Production of an invertebrate lysozyme of Scylla paramamosain in E.coli and evaluation of its antibacterial, antioxidant and anti-inflammatory effects

Expression of BSN314 lysozyme genes in Escherichia coli BL21: a study to demonstrate microbicidal and disintegarting potential of the cloned lysozyme

This study is an extension of our previous studies in which the lysozyme was isolated and purified from Bacillus subtilis BSN314 (Naveed et al., 2022; Naveed et al., 2023). In this study, the lysozyme genes were cloned into the E. coli BL21. For the expression of lysozyme in E. coli BL21, two target genes, Lyz-1 and Lyz-2, were ligated into the modified vector pET28a to generate pET28a-Lyz1 and pET28a-Lyz2, respectively. To increase the production rate of the enzyme, 0.5-mM concentration of IPTG was added to the culture media and incubated at 37 °C and 220 rpm for 24 h. Lyz1 was identified as N-acetylmuramoyl-L-alanine amidase and Lyz2 as D-alanyl-D-alanine carboxypeptidase. They were purified by multi-step methodology (ammonium sulfate, precipitation, dialysis, and ultrafiltration), and antimicrobial activity was determined. For Lyz1, the lowest MIC/MBC (0.25 μg/mL; with highest ZOI = 22 mm) were recorded against Micrococcus luteus, whereas the highest MIC/MBC with lowest ZOI were measured against Salmonella typhimurium (2.50 μg /mL; with ZOI = 10 mm). As compared with Aspergillus oryzae (MIC/MFC; 3.00 μg/mL), a higher concentration of lysozyme was required to control the growth of Saccharomyces cerevisiae (MIC/MFC; 50 μg/mL). Atomic force microscopy (AFM) was used to analyze the disintegrating effect of Lyz1 on the cells of selected Gram-positive bacteria, Gram-negative bacteria, and yeast. The AFM results showed that, as compared to Gram-negative bacteria, a lower concentration of lysozyme (Lyz1) was required to disintegrate the cell of Gram-positive bacteria.

Probiotics and biofilm interaction in aquaculture for sustainable food security: A review and bibliometric analysis

Aquaculture is one of the most significant food sources from the prehistoric period. As aquaculture intensifies globally, the prevalence and outbreaks of various pathogenic microorganisms cause fish disease and heavy mortality, leading to a drastic reduction in yield and substantial economic loss. With the modernization of the aquaculture system, a new challenge regarding biofilms or bacterial microenvironments arises worldwide, which facilitates pathogenic microorganisms to survive under unfavorable environmental conditions and withstand various treatments, especially antibiotics and other chemical disinfectants. However, we focus on the mechanistic association between those microbes which mainly form biofilm and probiotics in one of the major food production systems, aquaculture. In recent years, probiotics and their derivatives have attracted much attention in the fisheries sector to combat the survival strategy of pathogenic bacteria. Apart from this, Bibliometric analysis provides a comprehensive overview of the published literature, highlighting key research themes, emerging topics, and areas that require further investigation. This information is valuable for researchers, policymakers, and stakeholders in determining research priorities and allocating resources effectively.

Stabilization of Labile Lysozyme-Ligand Interactions in Native Electrospray Ionization Mass Spectrometry

Flavonoids are polyphenolic secondary metabolites with extensive biological activities and pharmacological effects. Exploring the interactions of flavonoids with proteins may be helpful for understanding their biological processes. Electrospray ionization mass spectrometry (ESI-MS) is a powerful tool to characterize the noncovalent protein-ligand (PL) complexes. However, some protein-flavonoid complexes are labile during electrospray ionization. Here, the labile lysozyme-flavonoid (rutin, icariin, and naringin) complexes were determined by direct ESI-MS without derivation. It has been found that low amounts of N-methylpyrrolidinone and dimethylformamide can protect labile lysozyme-flavonoid complexes away from dissociation during electrospray ionization process. The intact lysozyme-flavonoid complexes were specifically observed in mass spectra, and the measured binding affinities by ESI-MS were matched with the fluorescence data. The effects of additives on the analysis of lysozyme-flavonoid complexes were investigated by ESI-MS, combined with the molecular docking and fluorescence. This strategy was helpful to investigate the labile PL interactions by direct ESI-MS.

