Astaxanthin: Past, Present, and Future

Astaxanthin (AX), a lipid-soluble pigment belonging to the xanthophyll carotenoids family, has recently garnered significant attention due to its unique physical properties, biochemical attributes, and physiological effects. Originally recognized primarily for its role in imparting the characteristic red-pink color to various organisms, AX is currently experiencing a surge in interest and research. The growing body of literature in this field predominantly focuses on AXs distinctive bioactivities and properties. However, the potential of algae-derived AX as a solution to various global environmental and societal challenges that threaten life on our planet has not received extensive attention. Furthermore, the historical context and the role of AX in nature, as well as its significance in diverse cultures and traditional health practices, have not been comprehensively explored in previous works. This review article embarks on a comprehensive journey through the history leading up to the present, offering insights into the discovery of AX, its chemical and physical attributes, distribution in organisms, and biosynthesis. Additionally, it delves into the intricate realm of health benefits, biofunctional characteristics, and the current market status of AX. By encompassing these multifaceted aspects, this review aims to provide readers with a more profound understanding and a robust foundation for future scientific endeavors directed at addressing societal needs for sustainable nutritional and medicinal solutions. An updated summary of AXs health benefits, its present market status, and potential future applications are also included for a well-rounded perspective.

Heterologous Expression of the Plant-Derived Astaxanthin Biosynthesis Pathway in Yarrowia lipolytica for Glycosylated Astaxanthin Production

Astaxanthin is a high-value red pigment and antioxidant widely used in the pharmaceutical, cosmetic, and food industries. However, the hydrophobicity of astaxanthin causes its low bioavailability. Glycosylation can substantially increase the water solubility of astaxanthin, thus enhancing its bioavailability, photostability, and biological activities. In this study, we report for the first time the heterologous production of glycosylated astaxanthin in Yarrowia lipolytica. By appropriate removal of the chloroplast transit peptide, carotenoid 4-hydroxy-β-ring 4-dehydrogenase (HBFD) and carotenoid β-ring 4-dehydrogenase (CBFD) from Adonis aestivalis were expressed in a β-carotene-producing Y. lipolytica strain, resulting in astaxanthin production with a yield of 0.59 mg/L, 0.05 mg/g DCW. This is the first time to successfully construct a plant-derived astaxanthin synthesis pathway in yeast. Modularized assembly of CBFD and HBFD, replacement of the promoter upstream CBFD, increasing the precursor β-carotene supply, and regulating the expressions of CBFD and HBFD led to a 4.9-fold increase in astaxanthin production (3.46 mg/L). Finally, introduction of crtX from Pantoea ananatis ATCC 19321 into the astaxanthin-producing strain enabled glycosylated astaxanthin production, and the yield reached 1.47 mg/L, which is the highest yield of microbially produced glycosylated astaxanthin reported to date.

Transfer of Sphingorhabdus marina, Sphingorhabdus litoris, Sphingorhabdus flavimaris and Sphingorhabdus pacifica corrig. into the novel genus Parasphingorhabdus gen. nov. and Sphingopyxis baekryungensis into the novel genus Novosphingopyxis gen. nov. within the family Sphingomonadaceae

During a phylogenetic analysis of Sphingorhabdus and its closely related genera in the family Sphingomonadaceae, we found that the genus Sphingorhabdus and the species Sphingopyxis baekryungensis might not be properly assigned in the taxonomy. Phylogenetic, phenotypic and chemotaxonomic characterizations clearly showed that the genus Sphingorhabdus should be reclassified into two genera (Clade I and Clade II), for which the original genus name, Sphingorhabdus, is proposed to be retained only for Clade I, and a new genus named as Parasphingorhabdus gen. nov. is proposed for Clade II with four new combinations: Parasphingorhabdus marina comb. nov., Parasphingorhabdus litoris comb. nov., Parasphingorhabdus flavimaris comb. nov. and Parasphingorhabdus pacifica comb. nov. Moreover, Sphingopyxis baekryungensis should represent a novel genus in the family Sphingomonadaceae, for which the name Novosphingopyxis gen. nov. is proposed, with a combination of Novosphingopyxis baekryungensis comb. nov. The study provides a new insight into the taxonomy of closely related genera in the family Sphingomonadaceae.

Draft Genome Sequence of KCTC 12630, the Type Strain of the Novel Species Sphingomonas ginsengisoli

We report here the draft genome sequence of Sphingomonas ginsengisoli KCTC 12630^T. The draft genome has a size of 3,045,889 bp and a G+C content of 67.1%.

