Paracoccus Zeaxanthinifaciens Research Articles

Isolation and Characterization of Paracoccus maritimus sp. nov., from Intertidal Sediment.

A novel Paracoccus-related strain, designated YLB-12T, was isolated from a sediment sample from the tidal zone of Shapowei Port, Xiamen, Fujian Province, PR China. The novel strain is a Gram-stain-negative, short, rod-shaped, nonmotile, catalase- and oxidase-positive strain that grows at 10-37°C and pH 5.0-9.0 in the presence of 0-12.0% (w/v) NaCl. Phylogenetic analysis of the 16S rRNA gene sequences indicated that this strain belongs to the genus Paracoccus and that its highest sequence similarity was to Paracoccus homiensis DD-R11T (98.5%), followed by Paracoccus zeaxanthinifaciens ATCC 21588T (97.4%), Paracoccus rhizosphaerae LMG 26205T (97.2%), Paracoccus beibuensis CGMCC 1.7295T (97.1%) and Paracoccus halotolerans CFH 90064T (97.0%). The DNA‒DNA hybridization values between strain YLB-12T and the five closely related type strains ranged from 20.4 to 22.4%. The genomic G+C content of strain YLB-12T was 63.7%. In addition to diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and phosphatidylglycerol, the polar lipids of the strain YLB-12T also consisted of an unidentified glycolipid and four unidentified polar lipids. The cells contained summed feature 8 (C18: 1ω6c /C18: 1ω7c, 62.7%) as the major cellular fatty acid and ubiquinone-10 as the predominant menaquinone. On the basis of its phenotypic and genotypic characteristics, strain YLB-12T represents a novel species within the genus Paracoccus, for which the name Paracoccus maritimus sp. nov. is proposed. The type strain was YLB-12T (= MCCC 1A17213T = KCTC 82197T).

Paracoccus amoyensis sp. nov., isolated from the surface seawater along the coast of Xiamen Island, China.

Strain 11-3T was isolated from the surface seawater along the coast of Xiamen Island, China. Cells were Gram-stain-negative, oxidase- and catalase-positive, short and rod-shaped, nonmotile, 0.5-1.0 μm in width and 1.0-2.0 μm in length. Growth of strain 11-3T was at temperature of 15-37°C (optimum 28-35°C), at pH of 5.0-11.0 (optimum 7.0-9.0) and at salinity range of 0-10 (optimum 0.5-1). Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain 11-3T belonged to the genus Paracoccus and had the highest similarity with Paracoccus caeni MJ17T (98.1 %), followed by Paracoccus xiamenensis 12-3T (97.1 %), Paracoccus zeaxanthinifaciens ATCC 21588T (97.1 %), Paracoccus aestuarii DSM 19484T (97.0 %), Paracoccus liaowanqingii 2251T (97.0 %), Paracoccus fistulariae KCTC 22803T (97.0 %) and other species of the genus Paracoccus (95.2-96.8 %). The DNA-DNA hybridization values between strain 11-3T and the selected strains (P. caeni MJ17T, P. xiamenensis 12-3T, P. zeaxanthinifaciens ATCC 21588T, P. aestuarii DSM 19484T and P. liaowanqingii 2251T) were 19.4, 19.5, 21.6, 19.3 and 19.8 %, respectively. Corresponding, their ANI values were 77.53, 75.61, 75.36, 75.73 and 75.33 %, respectively. The major fatty acid was summed feature 8 (C18:1 ω6c/ω7c). The major respiratory quinone was Q10. The polar lipids included phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), diphosphatidylglycerol (DPG), unidentified glycolipid (GL) and unidentified aminolipid (AL). The DNA G+C content of strain 11-3T was 60.1 %. Based on results of the phylogenetic analysis, phenotypic and chemotaxonomic characteristics, strain 11-3T represents a novel species of the genus Paracoccus, for which the name Paracoccus amoyensis sp. nov. is proposed. The type strain is 11-3T (=MCCC 1A16380T=KCTC 72689T).

