Bacterial Melanin Research Articles

Obtaining Melanin-Synthesizing Strains of Bacillus thuringiensis and their Use for Biological Preparations.

A pivotal objective in crop production and plant protection lies in developing environmentally friendly insecticidal preparations and biostimulants. We employed Bacillus thuringiensis strains with varied insecticidal spectra and engineered melanogenic mutants. We demonstrated a significant increase in insecticidal activity in the isolated mutants. Meanwhile, there was no observable impact of the enhanced synthesis of water-soluble melanin on the nature and abundance of spore and crystal formation. This heightened efficacy can be attributed to the photoprotective qualities of the synthesized pigment, shielding spores and crystals against the detrimental effects of UV radiation and insolation. We demonstrated the high biological activity of water-soluble bacterial melanin through in vivo experiments involving multiple plant species. Our findings indicate that bacterial melanin is a potent phytostimulant. This preparation accelerates and amplifies plant growth and development processes, leading to a substantial increase in crop yield by 20-40%. The simultaneous synthesis of two biologically active substance, melanin and insecticidal toxins, ensures an elevated level of effectiveness in utilizing melaninogenic strains.

Regulatory effect of bacterial melanin on the isoforms of new superoxide-producing associates from rat tissues in rotenone-induced Parkinson’s disease

According to recent research, selective neuronal vulnerability in Parkinson’s disease (PD) results from several phenotypic traits, including calcium-dependent, feed-forward control of mitochondrial respiration leading to elevated reactive oxygen species and cytosolic calcium concentration, an extensive axonal arbor, and a reactive neurotransmitter. Therefore, antioxidant therapy is a promising direction in the treatment of PD. In vitro studies have indicated the survival-promoting activity of bacterial melanin (BM) on midbrain dopaminergic neuron cultures. It has been established that BM has a number of protective and anti-inflammatory properties, so there is a high probability of a protective effect of BM in the early stages of PD. In this study, PD was induced through the unilateral intracerebral administration of rotenone followed by bacterial melanin. Tissues (brain, lungs, and small intestine) from the observed groups underwent isolation and purification to extract isoforms of new thermostable superoxide (О2−)-producing associates between NADPH-containing lipoprotein (NLP) and NADPH oxidase-Nox (NLP-Nox). The optical absorption spectral characteristics, specific amounts, stationary concentration of the produced О2−, and the content of NADPH in the observed associates were determined. The optical absorption spectra of the NLP-Nox isoforms in the visible and UV regions in the experimental groups did not differ from those of the control group. However, compared with the control group, the specific content of the total fractions of NLP-Nox isoforms associated with PD groups was higher, especially in the small intestine. These findings suggest that the described changes may represent a novel mechanism for rotenone-induced PD. Furthermore, bacterial melanin demonstrated antioxidant properties and regulated membrane formation in the brain, lung, and small intestine. This regulation occurred by inhibiting the release of new membrane-bound formations (NLP-Nox associates) from these membranes while simultaneously regulating the steady-state concentration of the formed О2−.

New developments in sunscreens.

Topical sunscreen application is one of the most important photoprotection tool to prevent sun damaging effects in human skin at the short and long term. Although its efficacy and cosmeticity have significantly improved in recent years, a better understanding of the biological and clinical effects of longer wavelength radiation, such as long ultraviolet A (UVA I) and blue light, has driven scientists and companies to search for effective and safe filters and substances to protect against these newly identified forms of radiation. New technologies have sought to imbue sunscreen with novel properties, such as the reduction of calorific radiation. Cutaneous penetration by sunscreens can also be reduced using hydrogels or nanocrystals that envelop the filters, or by binding filters to nanocarriers such as alginate microparticles, cyclodextrins, and methacrylate polymers. Finally, researchers have looked to nature as a source of healthier products, such as plant products (e.g., mycosporines, scytonemin, and various flavonoids) and even fungal and bacterial melanin, which could potentially be used as substitutes or enhancers of current filters.

