A novel β-galactosidase gene (PbBgal35A) from Pedobacter sp. CAUYN2 was cloned and expressed in Escherichia coli. The gene had an open reading frame of 1917 bp, encoding 638 amino acids with a predicted molecular mass of 62.3 kDa. The deduced amino acid sequence of the gene shared the highest identity of 41% with a glycoside hydrolase family 35 β-galactosidase from Xanthomonas campestris pv. campestris (AAP86763.1). The recombinant β-galactosidase (PbBgal35A) was purified to homogeneity with a specific activity of 65.9 U/mg. PbBgal35A was optimally active at pH 5.0 and 50 °C, respectively, and it was stable within pH 4.5‒7.0 and up to 45 °C. PbBgal35A efficiently synthesized galacto-oligosaccharides from lactose with a conversion ratio of 32% (w/w) and fructosyl-galacto-oligosaccharides from lactulose with a conversion ratio of 21.9% (w/w). Moreover, the enzyme catalyzed the synthesis of galacto-oligosaccharides from low-content lactose in fresh milk, and the GOS conversion ratios of 17.1% (w/w) and 7.8% (w/w) were obtained when the reactions were performed at 45 and 4 °C, respectively. These properties make PbBgal35A an ideal candidate for commercial use in the manufacturing of GOS-enriched dairy products.

• MeSH
• bakteriální proteiny genetika   metabolismus   chemie   MeSH
• beta-galaktosidasa * genetika   metabolismus   chemie   izolace a purifikace   MeSH
• Escherichia coli genetika   metabolismus   MeSH
• exprese genu MeSH
• glykosylace MeSH
• klonování DNA * MeSH
• koncentrace vodíkových iontů MeSH
• laktosa * metabolismus   MeSH
• mléko mikrobiologie   MeSH
• molekulová hmotnost MeSH
• oligosacharidy metabolismus   MeSH
• Pedobacter * enzymologie   genetika   MeSH
• rekombinantní proteiny genetika   metabolismus   chemie   izolace a purifikace   MeSH
• sekvence aminokyselin MeSH
• stabilita enzymů * MeSH
• substrátová specifita MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH

The present study aimed to investigate the response of intestinal microbiota during 3 weeks' starvation of largemouth bass (Micropterus salmoides), an economically important freshwater fish, using 16S rRNA gene amplicon sequencing and PICRUSt2 predictive functional profiling. Overall, the microbiota was mainly represented by Mycoplasma, Pseudomonas, Acinetobacter, and Microbacterium in the initial group. This pattern contrasted with that of Cetobacterium and Aeromonas, which were major representative genera in the starved group. Significant differences in the richness and composition of intestinal microbial community induced by starvation were observed. Notably, earthy-musty off-flavor compounds (geosmin and 2-methylisoborneol) were significantly decreased during starvation, which were significantly correlated with the abundance of certain actinobacterial taxa, namely, Microbacterium and Nocardioides. Additionally, the functional pathways involved in synthesis of off-flavor compounds, protein digestion, fatty acid degradation, and biosynthesis of cofactors greatly decreased with starvation, indicating that microbiota modulated the specific metabolic pathway to adapt to food deprivation. These results emphasize that starvation can modulate diversity, community structure, and functions of the intestinal microbiota and mitigate the off-flavors, which has important implications for strategies to eliminate off-flavor odorants through the application of probiotics to manipulate the gut microbiome and ultimately enhance flesh quality of freshwater fish.

• MeSH
• mikrobiota * MeSH
• Percoidea * genetika   metabolismus   mikrobiologie   MeSH
• RNA ribozomální 16S genetika   MeSH
• střeva MeSH
• střevní mikroflóra * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH