Purification and partial characterization of a novel β-1,3-glucanase from the gut of sea cucumber Stichopus japonicus

Endogenous Proteases in Sea Cucumber (Apostichopus japonicas): Deterioration and Prevention during Handling, Processing, and Preservation

The sea cucumber is an essential nutrient source and a significant economic marine resource associated with successful aquaculture. However, sea cucumbers are highly susceptible to autolysis induced by endogenous protease after postmortem, and the phenomenon of body wall "melting" occurs, which seriously affects the food quality of products and the degree of acceptance by consumers. To satisfy the growing demand for fresh or processed sea cucumbers, we must clarify the autolysis mechanism of sea cucumbers and the methods to achieve autolysis regulation. In this paper, the factors leading to the quality deterioration and texture softening of sea cucumbers are reviewed, with emphasis on enzymatic characteristics, the autolysis mechanism, the effects of autolysis on the physicochemical properties of the body wall of the sea cucumber, and the development of potential natural protease inhibitors. We aim to provide some reference in future preservation and processing processes for sea cucumbers, promote new processing and preservation technologies, and advance the sea cucumber industry's development.

Chemical substances and their activities in sea cucumber Apostichopus japonicus: A review

Apostichopus japonicus, also known as Stichopus japonicus, with medicinal and food homologous figures, is a globally recognized precious ingredient with extremely high nutritional value. There is no relevant review available through literature search, so this article selects the research articles through the keywords "sea cucumber" and "Apostichopus japonicus (Stichopus japonicus)" in six professional databases, such as Wiley, PubMed, ScienceDirect, ACS, Springer, and Web of Science, from 2000 to the present, summarizing the extraction, isolation, and purification methods for the four major categories (polysaccharides, proteins and peptides, saponins, and other components) of the A. japonicus chemical substances and 10 effective biological activities of A. japonicus. Included are anticoagulation, anticancer/antitumor activities, hematopoiesis, regulation of gut microbiota, and immune regulatory activities that correspond to traditional efficacy. Literature support is provided for the development of medicines and functional foods and related aspects that play a leading role in future directions.

Potential of yeasts as biocontrol agents against Fusarium graminearum in vitro and on corn

AIMS

The antifungal effect of the yeast species Kluyveromyces marxianus, Meyerozyma caribbica, and Wickerhamomyces anomalus was evaluated against two Fusarium graminearum strains (FRS 26 and FSP 27) in vitro and on corn seeds.

METHODS AND RESULTS

The antifungal effect of the yeasts against F. graminearum was evaluated using scanning electron microscopy and extracellular chitinase and glucanase production to further elucidate the biocontrol mode of action. In addition, the germination percentage and vigor test were investigated after applying yeast on corn seeds. All the yeast strains inhibited fungal growth in vitro (57.4%-100.0%) and on corn seeds (18.9%-87.2%). In co-culture with antagonistic yeasts, F. graminearum showed collapsed hyphae and turgidity loss, which could be related to the ability of yeasts to produce chitinases and glucanases. The three yeasts did not affect the seed corn germination, and W. anomalus and M. caribbica increased corn seed growth parameters (germination percentage, shoot and root length, and shoot dry weight).

CONCLUSION

Meyerozyma caribbica and W. anomalus showed satisfactory F. graminearum growth inhibition rates and did not affect seed growth parameters. Further studies are required to evaluate the application of these yeasts to the crop in the field.

Characteristics of the Intestine Extracts and Their Effect on the Crude Collagen Fibers of the Body Wall from Sea Cucumber Apostichopus japonicus

Sea cucumbers Apostichopus japonicus will vomit their intestines during certain stimulations, and the collagen of the body wall will then be degraded. To define the effect of the sea cucumber intestine extracts on the body wall, the intestinal extracts and crude collagen fibers (CCF) of sea cucumber A. japonicus were prepared. According to the gelatin zymography, the type of endogenous enzymes in intestinal extracts were mainly serine endopeptidases with optimal activities at pH 9.0 and 40 °C. According to the rheology results, the viscosity of 3% CCF decreased from 32.7 Pa·s to 5.3 Pa·s by adding intestine extracts. The serine protease inhibitor phenylmethanesulfonyl fluoride inhibited the activity of intestinal extracts and increased the viscosity of collagen fibers to 25.7 Pa·s. The results proved that serine protease in the intestinal extracts participated in the process of body wall softening in sea cucumbers.

