Conversion of squid pen by Serratia ureilytica for the production of enzymes and antioxidants

Enzymes from Fishery and Aquaculture Waste: Research Trends in the Era of Artificial Intelligence and Circular Bio-Economy

In the era of the blue bio-economy, which promotes the sustainable utilization and exploitation of marine resources for economic growth and development, the fisheries and aquaculture industries still face huge sustainability issues. One of the major challenges of these industries is associated with the generation and management of wastes, which pose a serious threat to human health and the environment if not properly treated. In the best-case scenario, fishery and aquaculture waste is processed into low-value commodities such as fishmeal and fish oil. However, this renewable organic biomass contains a number of highly valuable bioproducts, including enzymes, bioactive peptides, as well as functional proteins and polysaccharides. Marine-derived enzymes are known to have unique physical, chemical and catalytic characteristics and are reported to be superior to those from plant and animal origins. Moreover, it has been established that enzymes from marine species possess cold-adapted properties, which makes them interesting from technological, economic and sustainability points of view. Therefore, this review centers around enzymes from fishery and aquaculture waste, with a special focus on proteases, lipases, carbohydrases, chitinases and transglutaminases. Additionally, the use of fishery and aquaculture waste as a substrate for the production of industrially relevant microbial enzymes is discussed. The application of emerging technologies (i.e., artificial intelligence and machine learning) in microbial enzyme production is also presented.

Efficient production of GlcNAc in an aqueous-organic system with a Chitinolyticbacter meiyuanensis SYBC-H1 mutant

OBJECTIVES

Shellfish waste is a primary source for making N-acetyl-D-glucosamine. Thus, establishing a high-efficiency and low-cost bioconversion method to produce N-acetyl-D-glucosamine directly from shellfish waste was promising.

RESULTS

A mutant C81 was obtained from Chitinolyticbacter meiyuanensis SYBC-H1 via ⁶⁰Co-γ irradiation. This mutant C81 showed the highest chitinase activity of 9.8 U/mL that was 85% higher than the parent strain. The mutant C81 exhibted improved antioxidant activities, including total antioxidant capacity, superoxide radical ability, and hydroxyl radical scavenging ability, compared to that of the parent strain. Four out of nine organic solvents increased the chitinase activity by 1.9%, 6.8%, 11.7%, and 15.8%, corresponding to methylbenzene, n-heptane, petroleum ether, and n-hexane, respectively. The biphase system composed of aqueous and hexane presented a five-fold reduction of cell viability compared to the control. Using a continuous fermentation bioconversion process, 4.2 g/L GlcNAc was produced from crayfish shell powder with a yield of 80% of the chitin content.

CONCLUSIONS

This study demonstrated that the mutant C81 is suitable for converting crayfish shell powder into GlcNAc in an aqueous-organic system.

Ramírez-González S, Sanzón-Gómez D. Nematicidal Activity of the Endophyte Serratia ureilytica against Nacobbus aberrans in Chili Plants (Capsicum annuum L.) and Identification of Genes Related to Biological Control

The genus Serratia is widely distributed in soil, water, plants, animals, invertebrates, and humans. Some species of this genus have antifungal, antibacterial, and nematicidal activity. In this work, the nematicidal activity of the endophytic strain of Serratia sp. in chili, Capsicum annuum L., is reported, where at a bacterial concentration of 4 × 109 cel/mL, the penetration of nematodes into the roots significantly decreased by 91 and 55% at 7 and 21 days after inoculation. This bacterial concentration also significantly decreased the number of galls, eggs, egg masses and reproduction factor produced by Nacobbus aberrans in Chili plants, with respect to the control where this bacterial strain was not applied. In the analysis of the genome of the strain, based on average nucleotide identity (ANI), the isolate could be affiliated to the species Serratia ureilytica. The size of the genome is 5.4 Mb, with a 59.3% content of GC. Genes related to the synthesis of chitinases, siderophores, proteases C, serralisins, hemolysin, and serrawettin W2 that have been reported for biocontrol of nematodes were identified in the genome. It is the first report of Serratia ureilytica with nematicidal activity. Based on these results of nematicidal activity, this strain can be evaluated in the field as an alternative in the biocontrol of Nacobbus aberrans in chili cultivation.

