Enhanced production of prodigiosin by Serratia marcescens FZSF02 in the form of pigment pellets

Prodigiosin: unveiling the crimson wonder - a comprehensive journey from diverse bioactivity to synthesis and yield enhancement

Prodigiosin (PG) is a red tripyrrole pigment from the prodiginine family that has attracted widespread attention due to its excellent biological activities, including anticancer, antibacterial and anti-algal activities. The synthesis and production of PG is of particular significance, as it has the potential to be utilized in a number of applications, including those pertaining to clinical drug development, food safety, and environmental management. This paper provides a systematic review of recent research on PG, covering aspects like chemical structure, bioactivity, biosynthesis, gene composition and regulation, and optimization of production conditions, with a particular focus on the biosynthesis and regulation of PG in Serratia marcescens. This provides a solid theoretical basis for the drug development and production of PG, and is expected to promote the further development of PG in medicine and other applications.

Improving Bioprocess Conditions for the Production of Prodigiosin Using a Marine Serratia rubidaea Strain

The enormous potential attributed to prodigiosin regarding its applicability as a natural pigment and pharmaceutical agent justifies the development of sound bioprocesses for its production. Using a Serratia rubidaea strain isolated from a shallow-water hydrothermal vent, optimization of the growth medium composition was carried out. After medium development, the bacterium temperature, light and oxygen needs were studied, as was growth inhibition by product concentration. The implemented changes led to a 13-fold increase in prodigiosin production in a shake flask, reaching 19.7 mg/L. The conditions allowing the highest bacterial cell growth and prodigiosin production were also tested with another marine strain: S. marcescens isolated from a tide rock pool was able to produce 15.8 mg/L of prodigiosin. The bioprocess with S. rubidaea was scaled up from 0.1 L shake flasks to 2 L bioreactors using the maintenance of the oxygen mass transfer coefficient (kLa) as the scale-up criterion. The implemented parameters in the bioreactor led to an 8-fold increase in product per biomass yield and to a final concentration of 293.1 mg/L of prodigiosin in 24 h.

Red bioactive pigment from Himalayan Janthinobacterium sp. ERMR3:09: optimization, characterization, and potential applications

Prodigiosin is a red pigment commonly produced as a secondary metabolite by Serratia marcescens. It exhibits inherent bioactivities, including antimicrobial and anticancer, with low to no toxic effects on normal cells. The present study investigates a bioactive prodigiosin production from an atypical, red-pigmented, potentially novel Janthinobacterium sp. ERMR3:09 isolated from a glacial moraine. Statistically optimized culture parameters, i.e., w/v 1.0% glucose and 0.08% peptone as carbon and nitrogen sources, temperature 20 °C, and media pH 7, resulted in a four-fold increase in the pigment yield. The upscaled production in an 8 L volume resulted in higher pigment production within a shorter period of 48 h. The ultra-performance liquid chromatography (UPLC) analysis validated the identity of the purified pigment as prodigiosin that showed thermostability at 75 °C for 3 h. Evaluation of antimicrobial activity showed potent inhibitory effects (> 50%) against the opportunistic pathogenic fungal and Gram-positive bacterial strains. The pigment showed significant cytotoxicity (p < 0.05) towards A549 and HeLa cell lines with IC50 values of 42.2 μM and 36.11 μM, respectively. The study demonstrated that microbial communities from extreme niches can be ideal sources of bioactive pigments with immense pharmaceutical potential vital for the development of non-synthetic therapeutic agents.

Growth Kinetics of Prodigiosin (Food Color) Produced by Novel Serratia marcescens bhu prodig Under Submerged Fermentation (SMF)

Prodigiosin is a promising food color due to its antibacterial, antimalarial, antimycotic characteristics, immunomodulating, and antitumor activities. Novel prodigiosin producing strain isolated from sugarcane field soil of Banaras Hindu University, India, characterized as Serratia marcescens bhu prodig by 16 sRNA. The effect of carbon, nitrogen source, and physical parameters (pH and temperature) on pigment yield was studied. The highest amount of pigment produced, which was 800.95 ± 0.05 mg/L, was detected when sorbitol and peptone were used as nitrogen and carbon source with pH 7 at 30 °C. The optimized condition scale-up in a bioreactor with a working capacity of 3.0 L, gave maximum pigment yield of 825 ± 0.05 mg/L with µ (Maximum specific growth rate), Yp/x, which represents the product yield coefficient, and Yp/s, which signifies the specific product yield coefficient and productivity of 0.3/h, 0.62, 0.80, and 0.02 g/L/h, respectively, after 72 h of cultivation in submerged fermentation (SMF). The isolated pigment was characterized as prodigiosin by the analysis of spectral data and GC-MS. The mass spectrophotometry investigation characterized pigment as 4-methoxy-5(5 methyl-4-pentyl-2H-pyrrol-2-ylidene)- 2,2-bipyrrole ring structure. The GC-MS chromatogram showed m/z of 323, representing prodigiosin. The prodigiosin yield and productivity obtained in the current finding were higher than in previous reports.

Transcriptome analysis reveals that yeast extract inhibits synthesis of prodigiosin by Serratia marcescens SDSPY-136

Prodigiosin (2-methyl-3-pentyl-6-methoxyprodiginine) is a valuable medicinal and edible natural pigment derived from Serratia marcescens. How prodigiosin synthesis is suppressed by environmental factors has not been investigated. Previous studies described a low level of prodigiosin production in the presence of yeast extracts. However, we have observed that S. marcescens SDSPY-136 did not synthesize prodigiosin in yeast extract culture. In this study, transcriptome sequencing of yeast extract cultures was used to estimate the metabolic control of the synthetic prodigiosin pathway in S. marcescens. Key phosphorylation enzymes in the glycolysis pathway, 6-phosphofructokinase, and glyceraldehyde 3-phosphate dehydrogenase, were downregulated by yeast extract and other carbon metabolism pathway genes were enhanced. Genes related to ribosomes, amino acid metabolism, and aminoacyl-tRNA biosynthesis were also highly up-regulated. The presence of metal ions in yeast extracts and the accumulation of fermentation metabolites alter the two-component signaling system, which regulated metabolism to various degrees. The results of metal ion testing suggested that prodigiosin inhibition could be caused by metal ions, such as zinc ion. The findings indicate that yeast extract may affect metabolism through multiple pathways in S. marcescens. This research sheds light on the mechanism of prodigiosin regulatory inhibition.

