Utilization of glycerol and crude glycerol for polysaccharide production by an endophytic fungus Chaetomium globosum CGMCC 6882

Recent advance on the production of microbial exopolysaccharide from waste materials

Polysaccharide has been widely used in the fields of industry, agriculture, food and medicine because of its excellent physicochemical properties and bioactivities. Compared to plant and animal polysaccharides, microbial exopolysaccharide has advantages of occupying less cultivated land, short fermentation period, controllable fermentation process and not restricted by seasons. However, due to the deterioration of global climates and outbreak of conflicts, food crisis has become more and more serious. Therefore, searching alternative substrates for microbial exopolysaccharide production has attracted worldwide attention, waste materials might be an ideal substitute due to its high-content nutrients. Present work discussed and reviewed the production of microbial exopolysaccharide from molasses, cheese whey, lignocellulosic biomass, fruit pomace and/or husk, crude glycerol and kitchen waste. It was found that commercial grade exopolysaccharides were mainly produced from waste materials via submerged fermentation, and pretreatment of waste materials is a commonly used strategy. Although industrial production of microbial exopolysaccharides with waste materials as substrate has not been reported, we hoped that this work could not only provide contribution for efficient utilization of waste materials, but also help for alleviating global food crises.

Study of Different Parameters Affecting Production and Productivity of Polyunsaturated Fatty Acids (PUFAs) and γ-Linolenic Acid (GLA) by Cunninghamella elegans Through Glycerol Conversion in Shake Flasks and Bioreactors

Microbial cultures repurposing organic industrial residues for value-added metabolite production is pivotal for sustainable resource use. Highlighting polyunsaturated fatty acids (PUFAs), particularly gamma-linolenic acid (GLA), renowned for their nutritional and therapeutic value. Notably, Zygomycetes' filamentous fungi harbor abundant GLA-rich lipid content, furthering their relevance in this approach. In this study, the strain C. elegans NRRL Y-1392 was evaluated for its capability to metabolize glycerol and produce lipids rich in GLA under different culture conditions. Various carbon-to-nitrogen ratios (C/N = 11.0, 110.0, and 220.0 mol/mol) were tested in batch-flask cultivations. The highest GLA production of 224.0 mg/L (productivity equal to 2.0 mg/L/h) was observed under nitrogen excess conditions, while low nitrogen content promoted lipid accumulation (0.59 g of lipids per g of dry biomass) without yielding more PUFAs and GLA. After improving the C/N ratio at 18.3 mol/mol, even higher PUFA (600 mg/L) and GLA (243 mg/L) production values were recorded. GLA content increased when the fungus was cultivated at 12 °C (15.5% w/w compared to 12.8% w/w at 28 °C), but productivity values decreased significantly due to prolonged cultivation duration. An attempt to improve productivity by increasing the initial spore population did not yield the expected results. The successful scale-up of fungal cultivations is evidenced by achieving consistent results (compared to flask experiments under corresponding conditions) in both laboratory-scale (Working Volume-Vw = 1.8 L; C/N = 18.3 mol/mol) and semi-pilot-scale (Vw = 15.0 L; C/N = 110.0 mol/mol) bioreactor experiments. To the best of our knowledge, cultivation of the fungus Cunninghamella elegans in glycerol-based substrates, especially in 20 L bioreactor experiments, has never been previously reported in the international literature. The successful scale-up of the process in a semi-pilot-scale bioreactor illustrates the potential for industrializing the bioprocess.

Antioxidant and antibacterial activities of a polysaccharide produced by Chaetomium globosum CGMCC 6882

In the present work, a Gynostemma pentaphyllum herb endophytic fungus of Chaetomium globosum CGMCC 6882 polysaccharide produced from tapioca starch (GCP-TS) with submerged fermentation was analyzed. GCP-TS contains rhamnose, glucosamine, galactose, glucose, mannose, and glucuronic acid in the molar ratio of 6.29: 0.55: 1.12: 22.93: 10.94: 3.54. Its weight-average molecular weight, number-average molecular weight and polydispersity were 4.73 × 10⁴ Da, 4.29 × 10⁴ Da and 1.103, respectively. Antioxidant results showed that GCP-TS had a concentration-dependent scavenging ability against DPPH radical, superoxide anion, hydroxyl radical, and ABTS radical. The corresponding scavenging capacities of GCP-TS aqueous solution at the concentration of 1.0 mg/mL were 45.11 ± 2.52, 43.58 ± 1.97, 36.27 ± 2.48, and 34.39 ± 2.06 %, respectively. Antibacterial activities of GCP-TS against Staphylococcus aureus and Escherichia coli were enhanced with the increase in its concentration, and its bacteriostatic activity against S. aureus was stronger than that against E. coli.

Characterization and Antibacterial Activity of a Polysaccharide Produced From Sugarcane Molasses by Chaetomium globosum CGMCC 6882

As a by-product of the sugar industry containing many sugars, proteins, nitrogenous materials, and heavy metals, molasses is rarely used for polysaccharide production. In the present work, a Chaetomium globosum CGMCC 6882 polysaccharide was produced from sugarcane molasses (CGP-SM) was successfully produced from sugarcane molasses. The yield of CGP-SM was 5.83 ± 0.09 g/l and its protein content was 2.41 ± 0.12% (w/w). Structural analysis showed that CGP-SM was a crystalline and amorphous polysaccharide containing rhamnose, glucosamine, galactose, glucose, mannose, fructose, and glucuronic acid in the molar ratio of 10.31: 1.14: 2.07: 59.55: 42.65: 1.92: 9.63. Meanwhile, weight-average molecular weight (Mw), number-average molecular weight (Mn), and polydispersity (Mw/Mn) of CGP-SM were 28.37 KDa, 23.66 KDa, and 1.199, respectively. Furthermore, the bacteriostatic assay indicated that CGP-SM inhibited the growth of Escherichia coli and Staphylococcus aureus in a concentration-dependent manner, and its inhibitory effect on S. aureus was higher than that of E. coli. Above all, this work provides a green method for the production of bioactive polysaccharide from sugarcane molasses.

Yarrowia lipolytica as a biorefinery platform for effluents and solid wastes valorization - challenges and opportunities

Due to its physiological and enzymatic features, Yarrowia lipolytica produces several valuable compounds from a wide range of substrates. Appointed by some authors as an industrial workhorse, Y. lipolytica has an extraordinary ability to use unrefined and complex low-cost substrates as carbon and nitrogen sources, aiding to reduce the waste surplus and to produce added-value compounds in a cost-effective way. Dozens of review papers regarding Y. lipolytica have been published till now, proving the interest that this yeast arouses in the scientific community. However, most of them are focused on metabolic pathways involved in substrates assimilation and product formation, or the development of synthetic biology tools in order to obtain engineered strains for biotechnological applications. This paper provides an exhaustive and up-to-date revision on the application of Y. lipolytica to valorize liquid effluents and solid wastes and its role in developing cleaner biotechnological approaches, aiming to boost the circular economy. Firstly, a general overview about Y. lipolytica is introduced, describing its intrinsic features and biotechnological applications. Then, an extensive survey of the literature regarding the assimilation of oily wastes (waste cooking oils, oil cakes and olive mill wastewaters), animal fat wastes, hydrocarbons-rich effluents, crude glycerol and agro-food wastes by Y. lipolytica strains will be discussed. This is the first article that brings together the environmental issue of all such residues and their valorization as feedstock for valuable compounds production by Y. lipolytica. Finally, it will demonstrate the potential of this non-conventional yeast to be used as a biorefinery platform.