Protecting books from mould damage by decreasing paper bioreceptivity to fungal attack using decoloured cell-free supernatant of Lysobacter enzymogenes C3

Foxing of Watercolor Paper and Environmental Control as Preventive Actions

In Singapore's hot and humid climate, watercolor papers are particularly prone to a paper oxidation issue known as foxing, which refers to the discoloration forming yellowish-brown stains on paper, changing the visual outcome of the watercolor artworks. This research investigates two most popular types of watercolor paper, made from 100 % cotton and cotton-wood-pulp mixture. Foxing was generally categorized into two types: biotic and abiotic foxing caused by fungi activities and the presence of metallic contaminants catalytic fungi growth. However, recent hypotheses further relate it to heterogeneous cellulose structures. Watercolor paper is typically produced in a well-controlled environment, which should theoretically reduce the occurrence of foxing, catalyzed by metallic contaminants. The research involved a comprehensive analysis of aged samples, from old watercolors, dating back to the 1990s and fresh watercolor paper samples. focusing on understanding the origin and causes of watercolor paper foxing based on cellulose content & structures. By comparing 100 % cotton and cotton wood-pulp blended watercolor paper, the susceptivity of foxing was hinted to be related to cellulose packing density. These findings will support further research in developing strategies for the conservation and storage of watercolor artworks.

Antifungal, repellency, and insecticidal activities of Cymbopogon distans and Ruta graveolens essential oils and their main chemical constituents

Essential oils produced by Cymbopogon distans and Ruta graveolens with a similar Chinese name could be explained as book fragrance in the Chinese idiom, "shu xiang men di", namely, a wealthy intellectual family according to ancient Chinese. Therefore , volatile oils from these two plants and their main compounds were tested to explore their antifungal, repellent and insecticide actions. In this study, essential olis (EOs) of C. distans exhibited significant antifungal activity against Rhizopus stolonifera ( 97%), Mucor racemosus (97%), and Trichoderma viride (84%); its main compounds display interesting activity, such as methyleugenol (87%) and elemicine (85%) against T. viride , and butyl hydroxytoluene against M. racemosus (90%) and R. stolonifera (95%). EOs of R. graveolens and other major chemical constituents showed weak inhibitory effects against other fungi ( Aspergillus flavus and Fusarium oxysporum ). Then, EOs ( C. distans and R. graveolens ) and its main compounds exhibited obvious repellent activity (more than 85%) at the concentration of 16 nL/cm², which was consistent with the repellency of the positive control (DEET). In terms of insecticidal activity, the mortality of C. distans volatile oil against R. padi (56.4%) was lower than that of R. graveolens volatile oil (92.4%), and all compounds showed strong lethal effects. These results provide a natural substance for controlling fungi and insects when storing books, and which can be used as a biological pesticide for industrial production. Through our study, the book fragrance in the Chinese idiom "shu xiang men di" was speculated to be the EO odor of C. distans.

Biosynthesis, regulation, and engineering of natural products from Lysobacter

Covering: up to August 2021Lysobacter is a genus of Gram-negative bacteria that was classified in 1987. Several Lysobacter species are emerging as new biocontrol agents for crop protection in agriculture. Lysobacter are prolific producers of new bioactive natural products that are largely underexplored. So far, several classes of structurally interesting and biologically active natural products have been isolated from Lysobacter. This article reviews the progress in Lysobacter natural product research over the past ten years, including molecular mechanisms for biosynthesis, regulation and mode of action, genome mining of cryptic biosynthetic gene clusters, and metabolic engineering using synthetic biology tools.