Isolation, Identification, and Antibacterial Properties of Prodigiosin, a Bioactive Product Produced by a New Serratia marcescens JSSCPM1 Strain: Exploring the Biosynthetic Gene Clusters of Serratia Species for Biological Applications

Prodigiosin pigment has high medicinal value, so exploring this compound is a top priority. This report presents a prodigiosin bioactive compound isolated from Serratia marcescens JSSCPM1, a new strain. The purification process of this compound involves the application of different chromatographic methods, including UV-visible spectroscopy, high-performance liquid chromatography (HPLC), and liquid chromatography-mass spectrometry (LC/MS). Subsequent analysis was performed using nuclear magnetic resonance (NMR) to achieve a deeper understanding of the compound's structure. Finally, through a comprehensive review of the existing literature, the structural composition of the isolated bioactive compound was found to correspond to that of the well-known compound prodigiosin. The isolated prodigiosin compound was screened for antibacterial activity against both Gram-positive and Gram-negative bacteria. The compound inhibited the growth of Gram-negative bacterial strains compared with Gram-positive bacterial strains. It showed a maximum minimum inhibitory concentration against Escherichia coli NCIM 2065 at a 15.9 ± 0.31 μg/mL concentration. The potential binding capabilities between prodigiosin and the OmpF porin proteins (4GCS, 4GCP, and 4GCQ) were determined using in silico studies, which are generally the primary targets of different antibiotics. Comparative molecular docking analysis indicated that prodigiosin exhibits a good binding affinity toward these selected drug targets.

PtrA regulates prodigiosin synthesis and biological functions in Serratia marcescens FZSF02

Serratia marcescens is a gram-negative bacterium that is able to produce many secondary metabolites, such as the prominent red pigment prodigiosin (PG). In this work, a ptrA-disrupted mutant strain with reduced PG production was selected from Tn5 transposon mutants. RT-qPCR results indicated that ptrA promoted elevated transcription of the pig gene cluster in S. marcescens FZSF02. Furthermore, we found that ptrA also controls several other important biological functions of S. marcescens, including swimming and swarming motilities, biofilm formation, hemolytic activity, and stress tolerance. In conclusion, this study demonstrates that ptrA is a PG synthesis-promoting factor in S. marcescens and provides a brief understanding of the regulatory mechanism of ptrA in S. marcescens cell motility and hemolytic activity.

Resourcefulness of propylprodigiosin isolated from Brevundimonas olei strain RUN-D1

A novel red-pigmented bacterium was isolated from a water sample collected at Osun River, Ede. Morphological and 16 S rRNA gene sequencing revealed that the bacterium is a strain of Brevundimonas olei, while its red pigment was identified using UV-visible, FTIR and GCMS as a derivative of propylprodigiosin. The maximum absorbance of 534 nm, the FTIR's 1344 cm^- 1 peak of prodigiosin's methoxyl C-O interaction, and the molecular ions from GCMS confirmed the pigment's identity. The pigments production was temperature-sensitive (25 °C), lost at > 28 °C, and in the presence of urea and humus. In addition, the pigment turned pink in the presence of hydrocarbons, while its red colour was retained with KCN and Fe₂SO_4, and enhanced by methylparaben. Furthermore, the pigment is stable in high temperature, salt, and acidic conditions, but changed to yellow in alkaline solution. The pigment, identified as propylprodigiosin (m/z 297), demonstrated broad-spectrum antibacterial activities against clinically important strains of Staphylococcus aureus (ATCC25923), Pseudomonas aeruginosa (ATCC9077), Bacillus cereus (ATCC10876), Salmonella typhi (ATCC13311), and Escherichia coli (DSM10974). The ethanol extract has the highest zones of inhibition of 29 ± 3.0, 26 ± 1.2, 22 ± 3.0, 22 ± 1.5, and 20 ± 2.0 mm, respectively. Furthermore, the acetone pigments interacted with cellulose and glucose such that increasing glucose concentrations showed linearity at 425 nm. Finally, the fastness of the pigments to fabrics was excellent, with percentage fadedness of 0 and - 43% light and washing tests, respectively, in the presence of Fe₂SO₄ as the mordant. The antibacterial nature of prodigiosin solutions and their good textile fastness to fabrics could be essential in manufacturing antiseptic materials such as bandages, hospital clothing and agricultural applications such as tubers preservation.Key points.

