Research background. Cellulose is an ingredient of waste materials that can be converted to other valuable substances. This is possible provided that, the polymer molecule will be degraded to smaller particles, used as a carbon source by microorganisms. Because of the frequently applied methods of pre-treatment of lignocellulosic materials, the cellulases derived from thermophilic microorganisms are particularly desirable. Experimental approach. We were looking for cellulolytic microorganisms able to grow at 50 °C. We described their morphological features and biochemical characteristics based on CMCase activity and the api®ZYM. The growth curves, during incubation at 50 °C, were examined using the microbioreactor BioLector®. Results and conclusions. 40 bacterial strains were isolated from fermenting hay, geothermal karst spring, hot spring and geothermal pond at 50 °C. The vast majority of the bacteria were Gram-positive and rod-shaped with the maximum growth temperature of at least 50 °C. We also demonstrated a large diversity of biochemical characteristics among the microorganism. The CMCase activity was confirmed for 27 strains. However, the hydrolysis capacities (HC) were significant in bacterial strains: BBLN1, BSO6, BSO10, BSO13 and BSO14, and reached 2.74, 1.62, 1.30, 1.38 and 8.02 respectively. Rapid and stable growth was presented, among others, by BBLN1, BSO10, BSO13 and BSO14. The strains fulfilled the selection conditions and were identified based on the 16S rDNA sequences. BBLN1, BSO10, BSO13 were classified as Bacillus licheniformis, whereas BSO14 as Paenibacillus lactis. Novelty and scientific contribution. We described cellulolytic activity and biochemical characteristics of many bacteria isolated from hot environments. We are also the first to report the cellulolytic activity of thermotolerant P.s lactis. Described strains can be a source of new thermostable cellulases, which are extremely desirable in various branches of the circular bioeconomy.
This study compares the microbial diversity and content of bioactive compounds in dried goji berries available on the Polish market to those of the most highly valued goji berries from the Ningxia region in China. The content of phenols, flavonoids, and carotenoids were determined, as well as the antioxidant capacities of the fruits. The quantitative and qualitative composition of the microbiota inhabiting the fruits was assessed using metagenomics by high-throughput sequencing on the Illumina platform. The highest quality was demonstrated by naturally dried fruits from the Ningxia region. These berries were characterized by a high content of polyphenols and high antioxidant activity, as well as high microbial quality. The lowest antioxidant capacity was shown by goji berries cultivated in Poland. However, they contained a high amount of carotenoids. The highest microbial contamination was found in the goji berries available in Poland (>106 CFU/g), which is important in terms of consumer safety. Despite the widely accepted benefits of consuming goji berries, both the country of cultivation and the preservation method may influence their composition, bioactivity, and microbial quality.
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