Biosynthesis of cycloartenol by expression of plant and bacterial oxidosqualene cyclases in engineered Rhodobacter capsulatus

Cyclic triterpenes are a large group of secondary metabolites produced by plants, fungi and bacteria. They have diverse biological functions, and offer potential health benefits for humans. Although various terpenes from the mono-, sesqui- and diterpene classes are easy to produce in engineered bacteria, heterologous synthesis of cyclic triterpenes is more challenging. We have recently shown that the triterpene cycloartenol can be produced in Rhodobacter capsulatus SB1003 but initial titers were low with 0.34mgL−1. To assess, if this phototrophic α-proteobacterium can be engineered for enhanced triterpene production, we followed two alternative strategies by comparing the performance of the R. capsulatus SB1003 wildtype strain with two recombinant strains carrying either a mevalonate pathway implemented from Paracoccus zeaxanthinifaciens or a deletion in the intrinsic carotenoid biosynthesis gene crtE. These strains are thus engineered for an enhanced isoprenoid biosynthesis or a suppressed precursor conversion by the competing carotenoid pathway. Moreover, three different cycloartenol synthase (CAS) genes from Arabidopsis thaliana or the myxobacterial strains Stigmatella aurantiaca Sga15 and DW4/3-1 were tested for heterologous cycloartenol synthesis. We found that the heterologous expression of mevalonate pathway enzymes had little impact on cycloartenol levels irrespective of the chosen CAS. In contrast, the use of the newly constructed carotenoid-deficient crtE deletion strain showed threefold increased cycloartenol product titers. We conclude that R. capsulatus is a promising alternative host for the functional expression of triterpene biosynthetic enzymes from plants and microbes. Apparently, product titers can also be improved by suppression of competing precursor consumption.

Paracoccus halotolerans sp. nov., isolated from a salt lake.

A novel Gram-stain-negative, aerobic, non-motile, coccus-shaped bacterium, designated CFH 90064T, was isolated from a salt lake sediment sample collected from Yuncheng city, Shanxi province, PR China. 16S rRNA gene sequence comparisons and phylogenetic analyses showed that the strain belonged to the genus Paracoccus and clustered with Paracoccus zeaxanthinifaciens R-1512T (98.2 % similarity), Paracoccus homiensis DD-R11T (97.6 % similarity) and Paracoccus fistulariae 22-5T (96.5 % similarity), respectively. Growth of strain CFH 90064T was observed at 10-37 °C, pH 6.0-9.0 and with NaCl concentrations of up to 6.0 % (w/v). Strain CFH 90064T contained Q-10 as the only isoprenoid quinone, and the major fatty acid was C18 : 1ω7c. Polar lipids of strain CFH 90064T comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, an unidentified glycolipid, an unidentified aminolipid and an unidentified phospholipid. The genome of strain CFH 90008T was 3.75 Mbp with a DNA G+C content of 65.1 %. Based on the phylogenetic analyses, low average nucleotide identity results, chemotaxonomic characteristics and differential physiological properties, strain CFH 90064T could not be classified into any recognized species of the genus Paracoccus, suggesting that this strain represents a novel species, for which the name Paracoccushalotolerans sp. nov. is proposed. The type strain is CFH 90064T (=CCTCC AB 2016131T=DSM 103234T).

Paracoccus pueri sp. nov., isolated from Pu'er tea.

