Purification and characterization of cold-adapted beta-agarase from an Antarctic psychrophilic strain

Improvement of Bacillus subtilis PI agarase production, hydrolysate scavenging capability assessment, and saccharification of algal biomass for green ethanol generation

The goal of the current work was to optimize the growth parameters needed to manufacture agarase enzyme from a non-marine PI strain of Bacillus subtilis on an agar-based medium. Using Plackett-Burman design (PBD), nine process parameters were evaluated, and agar, peptone, and yeast-extract were identified as the most significant independent factors influencing agarase production with confidence levels more than 90%. To evaluate the optimal concentrations of the indicated process parameters on agarase production, the Box-Behnken design (BBD) was applied. After optimization, B. subtilis strain PI produced 119.8 U/ml of agarase, representing a 1.36-fold increase. In addition the agar hydrolysate fermented products contain the liberated oligosaccharide acts as strong antioxidant which has 62.4% scavenging activity. Also, the agarase yields increased (1141.12, 1350.253, 1684.854 and 1921.863 U/ml) after substitution the agar with algal biomass of Carolina officinalis at different concentrations (2, 5, 10 and 15%), respectively. After completing the saccharification process, the resulted hydrolysate was used to produce ethanol through fermentation with Pichia pastoris yeast strain as an economical method giving yields (6.68317, 7.09748, 7.75648 and 8.22332 mg/ml), that are higher than using yeast extract peptone dextrose (YPD) medium (4.461 mg/ml).

Application of Marine Microbial Natural Products in Cosmetics

As the market size of the cosmetics industry increases, the safety and effectiveness of new products face higher requirements. The marine environment selects for species of micro-organisms with metabolic pathways and adaptation mechanisms different from those of terrestrial organisms, resulting in their natural products exhibiting unique structures, high diversity, and significant biological activities. Natural products are usually safe and non-polluting. Therefore, considerable effort has been devoted to searching for cosmetic ingredients that are effective, safe, and natural for marine micro-organisms. However, marine micro-organisms can be difficult, or impossible, to culture because of their special environmental requirements. Metagenomics technology can help to solve this problem. Moreover, using marine species to produce more green and environmentally friendly products through biotransformation has become a new choice for cosmetic manufacturers. In this study, the natural products of marine micro-organisms are reviewed and evaluated with respect to various cosmetic applications.

Expression and Characterization of a Novel Cold-Adapted and Stable β-Agarase Gene agaW1540 from the Deep-Sea Bacterium Shewanella sp. WPAGA9

The neoagaro-oligosaccharides, degraded from agarose by agarases, are important natural substances with many bioactivities. In this study, a novel agarase gene, agaW1540, from the genome of a deep-sea bacterium Shewanella sp. WPAGA9, was expressed, and the recombinant AgaW1540 (rAgaW1540) displayed the maximum activity under the optimal pH and temperature of 7.0 and 35 °C, respectively. rAgaW1540 retained 85.4% of its maximum activity at 0 °C and retained more than 92% of its maximum activity at the temperature range of 20-40 °C and the pH range of 4.0-9.0, respectively, indicating its extensive working temperature and pH values. The activity of rAgaW1540 was dramatically suppressed by Cu²⁺ and Zn²⁺, whereas Fe²⁺ displayed an intensification of enzymatic activity. The K_m and V_max of rAgaW1540 for agarose degradation were 15.7 mg/mL and 23.4 U/mg, respectively. rAgaW1540 retained 94.7%, 97.9%, and 42.4% of its maximum activity after incubation at 20 °C, 25 °C, and 30 °C for 60 min, respectively. Thin-layer chromatography and ion chromatography analyses verified that rAgaW1540 is an endo-acting β-agarase that degrades agarose into neoagarotetraose and neoagarohexaose as the main products. The wide variety of working conditions and stable activity at room temperatures make rAgaW1540an appropriate bio-tool for further industrial production of neoagaro-oligosaccharides.