Management of Iron Overload in Resource Poor Nations: A Systematic Review of Phlebotomy and Natural Chelators

Iron is an essential element and the most abundant trace metal in the body involved in oxygen transport and oxygen sensing, electron transfer, energy metabolism, and DNA synthesis. Excess labile and unchelated iron can catalyze the formation of tissue-damaging radicals and induce oxidative stress. English abstracts were identified in PubMed and Google Scholar using multiple and various search terms based on defined inclusion and exclusion criteria. Full-length articles were selected for systematic review, and secondary and tertiary references were developed. Although bloodletting or phlebotomy remains the gold standard in the management of iron overload, this systematic review is an updated account of the pitfalls of phlebotomy and classical synthetic chelators with scientific justification for the use of natural iron chelators of dietary origin in resource-poor nations.

Conversion of Squid Pen to Homogentisic Acid via Paenibacillus sp. TKU036 and the Antioxidant and Anti-Inflammatory Activities of Homogentisic Acid

The culture supernatant of Paenibacillus sp. TKU036, a bacterium isolated from Taiwanese soils, showed high antioxidant activity (85%) when cultured in a squid pen powder (SPP)-containing medium at 37 °C for three days. Homogentisic acid (2,5-dihydroxyphenylacetic acid, HGA) was isolated and found to be the major antioxidant in the culture supernatant of the SPP-containing medium fermented by Paenibacillus sp. TKU036. Tryptophan was also present in the culture supernatant. The results of high-performance liquid chromatography (HPLC) fingerprinting showed that HGA and tryptophan were produced via fermentation but did not pre-exist in the unfermented SPP-containing medium. Neither HGA nor tryptophan was found in the culture supernatants obtained from the fermentation of nutrient broth or other chitinous material, i.e., medium containing shrimp head powder, by Paenibacillus sp. TKU036. The production of HGA via microorganisms has rarely been reported. In this study, we found that squid pen was a potential carbon and nitrogen source for Paenibacillus sp. Tryptophan (105 mg/L) and HGA (60 mg/L) were recovered from the culture supernatant. The isolated HGA was found to have higher antioxidant activity (IC50 = 6.9 μg/mL) than α-tocopherol (IC50 = 17.6 μg/mL). The anti-inflammatory activity of the isolated HGA (IC50 = 10.14 μg/mL) was lower than that of quercetin (IC50 = 1.14 μg/mL). As a result, squid pen, a fishery processing byproduct, is a valuable material for the production of tryptophan and the antioxidant and anti-inflammatory HGA via microbial conversion.

An Amphiprotic Novel Chitosanase from Bacillus mycoides and Its Application in the Production of Chitooligomers with Their Antioxidant and Anti-Inflammatory Evaluation

The objectives of this investigation were to produce a novel chitosanase for application in industries and waste treatment. The transformation of chitinous biowaste into valuable bioactive chitooligomers (COS) is one of the most exciting applications of chitosanase. An amphiprotic novel chitosanase from Bacillus mycoides TKU038 using squid pen powder (SPP)-containing medium was retrieved from a Taiwan soil sample, which was purified by column chromatography, and characterized by biochemical protocol. Extracellular chitosanase (CS038) was purified to 130-fold with a 35% yield, and its molecular mass was roughly 48 kDa. CS038 was stable over a wide range of pH values (4-10) at 50 °C and exhibited an optimal temperature of 50 °C. Interestingly, the optimum pH values were estimated as 6 and 10, whereas CS038 exhibited chitosan-degrading activity (100% and 94%, respectively). CS038 had Km and Vmax values of 0.098 mg/mL and 1.336 U/min, separately, using different concentrations of water-soluble chitosan. A combination of the high performance liquid chromatography (HPLC) and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometer data revealed that the chitosan oligosaccharides obtained from the hydrolysis of chitosan by CS038 comprise oligomers with multiple degrees of polymerization (DP), varying from 3-9, as well as CS038 in an endolytic fashion. The TKU038 culture supernatant and COS mixture exhibited 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activities. The COS activities were dose dependent and correlated to their DP. The COS with high DP exhibited enhanced DPPH radical scavenging capability compared with COS with low DP. Furthermore, the COS exhibited inhibitory behavior on nitric oxide (NO) production in murine RAW 264.7 macrophage cells, which was induced by Escherichia coli O111 lipopolysaccharide (LPS). The COS with low DP possesses a more potent anti-inflammatory capability to decrease NO production (IC50, 76.27 ± 1.49 µg/mL) than that of COS with high DP (IC50, 82.65 ± 1.18 µg/mL). Given its effectiveness in production and purification, acidophilic and alkalophilic properties, stability over ranges of pH values, ability to generate COS, antioxidant activity, and anti-inflammatory, CS038 has potential applications in SPP waste treatment and industries for COS production as a medical prebiotic.