Chemical Structures and Pharmacological Properties of Typical Bioflavonoids in Polygonati Rhizoma (PGR)

Most medicines are coming with toxic and detrimental side effects. In addition, microbials are resisting the medicine. Therefore, alternative drugs with low toxic and side effects and low microbial resistance are needed. Plants offer good potential candidates due to a broad range of chemicals they contain. These chemicals have been studied, and research is still going on to probe chemical properties of plant chemicals. In China, traditional Chinese medicine is practised, whereby plant extracts are obtained, and then sold in packages for reasons like memory enhancement, cancer treatment, boosting immune system, and so on. Among the herbs cultivated in China is Polygonati rhizoma (PGR). This plant contains various bioflavonoids such as diosgenin, kaempferol, catechin, daidzein, and 3'-methoxydaidzein. In this review, we discussed the pharmacological effects of these chemicals, including luteolin antimicrobial activity in a manner that it circumvents antibiotic resistance; rutin antivenom property; kaempferol as an agent that mitigates neuropathic pain; genistein anticancer property; isorhamnetin's ability to alleviate chronic obstructive pulmonary diseases (COPD); proanthocyanidins' ability to deal with diabetic neuropathy and analgesic property of catechin.

The In Vitro Antimicrobial and Antibiofilm Activities of Lysozyme against Gram-Positive Bacteria

Objective

To analyze the in vitro antibacterial and antibiofilm activities of lysozyme (LYS) and its combination with various drugs against Gram-positive bacteria (GPB, n = 9), thus to provide an exploration direction for drug development.

Methods

The minimum inhibitory concentrations (MICs) of linezolid (LZD), amikacin (AMK), ceftriaxone/sulbactam (CRO/SBT), cefotaxime/sulbactam (CTX/SBT), piperacillin/sulbactam (PIP/SBT), doxycycline (DOX), levofloxacin (LVX), amoxicillin/clavulanate potassium (7 : 1, AK71), imipenem (IPM), azithromycin (AZM), and their combinations with LYS were determined with tuber twice dilution. The antimicrobial and antibiofilm activities of LYS, AZM, LVX, and their combinations with others were evaluated through MTT and crystal violet assay.

Results

High-dose LYS (30 μg/mL) combined with PIP/SBT and AK71, respectively, showed synergistic antibacterial activities against methicillin-resistant Staphylococcus aureus (MRSA), while it showed no synergistic activities when combined with other drugs. LYS and AZM inhibited the biofilm formation of one MRSA strain, but they and LVX had no similar activities against methicillin-resistant Staphylococcus epidermidis (MRSE) or vancomycin-resistant Enterococcus faecium (VREF). Particularly, LYS increased the permeability of biofilms of MRSA 33 and exhibited antibiofilm activities against MRSA 31 (inhibition rate = 38.1%) and MRSE 61 (inhibition rate = 46.6%). The combinations of PIP/SBT+LYS, AMK+LYS, and LZD+LYS showed stronger antibiofilm activities against MRSA 62, MRSE 62, MRSE 63, and VREF 11.

Conclusion

The antimicrobial and antibiofilm activities of LYS against MRSA were better than AZM, while that of LYS against MRSE and VREF, respectively, was similar with AZM and LVX.

Recombinant human β-defensin130 inhibited the growth of foodborne bacteria through membrane disruption and exerted anti-inflammatory activity

Foodborne pathogens causing food poisoning and infections are detrimental to human health, and the abuse of antibiotics induced severe antibiotic resistance in past decades. Thus, it is urgent to develop new antimicrobial agents. In the current study, human β-defensin 130 (hBD130), which is an antimicrobial peptide identified in human macrophages in 2017, was initially produced in Pichia pastoris. The purified hBD130 demonstrated broad bactericidal spectrum against foodborne pathogens through a membrane disruption, with concentrations ranging from 10 to 45 μg/mL. Moreover, hBD130 showed a low hemolytic effect and nearly no cytotoxicity to mammalian cells with a dosage of 400 μg/mL. In addition, the secretion amounts and mRNA levels of NO, IL-6, IL-1β, and TNF-α in LPS-induced mouse macrophage were significantly decreased with 1 mg/mL of hBD130. Taken together, these results showed that hBD130 is a promising antimicrobial agent to treat foodborne bacterial infections and inflammation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-022-01087-y.