A Gram-stain negative, aerobic, short rod-shaped, motile by flagella bacterial strain (THG-N2.35T), was isolated from Pu'er tea. Growth occurred at 10-40°C (optimum 28°C), at pH 4-7 (optimum 7) and at 0-5% NaCl (optimum 1%). Based on 16S rRNA gene sequence analysis, the near phylogenetic neighbours of strain THG-N2.35T were identified as Paracoccus hibisci KACC 18632T (99.0%), Paracoccus tibetensis CGMCC 1.8925T (98.7%), Paracoccus beibuensis CGMCC 1.7295T (98.2%), Paracoccus aestuarii KCTC 22049T (98.2%), Paracoccus rhizosphaerae LMG 26205T (98.1%), Paracoccus zeaxanthinifaciens ATCC 21588T (97.1%), Paracoccus marcusii DSM 11574T (97.0%). Levels of similarity between strain THG-N2.35T and other Paracoccus species were lower than 97.0%. DNA-DNA hybridization values between strain THG-N2.35T and P. hibisci KACC 18632T, P. tibetensis CGMCC 1.8925T, P. beibuensis CGMCC 1.7295T, P. aestuarii KCTC 22049T, P. rhizosphaerae LMG 26205T, P. zeaxanthinifaciens ATCC 21588T, P.marcusii DSM 11574T were 47.5% (42.3%, reciprocal analysis), 36.1% (32.3%), 24.7% (22.1%), 19.2% (16.3%), 11.3% (8.8%), 11.1% (10.8%), 6.1% (5.8%), respectively. The DNA G+C content of strain THG-N2.35T was 62.3mol%. The polar lipids were diphosphatidylglycerol, phosphatidyl-N-methylethanolamine, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylcholine. The quinone was ubiquinone-10 (Q-10). The major fatty acids were C10:0 3OH, C16:0, C18:0 and C18:1 ω7ϲ. On the basis of the phylogenetic analysis, chemotaxonomic data, physiological characteristics and DNA-DNA hybridization data, strain THG-N2.35T represent a novel species of the genus Paracoccus, for which the name Paracoccus pueri sp. nov. is proposed. The type strain is THG-N2.35T (=KACC 18934T=CCTCC AB 2016177T).

Zeaxanthin production by Paracoccus zeaxanthinifaciens ATCC 21588 in a lab-scale bubble column reactor: Artificial intelligence modelling for determination of optimal operational parameters and energy requirements

The operational optimization of zeaxanthin production by Paracoccus zeaxanthinifaciens ATCC 21588 in a bubble column reactor was performed by coupling genetic algorithm (GA) to an artificial neural network (ANN) model developed using experimental one-variable-at-a-time (OVAT) results. The effects of varying air flow rate (2-5 vvm) and inoculum size (4 and 8%) for different incubation time (30-80 h) were evaluated. Volumetric power input (P/V L ) and energy input (E) to the bubble column were then correlated with the ANN-GA optimized conditions. A maximum zeaxanthin production of 13.76±0.14 mg/L was observed at 4 vvm using an inoculum size of 4% (v/v) after 60 h of incubation in OVAT experiments with corresponding P/V L value of 231.57 W/m3 reflecting an energy consumption of 50.02 kJ during the fermentation period. The ANN based GA optimization predicted a maximum zeaxanthin production of 14.79 mg/L at 3.507 vvm, 4% inoculum size and 55.83 h against the experimental production of 15.09±0.51 mg/L corresponding to a P/V L value of 202.03 W/m3 reflecting to a significantly reduced energy input (40.01 kJ). The proposed OVAT based ANN-GA optimization approach can be used to simulate similar studies involving microbial fermentation in bioreactors.

Modelling and optimization of zeaxanthin production by Paracoccus zeaxanthinifaciens ATCC 21588 using hybrid genetic algorithm techniques