Recent advances in exopolysaccharides from Paenibacillus spp.: production, isolation, structure, and bioactivities

This review provides a comprehensive summary of the most recent developments of various aspects (i.e., production, purification, structure, and bioactivity) of the exopolysaccharides (EPSs) from Paenibacillus spp. For the production, in particular, squid pen waste was first utilized successfully to produce a high yield of inexpensive EPSs from Paenibacillus sp. TKU023 and P. macerans TKU029. In addition, this technology for EPS production is prevailing because it is more environmentally friendly. The Paenibacillus spp. EPSs reported from various references constitute a structurally diverse class of biological macromolecules with different applications in the broad fields of pharmacy, cosmetics and bioremediation. The EPS produced by P. macerans TKU029 can increase in vivo skin hydration and may be a new source of natural moisturizers with potential value in cosmetics. However, the relationships between the structures and activities of these EPSs in many studies are not well established. The contents and data in this review will serve as useful references for further investigation, production, structure and application of Paenibacillus spp. EPSs in various fields.

Screening of microorganisms from deep-sea mud for Antarctic krill (Euphausia superba) fermentation and evaluation of the bioactive compounds

Twelve kinds of strains were isolated from deep-sea mud which can use Antarctic krill powder as the sole carbon/nitrogen source. These strains were identified by 16s rDNA sequence analysis and grouped into eight different genera, including Bacillus, Shewanella, Psychrobacter, Klebsiella, Macrococcus, Aeromonas, Acinetobacter, and Saccharomyces. After fermentation of Antarctic krill powder using these strains, bioactive compounds including total phenolics, free amino acids, and enzyme activities were investigated. Meanwhile, antioxidant activities of the fermentation liquors were also detected. Results showed that bioactive compounds could be effectively produced through fermentation process by these strains, of which three strains (Bacillus subtilis OKF04, Macrococcus caseolyticus OKF09, and Aeromonas veronii OKF10) could produce more than 650 mg/L total phenolics or 2000 mg/L total free amino acids. In terms of enzyme activities, almost all of the strains showed protease activity and amylase activity, but only Bacillus cereus OKF01 and Bacillus megaterium OKF05 performed lipase activity and chitinase activity, respectively. All of the fermentation liquors showed antioxidant activity, within which Bacillus megaterium OKF05, Macrococcus caseolyticus OKF09, and Aeromonas veronii OKF10 displayed it more prominently. These results demonstrate that the Antarctic krill powder could be effectively converted by microorganisms isolated from deep-sea mud for production of bioactive compounds mixture.

Fish processing wastes for microbial enzyme production: a review

Fishery processing industries generate large amounts of by-products. The disposal of these wastes represents an increasing environmental and health problem. To avoid wasting these by-products, various disposal methods have been applied including, ensilation, fermentation, hydrolysate and fish oil production. Interestingly, fish by-products provide an excellent nutrient source for microbial growth useful in enzyme production process, which is largely governed by the cost related to the growth media. Fish wastes (heads, viscera, chitinous material, wastewater, etc.) were prepared and tested as growth substrates for microbial enzymes production such as protease, lipase, chitinolytic and ligninolytic enzymes. This new approach described in this review can reduce environmental problems associated with waste disposal and, simultaneously, lower the cost of microbial enzyme production.

A novel compound with antioxidant activity produced by Serratia ureilytica TKU013

The secondary metabolites from the cultured supernatant of Serratia ureilytica TKU013 with squid pen as the sole carbon/nitrogen source were isolated and ascertained the mechanism of biological activity. The EtOAc layer, which has high DPPH scavenging activity, was applied to silica gel column chromatography with a gradient of CH(2)Cl(2)/MeOH solvent system, to yield A-H and MeOH fractions. The DPPH scavenging activity and cytotoxic activities against Doay and HEp-2 cell lines of these fractions were examined. The active fractions were further applied to purification by RP-HPLC, to obtain seven compounds, including a novel compound, serlyticin-A (1), together with six known compounds, serranticin (2), serratamolide A (3), thymine (4), (4-hydroxyphenyl)acetic acid (5), methyl p-hydroxybenzoate (6), and uracil (7). Their structures were determined by physical and extensive spectral analyses such as 1D and 2D NMR data, as well as comparison with literature values. Furthermore, the major secondary metabolites of EtOAc extract of the cultured supernatant were examined by the fingerprinting data of the HPLC system.