Prodigiosin-Producing Serratia marcescens as the Causal Agent of a Red Colour Defect in a Blue Cheese

Technological defects in the organoleptic characteristics of cheese (odour, colour, texture, and flavour) reduce quality and consumer acceptance. A red colour defect in Cabrales cheese (a traditional, blue-veined, Spanish cheese made from raw milk) occurs infrequently but can have a notable economic impact on family-owned, artisanal cheesemaking businesses. This work reports the culture-based determination of Serratia marcescens as the microbe involved in the appearance of red spots on the surface and nearby inner areas of such cheese. Sequencing and analysis of the genome of one S. marcescens isolate, RO1, revealed a cluster of 16 genes involved in the production of prodigiosin, a tripyrrole red pigment. HPLC analysis confirmed the presence of prodigiosin in methanol extracts of S. marcescens RO1 cultures. The same was also observed in extracts from red areas of affected cheeses. The strain showed low survival rates under acidic conditions but was not affected by concentrations of up to 5% NaCl (the usual value for blue cheese). The optimal conditions for prodigiosin production by S. marscescens RO1 on agar plates were 32 °C and aerobic conditions. Prodigiosin has been reported to possess antimicrobial activity, which agrees with the here-observed inhibitory effect of RO1 supernatants on different bacteria, the inhibition of Enterobacteriaceae, and the delayed development of Penicillium roqueforti during cheesemaking. The association between S. marcescens and the red colour defect was strengthened by recreating the fault in experimental cheeses inoculated with RO1. The data gathered in this study point towards the starting milk as the origin of this bacterium in cheese. These findings should help in the development of strategies that minimize the incidence of pigmenting S. marcescens in milk, the red defect the bacterium causes in cheese, and its associated economic losses.

In Silico and In Vitro Antiviral Activity Evaluation of Prodigiosin from Serratia marcescens Against Enterovirus 71

Prodigiosin, a red linear tripyrrole pigment found in Serratia marcescens, is one such naturally occurring compound that has gained wide attention owing to its numerous biological activities, including antibacterial, antifungal, antimalarial, anticancer, and immunosuppressive properties. This study was conducted to evaluate the possible antiviral activity of prodigiosin against Enterovirus 71, a causative agent of hand, foot, and mouth disease (HFMD). Preliminary studies were done in silico by analyzing the interaction of prodigiosin with amino acid residues of five EV71-target proteins. Interaction refinement analysis with FireDock revealed that 2C helicase (-48.01 kcal/moL) has the most negative global energy, followed by capsid (-36.52 kcal/moL), 3C protease (-34.16 kcal/moL), 3D RNA polymerase (-30.93 kcal/moL) and 2A protease (-20.61 kcal/moL). These values are indicative of the interaction strength. Prodigiosin was shown to form chemical bonds with specific amino acid residues in capsid (Gln-30, Asn-223), 2A protease (Trp-33, Trp-142), 2C helicase (Tyr-150, His-151, Gln-169, Ser-212), 3C protease (Glu-50), and 3D RNA polymerase (Ala-239, Tyr-237). To investigate further, prodigiosin was extracted from S. marcescens using a methanolic extraction method. In vitro studies revealed that prodigiosin, with an IC50 value of 0.5112 μg/mL, reduced virus titers by 0.17 log (32.39%) in 30 min and 0.19 log (35.43%) in 60 min. The findings suggest that prodigiosin has antiviral activity with an intermediate inhibitory effect against EV71. As a result of this research, new biological activities of prodigiosin have been identified.

Natural Substrates and Culture Conditions to Produce Pigments from Potential Microbes in Submerged Fermentation

Pigments from bacteria, fungi, yeast, cyanobacteria, and microalgae have been gaining more demand in the food, leather, and textile industries due to their natural origin and effective bioactive functions. Mass production of microbial pigments using inexpensive and ecofriendly agro-industrial residues is gaining more demand in the current research due to their low cost, natural origin, waste utilization, and high pigment stimulating characteristics. A wide range of natural substrates has been employed in submerged fermentation as carbon and nitrogen sources to enhance the pigment production from these microorganisms to obtain the required quantity of pigments. Submerged fermentation is proven to yield more pigment when added with agro-waste residues. Hence, in this review, aspects of potential pigmented microbes such as diversity, natural substrates that stimulate more pigment production from bacteria, fungi, yeast, and a few microalgae under submerged culture conditions, pigment identification, and ecological functions are detailed for the benefit of industrial personnel, researchers, and other entrepreneurs to explore pigmented microbes for multifaceted applications. In addition, some important aspects of microbial pigments are covered herein to disseminate the knowledge.

Prodigiosin: a promising biomolecule with many potential biomedical applications

Pigments are among the most fascinating molecules found in nature and used by human civilizations since the prehistoric ages. Although most of the bio-dyes reported in the literature were discovered around the eighties, the necessity to explore novel compounds for new biological applications has made them resurface as potential alternatives. Prodigiosin (PG) is an alkaloid red bio-dye produced by diverse microorganisms and composed of a linear tripyrrole chemical structure. PG emerges as a really interesting tool since it shows a wide spectrum of biological activities, such as antibacterial, antifungal, algicidal, anti-Chagas, anti-amoebic, antimalarial, anticancer, antiparasitic, antiviral, and/or immunosuppressive. However, PG vehiculation into different delivery systems has been proposed since possesses low bioavailability because of its high hydrophobic character (XLogP3-AA = 4.5). In the present review, the general aspects of the PG correlated with synthesis, production process, and biological activities are reported. Besides, some of the most relevant PG delivery systems described in the literature, as well as novel unexplored applications to potentiate its biological activity in biomedical applications, are proposed.

Farnesol and tyrosol: novel inducers for microbial production of carotenoids and prodigiosin

This study was performed to elucidate the effects of two fungal quorum sensing molecules (tyrosol and farnesol) on carotenoid synthesis in the yeast Rhodotorula glutinis and prodigioin synthesis in the bacterium Serratia marcencens. Farnesol or tyrosol was directly added to the flask cultures at the beginning (immediately after inoculation with the preculture) of day 1 or the beginning (49th h) of day 3. The results demonstrated that tyrosol supplementation increased the synthesis of carotenoids but farnesol supplementation increased the synthesis of prodigiosin. It was found that adding farnesol or tyrosol into the culture on day 3 compared to day 1 caused more increments in pigment synthesis. The maximum increase (fivefold) in the synthesis of prodigiosin was achieved with 200 μL/L farnesol supplementation, whereas the maximum increase (2.13 fold) in the synthesis of carotenoids was achieved with 4 mg/L tyrosol supplementation. This is the first report about the effects of fungal quorum sensing molecules (farnesol and tyrosol) on the synthesis of carotenoids and prodigiosin in microorganisms. Due to non-human toxicity and low price and of farnesol and tyrosol, these molecules can be used as novel inducers for large-scale production of microbial pigments.

