Many marine microorganisms synthesize exopolysaccharides (EPSs), and some of these EPSs have been reported to have potential in different fields. However, the pharmaceutical potentials of marine EPSs are rarely reported. The EPS secreted by the Artic marine bacterium Polaribacter sp. SM1127 has good antioxidant activity, outstanding moisture-retention ability, and considerable protective property on human dermal fibroblasts (HDFs) at low temperature. Here, the effects of SM1127 EPS on skin wound healing and frostbite injury prevention were studied. Scratch wound assay showed that SM1127 EPS could stimulate the migration of HDFs. In the full-thickness cutaneous wound experiment of Sprague–Dawley (SD) rats, SM1127 EPS increased the wound healing rate and stimulated tissue repair detected by macroscopic observation and histologic examination, showing the ability of SM1127 EPS to promote skin wound healing. In the skin frostbite experiment of SD rats, pretreatment of rat skin with SM1127 EPS increased the rate of frostbite wound healing and promoted the repair of the injured skin significantly, indicating the good effect of SM1127 EPS on frostbite injury prevention. These results suggest the promising potential of SM1127 EPS in the pharmaceutical area to promote skin wound healing and prevent frostbite injury.

Proteases in the M23 family have specific activities toward elastin and bacterial peptidoglycan. The peptidoglycan-degrading property makes these proteases have potential as novel antimicrobials. Because M23 proteases cannot be maturely expressed in Escherichia coli, it is significant to improve the production of these enzymes in their wild strains. Pseudoalterin is a new M23 protease secreted by the deep-sea bacterium Pseudoalteromonas sp. CF6-2. In this study, the fermentation conditions of strain CF6-2 for pseudoalterin production were optimized using single factor experiments and response surface methodology to improve the enzyme yield. To reduce the fermentation cost, bovine artery powder instead of elastin was determined as a cheap and efficient inducer. Based on single factor experiments, artery powder content, culture temperature and culture time were determined as the main factors influencing pseudoalterin production and were further optimized by the central composite design. The optimal values of these factors were determined as: artery powder of 1.2%, culture temperature of 20.17 °C and culture time of 28.04 h. Under the optimized conditions, pseudoalterin production reached 100.02 ± 9.0 U/mL, more than twice of that before optimization. These results lay a good foundation for developing the biotechnological potential of pseudoalterin.

A Gram-negative, aerobic, non-flagellated and ovoid- or rod-shaped bacterium, designated strain SM1902T, was isolated from the sediment sampled at the Jia River estuary, Yantai, PR China. The strain grew at 10–37 °C (optimum, 25–30 °C), pH 6.0–10.0 (pH 7.0) and with 0.5–13.0 % (w/v) NaCl (2.5%). It reduced nitrate to nitrite, but did not produce bacteriochlorophyll a. The results of phylogenetic analysis based on 16S rRNA gene sequences revealed that strain SM1902T constituted a separated lineage within the family Rhodobacteraceae and was closely related to Meridianimarinicoccus roseus TG-679T and Phycocomes zhengii LMIT002T with 96.1 and 94.3 % 16S rRNA gene sequence similarities, respectively. The predominant cellular fatty acid was summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c). The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, an unidentified aminolipid and an unidentified lipid. The sole respiratory quinone was ubiquinone-10. The in silico DNA–DNA hybridization values between strain SM1902T and Meridianimarinicoccus roseus TG-679T and Phycocomes zhengii LMIT002T were 19.6 and 19.5 %, respectively; and the average nucleotide identity values between them were 76.1 and 74.2 %, respectively. The genomic DNA G+C content of strain SM1902T was 58.2 mol%. Based on the phylogenetic, chemotaxonomic and phenotypic data obtained in this study, strain SM1902T is considered to represent a novel species in a new genus within the family Rhodobacteraceae , for which the name Fluviibacterium aquatile gen. nov., sp. nov. is proposed. The type strain is SM1902T (=KCTC 72045T=MCCC 1K03596T=CCTCC AB 2018346T).

The use of antibiotics had reached a plateau due to antibiotic resistance, overuse, and residue. Bacteriophages have recently attracted considerable attention as alternative biocontrol agents. Here, we provide an up-to-date overview of phage applications in the food industry. We reviewed recently reported phages against ten typical foodborne pathogens, studies of competitive phage-encoded endolysins, and the primary outcomes of phage encapsulation in food packaging and pathogen detection. Furthermore, we identified existing barriers that still need to be addressed and proposed potential solutions to overcome these obstacles in the future.

Elastases have been widely studied because of their important uses as medicine and meat tenderizers. However, there are relatively few studies on marine elastases. Myroilysin, secreted by Myroides profundi D25 from deep-sea sediment, is a novel elastase. In this study, we examined the elastin degradation mechanism of myroilysin. When mixed with insoluble bovine elastin, myroilysin bound hydrophobically, suggesting that this elastase may interact with the hydrophobic domains of elastin. Consistent with this, analysis of the cleavage pattern of myroilysin on bovine elastin and recombinant tropoelastin revealed that myroilysin preferentially cleaves peptide bonds with hydrophobic residues at the P1 and/or P1′ positions. Scanning electron microscopy (SEM) of cross-linked recombinant tropoelastin degraded by myroilysin showed preferential damages of spherules over cross-links, as expected for a hydrophobic preference. The degradation process of myroilysin on bovine elastin fibres was followed by light microscopy and SEM, revealing that degradation begins with the formation of crevices and cavities at the fibre surface, with these openings increasing in number and size until the fibre breaks into small pieces, which are subsequently fragmented. Our results are helpful for developing biotechnological applications for myroilysin.

Pseudoalterin is the most abundant protease secreted by the marine sedimental bacterium Pseudoalteromonas sp. CF6-2 and is a novel cold-adapted metalloprotease of the M23 family. Proteases of the M23 family have high activity towards peptidoglycan and elastin, suggesting their promising biomedical and biotechnological potentials. To lower the fermentive cost and improve the pseudoalterin production of CF6-2, we optimized the fermentation medium by using single factor experiments, added 0.5% sucrose as a carbon source, and lowered the usage of artery powder from 1.2% to 0.6%. In the optimized medium, pseudoalterin production reached 161.15 ± 3.08 U/mL, 61% greater than that before optimization. We further conducted a small-scale fermentation experiment in a 5-L fermenter and a pilot-scale fermentation experiment in a 50-L fermenter. Pseudoalterin production during pilot-scale fermentation reached 103.48 ± 8.64 U/mL, 77% greater than that before the medium was optimized. In addition, through single factor experiments and orthogonal tests, we developed a compound stabilizer for pseudoalterin, using medically safe sugars and polyols. This stabilizer showed a significant protective effect for pseudoalterin against enzymatic thermal denaturation. These results lay a solid foundation for the industrial production of pseudoalterin and the development of its biomedical and biotechnological potentials.