In the present study, overall zeaxanthin production by Paracoccus zeaxanthinifaciens ATCC 21588 in a complex medium was optimized using hybrid statistical and mathematical approaches. Initially, Taguchi design was used to identify the most significant input parameters viz., glucose, yeast extract, pyridoxine hydrochloride and methyl palmitate. These parameters were then studied using central composite design to develop response surface methodology (RSM) and artificial neural network (ANN) models. The ANN model was found to be superior to RSM model for its mapping abilities based on statistical evaluation using the coefficient of determination (R2), root mean square error (RMSE) and standard error of prediction (SEP). The final optimization was performed by using genetic algorithm (GA), and the ANN-GA hybrid was found to be superior to RSM-GA hybrid with lower percent prediction error (1.55ANN-GA<5.09RSM-GA). The optimum condition predicted by the ANN-GA hybrid was 24.3 g/L glucose, 30 g/L yeast extract, 0.18 mg/L pyridoxine hydrochloride and 8 g/L methyl palmitate which yielded an average overall zeaxanthin production of 11.63 mg/L after 72 h of incubation at 30 °C. Our study signifies that P. zeaxanthinifaciens ATCC 21588 could be explored as an excellent alternative over current commercial processes for producing zeaxanthin.

Paracoccus beibuensis sp. nov., Isolated from the South China Sea

A Gram-negative, non-motile, short rod-shaped or spherical bacterial strain that accumulates poly-β-hydroxybutyrate (PHB) granules was isolated from the Beibu Gulf in the South China Sea. Cells have no polar or subpolar flagella, dividing by binary fission. Phylogenetic analyses based on 16S rRNA gene sequences showed that the strain formed a monophyletic branch at the periphery of the evolutionary radiation occupied by the genus Paracoccus, family Rhodobacteraceae, order Rhodobacterales, class Alphaproteobacteria. The closest neighbours were Paracoccus aestuarii strain B7(T) (97.2% similarity), Paracoccus zeaxanthinifaciens ATCC 21588(T) (97.1% similarity) and Paracoccus homiensis DD-R11(T) (96.8%). The predominant fatty acids were C(18:1) ω7c (82.1%), and significant amounts of C(18:0) (5.6%), C(10:0) 3-OH (2.3%) and C(16:0) (1.5%) were present. The predominant respiratory ubiquinone of strain JLT1284(T) was Q-10 and the DNA G+C content of strain JLT1284(T) was 67.0 mol%. The isolate was also distinguishable from members of the genus Paracoccus on the basis of phenotypic and biochemical characteristics. It is evident from the genotypic, chemotaxonomic and phenotypic data, therefore, that strain JLT1284(T) represents a novel species of the genus Paracoccus, for which the name Paracoccus beibuensis sp. nov. is proposed. The type strain is JLT1284(T)=LMG 24871(T)=CGMCC 1.7295(T)).

Paracoccus caeni sp. nov., isolated from sludge

A Gram-negative, non-motile bacterium, designated MJ17(T), was isolated from sludge at the Daejeon sewage disposal plant in South Korea. Comparative 16S rRNA gene sequence analysis showed that strain MJ17(T) belonged to the genus Paracoccus in the family Rhodobacteraceae of the class Alphaproteobacteria. 16S rRNA gene sequence similarities between strain MJ17(T) and type strains of species of the genus Paracoccus were 94.1-97.4 %. The highest similarities were between strain MJ17(T) and Paracoccus homiensis DD-R11(T), Paracoccus zeaxanthinifaciens ATCC 21588(T) and Paracoccus alcaliphilus JCM 7364(T) (97.4, 97.2 and 96.3 %, respectively). Strain MJ17(T) exhibited <22 % DNA-DNA relatedness with P. homiensis KACC 11518(T) and P. zeaxanthinifaciens JCM 21774(T). The G+C content of the genomic DNA was 58.7 mol%. Strain MJ17(T) contained ubiquinone Q-10. The major fatty acids were C(18 : 0) (11.3 %), C(16 : 0) (10.2 %) and summed feature 7 (containing one or more of C(18 : 1)ω7c, C(18 : 1)ω9c and C(18 : 1)ω12t; 54.3 %). Poly-β-hydroxybutyrate granules are formed. On the basis of phenotypic and genotypic properties and phylogenetic distinctiveness, strain MJ17(T) should be classified in a novel species of the genus Paracoccus, for which the name Paracoccus caeni sp. nov. is proposed. The type strain is MJ17(T) ( = KCTC 22480(T) = JCM 16385(T) = KEMB 9004-001(T)).

