RESUMEN
Levan, a ß-(2,6)-linked fructose polymer, exhibits diverse properties that impart versatility, rendering it a highly sought-after biopolymer with various industrial applications. Levan can be produced by various microorganisms using sucrose, food industry byproducts and agricultural wastes. Microbial levan represents the most potent cost-effective process for commercial-scale levan production. This study reviews the optimization of levan production by understanding its biosynthesis, physicochemical properties and the fermentation process. In addition, genetic and protein engineering for its increased production and emerging methods for its detection are introduced and discussed. All of these comprehensive studies could serve as powerful tools to optimize levan production and broaden its applications across various industries.
Asunto(s)
Fermentación , Fructanos , Fructanos/biosíntesis , Fructanos/metabolismo , Bacterias/metabolismo , Bacterias/genética , Ingeniería de Proteínas/métodos , Sacarosa/metabolismo , Hexosiltransferasas/metabolismo , Hexosiltransferasas/genética , Microbiología Industrial/métodosRESUMEN
Levan-type fructooligosaccharides (LFOS) exhibit significant biological activities and selectively promote the growth of certain beneficial bacteria. Levanase is an important enzyme for LFOS production. In this study, two isoforms of levanases, exo- and endo-type depolymerizing enzymes, from Bacillus subtilis HM7 isolated from Dynastes hercules larvae excrement were cloned, expressed, and characterized. The synergistic effect on the levan hydrolysis and kinetic properties of both isoforms were evaluated, indicating their cooperation in levan metabolism, where the endo-levanase catalyzes a rate-limiting step. In addition, homology models and molecular dynamics simulations revealed the key amino residues of the enzymes for levan binding and catalysis. It was found that both isoforms possessed distinct binding residues in the active sites, suggesting the importance of the specificity of the enzymes. Finally, we demonstrated the potential of endo-type levanase in LFOS synthesis using a one-pot reaction with levansucrase. Overall, this study fills the knowledge gap in understanding levanase's mechanism, making an important contribution to the fields of food science and biotechnology.
Asunto(s)
Bacillus subtilis , Glicósido Hidrolasas , Oligosacáridos , Bacillus subtilis/enzimología , Oligosacáridos/biosíntesis , Oligosacáridos/química , Glicósido Hidrolasas/metabolismo , Glicósido Hidrolasas/química , Glicósido Hidrolasas/genética , Cinética , Fructanos/biosíntesis , Fructanos/química , Hidrólisis , Simulación de Dinámica Molecular , Especificidad por Sustrato , Hexosiltransferasas/metabolismo , Hexosiltransferasas/química , Hexosiltransferasas/genética , CatálisisRESUMEN
BACKGROUND: Fructans are water-soluble carbohydrates that accumulate in wheat and are thought to contribute to a pool of stored carbon reserves used in grain filling and tolerance to abiotic stress. RESULTS: In this study, transgenic wheat plants were engineered to overexpress a fusion of two fructan biosynthesis pathway genes, wheat sucrose: sucrose 1-fructosyltransferase (Ta1SST) and wheat sucrose: fructan 6-fructosyltransferase (Ta6SFT), regulated by a wheat ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit (TaRbcS) gene promoter. We have shown that T4 generation transgene-homozygous single-copy events accumulated more fructan polymers in leaf, stem and grain when compared in the same tissues from transgene null lines. Under water-deficit (WD) conditions, transgenic wheat plants showed an increased accumulation of fructan polymers with a high degree of polymerisation (DP) when compared to non-transgenic plants. In wheat grain of a transgenic event, increased deposition of particular fructan polymers such as, DP4 was observed. CONCLUSIONS: This study demonstrated that the tissue-regulated expression of a gene fusion between Ta1SST and Ta6SFT resulted in modified fructan accumulation in transgenic wheat plants and was influenced by water-deficit stress conditions.
Asunto(s)
Proteínas Bacterianas , Fructanos , Hexosiltransferasas , Plantas Modificadas Genéticamente , Triticum , Triticum/genética , Triticum/metabolismo , Plantas Modificadas Genéticamente/genética , Fructanos/metabolismo , Fructanos/biosíntesis , Hexosiltransferasas/genética , Hexosiltransferasas/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Regulación de la Expresión Génica de las Plantas , Fusión GénicaRESUMEN
ABSTRACT The effect of plant growth-promoting bacteria inoculation on plant growth and the sugar content in Agave americana was assessed. The bacterial strains ACO-34A, ACO-40, and ACO-140, isolated from the A. americana rhizosphere, were selected for this study to evaluate their phenotypic and genotypic characteristics. The three bacterial strains were evaluated via plant inoculation assays, and Azospirillum brasilense Cd served as a control strain. Phylogenetic analysis based on the 16S rRNA gene showed that strains ACO-34A, ACO-40 and ACO-140 were Rhizobium daejeonense, Acinetobacter calcoaceticus and Pseudomonas mosselii, respectively. All of the strains were able to synthesize indole-3-acetic acid (IAA), solubilize phosphate, and had nitrogenase activity. Inoculation using the plant growth-promoting bacteria strains had a significant effect (p < 0.05) on plant growth and the sugar content of A. americana, showing that these native plant growth-promoting bacteria are a practical, simple, and efficient alternative to promote the growth of agave plants with proper biological characteristics for agroindustrial and biotechnological use and to increase the sugar content in this agave species.