Development of an Efficient Strategy to Improve Extracellular Polysaccharide Production of Ganoderma lucidum Using L-Phenylalanine as an Enhancer

Abstract

Ganoderma lucidum has been a well-known species of basidiomycetes for a long time, and has been widely applied in the fields of food and medicine. Based on the simulation results of model iZBM1060 in our previous research, the effect of L-phenylalanine on G. lucidum extracellular polysaccharides (EPSs) was investigated in this study. EPS production reached 0.91 g/L at 0.4 g/L L-phenylalanine after a 24 h culture, which was 62.5% higher than that of control (0.56 g/L). Transcriptome and genome analysis showed that L-phenylalanine deaminase and benzoate 4-hydroxylase (related to L-phenylalanine metabolism) were significantly up-regulated, while the cell wall mannoprotein gene was down-regulated. Transmission electronic microscopy (TEM) and atomic force microscopy results showed that the cell wall thickness decreased by 58.58%, and cell wall porosity increased in cells treated with L-phenylalanine, which probably contribute to the increasing EPS production. This study provides an efficient strategy for fungal polysaccharide production with high output and low cost.

Biofabrication of Nanocellulose–Mycelium Hybrid Materials

“…As mentioned in the introduction, similar to pellet formation, [ 23 ] EPS formation depends on many incubation‐related factors, including substrate content (carbon and nitrogen sources), temperature, pH, and incubation duration. [ 24–26 ] EPS can be consumed in the later stages of fungal growth as a strategy to accumulate carbon and mass, [ 24 ] but at the same time EPS secretion is hindered by denser hyphal cell walls. [ 26 ]…”

“…[ 24–26 ] EPS can be consumed in the later stages of fungal growth as a strategy to accumulate carbon and mass, [ 24 ] but at the same time EPS secretion is hindered by denser hyphal cell walls. [ 26 ]…”

“…[ 21 ] Depending on the culture conditions, the aggregates can develop into discrete pellets, [ 22 ] with compositions and hyphal morphologies that are influenced by various interrelated factors, such as colony conditions, growth medium, agitation rate, and broth viscosity. [ 21–23 ] Mycelium development is accompanied by the secretion of exopolysaccharides (EPS), [ 24–26 ] and various proteins, including hydrophobins. [ 27 ] White‐rot fungi express lignocellulosic‐degrading enzymes under specific conditions but the activity of these enzymes can be suppressed by the addition of easily digestible simple sugars or other nutrients into the growth medium.…”

Transcriptome dynamics and metabolite analysis revealed the candidate genes and regulatory mechanism of ganoderic acid biosynthesis during liquid superficial‐static culture of Ganoderma lucidum

“…Glucose, KH 2 PO 4 and MgSO 4 Á7H 2 O purchased from Sinopharm (Beijing, China), YNB purchased from BioDee Biotechnology Co., Ltd (Beijing, China), and tryptone purchased from OXOID (Hants, UK). The medium has been used many years to study the secondary metabolism of G. lucidium (Peng et al, 2015;Ma et al, 2018Ma et al, , 2019. The seed was in a 250-ml flask containing 80 ml medium and kept at 30°C on a rotary shaker (150 rpm) for ten days.…”

“…As a powerful tool to analyse differentially expressed genes (DEGs), transcriptome sequencing, or RNA‐Seq, has been used widely in studying specific biological processes of G. lucidum , such as heat stress response, nitric oxide response, copper‐induced and L‐phenylalanine enhancer effects (Gu et al ., 2017; Tan et al ., 2018; Ma et al ., 2019; Jain et al ., 2020). In addition, many studies also focused on the triterpenoid biosynthesis analysis through transcriptome sequencing in G. lucidum and other mushrooms (Xu et al ., 2013; Gu et al ., 2017; Wang et al, 2019).…”