Paracoccus fistulariae sp. nov., a lipolytic bacterium isolated from bluespotted cornetfish, Fistularia commersonii

A Gram-stain-negative, non-motile, non-spore-forming and short rod- or rod-shaped bacterial strain, designated 22-5(T), was isolated from a bluespotted cornetfish, Fistularia commersonii, and subjected to taxonomic study. Strain 22-5(T) grew optimally at 30&emsp14;°C and in the presence of 2-5 % (w/v) NaCl. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain 22-5(T) belonged to the genus Paracoccus and joined the cluster comprising Paracoccus homiensis DD-R11(T) and Paracoccus zeaxanthinifaciens ATCC 21588(T), with which strain 22-5(T) exhibited 97.4 and 96.9 % 16S rRNA gene sequence similarity, respectively. Strain 22-5(T) exhibited 94.0-96.6 % 16S rRNA gene sequence similarity with the other type strains of species of the genus Paracoccus. Strain 22-5(T) contained Q-10 as the predominant menaquinone and C(18 : 1)ω7c as the predominant fatty acid. In this study, P. zeaxanthinifaciens KCTC 22688(T) also contained Q-10 as the predominant isoprenoid quinone. The DNA G+C content of strain 22-5(T) was 63.6 mol%. Strain 22-5(T) exhibited 44 and 32 % DNA-DNA relatedness to P. homiensis KACC 11518(T) and P. zeaxanthinifaciens KCTC 22688(T), respectively. On the basis of phenotypic, phylogenetic and genetic data, strain 22-5(T) is considered to represent a novel species of the genus Paracoccus, for which the name Paracoccus fistulariae sp. nov. is proposed. The type strain is 22-5(T) (=KCTC 22803(T) =CCUG 58401(T)).

Development of efficient supercritical carbon dioxide extraction methodology for zeaxanthin from dried biomass of Paracoccus zeaxanthinifaciens

Zeaxanthin was extracted from dried biomass of Paracoccus zeaxanthinifaciens using supercritical carbon dioxide (SC-CO 2) with methanol as an entrainer. Solubility parameter of zeaxanthin, CO 2, and CO 2 with entrainer was calculated to correlate with experimental data. A maximum recovery of 65% was obtained using 3 ml methanol as entrainer per gram of lyophilized biomass at 300 bar and 40 °C. Higher and lower temperature and pressure conditions did not affect the yield appreciably. Other entrainers such as ethanol, acetone, isopropyl alcohol, and water were relatively ineffective in extraction of zeaxanthin from the bacterial biomass.

Paracoccus homiensis sp. nov., isolated from a sea-sand sample

Strain DD-R11(T), isolated from a sea-sand sample from Homi Cape, Pohang city, South Korea, was a Gram-negative, aerobic, motile, non-spore-forming, rod- to ovoid-shaped bacterium. Colonies grown on marine agar were circular, convex and colourless to creamy white. Growth occurred between 10 and 40 degrees C (optimum 25-30 degrees C) and at pH 5.0-9.0 (optimum pH 6.0-8.0). The strain could grow in up to 15 % NaCl (optimum 3-5 % NaCl). According to 16S rRNA gene sequence analysis, the strain was a member of the genus Paracoccus in the Alphaproteobacteria. Sequence similarities to type strains of the genus Paracoccus were between 94.6 and 98.3 %, showing the highest sequence similarity to Paracoccus zeaxanthinifaciens ATCC 21588(T). The DNA-DNA relatedness value of strain DD-R11(T) and P. zeaxanthinifaciens ATCC 21588(T) was 27 %. Strain DD-R11(T) was characterized by having ubiquinone 10 as the major respiratory quinone and C(18 : 1)omega7c as the predominant fatty acid. The DNA G+C content was 63.0 mol%. On the basis of its phenotypic and genotypic characteristics, it is suggested that DD-R11(T) represents a novel species of the genus Paracoccus, for which the name Paracoccus homiensis sp. nov. is proposed, with DD-R11(T) (=KACC 11518(T)=DSM 17862(T)) as the type strain.