Antibacterial activity of antimicrobial peptide gcDefb1 against foodborne pathogenic bacteria and its application in pork storage

Pork and its products are preferably contaminated by bacteria; thus, it is essential to develop low-cost, high-efficiency and biologically safe preservatives to prevent the growth of bacteria during storage. In the current study, grass carp β-defensin 1 (gcDefb1) was produced and purified from Pichia pastoris through the heterologous expression method. The in vitro antimicrobial assay demonstrated that yeast-derived gcDefb1 possesses a broad antibacterial spectrum, including both Gram-positive and -negative bacteria, and the MIC values against Escherichia coli ATCC 25,922 were as low as 30 μg/mL and showed no cytotoxicity or hemolytic activity. The bactericidal rate of gcDefb1 was less than 60 min by disrupting the cell membranes, and it inhibited the formation of bacterial biofilms. Moreover, gcDefb1 was used as a biopreservative for pork storage, indicating that the physicochemical and sensory qualities were improved. This study provides an efficient method to prepare and utilize gcDefb1 as a novel biopreservative.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-022-01060-9.

Antimicrobial property of Pichia pastoris-derived natto peptide against foodborne bacteria and its preservative potential to maintain pork quality during refrigerated storage

Pork spoilage caused by foodborne bacteria contamination always leads to substantial economic loss in the meat industry. The toxicity and drug resistance of chemical preservatives have raised public concerns about their safety and stability. In this study, natto peptide from Pichia pastoris was prepared using DNA recombinant technology. It showed an excellent antibacterial effect against Gram-positive and -negative bacteria, with minimum inhibitory concentrations (MICs) ranging from 6 to 30 μg/ml. Of note, natto peptide exhibited low cytotoxicity and hemolytic activity. The application of natto peptide on pork during refrigerated storage dramatically decreased the growth of Staphylococcus spp., Escherichia spp., and Pseudomonas spp. The bactericidal properties remained in force when natto peptide was used in pork models contaminated with artificial bacteria. Moreover, the application of natto peptide (90 μg/ml) inhibited the increase in pH variation and drip loss, decreased the generation of total volatile basic nitrogen (TVB-N) and thiobarbituric acid reactive substances (TBARS), and maintained a high sensory quality score during pork storage. These results implied that P. pastoris-derived natto peptide could extend the storage time of pork, and it has the potential to be a promising antiseptic biopreservative to replace chemical preservatives.

Ecological Risks Due to Immunotoxicological Effects on Aquatic Organisms

The immunotoxic effects of some anthropogenic pollutants on aquatic organisms are among the causes of concern over the presence of these pollutants in the marine environment. The immune system is part of an organism's biological defense necessarily for homeostasis. Thus, the immunotoxicological impacts on aquatic organisms are important to understand the effects of pollutant chemicals in the aquatic ecosystem. When aquatic organisms are exposed to pollutant chemicals with immunotoxicity, it results in poor health. In addition, aquatic organisms are exposed to pathogenic bacteria, viruses, parasites, and fungi. Exposure to pollutant chemicals has reportedly caused aquatic organisms to show various immunotoxic symptoms such as histological changes of lymphoid tissue, changes of immune functionality and the distribution of immune cells, and changes in the resistance of organisms to infection by pathogens. Alterations of immune systems by contaminants can therefore lead to the deaths of individual organisms, increase the general risk of infections by pathogens, and probably decrease the populations of some species. This review introduced the immunotoxicological impact of pollutant chemicals in aquatic organisms, including invertebrates, fish, amphibians, and marine mammals; described typical biomarkers used in aquatic immunotoxicological studies; and then, discussed the current issues on ecological risk assessment and how to address ecological risk assessment through immunotoxicology. Moreover, the usefulness of the population growth rate to estimate the immunotoxicological impact of pollution chemicals was proposed.