A comprehensive review of the control and utilization of aquatic animal products by autolysis-based processes: Mechanism, process, factors, and application

Animal aquatic products have high water content, abundant enzyme system and their own diverse microbial flora. These products are severely susceptible to autolysis and degradation after death, resulting in many adverse effects on storage, processing, and transportation. Among them, the endogenous enzyme are the key factor that caused the autolysis and degradation. Autolytic hydrolysis provides an effective way to maximize the use of aquatic by-products and achieve increased protein resources and reduce environmental pollution from by-products. To better acquaintance the autolysis phenomenon and regulation of the autolysis phenomenon. This paper reviews the autolytic mechanism, biochemical changes, influencing factors, and potential applications of animal aquatic products and their by-products to explore autolysis and its effective utilization and regulation. In addition, this study also emphasizes the importance of making full use of aquatic by-products. Furthermore, the research trends and future challenges of autolysis are also discussed. Autolysis can effectively transform aquatic products and by-products into bioactive hydrolysates. The hydrolysates produced by the autolysis of aquatic products and their by-products have attracted attention because of their wide applications in food, healthcare, and animal feed industries. However, the mechanism and regulation (promotion or inhibition) of autolysis should be further studied, and autolysate at the industrial level should be produced to provide high-value-added products for by-product processing and realize the sustainable utilization of resources.

A set of simple methods for detection and extraction of laminarinase

A carefully designed ammonium sulfate precipitation will simplify extraction of proteins and is considered to be a gold standard among various precipitation methods. Therefore, optimization of ammonium sulfate precipitation can be an important functional step in protein purification. The presence of high amounts of ammonium sulphate precludes direct detection of many enzymatically active proteins including reducing sugar assays (e.g. Nelson-Somogyi, Reissig and 3,5-dinitrosalicylic acid methods) for assessing carbohydrases (e.g. laminarinase (β (1-3)-glucanohydrolase), cellulases and chitinases). In this study, a simple method was developed using laminarin infused agarose plate for the direct analysis of the ammonium sulphate precipitates from Streptomyces rimosus AFM-1. The developed method is simple and convenient that can give accurate results even in presence of ammonium sulfate in the crude precipitates. Laminarin is a translucent substrate requiring the use of a stain to visualize the zones of hydrolysis in a plate assay. A very low-cost and locally available fluorescent optical fabric brightener Tinopal CBS-X has been used as a stain to detect the zones of hydrolysis. We also report simple methods to prepare colloidal chitin and cell free supernatant in this manuscript.

Expression and biochemical characterization of a multifunctional glycosidase from the thermophilic Bacillus licheniformis SR01

A gene (gkdA) (741 bp) encoding a putative protein of 247 amino acids was cloned from the Bacillus licheniformis SR01. The protein was expressed in Escherichia coli BL21 with a molecular mass estimated by SDS-PAGE of approximately 28.03 kDa and showed a calculating isoelectric point (pI) of 6.42. Structure analysis and function identification showed that the enzyme was a multifunctional glycosidase. Its specific activity was 0.013 U/μg. The recombinant glycosidase showed a maximum activity at 50°C and pH 7.0. It was very stable below 90°C and may have heat activation at higher temperatures. The relative residual activity was still more than 80% after 120 min at pH 5.0-10.0. The enzyme activity was inhibited by Cu²⁺, Fe²⁺, Ca²⁺, Mg²⁺, Co²⁺, Li⁺, SDS and EDTA, activated by Ca²⁺, and not affected by Mn²⁺ and K⁺. Under simulated stomach, and in vitro intestine, conditions, the enzyme retained 80%, and more than 100%, activity, respectively, after incubation for 90 min. The excellent properties of this enzyme, specifically its thermal stability and multifunctional abilities, give it potential application in the field of feed processing and other high-temperature processing industries.