A Novel Exopolymer-Producing Bacterium, Paracoccus zeaxanthinifaciens subsp. payriae, Isolated from a ?Kopara? Mat Located in Rangiroa, an Atoll of French Polynesia

An aerobic, mesophilic and heterotrophic marine bacterium designated RA19, able to produce two different exocellular polymers and zeaxanthin, was isolated from a French polynesian bacterial mat (localy named "kopara") situated in the atoll of Rangiroa. This microorganism, on the basis of its phenotypical features and the genotypic investigations, can be clearly assigned to the Parococcus zeaxanthinifaciens species and the name Parococcus zeaxanthinifaciens subsp. payriae is proposed. Optimal growth occurs between 30 degrees C and 35 degrees C, at pH between 6.5 and 7.5 and at ionic strength between 20 and 40 g/L of NaCl. The guanine-plus-cytosine content of DNA was 65.6%. This bacterium excreted, under laboratory conditions, two different polymers: a water-soluble exopolysaccharide (EPSI) consisting of 5 different sugars and a non-water-soluble macromolecule assumed to be of a glycoproteinic nature. The high sulfate content of the EPS1 and preliminary biological tests clearly showed that applications could be found in the very near future for both polymers in the cosmetic area. Their contribution to the viscous laminated microbial mat locally called "kopara" can be also mentioned.

A Superfamily of Voltage-gated Sodium Channels in Bacteria

NaChBac, a six-alpha-helical transmembrane-spanning protein cloned from Bacillus halodurans, is the first functionally characterized bacterial voltage-gated Na(+)-selective channel. As a highly expressing ion channel protein, NaChBac is an ideal candidate for high resolution structural determination and structure-function studies. The biological role of NaChBac, however, is still unknown. In this report, another 11 structurally related bacterial proteins are described. Two of these functionally expressed as voltage-dependent Na(+) channels (Na(V)PZ from Paracoccus zeaxanthinifaciens and Na(V)SP from Silicibacter pomeroyi). Na(V)PZ and Na(V)SP share approximately 40% amino acid sequence identity with NaChBac. When expressed in mammalian cell lines, both Na(V)PZ and Na(V)SP were Na(+)-selective and voltage-dependent. However, their kinetics and voltage dependence differ significantly. These single six-alpha-helical transmembrane-spanning subunits constitute a widely distributed superfamily (Na(V)Bac) of channels in bacteria, implying a fundamental prokaryotic function. The degree of sequence homology (22-54%) is optimal for future comparisons of Na(V)Bac structure and function of similarity and dissimilarity among Na(V)Bac proteins. Thus, the Na(V)Bac superfamily is fertile ground for crystallographic, electrophysiological, and microbiological studies.

Genetics of isoprenoid biosynthesis in Paracoccuszeaxanthinifaciens

The genes coding for all the enzymes involved in the conversion of acetyl-CoA to farnesyl diphosphate (FPP) in the zeaxanthin-producing bacterium Paracoccus zeaxanthinifaciens were cloned and characterized. Two genes encoding enzymes catalysing the condensation of two acetyl-CoA molecules to acetoacetyl-CoA were found. The six enzymes involved in the conversion of acetyl-CoA and acetoacetyl-CoA to isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) are grouped in an operon, designated the mevalonate operon. The gene encoding the enzyme catalysing two consecutive condensations, IPP and DMAPP to geranyl diphosphate (GPP) and IPP and GPP to FPP, is not clustered with any other gene encoding an enzyme of the isoprenoid pathway. Genes encoding enzymes involved in the biosynthesis of poly-hydroxyalkanoate and non-carotenoid isoprenoids found in P. zeaxanthinifaciens are also presented.