallocatechin gallate), EGCG (epigallocatechin gallate) and GA as well as the interactions among them were the most probably ones to influence, or be influenced by the fungal communities during the fermentation process of Fu brick tea. This study revealed fungal succession, metabolite changes and their relationships, provided new insights into the mechanisms for manufacturing process of Fu brick tea.