New strategy for enhancement of microbial viability in simulated gastric conditions based on display of starch-binding domain on cell surface

Rice bran as an encapsulating material to produce a healthy synbiotic product with improved gastrointestinal tolerance

To date, the coffee industry has the second highest market value in the world and consumer behavior has transitioned from drinking coffee just for its caffeine content to reduce sleepiness into an overall experience. Instant cold brew coffee in powder form can preserve the taste of coffee well; moreover, it is easy to transport. Several consumers have increasing interests in implementing lactic acid bacteria in healthy food due to their growing awareness of the probiotic's role. Several scholars have presented stress adaptation characteristics of single probiotic strains; however, comparisons of the stress-tolerant capacities of different probiotic strains are incomplete. Five lactic acid strains are tested for adaptation under four sublethal conditions. Lactobacillus casei is the most resilient probiotic in terms of heat and cold adaptation, while Lactobacillus acidophilus is more tolerant to low acid and bile salt; Then, these probiotics are subjected to a stress challenge that stimulates drying temperature, including a heat and cold stress challenge. The results show that acid adaptation can improve Lactobacillus acidophilus TISTR 1338 tolerance to harsh drying temperatures. In addition, encapsulation using prebiotic extracts from rice bran, with pectin and resistant starch combined through crosslinking and treated by freeze-drying, provides the highest encapsulation efficiency. In summary, acid-adapted L. acidophilus TISTR 1388 at the sublethal level can be applied to high and low temperature processing techniques. Additionally, the amount of viable probiotic after in vitro digestion remains at 5 log CFU/g, which is suitable for application in the production of synbiotic cold brew coffee.

Bacillus subtilis Spore Surface Display of Haloalkane Dehalogenase DhaA

The haloalkane dehalogenase DhaA can degrade sulfur mustard (2,2'-dichlorethyl sulfide; also known by its military designation HD) in a rapid and environmentally safe manner. However, DhaA is sensitive to temperature and pH, which limits its applications in natural or harsh environments. Spore surface display technology using resistant spores as a carrier to ensure enzymatic activity can reduce production costs and extend the range of applications of DhaA. To this end, we cloned recombinant Bacillus subtilis spores pHY300PLK-cotg-dhaa-6his/DB104(FH01) for the delivery of DhaA from Rhodococcus rhodochrous NCIMB 13064. A dot blotting showed that the fusion protein CotG-linker-DhaA accounted for 0.41% ± 0.03% (P < 0.01) of total spore coat proteins. Immunofluorescence analyses confirmed that DhaA was displayed on the spore surface. The hydrolyzing activity of DhaA displayed on spores towards the HD analog 2-chloroethyl ethylsulfide was 1.74 ± 0.06 U/mL (P < 0.01), with a specific activity was 0.34 ± 0.04 U/mg (P < 0.01). This is the first demonstration that DhaA displayed on the surface of B. subtilis spores retains enzymatic activity, which suggests that it can be used effectively in real-world applications including bioremediation of contaminated environments.

Prebiotic effects of resistant starch from purple yam (Dioscorea alataL.) on the tolerance and proliferation ability ofBifidobacterium adolescentis in vitro

Thein vitroprebiotic effects of resistant starch (RS), prepared by different treatments from purple yam, onBifidobacterium adolescentiswere investigated.

Recombinant CBM-fusion technology - Applications overview

Carbohydrate-binding modules (CBMs) are small components of several enzymes, which present an independent fold and function, and specific carbohydrate-binding activity. Their major function is to bind the enzyme to the substrate enhancing its catalytic activity, especially in the case of insoluble substrates. The immense diversity of CBMs, together with their unique properties, has long raised their attention for many biotechnological applications. Recombinant DNA technology has been used for cloning and characterizing new CBMs. In addition, it has been employed to improve the purity and availability of many CBMs, but mainly, to construct bi-functional CBM-fused proteins for specific applications. This review presents a comprehensive summary of the uses of CBMs recombinantly produced from heterologous organisms, or by the original host, along with the latest advances. Emphasis is given particularly to the applications of recombinant CBM-fusions in: (a) modification of fibers, (b) production, purification and immobilization of recombinant proteins, (c) functionalization of biomaterials and (d) development of microarrays and probes.

Exploiting the peptidoglycan-binding motif, LysM, for medical and industrial applications

The lysin motif (LysM) was first identified by Garvey et al. in 1986 and, in subsequent studies, has been shown to bind noncovalently to peptidoglycan and chitin by interacting with N-acetylglucosamine moieties. The LysM sequence is present singly or repeatedly in a large number of proteins of prokaryotes and eukaryotes. Since the mid-1990s, domains containing one or more of these LysM sequences originating from different LysM-containing proteins have been examined for purely scientific reasons as well as for their possible use in various medical and industrial applications. These studies range from detecting localized binding of LysM-containing proteins onto bacteria to actual bacterial cell surface analysis. On a more applied level, the possibilities of employing the LysM domains for cell immobilization, for the display of peptides, proteins, or enzymes on (bacterial) surfaces as well as their utility in the development of novel vaccines have been scrutinized. To serve these purposes, the chimeric proteins containing one or more of the LysM sequences have been produced and isolated from various prokaryotic and eukaryotic expression hosts. This review gives a succinct overview of the characteristics of the LysM domain and of current developments in its application potential.