Analysis of Carotenoids in Haloarchaea Species from Atacama Saline Lakes by High Resolution UHPLC-Q-Orbitrap-Mass Spectrometry: Antioxidant Potential and Biological Effect on Cell Viability

Microbial bacterioruberin: The new C50 carotenoid player in food industries

The demand for natural products has significantly increased, driving interest in carotenoids as bioactive compounds for both human and animal consumption. Carotenoids, natural pigments with several biological properties, like antioxidant and antimicrobial, are increasingly preferred over synthetic colorants by the consumers (chemophobia). The global carotenoid market is projected to reach US$ 2.45 billion by 2034, driven by consumer preferences for natural ingredients and regulatory restrictions on synthetic products. Among carotenoids, bacterioruberin (BR), a C50 carotenoid naturally found in microbial hyperhalophilic archaea and in moderate halophilic archaea, stands out for its exceptional antioxidant capabilities, surpassing even well-known carotenoids like astaxanthin. BR's and its derivatives unique structure, with 13 conjugated double bonds and four -OH groups, contributes to its potent antioxidant activity and potential applications in food, feed, supplements, pharmaceuticals, and cosmeceuticals. This review explores BR's chemical and biological properties, upstream and downstream technologies, analytical techniques, market applications, and prospects in the colorants industry. While BR is not intended to replace existing carotenoids, its inclusion enriches the range of natural products available to meet the rising demand for natural alternatives. Furthermore, BR's promising antioxidant capacity positions it as a key player in the future carotenoid market, offering diverse industries a natural and potent alternative for several applications.

Exploring traditional and modern approaches for extracting bioactive compounds from Ferulago trachycarpa

For more than two millennia, Ferulago species have been revered as therapeutic herbs, maintaining their significance in present-day folk medicine practices. Therefore, the present study was conducted to investigate the phytochemical composition, inhibitory effects on metabolic enzymes, and possible therapeutic applications of F. trachycarpa, specifically focusing on its efficacy in diabetes management, anticholinergic effects, and antioxidant capabilities. The current investigation comprised an evaluation of a range of extracts acquired via conventional and modern methodologies, such as soxhlet (SOX), maceration (MAC) accelerated solvent extraction (ASE), homogenizer-assisted extraction (HAE), supercritical fluid extraction (SFE), microwave-assisted extraction (MW), and ultrasound-assisted extraction (UAE). Various techniques were employed to assess their antioxidant capacity and enzyme inhibition. Furthermore, the research utilized ultra-high performance liquid chromatography-MS/MS (UHPLC-MS/MS) to ascertain the principal phenolic compounds that are responsible for the antioxidant capacity observed in the various F. trachycarpa extracts. Among these, extracts from HAE, ASE, and MW revealed the most promise across all methodologies tested for their antioxidant potential. Furthermore, SFE and MAC extracts inhibited the most enzymes, including cholinesterases, tyrosinase, α -amylase, and α -glycosidase, indicating their potential as efficient natural treatments for several health-related issues.

Extreme halophilic Archaea: Halobacterium salinarum carotenoids characterization and antioxidant properties

Important marine microorganisms are resources of renewable energy that may face global population growth and needs. The application of biomass metabolites, such as carotenoids and their derivatives, may solve some agro-food health problems. Herein, a new halophilic Archaea Halobacterium salinarum producing carotenoid was screened from a Tunisian solar Saltworks (Sfax). The identification of the carotenoid pigments was carried out using HPLC-MS/MS. The predominant pigments produced by this Halobacterium were bacterioruberin and its derivatives and the carotenoids production was found to be of 21.51 mg/mL. Moreover, the data revealed that the carotenoids extract exhibited a high antioxidant activity across four oxidizing assays. The present results suggested that carotenoids extracted from halophilic Archaea are interesting sources of natural antioxidants for future innovative applications in agro-food, cosmetic and health fields.