Isolation and Elucidation of Bacterial Melanin's Sun Protection Factor (SPF) for Photoprotection in Cosmetics

The outline of our work delineates the isolation and evaluation of sun screening activity of melanin producers such as Pseudomonas mosselli STGRDS1, Pseudomonas putida STGRDS3, Bacillus amyloliquefaciens STGRDV11, Bacillus subtilis STGRDV5 and Bacillus cereus STGRDT12. All of the isolates were tested against the fungal melanin STGRDM1, which was used as control throughout the study. The Sun Protection Factor (SPF) of formulated creams containing 5% and 10% of melanin was determined with values ranging from 1.96 ± 0.008 to 26.33 ± 0.061; further, the transmission spectroscopy was used to calculate the percentage of protection factor that stipulates the potentiality of pigments showing sunscreen effect.

The effect of natural biostimulants on a productivity of different varieties of chickpea

The effect of biostimulants Agrimitin and Bacterial Melanin on winter variety Karin, spring varieties Anush and Leninakan 313 varieties of chickpea under the conditions of Armavir region of the Ararat valley, was studied. Pre-sowing treatment of seeds with biostimulants was carried out with Agrimitin 2.5 nmol. - 12 and Bacterial Melanin 0.035% - 24 hours’ exposures, respectively. The field experiments were carried out with three repetitions, in 25m2 test plots, with a sowing rate of 500 thousand seeds/ha. The results of the study show that biostimulants improved the structural elements and productivity indicators of the chickpea crop, which contributed to the increase in yield. In the Agrimitin-treated version of the Karin variety, biological and actual yield indicators exceeded the control by 6.9 and 4.8 t/ha. The Agrimitin preparation compare with Bacterial Melanin for all varieties displayed a highest result. Among the tested varieties, the winter variety Karin provided an unprecedentedly high seed yield.

Isolation, purification, and characterization of novel melanin from the submerged fermentation of Rhizobium radiobacter

In this study, a novel water-insoluble bacterial melanin was first isolated and purified from the fermentation culture of Gram-negative bacterial Rhizobium radiobacter ATCC 1333 through the thermal acid-alkali treatment. The highest extracellular melanin production was 3.46 ± 0.07 g·L−1 when the initial glutamic acid concentration was 10 g·L−1. The molecular weight of the purified bacterial melanin (TPBM) was 686 g/mol. The molecular formula (C34H30N4O12) and chemical structure were defined based on FT-IR, MALDI-TOF/MS, Py–GC/MS NMR (1H and 13C), and elemental analyses. Furthermore, UV–vis spectroscopy results indicated that TPBM showed maximum absorption at around 222 nm. TPBM was easily soluble in alkaline solutions, but hardly-soluble in aqueous and majority of the organic solvents. In addition, TPBM was stable to temperature, light, reducing agent, and most metal ions. However, TPBM could be bleached when subjected to the action of oxidants and precipitated with FeCl3 and AgNO3. TPBM (50 µg·mL−1) possessed high DPPH free radical (89.74% ± 1.10%) and hydroxyl scavenging properties (84.12% ± 1.31%). Finally, TPBM displayed potential anti-bacterial properties against E. coli, S. aureus, A. baumanii, and M. albican. These results provided a theoretical basis for the later development and utilization of TPBM.

Melanin biopolymer synthesis using a new melanogenic strain of Flavobacterium kingsejongi and a recombinant strain of Escherichia coli expressing 4-hydroxyphenylpyruvate dioxygenase from F. kingsejongi

BackgroundMelanins are a heterologous group of biopolymeric pigments synthesized by diverse prokaryotes and eukaryotes and are widely utilized as bioactive materials and functional polymers in the biotechnology industry. Here, we report the high-level melanin production using a new melanogenic Flavobacterium kingsejongi strain and a recombinant Escherichia coli overexpressing F. kingsejongi 4-hydroxyphenylpyruvate dioxygenase (HPPD).ResultsMelanin synthesis of F. kingsejongi strain was confirmed via melanin synthesis inhibition test, melanin solubility test, genome analysis, and structural analysis of purified melanin from both wild-type F. kingsejongi and recombinant E. coli expressing F. kingsejongi HPPD. The activity of F. kingsejongi HPPD was demonstrated via in vitro assays with 6 × His-tagged and native forms of HPPD. The specific activity of F. kingsejongi HPPD was 1.2 ± 0.03 μmol homogentisate/min/mg-protein. Bioreactor fermentation of F. kingsejongi produced a large amount of melanin with a titer of 6.07 ± 0.32 g/L, a conversion yield of 60% (0.6 ± 0.03 g melanin per gram tyrosine), and a productivity of 0.03 g/L·h, indicating its potential for industrial melanin production. Additionally, bioreactor fermentation of recombinant E. coli expressing F. kingsejongi HPPD produced melanin at a titer of 3.76 ± 0.30 g/L, a conversion yield of 38% (0.38 ± 0.03 g melanin per gram tyrosine), and a productivity of 0.04 g/L·h.ConclusionsBoth strains showed sufficiently high fermentation capability to indicate their potential as platform strains for large-scale bacterial melanin production. Furthermore, F. kingsejongi strain could serve as a model to elucidate the regulation of melanin biosynthesis pathway and its networks with other cellular pathways, and to understand the cellular responses of melanin-producing bacteria to environmental changes, including nutrient starvation and other stresses.