Utilization of Cassava Wastewater for Low-Cost Production of Prodigiosin via Serratia marcescens TNU01 Fermentation and Its Novel Potent α-Glucosidase Inhibitory Effect

The purpose of this study was to reuse cassava wastewater (CW) for scaled-up production, via the fermentation of prodigiosin (PG), and to conduct an evaluation of its bioactivities. PG was produced at the yield of high 6150 mg/L in a 14 L-bioreactor system, when the designed novel medium (7 L), containing CW and supplemented with 0.25% casein, 0.05% MgSO₄, and 0.1% K₂HPO₄, was fermented with Serratia marcescens TNU01 at 28 °C in 8 h. The PG produced and purified in this study was assayed for some medical effects and showed moderate antioxidant, high anti-NO (anti-nitric oxide), and potential α-glucosidase inhibitory activities. Notably, PG was first reported as a novel effective α-glucosidase inhibitor with a low IC50 value of 0.0183 µg/mL. The commercial anti-diabetic drug acarbose was tested for comparison and had a lesser effect with a high IC50 value of 328.4 µg/mL, respectively. In a docking study, the cation form of PG (cation-PG) was found to bind to the enzyme α-glucosidase by interacting with two prominent amino acids, ASP568 and PHE601, at the binding site on the target enzyme, creating six linkages and showing a better binding energy score (−14.6 kcal/mol) than acarbose (−10.5 kcal/mol). The results of this work suggest that cassava wastewater can serve as a low-cost raw material for the effective production of PG, a potential antidiabetic drug candidate.

Prodigiosin production from Serratia marcescens strain CSK and their antioxidant, antibacterial, cytotoxic effect and in silico study of caspase-3 apoptotic protein

The present study emphasizes the production and optimization of prodigiosin (PG) pigment from Serratia marcescens strain CSK, which was isolated from Shevaroy Hills, Salem district, Tamil Nadu, India. The response surface methodology analysis was applied for the optimization process of PG production. The maximum production of PG (2950 mg/L) was obtained at pH 7.0 with the addition of tryptophan (4.0 g/L) and sucrose (3.0 g/L) with 60 h of incubation. Further, the PG was characterized using high-performance liquid chromatography, Fourier-transform infrared spectroscopy, and gas chromatography-mass spectrometry. The purified PG exhibited strong antioxidant and antibacterial activities. Also, PG's cytotoxic effects against human breast cancer (MCF-7) cells were observed through acridine orange-ethidium bromide (AO-EB) and Hoechst staining. Molecular dockingstudies revealed that PG could bind positively to the caspase-3 (breast cancer protein 1RE1) binding site with a binding energy score of 17.37 kcal/mol. Overall, the novel PG was found to be an anticancer drug for potential applications in the pharmaceutical industry.

Draft genome sequence of a prodigiosin-hyperproducing Serratia marcescens strain isolated from Cairo, Egypt

Serratia marcescens is a Gram-negative bacterium with both environmental and host-associated strains. Pigmentation is reportedly inversely correlated with infection frequency, and prodigiosin is one of Serratia pigments that has medical and industrial applications. Here, we report the draft genome sequence of prodigiosin-hyperproducing Serratia marcescens strain N2, isolated from Cairo, Egypt. The sequence is assembled into 142 contigs, with a combined size of 5,570,793 bp. The assembled genome carries typical S. marcescens genes, with potential prodigiosin-biosynthesizing genes detected.

Epiphytic Bacteria from Sweet Pepper Antagonistic In Vitro to Ralstonia solanacearum BD 261, a Causative Agent of Bacterial Wilt

Biological control of plant pathogens, particularly using microbial antagonists, is posited as the most effective, environmentally-safe, and sustainable strategy to manage plant diseases. However, the roles of antagonists in controlling bacterial wilt, a disease caused by the most devastating and widely distributed pathogen of sweet peppers (i.e., R. solanacearum), are poorly understood. Here, amplicon sequencing and several microbial function assays were used to depict the identities and the potential antagonistic functions of bacteria isolated from 80 red and green sweet pepper fruit samples, grown under hydroponic and open soil conditions, with some plants, fungicide-treated while others were untreated. Amplicon sequencing revealed the following bacterial strains: Bacillus cereus strain HRT7.7, Enterobacter hormaechei strain SRU4.4, Paenibacillus polymyxa strain SRT9.1, and Serratia marcescens strain SGT5.3, as potential antagonists of R. solanacearum. Optimization studies with different carbon and nitrogen sources revealed that maximum inhibition of the pathogen was produced at 3% (w/v) starch and 2,5% (w/v) tryptone at pH 7 and 30 °C. The mode of action exhibited by the antagonistic isolates includes the production of lytic enzymes (i.e., cellulase and protease enzymes) and siderophores, as well as solubilization of phosphate. Overall, the results demonstrated that the maximum antimicrobial activity of bacterial antagonists could only be achieved under specific environmental conditions (e.g., available carbon and nitrogen sources, pH, and temperature levels), and that bacterial antagonists can also indirectly promote crop growth and development through nutrient cycling and siderophore production.

