Bioproduction and optimization of newly characterized melanin pigment from Streptomyces djakartensis NSS-3 with its anticancer, antimicrobial, and radioprotective properties.

BACKGROUND: Melanin is a natural pigment that is considered a promising biomaterial for numerous biotechnological applications across several industries. Melanin has biomedical applications as antimicrobial, anticancer, and antioxidant properties. Additionally, in the pharmaceutical and cosmetic industries, it is used in drug delivery and as a radioprotective agent. Also, melanin has environmental uses in the fields of bioremediation and the food industry. The biosynthesis of melanin pigment is an area of interest for researchers due to its multifunctionality, high compatibility, and biodegradability. Therefore, our present work is the first attempt to characterize and optimize the productivity of melanin pigment from Streptomyces djakartensis NSS-3 concerning its radioprotection and biological properties. RESULTS: Forty isolates of soil actinobacteria were isolated from the Wadi Allaqui Biosphere Reserve, Egypt. Only one isolate, ACT3, produced a dark brown melanin pigment extracellularly. This isolate was identified according to phenotypic properties and molecular phylogenetic analysis as Streptomyces djakartensis NSS-3 with accession number OP912881. Plackett-Burman experimental design (PBD) and response surface methodology (RSM) using a Box-Behnken design (BBD) were performed for optimum medium and culturing conditions for maximum pigment production, resulting in a 4.19-fold improvement in melanin production (118.73 mg/10 mL). The extracted melanin pigment was purified and characterized as belonging to nitrogen-free pyomelanin based on ultraviolet-visible spectrophotometry (UV-VIS), Fourier transform infrared (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and NMR studies. Purified melanin demonstrated potent scavenging activity with IC50 values of 18.03 µg/mL and revealed high potency as sunscreens (in vitro SPF = 18.5). Moreover, it showed a nontoxic effect on a normal cell line (WI38), while it had a concentration-dependent anticancer effect on HCT116, HEPG, and MCF7 cell lines with IC50 = 108.9, 43.83, and 81.99 µg/mL, respectively. Also, purified melanin had a detrimental effect on the tested MDR bacterial strains, of which PA-09 and SA-04 were clearly more susceptible to melanin compared with other strains with MICs of 6.25 and 25 µg/mL, respectively. CONCLUSION: Our results demonstrated that the newly characterized pyomelanin from Streptomyces djakartensis NSS-3 has valuable biological properties due to its potential photoprotective, antioxidant, anticancer, antimicrobial, and lack of cytotoxic activities, which open up new prospects for using this natural melanin pigment in various biotechnological applications and avoiding chemical-based drugs.

Exploring the potential of 1,8-cineole from cardamom oil against food-borne pathogens: Antibacterial mechanisms and its application in meat preservation.

Food-borne pathogenic bacteria are a major public health concern globally. Traditional control methods using antibiotics have limitations, leading to the exploration of alternative strategies. Essential oils such as cardamom possess antimicrobial properties and have shown efficacy against food-borne pathogenic bacteria. The utilization of essential oils and their bioactive constituents in food preservation is a viable strategy to prolong the shelf-life of food products while ensuring their quality and safety. To the best of our knowledge, there are no studies that have utilized 1,8-cineole (the main active constituent of cardamom essential oil) as a preservative in meat, so this study might be the first to utilize 1,8-cineole as an antibacterial agent in meat preservation. The application of 1,8-cineole had a significant suppressive impact on the growth rate of Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Salmonella Typhimurium in meat samples stored for 7 days at 4 °C. Additionally, the surface color of the meat samples was not negatively impacted by the application of 1,8-cineole. The minimum inhibitory concentration was 12.5-25 mg/ml, and the minimum bactericidal concentration was 25-50.0 mg/ml. The bacterial cell membrane may be the target of cardamom, causing leakage of intracellular proteins, ATP, and DNA. The obtained data in this study may pave a new avenue for using 1,8-cineole as a new perspective for dealing with this problem of food-borne pathogens and food preservation, such as meat.