Biodegradation of shrimp processing bio-waste and concomitant production of chitinase enzyme and N-acetyl-D-glucosamine by marine bacteria: production and process optimization

A total of 250 chitinolytic bacteria from 68 different marine samples were screened employing enrichment method that utilized native chitin as the sole carbon source. After thorough screening, five bacteria were selected as potential cultures and identified as; Stenotrophomonas sp. (CFR221 M), Vibrio sp. (CFR173 M), Phyllobacteriaceae sp. (CFR16 M), Bacillus badius (CFR198 M) and Bacillus sp. (CFR188 M). All five strains produced extracellular chitinase and GlcNAc in SSF using shrimp bio-waste. Scanning electron microscopy confirmed the ability of these marine bacteria to adsorb onto solid shrimp bio-waste and to degrade chitin microfibers. HPLC analysis of the SSF extract also confirmed presence of 36-65 % GlcNAc as a product of the degradation. The concomitant production of chitinase and GlcNAc by all five strains under SSF using shrimp bio-waste as the solid substrate was optimized by 'one factor at a time' approach. Among the strains, Vibrio sp. CFR173 M produced significantly higher yields of chitinase (4.8 U/g initial dry substrate) and GlcNAc (4.7 μmol/g initial dry substrate) as compared to other cultures tested. A statistically designed experiment was applied to evaluate the interaction of variables in the biodegradation of shrimp bio-waste and concomitant production of chitinase and GlcNAc by Vibrio sp. CFR173 M. Statistical optimization resulted in a twofold increase of chitinase, and a 9.1 fold increase of GlcNAc production. These results indicated the potential of chitinolytic marine bacteria for the reclamation of shrimp bio-waste, as well as the potential for economic production of chitinase and GlcNAc employing SSF using shrimp bio-waste as an ideal substrate.

Isolation and identification of a novel antioxidant with antitumour activity from Serratia ureilytica using squid pen as fermentation substrate

The antioxidant activity of the culture supernatant of Serratia ureilytica TKU013 with squid pen as the sole carbon/nitrogen source was assessed by three methods, and the phenolic contents were assayed. The supernatant with the highest antioxidant activity was further purified by liquid-liquid partition, revealing the ethyl acetate extract exhibited the strongest antioxidant activity and the highest total phenolic content. Eight fractions were retrieved from silica gel column chromatography of this extract, designated F1-F8. F4 was found to possess the strong antioxidative activity and the highest total phenolic content and also exhibited strong cytotoxic activities against two different tumoural cell lines. A new compound (Serranticin) with antioxidant and antitumor activity was obtained from F4. The structure of Serranticin is analogous to that of siderophores (hexacoordinated catecholamine), which are iron chelators. As such, Serranticin has the potential for use as a deferration agent in various iron overload diseases.

A novel nonionic surfactant- and solvent-stable alkaline serine protease from Serratia sp. SYBC H with duckweed as nitrogen source: production, purification, characteristics and application

A novel nonionic surfactant- and hydrophilic solvent-stable alkaline serine protease was purified from the culture supernatant of Serratia sp. SYBC H with duckweed as nitrogen source. The molecular mass of the purified protease is about 59 kDa as assayed via SDS-PAGE. The protease is highly active over the pH range between 5.0 and 11.0, with the maximum activity at pH 8.0. It is also fairly active over the temperature range between 30 and 80°C, with the maximum activity at 40°C. The protease activity was substantially stimulated by Mn(2+) and Na(+) (5 mM), up to 837.9 and 134.5% at 40°C, respectively. In addition, Mn(2+) enhanced the thermostability of the protease significantly at 60°C. Over 90% of its initial activity remained even after incubating for 60 min at 40°C in 50% (v/v) hydrophilic organic solvents such as DMF, DMSO, acetone and MeOH. The protease retained 81.7, 83.6 and 76.2% of its initial activity in the presence of nonionic surfactants 20% (v/v) Tween 80, 25% (v/v) glycerol and Triton X-100, respectively. The protease is strongly inhibited by PMSF, suggesting that it is a serine protease. Washing experiments revealed that the protease has an excellent ability to remove blood stains.