We report here the draft genome sequence of Sphingomonas ginsengisoli KCTC 12630^T. The draft genome has a size of 3,045,889 bp and a G+C content of 67.1%. The availability of the genome sequence will provide a better understanding of strain KCTC 12630^T and the genus Sphingomonas.

Sphingomonas floccifaciens sp. nov., isolated from subterranean sediment

A Gram-stain-negative, non-motile, non-sporulating, rod-shaped, orange-pigmented bacterium, designated strain FQM01^T, was isolated from a subterranean sediment sample in the Mohe permafrost area, China. Strain FQM01^T grew optimally at 25 °C, pH 7.0 and NaCl concentration of 0 % (w/v). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain FQM01^T belonged to the genus Sphingomonas. The closest phylogenetic relative was Sphingomonas spermidinifaciens GDMCC 1.657^T (97.6 %), followed by Sphingomonas mucosissima DSM 17494^T (97.2 %). The DNA G+C content of the isolate was 66.9 mol%. Strain FQM01^T contained Q-10 as the predominant ubiquinone, and C18 : 1ω6c and/or C18 : 1ω7c, C16 : 1ω6c and/or C16 : 1ω7c, C16 : 0, C14 : 0 2-OH and C18 : 1ω7c 11 methyl as the major fatty acids. Major polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, sphingoglycolipid and an unidentified glycolipid. Only sym-homospermidine was detected as the polyamine. On the basis of phylogenetic and phenotypic data, strain FQM01^T is considered to represent a novel species of Sphingomonas for which the name Sphingomonasfloccifaciens sp. nov. is proposed. The type strain is FQM01^T (=CGMCC 1.15797^T=KCTC 52630^T).

Sphingomonas turrisvirgatae sp. nov., an agar-degrading species isolated from freshwater

A yellow pigmented and agar-pitting colony was isolated from a water sample obtained from a drainage ditch within a disused system of constructed wetlands. The strain was purified and named MCT13^T. This rod-shaped, Gram-negative, oxidase- and catalase-positive, aerobic, non-spore-forming, and non-motile strain formed round colonies and grew optimally at pH 7.5±0.2, at 28-30 °C on LB agar, with 0-0.5 % NaCl. The 16S rRNA gene sequence analysis placed the MCT13^T isolate within the Sphingomonas (sensu stricto) cluster. The DNA G+C content was 65.3 %. The only observed ubiquinone was Q10. The major fatty acids included C17 : 1ω6c and C18 : 1ω7c/C18 : 1ω6c. The major polar lipids were sphingoglycolipid, diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The major polyamine was spermidine. The 16S rRNA gene phylogenetic analysis performed on the whole sequence, showed the closest relative of MCT13^T to be Sphingomonas koreensis (98.52 %); however, there are several genotypic and phenotypic differences between the novel isolate and the type strain JSS26^T of S. koreensis. On the basis of these results, strain MCT13^T represents a novel species in the genus Sphingomonas, for which the name Sphingomonas turrisvirgatae sp. nov. is proposed. The type strain is MCT13^T (=DSM 105457^T=BAC RE RSCIC 7^T).

Genomewide characterisation of the genetic diversity of carotenogenesis in bacteria of the order Sphingomonadales

The order Sphingomonadales is a taxon of bacteria with a variety of physiological features and carotenoid pigments. Some of the coloured strains within this order are known to be aerobic anoxygenic phototrophs that contain characteristic photosynthesis gene clusters (PGCs). Previous work has shown that majority of the ORFs putatively involved in the biosynthesis of C₄₀ carotenoids are located outside the PGCs in these strains. The main purpose of this study was to understand the genetic basis for the various colour/carotenoid phenotypes of the strains of Sphingomonadales. Comparative analyses of the genomes of 41 strains of this order revealed that there were different patterns of clustering of carotenoid biosynthesis (crt) ORFs, with four ORF clusters being the most common. The analyses also revealed that co-occurrence of crtY and crtI is an evolutionarily conserved feature in Sphingomonadales and other carotenogenic bacteria. The comparisons facilitated the categorisation of bacteria of this order into four groups based on the presence of different crt ORFs. Yellow coloured strains most likely accumulate nostoxanthin, and contain six ORFs (group I: crtE, crtB, crtI, crtY, crtZ, crtG). Orange coloured strains may produce adonixanthin, astaxanthin, canthaxanthin and erythroxanthin, and contain seven ORFs (group II: crtE, crtB, crtI, crtY, crtZ, crtG, crtW). Red coloured strains may accumulate astaxanthin, and contain six ORFs (group III: crtE, crtB, crtI, crtY, crtZ, crtW). Non-pigmented strains may contain a smaller subset of crt ORFs, and thus fail to produce any carotenoids (group IV). The functions of many of these ORFs remain to be characterised.