Isolation and Characterization of Biosurfactant-Producing Bacteria from Amapaense Amazon Soils

The objective of this research was to perform screening of biosurfactant-producing bacteria from Amapaense Amazon soils. Floodplain- and upland-forest soils of three municipalities of the Amapá state were isolated and identified. The isolates were cultured in nutrient broth with olive oil, and their extracts were evaluated according to drop collapse, oil dispersion, emulsification, and surface tension tests. From three hundred and eighteen isolates, the 43 bacteria were selected and identified by 16S rDNA gene sequencing, indicating the presence of three different genera, Serratia, Paenibacillus, and Citrobacter. The extracellular biosurfactant production pointed out the 15 most efficient bacteria that presented high emulsification capacity (E₂₄ > 48%) and stability (less than 10% of drop after 72 h) and great potential to reduce the surface tension (varying from 49.40 to 34.50 mN·m⁻¹). Cluster analysis classified genetically related isolates in different groups, which can be connected to differences in the amount or the sort of biosurfactants. Isolates from Serratia genus presented better emulsification capacity and produced a more significant surface tension drop, indicating a promising potential for biotechnological applications.

Bioproduction of Prodigiosin from Fishery Processing Waste Shrimp Heads and Evaluation of Its Potential Bioactivities

The aim of this work was to reuse a fish processing waste, shrimp head powder (SHP), for the production of prodigiosin (PG) via microbial technology and to assess its potential bioactivities. PG was produced in a 12 L-bioreactor system, and the highest PG productivity of 6310 mg L−1 was achieved when Serratia marcescens CC17 was used for fermentation in a novel designed medium (6.75 L) containing 1.5% C/N source (SHP/casein = 9/1), 0.02% K2SO4, ans 0.025% Ca3(PO4)2, with initial pH 7.0, and fermentation was performed at 28 °C for 8 h. The purified PG showed moderate antioxidants, efficient anti-NO (anti-nitric oxide), and acetylcholinesterase (AChE) inhibitory activities. In a docking study, PG showed better binding energy scores (−12.3 kcal/mol) and more interactions (6 linkages) with several prominent amino acids in the biding sites on AChE that were superior to those of Berberine chloride (−10.8 kcal/mol and one linkage). Notably, this is the first investigation using shrimp heads for the mass bioproduction of PG with high productivity, and Ca3(PO4)2 salt was also newly found to significantly enhance PG production by S. marcescens. This study also provided available data on the anti-NO and anti-AChE effects of PG, especially from the docking simulation PG towards AChE that was described for the first time in this study. The above results suggest that SHP is a good material for the cost-effective bioproduction of PG, which is a potential candidate for anti-NO and anti-Alzheimer drugs.

Identification of Essential Genes Associated With Prodigiosin Production in Serratia marcescens FZSF02

Prodigiosin is a promising secondary metabolite produced mainly by Serratia strains. To study the global regulatory mechanism of prodigiosin biosynthesis, a mutagenesis library containing 23,000 mutant clones was constructed with the EZ-Tn5 transposon, and 114 clones in the library showed altered prodigiosin production ability. For 37 of the 114 clones, transposon insertion occurred on the prodigiosin biosynthetic cluster genes; transposon inserted genes of the 77 clones belonged to 33 different outside prodigiosin biosynthetic cluster genes. These 33 genes can be divided into transcription-regulating genes, membrane protein-encoding genes, and metabolism enzyme-encoding genes. Most of the genes were newly reported to be involved in prodigiosin production. Transcriptional levels of the pigA gene were significantly downregulated in 22 mutants with different inserted genes, which was in accordance with the phenotype of decreased prodigiosin production. Functional confirmation of the mutant genes involved in the pyrimidine nucleotide biosynthesis pathway was carried out by adding orotate and uridylate (UMP) into the medium. Gene complementation confirmed the regulatory function of the EnvZ/OmpR two-component regulatory system genes envZ and ompR in prodigiosin production.

Prodigiosin inhibits bacterial growth and virulence factors as a potential physiological response to interspecies competition

Prodigiosin, a red linear tripyrrole pigment, has long been recognised for its antimicrobial property. However, the physiological contribution of prodigiosin to the survival of its producing hosts still remains undefined. Hence, the aim of this study was to investigate the biological role of prodigiosin from Serratia marcescens, particularly in microbial competition through its antimicrobial activity, towards the growth and secreted virulence factors of four clinical pathogenic bacteria (methicillin-resistant Staphylococcus aureus (MRSA), Enterococcus faecalis, Salmonella enterica serovar Typhimurium and Pseudomonas aeruginosa) as well as Staphylococcus aureus and Escherichia coli. Prodigiosin was first extracted from S. marcescens and its purity confirmed by absorption spectrum, high performance liquid chromatography (HPLC) and liquid chromatography-tandem mass spectrophotometry (LC-MS/MS). The extracted prodigiosin was antagonistic towards all the tested bacteria. A disc-diffusion assay showed that prodigiosin is more selective towards Gram-positive bacteria and inhibited the growth of MRSA, S. aureus and E. faecalis and Gram-negative E. coli. A minimum inhibitory concentration of 10 μg/μL of prodigiosin was required to inhibit the growth of S. aureus, E. coli and E. faecalis whereas > 10 μg/μL was required to inhibit MRSA growth. We further assessed the effect of prodigiosin towards bacterial virulence factors such as haemolysin and production of protease as well as on biofilm formation. Prodigiosin did not inhibit haemolysis activity of clinically associated bacteria but was able to reduce protease activity for MRSA, E. coli and E. faecalis as well as decrease E. faecalis, Salmonella Typhimurium and E. coli biofilm formation. Results of this study show that in addition to its role in inhibiting bacterial growth, prodigiosin also inhibits the bacterial virulence factor protease production and biofilm formation, two strategies employed by bacteria in response to microbial competition. As clinical pathogens were more resistant to prodigiosin, we propose that prodigiosin is physiologically important for S. marcescens to compete against other bacteria in its natural soil and surface water environments.