Unveiling the Potential of Algal Extracts as Promising Antibacterial and Antibiofilm Agents against Multidrug-Resistant Pseudomonas aeruginosa: In Vitro and In Silico Studies including Molecular Docking.

Multidrug-resistant Pseudomonas aeruginosa poses a global challenge due to its virulence and biofilm-forming ability, leading to persistent infections. This study had a dual focus: first, it aimed to investigate the biofilm activity and antibiotic resistance profiles of Pseudomonas aeruginosa isolates obtained from a fish-rearing farm. Second, it explored the potential of algal extracts as effective antibacterial and antibiofilm agents. The study analyzed 23 isolates of P. aeruginosa from the farm, assessing antibiotic resistance and biofilm formation. The antimicrobial and antibiofilm activities of two algal extracts, Arthrospira platensis (cyanobacteria) acetone extract (AAE) and Polysiphonia scopulorum (Rhodophyta) methanol extract (PME), were tested individually and combined (COE). The effects on biofilm-related gene expression were examined. AAE, PME, and COE were evaluated for antimicrobial and antibiofilm properties. Biofilm-related gene expression was measured and the extracts were analyzed for physicochemical properties and toxicity. Most P. aeruginosa isolates (86.9%) were antibiotic-resistant and formed biofilms. AAE, PME, and COE displayed promising antibacterial and antibiofilm effects, with COE being particularly effective. COE reduced a key biofilm-related gene expression. The fatty acid content (56% in AAE and 34% in PME) correlated with the effects. Specific compounds, such as phytol, bromophenol, and dihydroxy benzaldehyde, contributed to the activities. The extracts showed favorable characteristics and interactions with FabZ protein amino acids. This study suggests the potential of algal extracts as antibacterial and antibiofilm agents against drug-resistant infections. Further exploration in clinical applications is warranted.

Biodegradation of willow sawdust by novel cellulase-producing bacterial consortium from wood-feeding termites for enhancing methane production.

This study was designed to develop a cellulase-producing bacterial consortium (CBC) from wood-feeding termites that could effectively degrade willow sawdust (WSD) and consequently enhance methane production. The bacterial strains Shewanella sp. SSA-1557, Bacillus cereus SSA-1558, and Pseudomonas mosselii SSA-1568 exhibited significant cellulolytic activity. Their CBC consortium showed positive effects on cellulose bioconversion, resulting in accelerated WSD degradation. After nine days of pretreatment, the WSD had lost 63%, 50%, and 28% of its cellulose, hemicellulose, and lignin, respectively. The hydrolysis rate of treated WSD (352 mg/g) was much higher than that of untreated WSD (15.2 mg/g). The highest biogas production (66.1 NL/kg VS) with 66% methane was observed in the anaerobic digester M-2, which contained a combination of pretreated WSD and cattle dung in a 50/50 ratio. The findings will enrich knowledge for the development of cellulolytic bacterial consortia from termite guts for biological wood pretreatment in lignocellulosic anaerobic digestion biorefineries.

Effects of Silybum marianum L. Seed Extracts on Multi Drug Resistant (MDR) Bacteria.