Enzymes from Seafood Processing Waste and Their Applications in Seafood Processing

Commercial fishery processing results in discards up to 50% of the raw material, consisting of scales, shells, frames, backbones, viscera, head, liver, skin, belly flaps, dark muscle, roe, etc. Besides, fishing operations targeted at popular fish and shellfish species also result in landing of sizeable quantity of by-catch, which are not of commercial value because of their poor consumer appeal. Sensitivity to rapid putrefaction of fishery waste has serious adverse impact on the environment, which needs remedial measures. Secondary processing of the wastes has potential to generate a number of valuable by-products such as proteins, enzymes, carotenoids, fat, and minerals, besides addressing environmental hazards. Fishery wastes constitute good sources of enzymes such as proteases, lipases, chitinase, alkaline phosphatase, transglutaminase, hyaluronidase, acetyl glycosaminidase, among others. These enzymes can have diverse applications in the seafood industry, which encompass isolation and modification of proteins and marine oils, production of bioactive peptides, acceleration of traditional fermentation, peeling and deveining of shellfish, scaling of finfish, removal of membranes from fish roe, extraction of flavors, shelf life extension, texture modification, removal of off-odors, and for quality control either directly or as components of biosensors. Enzymes from fish and shellfish from cold habitats are particularly useful since they can function comparatively at lower temperatures thereby saving energy and protecting the food products. Potentials of these applications are briefly discussed.

Depiction of carbohydrate-active enzyme diversity in Caldicellulosiruptor sp. F32 at the genome level reveals insights into distinct polysaccharide degradation features

Diverse and distinctive encoding sequences of CAZyme in the genome of Caldicellulosiruptor sp. F32 enable the deconstruction of unpretreated lignocellulose.

Purification, characterization, cDNA cloning and in vitro expression of a serine proteinase from the intestinal tract of sea cucumber (Stichopus japonicus) with collagen degradation activity

Sea cucumber (Stichopus japonicus) autolysis during transportation and processing is a major problem and the specific proteinases responsible for autolysis have not yet been identified. In the present study, a 34 kDa serine proteinase (SP) was isolated to high purity from sea cucumber intestinal tract by a series of column chromatographies. Peptide mass fingerprinting revealed that six peptide fragments were identical to a proprotein convertase subtilisin/kexin type 9 preproprotein from sea cucumber A. japonicus. The enzyme hydrolyzed gelatin effectively at pH 6.0-9.0 and 35-40 °C, and the enzyme activity was strongly inhibited by SP inhibitors. Sea cucumber collagen was hydrolyzed significantly by purified SP at 37 °C and more gradually at 4 °C, suggesting that SP may be involved in autolysis. In addition, the SP gene that codes for 377 amino acid residues was cloned into an E. coli expression vector and expressed in vitro. A polyclonal antibody against rSP was prepared and found to react specifically against both rSP and endogenous SP, which may prove useful for future studies on the physiological functions of SP.

Purification and molecular characterization of exo-beta-1,3-glucanases from the marine yeast Williopsis saturnus WC91-2

The extracellular beta-1,3-glucanases in the supernatant of cell culture of the marine yeast Williopsis saturnus WC91-2 was purified to homogeneity with a 115-fold increase in specific beta-1,3-glucanase activity as compared to that in the supernatant by ultrafiltration, gel filtration chromatography, and anion-exchange chromatography. According to the data from sodium dodecyl sulfate polyacrylamide gel electrophoresis, the molecular mass of the purified enzyme was estimated to be 47.5 kDa. The purified enzyme could convert laminarin into monosaccharides and disaccharides, but had no killer toxin activity. The optimal pH and temperature of the purified enzyme were 4.0 and 40 degrees C, respectively. The enzyme was significantly stimulated by Li+, Ni2+, and Ba2+. The enzyme was inhibited by phenylmethylsulfonyl fluoride, iodoacetic acid, ethylenediamine tetraacetic acid, ethylene glycol bis(2-aminoethyl ether)-N,N,N',N'-tetraacetic acid, and 1,10-phenanthroline. The Km and Vmax values of the purified enzyme for laminarin were 3.07 mg/ml and 4.02 mg/min ml, respectively. Both matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectroscopy and DNA sequencing identified a peptide YIEAQLDAFEKR which is the conserved motif of the beta-1,3-glucanases from other yeasts.