Production and application of purified mutanase from novel Cellulosimicrobium funkei SNG1 in the in vitro biofilm degradation

Mutanase (α-1,3-glucanase) is an inducible extracellular enzyme with potential medical applications in dentistry. A novel Cellulosimicrobium funkei strain SNG1 producing mutanase enzyme using α-1,3-glucans was isolated, and the enzyme was optimized for increased productivity using the one-factor-at-a-time approach. Maximum growth and enzyme-specific activity (2.12 ± 0.4 U/mg) were attained in a production medium with pH 7.0 and 1% α-1,3-glucans as carbon source, incubated at 37°C for 30 h. The result showed a five-fold increase in activity compared to unoptimized conditions (0.40 U/mg). The enzyme was purified by gel-filtration chromatography, and recovered with a yield of 29.03% and a specific activity increase of 10.9-fold. The molecular mass of the monomeric enzyme is 137 kDa. The pH and temperature optima are 6.0 and 45°C with K_m of 1.28 ± 0.11 mg for α-1,3-glucans. The enzyme activity was stimulated by adding Co²⁺ , Ca²⁺ , Cu²⁺ , and was entirely inhibited by Hg²⁺ . On 2-h incubation, the purified enzyme effectively degraded in vitro film with an 82.68% degradation rate and a saccharification yield of 30%.

A comprehensive review on mutan (a mixed linkage of α-1-3 and α-1-6 glucans) from bacterial sources

Mutan is an extracellular sticky polymer having α-1-3 and α-1-6 glycosidic linkages with a large diversity in molecular weights and structures depending on the source. These compounds are reported to be highly thermostable and also have potential physiochemical and biological applications. The main aim of this review is to provide an overview of glucosyltransferases and their role in mutan synthesis. The production strategies and structural properties of bacterial mutans are discussed with a goal to improve production efficiency. The physicochemical features, chemical modifications, potential industrial applications and future prospects are also discussed. According to data, mutan and its derivatives will play a larger role in medicinal sectors and as thermoplastics in the near future.Abbreviations: ABTS: 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid; BHI: Brain heart infusion broth; ¹³C (HSQC) NMR: Heteronuclear Single Quantum Coherence NMR; CBMs: Carbohydrate binding modules; DPPH: 2,2-diphenyl-1-picrylhydrazyl; FTIR: Fourier-transform infrared spectroscopy; GC-MS: Gas chromatography-mass spectrometry; GPC: Gel permeation chromatography; Gtfs: Glucosyltransferases; ¹H (DQF-COSY): Double-quantum filtered correlation spectroscopy; HPAEC-PAD: High-performance anion exchange chromatography with pulsed amperometric detection; HPLC: High performance liquid chromatography; HPSEC-RI: High-performance size exclusive chromatography coupled with refractive index; HPSEC-MALLS: High-performance size exclusive chromatography with multi-angle laser light scattering detection; MALDI-TOF: Matrix-Assisted Laser Desorption/Ionization-Time of Flight mass spectrometry; M_w: Weight-average molecular weight; MWD: Molecular weight distribution; NMR: Nuclear magnetic resonance spectroscopy; TEM: Transmission electron microscopy; THB: Todd Hewitt Broth; TTY: Tryticase tryptose yeast extract broth.

Natural microbial polysaccharides as effective factors for modification of the catalytic properties of fungal cellobiose dehydrogenase

Polysaccharides are biopolymers composed of simple sugars like glucose, galactose, mannose, fructose, etc. The major natural sources for the production of polysaccharides include plants and microorganisms. In the present work, four bacterial and two fungal polysaccharides (PS or EPS) were used for the modification and preservation of Pycnoporus sanguineus cellobiose dehydrogenase (CDH) activity. It was found that the presence of polysaccharide preparations clearly enhanced the stability of cellobiose dehydrogenase compared to the control value (4 °C). The highest stabilization effect was observed for CDH modified with Rh110EPS. Changes in the optimum pH in the samples of CDH incubated with the chosen polysaccharide modifiers were evidenced as well. The most significant effect was observed for Rh24EPS and Cu139PS (pH 3.5). Cyclic voltammetry used for the analysis of electrochemical parameters of modified CDH showed the highest peak values after 30 days of incubation with polysaccharides at 4 °C. In summary, natural polysaccharides seem to be an effective biotechnological tool for the modification of CDH activity to increase the possibilities of its practical applications in many fields of industry.