Protective effect of bacterial melanin in the substantia nigra in a rat model of Parkinson's disease

The major cause of Parkinson's disease is progressive disturbance of dopaminergic neurons of the substantia nigra, as well as their nerve endings located in the striatum. Therefore, therapy aimed at slowing the death of dopaminergic neurons can be effective. In recent decades, various types of neuroprotective agents have been successfully used in the treatment of neurodegenerative diseases, after which the restoration of structural disfunctions of the CNS is accelerated. In the present study, we used bacterial melanin, the therapeutic effect of which is due to the improvement of the trophic effects of the brain tissue, inhibition of the inflammatory process and gliosis. The comparative study of morphological and functional state of the substantia nigra pars compacta in a rotenone model of Parkinson's disease and combined with introduction of bacterial melanin was carried out. For morphological and histochemical study, the method of detecting the activity of Ca2 + - dependent acid phosphatase was used. The analysis of the data obtained showed that during rotenone intoxication, neuronal death and substantia nigra depigmentation are observed, as well as sharp morphological changes in intracellular structures occur, which indicates gross metabolic and morphological disorders. With the introduction of bacterial melanin, there is a tendency to preserve the normal morphological picture of the neurons of the substantia nigra pars compacta, in comparison with the Parkinson's disease model. Thus, bacterial melanin acts as a neuroprotective agent and has a supportive role in Parkinson's disease. 
 Keywords: bacterial melanin, Parkinson's Disease, substantia nigra

Influence of bacterial melanine on morphological indicators of seeds germination of high-decorative species of flora of Belarus

Aim. The purpose of the work is to study the effect of a biological product based on the melaninogenic strain of Bacillus thuringiensis on germination and morphological parameters of highly decorative species of the flora of Belarus, promising for landscaping in the urban environment. Methods. Seed germination in laboratory conditions used with soaking in solutions of bacterial melanin in concentrations of 0.04, 0.025, 0.01%. Water and Terrasil at a concentration of 0.01 was used for a comparative evaluation of the effectiveness. Results. Morphological parameters were estimated during germination of the seeds of Verbascum thapsus L., Verbascum nigrum L., Centaurea scabiosa L., Betonica officinalis L., Viscaria vulgaris Bernh. treated with various concentrations of the stimulant. Conclusions. The effect of the bacterial melanin on the morphological parameters of plants was species- and dospecific. The optimal concentration for use on the studied plants should include concentrations up to 0.025%. The most pronounced effect of the use of the drug was revealed in the first days of seed germination, which allows the use of bacterial melanin to increase the germination of seedlings.
 Keywords: bacterial melanin, stimulant, seed germination, highly decorative species of flora.

In-vitro Effects of Bacterial Melanin in Macrophage “RAW 264.7” Cell Culture

Biotechnologically obtained bacterial melanin (BM) has been extensively studied as a potential pharmacological preparation with neuroprotective and anti-inflammatory effects. Anti-inflammatory action of BM was tested in animal model of induced enceph

Bacterial melanin production by heterologous expression of 4‑hydroxyphenylpyruvate dioxygenase from Pseudomonas aeruginosa.