Bacterioruberin extract from Haloarchaea Haloferax marinum: Component identification, antioxidant activity and anti-atrophy effect in LPS-treated C2C12 myotubes

Carotenoids are natural pigments utilized as colourants and antioxidants across food, pharmaceutical and cosmetic industries. They exist in carbon chain lengths of C30, C40, C45 and C50, with C40 variants being the most common. Bacterioruberin (BR) and its derivatives are part of the less common C50 carotenoid group, synthesized primarily by halophilic archaea. This study analysed the compositional characteristics of BR extract (BRE) isolated from 'Haloferax marinum' MBLA0078, a halophilic archaeon isolated from seawater near Yeoungheungdo Island in the Republic of Korea, and investigated its antioxidant activity and protective effect on lipopolysaccharide (LPS)-induced C2C12 myotube atrophy. The main components of BRE included all-trans-BR, monoanhydrobacterioruberin, 2-isopentenyl-3,4-dehydrorhodopin and all-trans-bisanhydrobacterioruberin. BRE exhibited higher antioxidant activity and DNA nicking protection activity than other well-known C40 carotenoids, such as β-carotene, lycopene and astaxanthin. In C2C12 myotubes, LPS treatment led to a reduction in myotube diameter and number, as well as the hypertranscription of the muscle-specific ubiquitin ligase MAFbx and MuRF1. BRE mitigated these changes by activating the Akt/mTOR pathway. Furthermore, BRE abolished the elevated cellular reactive oxygen species levels and the inflammation response induced by LPS. This study demonstrated that 'Hfx. marinum' is an excellent source of natural microbial C50 carotenoids with strong antioxidant capacity and may offer potential protective effects against muscle atrophy.

Metabolic profiling and enzyme inhibitory activity of the essential oil of citrus aurantium fruit peel

BACKGROUND

Bitter orange (Citrus aurantium) is a fruiting shrub native to tropical and subtropical countries around the world and cultivated in many regions due to its nutraceutical value. The current study investigated the metabolic profiling and enzyme inhibitory activities of volatile constituents derived from the C. aurantium peel cultivated in Egypt by three different extraction methods.

METHODS

The volatile chemical constituents of the peel of C. aurantium were isolated using three methods; steam distillation (SD), hydrodistillation (HD), and microwave-assisted hydrodistillation (MAHD), and then were investigated by GC-MS. The antioxidant potential was evaluated by different assays such as DPPH, ABTS, FRAP, CUPRAC, and phosphomolybdenum and metal chelating potential. Moreover, the effect of enzyme inhibition of the three essential oils was tested using BChE, AChE, tyrosinase, glucosidase, as well as amylase assays.

RESULTS

A total of six compounds were detected by GC/MS analysis. The major constituent obtained by all three extraction methods was limonene (98.86% by SD, 98.68% by HD, and 99.23% by MAHD). Differences in the composition of the compounds of the three oils were observed. The hydrodistillation technique has yielded the highest number of compounds, notably two oxygenated monoterpenes: linalool (0.12%) and α-terpineol acetate (0.1%).

CONCLUSION

In our study differences in the extraction methods of C. aurantium peel oils resulted in differences in the oils' chemical composition. Citrus essential oils and their components showed potential antioxidant, anticholinesterase, antimelanogenesis, and antidiabetic activities. The presence of linalool and α-terpineol acetate may explain the superior activity observed for the oil isolated by HD in both radical scavenging and AChE inhibition assays, as well as in the enzyme inhibition assays.

Optimization of bacterioruberin production from Halorubrum ruber and assessment of its antioxidant potential

Haloarchaea produce bacterioruberin, a major C50 carotenoid with antioxidant properties that allow for its potential application in the food, cosmetic, and pharmaceutical industries. This study aimed to optimize culture conditions for total carotenoid, predominantly comprising bacterioruberin, production using Halorubrum ruber MBLA0099. A one-factor-at-a-time and statistically-based experimental design were applied to optimize the culture conditions. Culture in the optimized medium caused an increase in total carotenoid production from 0.496 to 1.966 mg L- 1 Maximal carotenoid productivity was achieved in a 7-L laboratory-scale fermentation and represented a 6.05-fold increase (0.492 mg L-1 d-1). The carotenoid extracts from strain MBLA0099 exhibited a 1.8-10.3-fold higher antioxidant activity in vitro, and allowed for a higher survival rate of Caenorhabditis elegans under oxidative stress conditions. These results demonstrated that Hrr. ruber MBLA0099 has significant potential as a haloarchaon for the commercial production of bacterioruberin.

