Enhancement of mycelial growth and polysaccharide production in Ganoderma lucidum (the Chinese medicinal fungus, `Lingzhi') by the addition of ethanol
Methanol, ethanol, 1-propanol and 2-propanol, at 1.5% (v/v), enhanced the growth and polysaccharide production of Ganoderma lucidum. Ethanol was the most effective at 1.5% (v/v) for increasing the biomass production, however, the maximal polysaccharide concentration was produced with 2% (v/v) ethanol in the medium. There was no new polysaccharide component produced by the addition of ethanol.
Fed-batch fermentation of Ganoderma lucidum for hyperproduction of polysaccharide and ganoderic acid
Abstract A process for simultaneous efficient production of bioactive ganoderic acid (GA) and Ganoderma polysaccharide by fed-batch fermentation of Ganoderma lucidum was developed. Effects of carbon source and initial sugar concentration on the production of GA and polysaccharide were studied at first. Sucrose as a carbon source was suitable for the extracellular polysaccharide (EPS) production although the cells could not grow well. Lactose was beneficial for the cell growth and production of GA and intracellular polysaccharide (IPS). When the initial lactose concentration exceeded 35 g/l, the GA accumulation was decreased. The GA production was remarkably improved by pulse feeding of lactose, when its residual concentration was between 10 and 5 g/l. The fed-batch fermentation process in shake flasks could be successfully reproduced in stirred bioreactors (STR) with dissolved oxygen (DO) controlled between 20 and 35% of air saturation during fermentation. The maximum cell density reached 21.89±0.35 and 20.95±0.01 g DW/l in STR and flasks, respectively. The production of EPS reached 0.87±0.05 (STR) and 0.75±0.05 g/l (flask), and the total production of IPS reached 2.49±0.07 (STR) and 2.40±0.05 g/l (flask). The total production of GA reached 367.1±17.4 and 297.9±13.7 mg/l for STR and flask, respectively, and their corresponding productivity was 29.6±0.5 and 14.3±0.1 mg/l per day. Not only the cell density but also the content, production and productivity of GA and IPS obtained in this work are the highest reported in agitated fermentation of G. lucidum.
Gut immunity in Lepidopteran insects.
Lepidopteran insects constitute one of the largest fractions of animals on earth, but are considered pests in their relationship with man. Key to the success of this order of insects is its ability to digest food and absorb nutrition, which takes place in the midgut. Because environmental microorganisms can easily enter Lepidopteran guts during feeding, the innate immune response guards against pathogenic bacteria, virus and microsporidia that can be devoured with food. Gut immune responses are complicated by both resident gut microbiota and the surrounding peritrophic membrane and are distinct from immune responses in the body cavity, which depend on the function of the fat body and hemocytes. Due to their relevance to agricultural production, studies of Lepidopteran insect midgut and immunity are receiving more attention, and here we summarize gut structures and functions, and discuss how these confer immunity against different microorganisms. It is expected that increased knowledge of Lepidopteran gut immunity may be utilized for pest biological control in the future.