Pyomelanin is a reddish-brown pigment produced by bacteria of different genera and plays a variety of physiological roles. Proposals have been regarding the use of pyomelanin in various environmental, industrial and, more recently, cosmetic applications. In Pseudomonas aeruginosa, the enzyme 4‑hydroxyphenylpiruvate dioxygenase (Hpd) converts 4-hydroxyphenylpiruvate into homogentisic acid, which represents the key intermediate for melanin biosynthesis. This work aimed to obtain Escherichia coli cells overexpressing hpd gene from the PAO1 strain to produce large amounts of pyomelanin for biotechnological purposes. The recombinant dioxygenase expression gave E. coli JM109 the ability to produce pyomelanin. A series of biotransformations led us to choose the best experimental conditions for pyomelanin production. Cells were grown at the mid-exponential phase in a mineral medium with added glucose 10 mM as carbon and energy sources and casamino acid 0.2% w/v as an amino acid source. The administration of tyrosine 1 mM after 30 min of exposure to arabinose 1% w/v made it possible to purify 213 mg/L of pyomelanin after 6 days of biotransformation. In addition to the interesting biotechnological outcomes, the resulting expression system supports the correlation between the hpd gene from P. aeruginosa PAO1 and pyomelanin synthesis.

The Protective Effect of Conjugated Bacterial Melanin with Titanium Oxide against UV

Introduction: Some Azotobacter species can produce melanin. Melanin protects against UV. The purpose of this study was to isolate Azotobacter with the power of producing melanin and optimize its production and the effect of its combination with titanium oxide nanoparticles on the protection against ultraviolet light (UV). Materials & Methods: Overall, 200 soil samples from different parts of Qom, Iran, were cultured on Ashby's mannitol agar medium using Bio-test method. The effect of optimization of conditions such as pH, temperature, glucose source, amino acid sources, and aeration on the amount of melanin production was assessed. Afterwards, melanin was extracted, conjugated with titanium nanosilicate compound, and then the effect of each of the compounds on Escherichia coli was examined under the influence of UV based on time. Findings: Melanin-producing Azotobacter vinelandii species were isolated. The optimum pH was determined about 7.5. Glucose at different concentrations (1-6%) reduced the production of the product. Methionine amino acid had an inhibitory effect, while tyrosine amino acid increased the production rate. Tryptophan amino acid at 0.1-0.7% also increased the production rate, while cysteine and phenylalanine did not change the production rate. The combination of titanium oxide with melanin showed a significant protective effect against Escherichia coli bacterium under the influence of UV. Discussion & Conclusions: Native isolates of Azotobacter isolated from agricultural soil with the power of producing melanin can be used as a source for its use in the industry.

Development of technology for obtaining water-soluble bacterial melanin and determination of some of pigment properties

Development of technology for obtaining water-soluble bacterial melanin and determination of some of pigment properties

Characterization of Molecular Composition of Bacterial Melanin Isolated from Streptomyces glaucescens Using Ultra-High-Resolution FT-ICR Mass Spectrometry

Characterization of Molecular Composition of Bacterial Melanin Isolated from Streptomyces glaucescens Using Ultra-High-Resolution FT-ICR Mass Spectrometry

Comparative EPR studies of free radicals in melanin synthesized by Bacillus weihenstephanensis soil strains

EPR spectroscopy was used to examine the properties of and free radical concentrations in atypical water-soluble melanin-like pigments from Bacillus weihenstephanensis strains. The same EPR spectral shape was observed in bacterial melanins as in eumelanin. The EPR lines were homogeneously broadened. Continuous microwave saturation of the EPR lines indicated slow spin-lattice relaxation processes in the samples. Strong dipolar interactions characterized the tested melanin samples. Higher free radical concentrations were found in bacterial melanin than in synthetic melanin. The free radical concentrations in melanin from B. weihenstephanensis increased in the following order: strain JAS 81/4<JAS 83/3<JAS 86/1<JAS 39/1.

Sponge-Associated Bacteria Produce Non-cytotoxic Melanin Which Protects Animal Cells from Photo-Toxicity.