Implications of agar and agarase in industrial applications of sustainable marine biomass

Agar, a major component of the cell wall of red algae, is an interesting heteropolysaccharide containing an unusual sugar, 3,6-anhydro-L-galactose. It is widely used as a valuable material in various industrial and experimental applications due to its characteristic gelling and stabilizing properties. Agar-derived oligosaccharides or mono-sugars produced by various agarases have become a promising subject for research owing to their unique biological activities, including anti-obesity, anti-diabetic, immunomodulatory, anti-tumor, antioxidant, skin-whitening, skin-moisturizing, anti-fatigue, and anti-cariogenic activities. Agar is also considered as an alternative sustainable source of biomass for chemical feedstock and biofuel production to substitute for the fossil resource. In this review, we summarize various biochemically characterized agarases, which are useful for industrial applications, such as neoagarooligosaccharide or agarooligosaccharide production and saccharification of agar. Additionally, we succinctly discuss various recent studies that have been conducted to investigate the versatile biological activities of agar-derived saccharides and biofuel production from agar biomass. This review provides a basic framework for understanding the importance of agarases and agar-derived saccharides with broad applications in pharmaceutical, cosmetic, food, and bioenergy industries.

Agarolytic culturable bacteria associated with three antarctic subtidal macroalgae

Bacterial communities of Antarctic marine macroalgae remain largely underexplored in terms of diversity and biotechnological applications. In this study, three Antarctic subtidal macroalgae (Himantothallus grandifolius, Pantoneura plocamioides and Plocamium cartilagineum), two of them endemic of Antarctica, were investigated as a source for isolation of agar-degrading bacteria. A total of 21 epiphytic isolates showed agarolytic activity at low temperature on agar plates containing agar as the sole carbon source. 16S rRNA identification showed that the agar-degrading bacteria belonged to the genera Cellulophaga, Colwellia, Lacinutrix, Olleya, Paraglaciecola, Pseudoalteromonas and Winogradskyella. The agarase enzyme from a potential new species of the genus Olleya was selected for further purification. The enzyme was purified from the culture supernatant of Olleya sp. HG G5.3 by ammonium sulfate precipitation and ion-exchange chromatography. Molecular weight of the agarase was estimated to be 38 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The purified enzyme exhibited activity at 4 °C, retaining > 50% of its maximum activity at this temperature. This is the first study reporting the phylogeny of agar-degrading bacteria isolated from Antarctic subtidal macroalgae and the results suggest the huge potential of Antarctic algae-associated bacteria as a source of cold-active hydrolytic enzymes of biotechnological interest.

Agar-degrading bacteria isolated from Antarctic macroalgae

This study describes the taxonomic diversity of pigmented, agar-degrading bacteria isolated from the surface of macroalgae collected in King George Island, Antarctica. A total of 30 pigmented, agarolytic bacteria were isolated from the surface of the Antarctic macroalgae Adenocystis utricularis, Monostroma hariotii, Iridaea cordata, and Pantoneura plocamioides. Based on the 16S rRNA data, the agarolytic isolates were affiliated to the genera Algibacter, Arthrobacter, Brachybacterium, Cellulophaga, Citricoccus, Labedella, Microbacterium, Micrococcus, Salinibacterium, Sanguibacter, and Zobellia. Isolates phylogenetically related to Cellulophaga algicola showed the highest agarase activity in culture supernatants when tested at 4 and 37 °C. This is the first investigation of pigmented agar-degrading bacteria, members of microbial communities associated with Antarctic macroalgae, and the results suggest that they represent a potential source of cold-adapted agarases of possible biotechnological interest.

Horizontal Transfer of a Novel Soil Agarase Gene from Marine Bacteria to Soil Bacteria via Human Microbiota

Seaweed is receiving an increasing amount of attention as a “sea vegetable”. The microbiota of coastal populations may acquire seaweed associated enzymes through marine food. Several agarases have been found in non-marine environments; however, their origin is unknown. In this study, a hypothetical protein, Aga1, was identified as an agarase from an inland soil agar-degrading bacterium, Paenibacillus sp. SSG-1.Having low similarity to known glycoside hydrolases, Aga1 may be a distant member of the glycoside hydrolase family 86. Aga1 has good pH stability (pH 3–11) and is stable in the presence of various metal ions. Aga1 is an exo-type β-agarase that produces NA 4 (neoagarotetraose) and NA 6 (neoagarohexaose) as its main products. In addition, Aga1 may be a cell-surface-binding protein. The bioinformatic analysis showed aga1 may have been transfered together with its surrounding genes, from marine bacteria to soil bacteria via human microbiota. The use of seaweed as food and the disposal of human faeces or saliva were the most likely reasons for this gene transfer pathway. Notably, the results also indicated that microbes from inland humans may degrade agar and that these microbes may have acquired seaweed associated genes because of increased seaweed in diets.