Moss habitats distinctly affect their associated bacterial community structures as revealed by the high-throughput sequencing method

To better understand the factors that influence the distribution of bacteria associated with mosses, the communities inhabiting in five moss species from two different habitats in Beijing Songshan National Nature Reserve were investigated using the high-throughput sequencing method. The sequencing was performed based on the bacterial 16S rRNA and 16S rDNA libraries. Results showed that there are abundant bacteria inhabiting in all the mosses sampled. The taxonomic analysis of these bacteria showed that they mainly consisted of those in the phyla Proteobacteria and Actinobacteria, and seldom were from phylum Armatimonadetes, Bacteroidetes and Firmicutes. The hierarchical cluster tree, based on the OTU level, divided the bacteria associated with all samples into two branches according to the habitat types of the host (terrestrial and aquatic). The PCoA diagram further divided the bacterial compositions into four groups according to both types of habitats and the data sources (DNA and RNA). There were larger differences in the bacterial community composition in the mosses collected from aquatic habitat than those of terrestrial one, whether at the DNA or RNA level. Thus, this survey supposed that the habitat where the host was growing was a relevant factor influencing bacterial community composition. In addition, the bacterial community detected at the RNA level was more sensitive to the habitat of the growing host, which could also be proved by the significantly differences in the predicted function by PICRUSt and the metabolically active dominant genera between different groups. This study expands the knowledge about the interactions between mosses and microbes.

Sphingomonas jeddahensis sp. nov., isolated from Saudi Arabian desert soil

A novel Sphingomonas strain was isolated from a sample of desert soil collected near Jeddah in Saudi Arabia. A polyphasic approach was performed to characterize this strain, initially designated as G39^T. Cells of strain G39^T are motile, Gram-negative, catalase- and oxidase-positive. The strain is able to grow aerobically at 20-35 °C, pH 6.5-8 and tolerates up to 4 % (w/v) NaCl. Based on 16S rRNA gene sequence similarity, the closest relative type strains of G39^T are Sphingomonas mucosissima DSM 17494^T (98.6 %), S. dokdonensis DSM 21029^T (98.4 %) and S. hankookensis DSM 23329^T (97.4 %). Furthermore, the average nucleotide identities between the draft genome sequence of strain G39^T and the genome sequences of all other available and related Sphingomonas species are significantly below the threshold of 94 %. The G+C content of the draft genome (3.12 Mbp) is 65.84 %. The prevalent (>5 %) cellular fatty acids of G39^T were C18 : 1ω7c, C16 : 1ω7c and/or C16 : 1ω6c, C14 : 0 2-OH and C16 : 0. The only detectable respiratory quinone was ubiquinone-10 and the polar lipids profile is composed of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, sphingoglycolipid, as well as unidentified lipids, phospholipids and glycolipids. The results of the conducted polyphasic approach confirmed that this isolate represents a novel species of the genus Sphingomonas, for which the name Sphingomonas jeddahensis sp. nov. is proposed. The type strain of this species is G39^T (=DSM 103790^T=LMG 29955^T).

Sphingomonas montana sp. nov., isolated from a soil sample from the Tanggula Mountain in the Qinghai Tibetan Plateau