Melanin is a photo-protective polymer found in many organisms. Our research shows that the bacteria associated with darkly pigmented sponges (Haliclona pigmentifera, Sigmadocia pumila, Fasciospongia cavernosa, Spongia officinalis, and Callyspongia diffusa) secrete non-cytotoxic melanin, with antioxidant activity that protects animal cells from photo-toxicity. Out of 156 bacterial strains screened, 22 produced melanin and these melanin-producing bacteria (MPB) were identified as Vibrio spp., Providencia sp., Bacillus sp., Shewanella sp., Staphylococcus sp., Planococcus sp., Salinococcus sp., and Glutamicibacter sp. Maximum melanin production was exhibited by Vibrio alginolyticus Marine Microbial Reference Facility (MMRF) 534 (50mgml-1), followed by two isolates of Vibrio harveyi MMRF 535 (40mgml-1) and MMRF 546 (30mgml-1). Using pathway inhibition assay and FT-IR spectral analysis, we identified the melanin secreted into the culture medium of MPB as 1,8-dihydroxynaphthalene-melanin. The bacterial melanin was non-cytotoxic to mouse fibroblast L929 cells and brine shrimps up to a concentration of 200 and 500ppm, respectively. Bacterial melanin showed antioxidant activity at very low concentration (IC50-9.0ppm) and at 50ppm, melanin protected L929 cells from UV-induced intracellular reactive oxygen stress. Our study proposes sponge-associated bacteria as a potential source of non-cytotoxic melanin with antioxidant potentials.

Detection of Ca2+-dependent acid phosphatase activity identifies neuronal integrity in damaged rat central nervous system after application of bacterial melanin

The study aims to confirm the neuroregenerative effects of bacterial melanin (BM) on central nervous system injury using a special staining method based on the detection of Ca2+-dependent acid phosphatase activity. Twenty-four rats were randomly assigned to undergo either unilateral destruction of sensorimotor cortex (group I; n = 12) or unilateral rubrospinal tract transection at the cervical level (C3–4) (group II; n = 12). In each group, six rats were randomly selected after surgery to undergo intramuscular injection of BM solution (BM subgroup) and the remaining six rats were intramuscularly injected with saline (saline subgroup). Neurological testing confirmed that BM accelerated the recovery of motor function in rats from both BM and saline subgroups. Two months after surgery, Ca2+-dependent acid phosphatase activity detection in combination with Chilingarian’s calcium adenoside triphosphate method revealed that BM stimulated the sprouting of fibers and dilated the capillaries in the brain and spinal cord. These results suggest that BM can promote the recovery of motor function of rats with central nervous system injury; and detection of Ca2+-dependent acid phosphatase activity is a fast and easy method used to study the regeneration-promoting effects of BM on the injured central nervous system.

Effects of Bacterial Melanin on Neuronal Activity in the Rat Sensorimotor Cortex

We examined post-stimulation changes in the electrical activity of neurons of the rat sensorimotor cortex after intapraperitoneal injections or direct applications of bacterial melanin (a strict analog of neuromelanin). Activation of cortical neurons was evoked by high-frequency stimulation of the hindlimb peripheral nerves. The patterns of within-stimulation responses and long-lasting post-stimulation effects were rather similar in both subgroups (with systemic introductions or direct applications of melanin). Comparison of the results of previous electrophysiological experiments, where the effects of melanin on electrical activity generated by neurons of the substantia nigra pars compacta were studied, showed close similarities of the effects of this agent (mostly activating influence of bacterial melanin with the predominance of excitatory/facilitatory post-stimulation modifications of spike activity). The effects of bacterial melanin can contribute to the recovery processes in neurodegenerative diseases.

Bacterial melanin promotes recovery after sciatic nerve injury in rats.

Bacterial melanin, obtained from the mutant strain of Bacillus Thuringiensis, has been shown to promote recovery after central nervous system injury. It is hypothesized, in this study, that bacterial melanin can promote structural and functional recovery after peripheral nerve injury. Rats subjected to sciatic nerve transection were intramuscularly administered bacterial melanin. The sciatic nerve transected rats that did not receive intramuscular administration of bacterial melanin served as controls. Behavior tests showed that compared to control rats, the time taken for instrumental conditioned reflex recovery was significantly shorter and the ability to keep the balance on the rotating bar was significantly better in bacterial melanin-treated rats. Histomorphological tests showed that bacterial melanin promoted axon regeneration after sciatic nerve injury. These findings suggest that bacterial melanin exhibits neuroprotective effects on injured sciatic nerve, contributes to limb motor function recovery, and therefore can be used for rehabilitation treatment of peripheral nerve injury.

Bacterial Melanin as a Potential Targeted Therapy for the ParkinsonÂ’s Disease

Bacterial Melanin as a Potential Targeted Therapy for the ParkinsonÂ’s Disease