Some novel bioactivities of Virgibacillus halodenitrificans carotenoids, isolated from Wadi El-Natrun lakes

Carotenoids come in second among the most frequent natural pigments and are utilized in medications, nutraceuticals, cosmetics, food pigments, and feed supplements. Based on recent complementary work, Virgibacillus was announced for the first time as a member of Wadi El-Natrun salt and soda lakes microbiota, identified as Virgibacillus halodenitrificans, and named V. halodenitrificans DASH; hence, this work aimed to investigate several in vitro medicinal bioactivities of V. halodenitrificans DASH carotenoids. The carotenoid methanolic extract showed antioxidant activity based on diphenylpicrylhydrazyl (DPPH) scavenging capacity with a half-maximal concentration (IC50) of 1.6 mg/mL as well as nitric oxide (NO) scavenging action expressed by an IC50 of 46.4 µg/mL. The extract showed considerable inhibitory activity for alpha-amylase (α-amylase) and alpha-glucosidase (α-glucosidase) enzymes (IC50 of 100 and 173.4 μg/mL, respectively). Moreover, the extract displayed selective anticancer activity against Caco-2 (IC50 = 138.96 µg/mL) and HepG-2 cell lines (IC50 = 31.25 µg/mL), representing colorectal adenocarcinoma and hepatoblastoma. Likewise, the extract showed 98.9 % clearance for human hepatitis C virus (HCV) using reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR), HCV-NS5B polymerase activity inhibition (IC50 = 27.4 µg/mL), and selective inhibitory activity against human coronavirus (HCoV 229E) using the plaque reduction assay (IC50 = 53.5 µg/mL). As far as we can tell, the anticancer, antiviral, and antidiabetic attributes of Virgibacillus carotenoids are, de novo, reported in this work which accordingly invokes further exploration of the other medicinal, biotechnological, and industrial applications of Virgibacillus and haloalkaliphilic bacteria carotenoids.

Antioxidant Capacity of Carotenoid Extracts from the Haloarchaeon Halorhabdus utahensis

Herein, we report on the production, characterization, and antioxidant power assessment of carotenoids from the haloarchaeon Halorhabdus utahensis. It was grown at 37 °C and 180 rpm agitation in halobacteria medium supplemented with glucose, fructose, and xylose, each at concentrations of 0.2%, 1%, and 2%, and the carotenoid yield and composition were investigated. The microorganism produced the carotenoids under all the conditions tested, and their amount followed the order glucose < xylose < fructose. The highest yield was achieved in 2% fructose growth medium with 550.60 ± 7.91 μg/g dry cell and 2428.15 ± 49.33 μg/L. Separation and identification of the carotenoids were performed by RP-HPLC and HPLC/APCI-ITMSn. Bacterioruberin was the main carotenoid detected and accounted for 60.6%, 56.4%, and 58.9% in 2% glucose, 1% xylose, and 2% fructose extracts, respectively. Several geometric isomers of bacterioruberin were distinguished, and representatives of monoanhydrobacterioruberin, and bisanhydrobacterioruberin were also detected. The assignment to cis-isomers was attempted through analysis of the UV/Vis spectra, intensity of cis peaks, and spectral fine structures. The extracts exhibited superoxide scavenging activity higher than butylhydroxytoluene, ascorbic acid, and Trolox, selected as antioxidant references. The anti-hyaluronidase capacity was investigated, and the 2% fructose extract showed the highest activity reaching 90% enzyme inhibition with 1.5 μg. The overall data confirm that Hrd. utahensis can be regarded as an interesting source of antioxidants that can find applications in the food and cosmetic sectors.

Identification, Antioxidant Capacity, and Matrix Metallopeptidase 9 (MMP-9) In Silico Inhibition of Haloarchaeal Carotenoids from Natronococcus sp. and Halorubrum tebenquichense