Enhanced production of prodigiosin by Serratia marcescens UCP 1549 using agrosubstrates in solid-state fermentation

This work aimed to investigate the production of prodigiosin by S. marcescens UCP 1549 in solid-state fermentation (SSF), as a sustainable alternative for reducing the production costs and environmental impact. Thus, different agro-industrial substrates were used in the formulation of the prodigiosin production medium, obtaining the maximum yield of pigment (119.8 g/kg dry substrate) in medium consisting of 5 g wheat bran, 5% waste soybean oil and saline solution. The pigment was confirmed as prodigiosin by the maximum absorbance peak at 535 nm, R_f 0.9 in TLC, and the functional groups by infrared spectrum (FTIR). Prodigiosin demonstrated stability at different values of temperature, pH and NaCl concentrations and antimicrobial properties, as well as not show any toxicity. These results confirm the applicability of SSF as a sustainable and promising technology and wheat bran as potential agrosubstrate to produce prodigiosin, making the bioprocess economic and competitive for industrial purposes.

Bioprocessing of Marine Chitinous Wastes for the Production of Bioactive Prodigiosin

Recently, microbial prodigiosin (PG) has received much attention due to its numerous beneficial applications. The aim of this study was to establish the bioprocessing of marine chitinous wastes (MCWs) for the cost-effective preparation of PG. Of the MCWs, demineralized shrimp shell powders (de-SSP) were found to be a potential source of carbon/nitrogen (C/N) for PG production by bacterial fermentation using Serratia marcescens strains. Further, PG scale-up production was investigated in a 15 L bioreactor system, and the highest yield (6200 mg/L) was achieved during fermentation using 5 L of a novel-designed culture broth that included 1.60% C/N sources (a de-SSP/casein ratio of 7/3), 0.02% K₂SO_4, and 0.05% K₂HPO₄, with an initial pH of 6–7. Fermentation was conducted in the dark at 27.5 °C for 8.0 h. This study was the first to report on the utilization of shrimp wastes for cost-effective, large-scale (5 L/pilot) PG production with high productivity (6200 mg/L) in a short cultivation time. The combination of 0.02% K₂SO₄ and 0.05% K₂HPO₄ was also found to be a novel salt composition that significantly enhanced PG yield. The red compound was purified and confirmed as PG after analyzing its HPLC profile, mass, and UV/vis spectra. The purified PG was then tested for its bioactivities and showed effective anticancer activities, moderated antioxidant activities, and novel anti-NO effects.

Evolution of virulence in a novel family of transmissible mega-plasmids

Some Serratia entomophila isolates have been successfully exploited in biopesticides due to their ability to cause amber disease in larvae of the Aotearoa (New Zealand) endemic pasture pest, Costelytra giveni. Anti-feeding prophage and ABC toxin complex virulence determinants are encoded by a 153-kb single-copy conjugative plasmid (pADAP; amber disease-associated plasmid). Despite growing understanding of the S. entomophila pADAP model plasmid, little is known about the wider plasmid family. Here, we sequence and analyse mega-plasmids from 50 Serratia isolates that induce variable disease phenotypes in the C. giveni insect host. Mega-plasmids are highly conserved within S. entomophila, but show considerable divergence in Serratia proteamaculans with other variants in S. liquefaciens and S. marcescens, likely reflecting niche adaption. In this study to reconstruct ancestral relationships for a complex mega-plasmid system, strong co-evolution between Serratia species and their plasmids were found. We identify 12 distinct mega-plasmid genotypes, all sharing a conserved gene backbone, but encoding highly variable accessory regions including virulence factors, secondary metabolite biosynthesis, Nitrogen fixation genes and toxin-antitoxin systems. We show that the variable pathogenicity of Serratia isolates is largely caused by presence/absence of virulence clusters on the mega-plasmids, but notably, is augmented by external chromosomally encoded factors.

High-level production of microbial prodigiosin: A review

Prodigiosin is a natural red pigment derived primarily from secondary metabolites of microorganisms, especially Serratia marcescens. It can also be chemically synthesized. Prodigiosin has been proven to have antitumor, antibacterial, antimalaria, anti-insect, antialgae, and immunosuppressive activities, and is gaining increasing important in the global market because of its great potential application value in clinical medicine development, environmental treatment, preparation of food additives, and so on. Due to the low efficiency of prodigiosin chemical synthesis, high-level prodigiosin of production by microorganisms are necessary for prodigiosin applications. In this paper, the production of prodigiosin by microorganism in recent decades is reviewed. The methods and strategies for increasing the yield of prodigiosin are discussed from the aspects of medium composition, additives, factors affecting production conditions, strain modification, and fermentation methods.

Natural Pigments of Bacterial Origin and Their Possible Biomedical Applications

Microorganisms are considered one of the most promising niches for prospecting, production, and application of bioactive compounds of biotechnological interest. Among them, bacteria offer certain distinctive advantages due to their short life cycle, their low sensitivity to seasonal and climatic changes, their easy scaling as well as their ability to produce pigments of various colors and shades. Natural pigments have attracted the attention of industry due to an increasing interest in the generation of new products harmless to humans and nature. This is because pigments of artificial origin used in industry can have various deleterious effects. On this basis, bacterial pigments promise to be an attractive niche of new biotechnological applications, from functional food production to the generation of new drugs and biomedical therapies. This review endeavors to establish the beneficial properties of several relevant pigments of bacterial origin and their relation to applications in the biomedical area.

Biotechnological Activities and Applications of Bacterial Pigments Violacein and Prodigiosin

In this review, we discuss violacein and prodigiosin, two chromogenic bacterial secondary metabolites that have diverse biological activities. Although both compounds were "discovered" more than seven decades ago, interest into their biological applications has grown in the last two decades, particularly driven by their antimicrobial and anticancer properties. These topics will be discussed in the first half of this review. The latter half delves into the current efforts of groups to produce these two compounds. This includes in both their native bacterial hosts and heterogeneously in other bacterial hosts, including discussing some of the caveats related to the yields reported in the literature, and some of the synthetic biology techniques employed in this pursuit.

