In today's world, there is an increasing trend towards the use of renewable, cheap and readily available biomass in the production of a wide variety of fine and bulk chemicals in different biorefineries. Biorefineries utilize the activities of microbial cells and their enzymes to convert biomass into target products. Many of these processes require enzymes which are operationally stable at high temperature thus allowing e.g. easy mixing, better substrate solubility, high mass transfer rate, and lowered risk of contamination. Thermophiles have often been proposed as sources of industrially relevant thermostable enzymes. Here we discuss existing and potential applications of thermophiles and thermostable enzymes with focus on conversion of carbohydrate containing raw materials. Their importance in biorefineries is explained using examples of lignocellulose and starch conversions to desired products. Strategies that enhance thermostablity of enzymes both in vivo and in vitro are also assessed. Moreover, this review deals with efforts made on developing vectors for expressing recombinant enzymes in thermophilic hosts.

Marine macroalgal (seaweed) polysaccharides are highly promising for next-generation applications in several industries. However, despite the reported comprehensive potential of these polysaccharides, commercial products are scarce on the market. Seaweed cultivations are increasing in number and production quantity, owing to an elevated global trend of utilization interest in seaweed. The extraction of polysaccharides from seaweed generally generates low yields, but novel methods are being developed to facilitate and improve the extraction processes. Current areas of applications for seaweed polysaccharides mainly take advantage of the physicochemical properties of certain polysaccharides, such as gelling, thickening and emulsifying. However, many of the numerous bioactivities reported are still only at research level and lack clinical evidence for commercialization. It has been suggested the construction of smaller units may generate better defined molecules that are more suitable for biomedical applications. Enzymatic modification is a promising tool for the generation of more defined, targeted biomolecules. This review covers; structural differences between the most predominant marine algal polysaccharides, extraction processes, modification alternatives, as well as a summary of current and potential next-generation application areas.

The mucolytic human gut microbiota specialist Akkermansia muciniphila is proposed to boost mucin-secretion by the host, thereby being a key player in mucus turnover. Mucin glycan utilization requires the removal of protective caps, notably fucose and sialic acid, but the enzymatic details of this process remain largely unknown. Here, we describe the specificities of ten A. muciniphila glycoside hydrolases, which collectively remove all known sialyl and fucosyl mucin caps including those on double-sulfated epitopes. Structural analyses revealed an unprecedented fucosidase modular arrangement and explained the sialyl T-antigen specificity of a sialidase of a previously unknown family. Cell-attached sialidases and fucosidases displayed mucin-binding and their inhibition abolished growth of A. muciniphila on mucin. Remarkably, neither the sialic acid nor fucose contributed to A. muciniphila growth, but instead promoted butyrate production by co-cultured Clostridia. This study brings unprecedented mechanistic insight into the initiation of mucin O-glycan degradation by A. muciniphila and nutrient sharing between mucus-associated bacteria.

Xylan has a main chain consisting of β-1,4-linked xylose residues with diverse substituents. Endoxylanases cleave the xylan chain at cleavage sites determined by the substitution pattern and thus give different oligosaccharide product patterns. Most known endoxylanases belong to glycoside hydrolase (GH) families 10 and 11. These enzymes work well on unsubstituted xylan but accept substituents in certain subsites. The GH11 enzymes are more restricted by substituents, but on the other hand, they are normally more active than the GH10 enzymes on insoluble substrates, because of their smaller size. GH5 endoxylanases accept arabinose substituents in several subsites and require it in the − 1 subsite. This specificity makes the GH5 endoxylanases very useful for degradation of highly arabinose-substituted xylans and for the selective production of arabinoxylooligosaccharides, without formation of unsubstituted xylooligosaccharides. The GH30 endoxylanases have a related type of specificity in that they require a uronic acid substituent in the − 2 subsite, which makes them very useful for the production of uronic acid substituted oligosaccharides. The ability of dietary xylooligosaccharides to function as prebiotics in humans is governed by their substitution patterns. Endoxylanases are thus excellent tools to tailor prebiotic oligosaccharides to stimulate various types of intestinal bacteria and to cause fermentation in different parts of the gastrointestinal tract. Continuously increasing knowledge on the function of the gut microbiota and discoveries of novel endoxylanases increase the possibilities to achieve health-promoting effects.

The thermophile Rhodothermus marinus produces extracellular polysaccharides (EPSs) that forms a distinct cellular capsule. Here, the first data on EPS production in strains DSM4252T and MAT493 are reported and compared. Cultures of both strains, supplemented with either glucose, sucrose, lactose or maltose showed that the EPS were produced both in the exponential and stationary growth phase and that production in the exponential phase was boosted by maltose supplementation, while stationary phase production was boosted by lactose. The latter was higher, resulting in 8.8 (DSM4252T) and 13.7mg EPS/g cell dry weight (MAT493) in cultures in marine broth supplemented with 10g/L lactose. The EPSs were heteropolymeric with an average molecular weight of 8×104Da and different monosaccharides, including arabinose and xylose. FT-IR spectroscopy revealed presence of hydroxyl, carboxyl, N-acetyl, amine, and sulfate ester groups, showing that R. marinus produces unusual sulfated EPS with high arabinose and xylose content.