Natural pigments from haloarchaea are of great interest; bacterioruberin is the major pigment, it shows higher antioxidant power when compared with β-carotene. However, characterization of bacterioruberin and its isomers along with its antioxidant and the matrix metallopeptidase 9 (MMP-9) inhibition activities in extracts from Natronoccoccus sp. TC6 and Halorubrum tebenquichense SU10 was not previously described, being the aim of this work. The carotenoids profile was performed by UV-Vis spectrophotometry, thin-layer chromatography, nuclear magnetic resonance spectroscopy, and high-resolution mass spectrometry (UPLC-ESI-MS/MS). Antioxidant capacity was determined for DPPH, ABTS, and FRAP. In addition, MMP-9 inhibition was studied using docking simulations. The carotenoid profile of studied strains was composed of bacterioruberin, some derivatives like mono, bis, and tris anhydrobacterioruberin, and also some bacterioruberin cis isomers. The carotenoid pools showed antioxidant capacity for DPPH > ABTS > FRAP; Natronococcus sp. TC6 carotenoid pool was better for ABTS and DPPH, while Halorubrum tebenquichense SU10 carotenoid pool was better for FRAP. Additionally, docking and molecular dynamics suggest that bacterioruberin inhibits MMP-9 through hydrophobic interactions near the catalytic site. Bacterioruberin shows the higher binding energy of -8.3 (kcal/mol). The carotenoids profile of both strains was elucidated, their antioxidant activity and singular participation of each carotenoid on MMP-9 in silico inhibition were evaluated.

More Than Pigments: The Potential of Astaxanthin and Bacterioruberin-Based Nanomedicines

Carotenoids are natural products regulated by the food sector, currently used as feed dyes and as antioxidants in dietary supplements and composing functional foods for human consumption. Of the nearly one thousand carotenoids described to date, only retinoids, derived from beta carotene, have the status of a drug and are regulated by the pharmaceutical sector. In this review, we address a novel field: the transformation of xanthophylls, particularly the highly marketed astaxanthin and the practically unknown bacterioruberin, in therapeutic agents by altering their pharmacokinetics, biodistribution, and pharmacodynamics through their formulation as nanomedicines. The antioxidant activity of xanthophylls is mediated by routes different from those of the classical oral anti-inflammatory drugs such as corticosteroids and non-steroidal anti-inflammatory drugs (NSAIDs): remarkably, xanthophylls lack therapeutic activity but also lack toxicity. Formulated as nanomedicines, xanthophylls gain therapeutic activity by mechanisms other than increased bioavailability. Loaded into ad hoc tailored nanoparticles to protect their structure throughout storage and during gastrointestinal transit or skin penetration, xanthophylls can be targeted and delivered to selected inflamed cell groups, achieving a massive intracellular concentration after endocytosis of small doses of formulation. Most first reports showing the activities of oral and topical anti-inflammatory xanthophyll-based nanomedicines against chronic diseases such as inflammatory bowel disease, psoriasis, atopic dermatitis, and dry eye disease emerged between 2020 and 2023. Here we discuss in detail their preclinical performance, mostly targeted vesicular and polymeric nanoparticles, on cellular models and in vivo. The results, although preliminary, are auspicious enough to speculate upon their potential use for oral or topical administration in the treatment of chronic inflammatory diseases.

Microalgae, Seaweeds and Aquatic Bacteria, Archaea, and Yeasts: Sources of Carotenoids with Potential Antioxidant and Anti-Inflammatory Health-Promoting Actions in the Sustainability Era

Carotenoids are a large group of health-promoting compounds used in many industrial sectors, such as foods, feeds, pharmaceuticals, cosmetics, nutraceuticals, and colorants. Considering the global population growth and environmental challenges, it is essential to find new sustainable sources of carotenoids beyond those obtained from agriculture. This review focuses on the potential use of marine archaea, bacteria, algae, and yeast as biological factories of carotenoids. A wide variety of carotenoids, including novel ones, were identified in these organisms. The role of carotenoids in marine organisms and their potential health-promoting actions have also been discussed. Marine organisms have a great capacity to synthesize a wide variety of carotenoids, which can be obtained in a renewable manner without depleting natural resources. Thus, it is concluded that they represent a key sustainable source of carotenoids that could help Europe achieve its Green Deal and Recovery Plan. Additionally, the lack of standards, clinical studies, and toxicity analysis reduces the use of marine organisms as sources of traditional and novel carotenoids. Therefore, further research on the processing of marine organisms, the biosynthetic pathways, extraction procedures, and examination of their content is needed to increase carotenoid productivity, document their safety, and decrease costs for their industrial implementation.