Utilization of Crab Waste for Cost-Effective Bioproduction of Prodigiosin

This study aimed to establish the culture process for the cost-effective production of prodigiosin (PG) from demineralized crab shell powder (de-CSP), a fishery processing byproduct created via fermentation. Among the tested PG-producing strains, Serratia marcescens TNU02 was demonstrated to be the most active strain. Various ratios of protein/de-CSP were used as the sources of C/N for PG biosynthesis. The PG yield was significantly enhanced when the casein/de-CSP ratio was controlled in the range of 3/7 to 4/6. TNU02 produced PG with a high yield (5100 mg/L) in a 15 L bioreactor system containing 4.5 L of a newly-designed liquid medium containing 1.6% C/N source (protein/de-CSP ratio of 3/7), 0.02% (NH₄)₂SO₄, 0.1% K₂HPO₄, and an initial pH of 6.15, at 27 °C for 8 h in dark conditions. The red pigment was purified from the culture broth and then quantified as being PG by specific Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) and UV spectra analysis. The purified PG demonstrated moderate antioxidant and effective inhibition against four cancerous cell lines. Notably, this study was the first to report on using crab wastes for PG bioproduction with high-level productivity (5100 mg/L) in a large scale (4.5 L per pilot) in a short period of fermentation time (8 h). The salt compositions, including (NH₄)₂SO₄ and K₂HPO₄, were also a novel finding for the enhancement of PG yield by S. marcescens in this report.

Sotolon is a natural virulence mitigating agent in Serratia marcescens

Serratia marcescens is an emerging opportunistic bacterium that can cause healthcare-associated infections. The high rate of multidrug resistance and the ability to produce a set of virulence factors, by which it can produce infectious diseases makes it urgent to find an alternative approach to the treatment of such infections. Disarming of virulence by targeting of quorum sensing (QS) as the regulating mechanism of virulence is a promising approach that has no effect on bacterial growth that is considered a key factor in emergence of resistance. This study was designed to investigate the ability of sub-inhibitory concentrations (sub-MICs) of sotolon to attenuate virulence of a clinical isolate of S. marcescens. Sotolon at 25 and 50 μg/ml inhibited 35.2 and 47.5% of biofilm formation, respectively. The inhibition of swimming motility were 41.4 and 69.3%, while that of swarming motility were 77.6 and 86.8% at 25 and 50 µg/ml, respectively. Moreover, sotolon reduced prodigiosin production by 76.6 and 87.6% at concentrations of 25 and 50 µg/ml, respectively. Protease activity was reduced by 25 µg/ml of sotolon by 54.8% and was completely blocked at 50 µg/ml. The relative expression of genes regulating virulence factors decreased by 40% for fimA, 29% for fimC, 59% for flhC, 57% for flhD, 39% for bsmB, 37% for rssB, 49% for rsmA, 54% for pigP, and 62% for shlA gene in the presence of 50 µg/ml sotolon. In conclusion, sotolon is an anti-virulence agent that could be used for the treatment of S.marcescens hospital-acquired infections.

Production and Potential Applications of Bioconversion of Chitin and Protein-Containing Fishery Byproducts into Prodigiosin: A Review

The technology of microbial conversion provides a potential way to exploit compounds of biotechnological potential. The red pigment prodigiosin (PG) and other PG-like pigments from bacteria, majorly from Serratia marcescens, have been reported as bioactive secondary metabolites that can be used in the broad fields of agriculture, fine chemicals, and pharmacy. Increasing PG productivity by investigating the culture conditions especially the inexpensive carbon and nitrogen (C/N) sources has become an important factor for large-scale production. Investigations into the bioactivities and applications of PG and its related compounds have also been given increased attention. To save production cost, chitin and protein-containing fishery byproducts have recently been investigated as the sole C/N source for the production of PG and chitinolytic/proteolytic enzymes. This strategy provides an environmentally-friendly selection using inexpensive C/N sources to produce a high yield of PG together with chitinolytic and proteolytic enzymes by S. marcescens. The review article will provide effective references for production, bioactivity, and application of S. marcescens PG in various fields such as biocontrol agents and potential pharmaceutical drugs.

Microbial Reclamation of Chitin and Protein-Containing Marine By-Products for the Production of Prodigiosin and the Evaluation of Its Bioactivities

Chitin and protein-containing marine by-products (CPCMBPs), including crab shells, squid pens, and shrimp shells, were investigated as the sole carbon/nitrogen (C/N) source for prodigiosin (PG) production by Serratia marcescens TNU01 in a 250 mL Erlenmeyer flask and a 10 L bioreactor system. Among the used C/N source of CPCMBPs, squid pens powder (SPP) showed the most optimum PG productivity. Different ratios of chitin/protein combination were also used as the C/N sources for PG production. With a similar chitin/protein ratio (4/6) of squid pens, a significant PG productivity was achieved when the chitin/protein ratios were controlled in the range of 3/7-4/6. Maximum PG yield (3450 mg/L) by S. marcescens TNU01 was achieved in the bioreactor system containing 3 L medium of 1.75% SPP, 0.03% K₂HPO₄, and 0.05% MgSO₄ at 25 °C for 12 h in dark. The results of in vitro bioassays reveal that the purified PG possesses acetylcholinesterase inhibitory activity and antioxidant as well as anticancer activities. This study suggests that squid pens may have the potential to be used for cost effective production of bioactive PG at a large-scale.