An orange pigmented, Gram-staining negative, aerobic, motile, rod-shaped bacterium isolated from a soil from the Tanggula Mountain, China was studied using a polyphasic approach. Based on 16S rRNA gene sequence similarity, strain W16RD^T was found to be closely related to Sphingomonas prati DSM 103336^T (99%), Sphingomonas fennica DSM 13665^T (97.21%), followed by Sphingomonas laterariae DSM 25432^T (96.44%), Sphingomonas haloaromaticamans CGMCC 1.10206 ^T (96.36%) and Sphingomonas formosensis DSM 24164^T (96.06%). The strain was found to be catalase and oxidase positive and was found to grow optimally at temperatures of 20-25 °C, pH 8 and tolerated NaCl concentration up to 1% (w/v). The major fatty acids identified were summed feature eight comprising C_18:1 ω 7c and/or C_18:1 ω 6c (39.2%), summed feature three comprising of C_16:1 ω7c and/or C_16:1 ω6c (36.7%) and C_16:0 (7.0%). The polar lipids detected were phosphatidylcholine, sphingoglycolipid, phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, phosphatidyldimethylethanolamine, phosphatidylmonomethylethanolamine, and three unidentified lipids. The strain possessed ubiquinone-10 (Q-10) as the predominant respiratory quinone. Along with other distinguishing characteristics, we also describe the draft genome of strain W16RD^T. The final assembled draft genome sequence is 3,722,743 bp with 3390 coding and 48 RNA (45 tRNA and 3 rRNA) genes. The DNA G+C content of the genomic DNA was determined to be 67%. The DNA-DNA relatedness value between the strain W16RD^T and its closest phylogenetic relatives S. prati DSM 103336^T, S. fennica DSM 13665^T, S. laterariae DSM 25432^T, and S. haloaromaticamans CGMCC 1.10206^T were 52.17, 47.60, 20.93 and 17.09% respectively. The strain W16RD^T could be distinguished genotypically and phenotypically from the recognized species belonging to the genus Sphingomonas and thus represents a novel species, for which the name Sphingomonas montana sp. nov. is proposed. The type strain is W16RD^T (=CGMCC 1.15646^T = DSM 103337^T).

Comparative analysis of bacteria associated with different mosses by 16S rRNA and 16S rDNA sequencing

To understand the differences of the bacteria associated with different mosses, a phylogenetic study of bacterial communities in three mosses was carried out based on 16S rDNA and 16S rRNA sequencing. The mosses used were Hygroamblystegium noterophilum, Entodon compressus and Grimmia montana, representing hygrophyte, shady plant and xerophyte, respectively. In total, the operational taxonomic units (OTUs), richness and diversity were different regardless of the moss species and the library level. All the examined 1183 clones were assigned to 248 OTUs, 56 genera were assigned in rDNA libraries and 23 genera were determined at the rRNA level. Proteobacteria and Bacteroidetes were considered as the most dominant phyla in all the libraries, whereas abundant Actinobacteria and Acidobacteria were detected in the rDNA library of Entodon compressus and approximately 24.7% clones were assigned to Candidate division TM7 in Grimmia montana at rRNA level. The heatmap showed the bacterial profiles derived from rRNA and rDNA were partly overlapping. However, the principle component analysis of all the profiles derived from rDNA showed sharper differences between the different mosses than that of rRNA-based profiles. This suggests that the metabolically active bacterial compositions in different mosses were more phylogenetically similar and the differences of the bacteria associated with different mosses were mainly detected at the rDNA level. Obtained results clearly demonstrate that combination of 16S rDNA and 16S rRNA sequencing is preferred approach to have a good understanding on the constitution of the microbial communities in mosses.

Sphingomonaszeicaulis sp. nov., an endophytic bacterium isolated from maize root

A novel Gram-staining-negative, aerobic and rod-shaped strain designated 541T was isolated from surface-sterilized root tissue of maize, collected from the Fangshan District of Beijing, People's Republic of China, and was subjected to a taxonomic study using a polyphasic approach. According to a phylogenetic tree based on 16S rRNA gene sequences, strain 541T represented a member of the genus Sphingomonas and clustered with Sphingomonas sanxanigenens DSM 19645T, with which it shared the highest 16S rRNA gene sequence similarity (98.8 %). The predominant respiratory quinone was ubiquinone-10 (Q-10), the major polyamine was sym-homospermidine and the major cellular fatty acids were C18 : 1ω7c (50.9 %), C16 : 0 (22.0 %) and C14 : 0 2-OH (11.4 %). The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine and sphingoglycolipid. The DNA G+C content was 64.7 mol%. DNA-DNA relatedness between strain 541T and its closest phylogenetic relative Sphingomonas sanxanigenens DSM 19645T was 50.8 %. The results of physiological and biochemical tests and the differences in the fatty acid profiles allowed a clear phenotypic differentiation of strain 541T from closely related species of the genus Sphingomonas. Strain 541T represents a novel species within the genus Sphingomonas, for which the nameSphingomonas zeicaulis sp. nov. is proposed, with the type strain 541T (=CGMCC 1.15008T=DSM 100587T).