Up-Regulation of the Nrf2/HO-1 Antioxidant Pathway in Macrophages by an Extract from a New Halophilic Archaea Isolated in Odiel Saltworks

The production of reactive oxygen species (ROS) plays an important role in the progression of many inflammatory diseases. The search for antioxidants with the ability for scavenging free radicals from the body cells that reduce oxidative damage is essential to prevent and treat these pathologies. Haloarchaea are extremely halophilic microorganisms that inhabit hypersaline environments, such as saltworks or salt lakes, where they have to tolerate high salinity, and elevated ultraviolet (UV) and infrared radiations. To cope with these extreme conditions, haloarchaea have developed singular mechanisms to maintain an osmotic balance with the medium, and are endowed with unique compounds, not found in other species, with bioactive properties that have not been fully explored. This study aims to assess the potential of haloarchaea as a new source of natural antioxidant and anti-inflammatory agents. A carotenoid-producing haloarchaea was isolated from Odiel Saltworks (OS) and identified on the basis of its 16S rRNA coding gene sequence as a new strain belonging to the genus Haloarcula. The Haloarcula sp. OS acetone extract (HAE) obtained from the biomass contained bacterioruberin and mainly C18 fatty acids, and showed potent antioxidant capacity using ABTS assay. This study further demonstrates, for the first time, that pretreatment with HAE of lipopolysaccharide (LPS)-stimulated macrophages results in a reduction in ROS production, a decrease in the pro-inflammatory cytokines TNF-α and IL-6 levels, and up-regulation of the factor Nrf2 and its target gene heme oxygenase-1 (HO-1), supporting the potential of the HAE as a therapeutic agent in the treatment of oxidative stress-related inflammatory diseases.

Haloarchaeal carotenoids exert an in vitro antiproliferative effect on human breast cancer cell lines

Oxidative stress has been linked to the onset and progression of different neoplasia. Antioxidants might help prevent it by modulating biochemical processes involved in cell proliferation. Here, the aim was to evaluate the in vitro cytotoxic effect of Haloferax mediterranei bacterioruberin-rich carotenoid extracts (BRCE) (0-100 µg/ml) in six BC cell lines, representative of the intrinsic phenotypes and a healthy mammary epithelium cell line. Cell index values were obtained using xCELLigence RTCA System. Furthermore, cell diameter, viability, and concentration were measured at 12 h, 24 h, and 30 h. We found that BC cells were selectively affected by BRCE (SI > 1, p < 0.005). After 30 h, the population of BC cells exposed to 100 µg/ml was 11.7-64.6% of the control (p = 0.0001-0.0009). Triple-negative cells were significantly affected [MDA-MB-231 (IC₅₀ 51.8 µg/ml, p < 0.0001) and MDA-MB-468 (IC₅₀ 63.9 µg/ml, p < 0.0001)]. Cell size was also reduced after 30 h treatment in 3.8 (± 0.1) µm and 3.3 (± 0.02) µm for SK-BR-3 (p < 0.0001) and MDA-MB-468 (p < 0.0001), respectively. In conclusion, Hfx. mediterranei BRCE exerts a cytotoxic effect on BC cell lines representative of all studied intrinsic subtypes. Furthermore, results obtained for MDA-MB-231 and MDA-MB-468 are very promising, considering the aggressive behaviour of the triple-negative BC subtype.

Natural Carotenoids: Recent Advances on Separation from Microbial Biomass and Methods of Analysis

Biotechnologically produced carotenoids occupy an important place in the scientific research. Owing to their role as natural pigments and their high antioxidant properties, microbial carotenoids have been proposed as alternatives to their synthetic counterparts. To this end, many studies are focusing on their efficient and sustainable production from renewable substrates. Besides the development of an efficient upstream process, their separation and purification as well as their analysis from the microbial biomass confers another important aspect. Currently, the use of organic solvents constitutes the main extraction process; however, environmental concerns along with potential toxicity towards human health necessitate the employment of "greener" techniques. Hence, many research groups are focusing on applying emerging technologies such as ultrasounds, microwaves, ionic liquids or eutectic solvents for the separation of carotenoids from microbial cells. This review aims to summarize the progress on both the biotechnological production of carotenoids and the methods for their effective extraction. In the framework of circular economy and sustainability, the focus is given on green recovery methods targeting high-value applications such as novel functional foods and pharmaceuticals. Finally, methods for carotenoids identification and quantification are also discussed in order to create a roadmap for successful carotenoids analysis.

