RESUMEN
Phedimus aizoon has been utilized as a medicinal plant in Asia. However, the production of phytochemical-rich extracts from P. aizoon and the evaluation of their bioactivity are limited. Herein, phytochemical-rich extracts were prepared by ultrasound-assisted extraction of P. aizoon, with a high extraction yield of 16.56%. The extracts contained about 126 mg of phenolics and 31 mg of flavonoids per g of the extracts. The chromatographic analysis (GC-MS and HPLC analyses) identified 19 notable phytochemicals of the extracts from P. aizoon, including pentacosane, hexadecanoic acid, gallic acid, vanillic acid, and quercetin. The gallic acid content of the extracts was relatively high at 2.75 mg/g. The identified compounds are known to have various bioactivities, such as antioxidant, antibacterial, and antifungal activities. In fact, the prepared extracts exhibited antioxidant activity at 24-28% of that of ascorbic acid. In addition, it showed antibacterial activity against both Escherichia coli (Gram-negative bacteria) and Staphylococcus aureus (Gram-positive bacteria). This study highlights that P. aizoon deserves attention as a natural bioactive substance and emphasizes the need for applications of the extracts from P. aizoon.
RESUMEN
Bacterial cellulose (BC), a natural polymer synthesized by bacteria, has received considerable attention owing to its impressive physicomechanical properties. However, the low productivity of BC-producing strains poses a challenge to industrializing this material and making it economically viable. In the present study, UV-induced random mutagenesis of Gluconacetobacter xylinus ATCC 53524 was performed to improve BC production. Sixty mutants were obtained from the following mutagenesis procedure: the correlation between UVC fluence and cell death was investigated, and a limited viability condition was determined as a UVC dose to kill 99.99 %. Compared to the control strain, BC production by the mutant strains LYP25 and LYP23 improved 46.4 % and 44.9 %, respectively. Fermentation profiling using the selected strains showed that LYP25 was superior in glucose consumption and BC production, 13.8 % and 41.0 %, respectively, compared to the control strain. Finally, the physicochemical properties of LYP25-derived BC were similar to those of the control strain; thus, the mutant strain is expected to be a promising producer of BC in the bio-industry based on improved productivity.
Asunto(s)
Gluconacetobacter xylinus , Gluconacetobacter , Gluconacetobacter/genética , Celulosa/química , Fermentación , Gluconacetobacter xylinus/genética , Gluconacetobacter xylinus/metabolismo , Glucosa/metabolismoRESUMEN
Bacterial cellulose (BC) is gaining attention as a carbon-neutral alternative to plant cellulose, and as a means to prevent deforestation and achieve a carbon-neutral society. However, the high cost of fermentation media for BC production is a barrier to its industrialization. In this study, chestnut shell (CS) hydrolysates were used as a carbon source for the BC-producing bacteria strain, Gluconacetobacter xylinus ATCC 53524. To evaluate the suitability of the CS hydrolysates, major inhibitors in the hydrolysates were analyzed, and BC production was profiled during fermentation. CS hydrolysates (40 g glucose/l) contained 1.9 g/l acetic acid when applied directly to the main medium. As a result, the BC concentration at 96 h using the control group and CS hydrolysates was 12.5 g/l and 16.7 g/l, respectively (1.3-fold improved). In addition, the surface morphology of BC derived from CS hydrolysates revealed more densely packed nanofibrils than the control group. In the microbial BC production using CS, the hydrolysate had no inhibitory effect during fermentation, suggesting it is a suitable feedstock for a sustainable and eco-friendly biorefinery. To the best of our knowledge, this is the first study to valorize CS by utilizing it in BC production.