Wound infections became a great challenge, especially after the emergence of bacterial resistance to commonly used antibiotics. Medicinal plants can be the source of alternative antibacterial agents effective against multi drug resistant (MDR) bacteria. This research aimed to evaluate the effectiveness of different Silybum marianum seed extracts in fighting MDR bacteria that infect wounds. First, thirty purified bacterial cultures obtained from superficial, infected wounds were subjected to antibiotic sensitivity tests. The selected MDR isolates were then used to test the antimicrobial effects of different S. marianum seed extracts. The most potent extract was evaluated for its impact on the ultrastructure of the cells of sensitive bacterial isolates using transmission electron microscopy (TEM). The bioactive ingredients of this extract were analyzed by means of gas chromatography-mass spectroscopy (GC-MS). Then, in-silico absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties were predicted for the main components. The results indicated that four out of 30 bacterial isolates were considered MDR bacteria. Primary morphological features of colonies, secondary (automatic) identification using the Biomerieux Vitek 2 System, and 16S rRNA sequencing of the four isolates confirmed that they represent Staphylococcus aureus, Stenotrophomonas maltophilia, Klebsiella pneumoniae, and Escherichia coli. Among different extracts of S. marianum seeds, ethanol extract showed the strongest inhibitory effect on both Gram-positive and Gram-negative bacteria, with minimum inhibitory concentration (MIC) values between 9.375 and 1.172 mg/mL. However, at concentrations four times higher, this extract was unable to kill bacterial cells, indicating that it had a bacteriostatic effect on the tested MDR strains. TEM revealed denaturation and distorted cell ultrastructure in S. aureus and S. maltophilia after exposure to ethanol extract. In addition, GC-MS analysis of the ethanol extract identified nine compounds known to have important biological activities, and ADMET analysis showed good drug-likeness for two of these compounds. Consequently, S. marianum seeds could be a good source of alternative bacteriostatic agents effective against MDR bacterial strains that cause wound infections.

Construction of a novel microbial consortium valued for the effective degradation and detoxification of creosote-treated sawdust along with enhanced methane production.

Lignocellulosic biomass represents an unlimited and ubiquitous energy source, which can effectively address current global challenges, including climate change, greenhouse gas emissions, and increased energy demand. However, lignocellulose recalcitrance hinders microbial degradation, especially in case of contaminated materials such as creosote (CRO)-treated wood, which necessitates appropriate processing in order to eliminate pollution. This study might be the first to explore a novel bacterial consortium SST-4, for decomposing birchwood sawdust, capable of concurrently degrading lignocellulose and CRO compounds. Afterwards, SST-4 which stands for molecularly identified bacterial strains Acinetobacter calcoaceticus BSW-11, Shewanella putrefaciens BSW-18, Bacillus cereus BSW-23, and Novosphingobium taihuense BSW-25 was evaluated in terms of biological sawdust pre-treatment, resulting in effective lignocellulose degradation and 100% removal of phenol and naphthalene. Subsequently, the maximum biogas production observed was 18.7 L/kg VS, while cumulative methane production was 162.8 L/kg VS, compared to 88.5 without microbial pre-treatment. The cumulative energy production from AD-I and AD-II through biomethanation was calculated as 3177.1 and 5843.6 KJ/kg, respectively. The pretreatment process exhibited a significant increase in the energy yield by 83.9%. Lastly, effective CRO detoxification was achieved with EC50 values exceeding 90%, showing the potential for an integrated process of effective contaminated wood management and bioenergy production.

Lycium shawii Roem. & Schult.: A new bioactive antimicrobial and antioxidant agent to combat multi-drug/pan-drug resistant pathogens of wound burn infections.

The Multidrug Drug Resistance (MDR) and Pan-Drug Resistance (PDR) remain an intractable challenge issue in public health, worldwide. Plant extracts-based biological macromolecules containing a diverse array of secondary metabolites could be potentially used as alternative approaches to control or limit MDR/PDR infections. Plants of the Solanaceae family exhibit a wide variety of secondary metabolites with antioxidant and antimicrobial properties, which render them a significant role in food and pharmaceutical applications. To our knowledge, this is the first report on phytochemical constituents, antioxidant, antimicrobial activities and in vivo toxicological safety of Lycium shawii leaf extracts. Results revealed that phenolics and flavonoids were found to be the most abundant compounds in all extracts. Antioxidant activity of extracts was measured using DPPH• and ABTS•+ assays and the methanol extract displayed superior scavenging activity (IC50 = 0.06 and 0.007 mg/mL for DPPH• and ABTS•+, respectively). Results of the GC-MS analysis revealed the identity of 10 compounds. Moreover, in vivo toxicological assessment can confirm the safety of L. shawii for use. Overall, L. shawii leaves are a promising natural source for the development of novel antimicrobial and antioxidant agents that could potentially combat clinical MDR/PDR pathogens.