Effects of oil substrate supplementation on production of prodigiosin by Serratia nematodiphila for dye-sensitized solar cell

Bacterial pigments are potential substitute of chemical photosensitizer for dye-sensitized solar cell (DSSC) due to its non-toxic property and cost-effective production from microbial fermentation. Serratia nematodiphila YO1 was isolated from waterfall in Malaysia and identified using 16S ribosomal RNA. Characterization of the red pigment produced by the bacteria has confirmed the pigment as prodigiosin. Prodigiosin was produced from the fermentation of the bacteria in the presence of different oil substrates. Palm oil exhibited the best performance of cell growth and equivalent prodigiosin yield compared to olive oil and peanut oil. Prodigiosin produced with palm oil supplementation was 93 mg/l compared to 7.8 mg/l produced without supplementation, which recorded 11.9 times improvement. Specific growth rate of the cells improved 1.4 times when palm oil was supplemented in the medium. The prodigiosin pigment produced showed comparable performance as a DSSC sensitizer by displaying an open circuit voltage of 336.1 mV and a maximum short circuit current of 0.098 mV/cm². This study stands a novelty in proving that the production of prodigiosin is favorable in the presence of palm oil substrate with high saturated fat content, which has not been studied before. This is also among the first bacterial prodigiosin tested as photosensitizer for DSSC application.

In vitro synergy testing of prodigiosin in combination with inhibitors of cell wall synthesis against Mycobacterium smegmatis

The cell wall is not a target of currently used therapeutics as Mycobacterium are considered naturally resistant to most β-lactam antibiotics. Therefore, combinations of conventional antibiotics with antibiotic activity-enhancing compounds offer a productive treatment strategy and address the widespread emergence of antibiotic-resistant strains. The first area of research was the study of a comparative analysis of disk diffusion testing and the broth dilution method for evaluating the susceptibility of M. smegmatis to antimicrobial agents. A comparative analysis of the susceptibility to antimicrobial agents alone showed that M. smegmatis was the most susceptible to ceftriaxone and kanamycin, and moderately sensitive to vancomycin and prodigiosin. Compared to the susceptibility of the antibacterial combinations, the isolate was not susceptible to antibacterial combinations with prodigiosin in disk diffusion testing. The second area of research was the study of the synergic activity of prodigiosin of S. marcescens and inhibitors of cell wall synthesis manifested by their simultaneous effect on M. smegmatis. The greatest increase in the sensitivity of test-culture of mycobacteria occurred with ampicillin, benzylpenicillin, cephazolin and ceftriaxone in combination with prodigiosin of S. marcescens. The presented combination of antibiotics and prodigiosin reduce the required concentration of the antibiotic and by amplifying the effect of compounds inhibiting cell wall synthesis, thereby giving lower FICI values. These data indicate the possibility of using prodigiosin as a promising candidate for the development of "accompaniment-preparations" for antibiotics for the additional therapy of infectious diseases caused by Mycobacterium spp. and can suspend the likelihood of developing resistance to antibiotics. The cell wall is not a target of currently used therapeutics as Mycobacterium are considered naturally resistant to most β-lactam antibiotics. Therefore, combinations of conventional antibiotics with antibiotic activity-enhancing compounds offer a productive treatment strategy and address the widespread emergence of antibiotic-resistant strains. The first area of research was the study of a comparative analysis of disk diffusion testing and the broth dilution method for evaluating the susceptibility of M. smegmatis to antimicrobial agents. A comparative analysis of the susceptibility to antimicrobial agents alone showed that M. smegmatis was the most susceptible to ceftriaxone and kanamycin, and moderately sensitive to vancomycin and prodigiosin. Compared to the susceptibility of the antibacterial combinations, the isolate was not susceptible to antibacterial combinations with prodigiosin in disk diffusion testing. The second area of research was the study of the synergic activity of prodigiosin of S. marcescens and inhibitors of cell wall synthesis manifested by their simultaneous effect on M. smegmatis. The greatest increase in the sensitivity of test-culture of mycobacteria occurred with ampicillin, benzylpenicillin, cephazolin and ceftriaxone in combination with prodigiosin of S. marcescens. The presented combination of antibiotics and prodigiosin reduce the required concentration of the antibiotic and by amplifying the effect of compounds inhibiting cell wall synthesis, thereby giving lower FICI values. These data indicate the possibility of using prodigiosin as a promising candidate for the development of "accompaniment-preparations" for antibiotics for the additional therapy of infectious diseases caused by Mycobacterium spp. and can suspend the likelihood of developing resistance to antibiotics.

Novel Efficient Bioprocessing of Marine Chitins into Active Anticancer Prodigiosin

Marine chitins (MC) have been utilized for the production of vast array of bioactive products, including chitooligomers, chitinase, chitosanase, antioxidants, anti-NO, and antidiabetic compounds. The aim of this study is the bioprocessing of MC into a potent anticancer compound, prodigiosin (PG), via microbial fermentation. This bioactive compound was produced by Serratia marcescens TKU011 with the highest yield of 4.62 mg/mL at the optimal conditions of liquid medium with initial pH of 5.65-6.15 containing 1% α-chitin, 0.6% casein, 0.05% K₂HPO₄, and 0.1% CaSO₄. Fermentation was kept at 25 °C for 2 d. Notably, α-chitin was newly investigated as the major potential material for PG production via fermentation; the salt CaSO₄ was also found to play the key role in the enhancement of PG yield of Serratia marcescens fermentation for the first time. PG was qualified and identified based on specific UV, MALDI-TOF MS analysis. In the biological activity tests, purified PG demonstrated potent anticancer activities against A549, Hep G2, MCF-7, and WiDr with the IC₅₀ values of 0.06, 0.04, 0.04, and 0.2 µg/mL, respectively. Mytomycin C, a commercial anti-cancer compound was also tested for comparison purpose, showing weaker activity with the IC₅₀ values of 0.11, 0.1, 0.14, and 0.15 µg/mL, respectively. As such, purified PG displayed higher 2.75-fold, 1.67-fold, and 3.25-fold efficacy than Mytomycin C against MCF-7, A549, and Hep G2, respectively. The results suggest that marine chitins are valuable sources for production of prodigiosin, a potential candidate for cancer drugs.