Gene expression analysis of inflammation-related genes in macrophages treated with α-(1 → 3, 1 → 6)-D-glucan extracted from Streptococcus mutans

Streptococcus mutans is a gram-positive bacterium that causes tooth decay. The exopolyssacharides, mostly glucans synthesized by the bacterium are responsible for establishing pathogenic bio-films associated with dental caries disease. The regulatory immune and inflammatory reactions implicated by the synthesized glucans are still not clearly understood. In this study, a water-soluble exopolyssacharide (WSP) was extracted from culture of Str. mutans. The structural properties of WSP, [α-(1 → 3, 1 → 6)-D-glucan] were confirmed using Fourier-transform infrared spectroscopy and ¹³C-nuclear magnetic resonance spectroscopy. Furthermore, the effects of WSP on the global gene expression of the macrophage-like RAW 264.7 cells were analyzed using mRNA-seq analysis. Using Gene Ontology analysis, we compiled a total of 24,421 genes that were upregulated or downregulated by more than 5.0-fold and 0.3-fold, respectively. Most of the transcripts were grouped under immune response and inflammation-related gene categories. Among the 802 immunity-related genes analyzed, chemokine ligand 7 (Ccl7), interleukin-1β (IL-1β), interleukin-1α (IL-1α) and interleukin-6 (IL-6) were upregulated after WSP exposure. In addition, among a total of 344 genes related to inflammation, Ccl7, IL-1α and IL-6 were upregulated. These results suggest that [α-(1 → 3, 1 → 6)-D-glucan] from Str. mutans produces activates macrophages and may contribute to the immune and inflammatory response to periodontal disease.

The mechanisms of hyphal pellet formation mediated by polysaccharides, α-1,3-glucan and galactosaminogalactan, in Aspergillus species

Filamentous fungi are widely used for production of enzymes and chemicals, and are industrially cultivated both in liquid and solid cultures. Submerged culture is often used as liquid culture for filamentous fungi. In submerged culture, filamentous fungi show diverse macromorphology such as hyphal pellets and dispersed hyphae depending on culture conditions and genetic backgrounds of fungal strains. Although the macromorphology greatly affects the productivity of submerged cultures, the specific cellular components needed for hyphal aggregation after conidial germination have not been characterized. Recently we reported that the primary cell wall polysaccharide α-1,3-glucan and the extracellular polysaccharide galactosaminogalactan (GAG) contribute to hyphal aggregation in Aspergillus oryzae, and that a strain deficient in both α-1,3-glucan and GAG shows dispersed hyphae in liquid culture. In this review, we summarize our current understanding of the contribution of chemical properties of α-1,3-glucan and GAG to hyphal aggregation. Various ascomycetes and basidiomycetes have α-1,3-glucan synthase gene(s). In addition, some Pezizomycotina fungi, including species used in the fermentation industry, also have GAG biosynthetic genes. We also review here the known mechanisms of biosynthesis of α-1,3-glucan and GAG. Regulation of the biosynthesis of the two polysaccharides could be a potential way of controlling formation of hyphal pellets.

A Report on Fungal (1→3)-α-d-glucans: Properties, Functions and Application

The cell walls of fungi are composed of glycoproteins, chitin, and α- and β-glucans. Although there are many reports on β-glucans, α-glucan polysaccharides are not yet fully understood. This review characterizes the physicochemical properties and functions of (1→3)-α-d-glucans. Particular attention has been paid to practical application and the effect of glucans in various respects, taking into account unfavourable effects and potential use. The role of α-glucans in plant infection has been proven, and collected facts have confirmed the characteristics of Aspergillus fumigatus infection associated with the presence of glucan in fungal cell wall. Like β-glucans, there are now evidence that α-glucans can also stimulate the immune system. Moreover, α-d-glucans have the ability to induce mutanases and can thus decompose plaque.