Bioactive molecules from haloarchaea: Scope and prospects for industrial and therapeutic applications

Marine environments and salty inland ecosystems encompass various environmental conditions, such as extremes of temperature, salinity, pH, pressure, altitude, dry conditions, and nutrient scarcity. The extremely halophilic archaea (also called haloarchaea) are a group of microorganisms requiring high salt concentrations (2-6 M NaCl) for optimal growth. Haloarchaea have different metabolic adaptations to withstand these extreme conditions. Among the adaptations, several vesicles, granules, primary and secondary metabolites are produced that are highly significant in biotechnology, such as carotenoids, halocins, enzymes, and granules of polyhydroxyalkanoates (PHAs). Among halophilic enzymes, reductases play a significant role in the textile industry and the degradation of hydrocarbon compounds. Enzymes like dehydrogenases, glycosyl hydrolases, lipases, esterases, and proteases can also be used in several industrial procedures. More recently, several studies stated that carotenoids, gas vacuoles, and liposomes produced by haloarchaea have specific applications in medicine and pharmacy. Additionally, the production of biodegradable and biocompatible polymers by haloarchaea to store carbon makes them potent candidates to be used as cell factories in the industrial production of bioplastics. Furthermore, some haloarchaeal species can synthesize nanoparticles during heavy metal detoxification, thus shedding light on a new approach to producing nanoparticles on a large scale. Recent studies also highlight that exopolysaccharides from haloarchaea can bind the SARS-CoV-2 spike protein. This review explores the potential of haloarchaea in the industry and biotechnology as cellular factories to upscale the production of diverse bioactive compounds.

Carbon Source Influences Antioxidant, Antiglycemic, and Antilipidemic Activities of Haloferax mediterranei Carotenoid Extracts

Haloarchaeal carotenoids have attracted attention lately due to their potential antioxidant activity. This work studies the effect of different concentrations of carbon sources on cell growth and carotenoid production. Carotenoid extract composition was characterized by HPLC-MS. Antioxidant activity of carotenoid extracts obtained from cell cultures grown under different nutritional conditions was determined by 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH), Ferric Reducing Ability Power (FRAP) and β-carotene bleaching assays. The ability of these carotenoid extracts to inhibit α-glucosidase, α-amylase, and lipase enzymes was also assessed to determine if they could be used to reduce blood glucose and lipid absorption. The maximum production of carotenoids (92.2 µg/mL) was observed combining 12.5% inorganic salts and 2.5% of glucose/starch. Antioxidant, hypoglycemic, and antilipidemic studies showed that higher carbon availability in the culture media leads to changes in the extract composition, resulting in more active haloarchaeal carotenoid extracts. Carotenoid extracts obtained from high-carbon-availability cell cultures presented higher proportions of all-trans-bacterioruberin, 5-cis-bacterioruberin, and a double isomeric bacterioruberin, whereas the presence 9-cis-bacterioruberin and 13-cis-bacterioruberin decreased. The production of haloarchaeal carotenoids can be successfully optimized by changing nutritional conditions. Furthermore, carotenoid composition can be altered by modifying carbon source concentration. These natural compounds are very promising in food and nutraceutical industries.

Characterization and biological activities of carotenoids produced by three haloarchaeal strains isolated from Algerian salt lakes

Halophilic archaea represent a promising natural source of carotenoids. However, little information is available about these archaeal metabolites and their biological effects. In the present work, carotenoids of strains Haloferax sp. ME16, Halogeometricum sp. ME3 and Haloarcula sp. BT9, isolated from Algerian salt lakes, were produced, extracted and identified by high-performance liquid chromatography-diode array detector and liquid chromatography-mass spectrometry. Analytical results revealed a variation in the composition depending on the strain with a predominance of bacterioruberin. The evaluation of antioxidant capacity using ABTS [(2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] and DPPH (2,2-diphenyl-1-picrylhydrazyl) assays showed that these extracts have a strong antioxidant potential, in particular those of Haloferax sp. ME16 which displayed antioxidant power significantly higher than that of ascorbic acid used as standard. Antibacterial activity of carotenoid extracts against four human-pathogenic strains and four fish-pathogenic strains was evaluated by agar disk diffusion method. The results showed a good antibacterial activity. These findings suggest that the C₅₀ carotenoids from the studied strains offer promising prospects for biotechnological applications.