Supercritical carbon dioxide micronization of zeaxanthin from moderately thermophilic bacteria Muricauda lutaonensis CC-HSB-11T

Overproduction of Xanthophyll Pigment in Flavobacterium sp. JSWR-1 under Optimized Culture Conditions

Flavobacterium can synthesize xanthophyll, particularly the pigment zeaxanthin, which has significant economic value in nutrition and pharmaceuticals. Recently, the use of carotenoid biosynthesis by bacteria and yeast fermentation technology has shown to be very efficient and offers significant advantages in large-scale production, cost-effectiveness, and safety. In the present study, JSWR-1 strain capable of producing xanthophyll pigment was isolated from a freshwater reservoir in Wanju-gun, Republic of Korea. Based on the morphological, physiological, and molecular characteristics, JSWR-1 classified as belonging to the Flavobacterium species. The bacterium is strictly aerobic, Gram-negative, rod-shaped, and psychrophilic. The completed genome sequence of the strain Flavobacterium sp. JSWR-1 is predicted to be a single circular 3,425,829-bp chromosome with a G+C content of 35.2% and 2,941 protein-coding genes. The optimization of carotenoid production was achieved by small-scale cultivation, resulting in zeaxanthin being identified as the predominant carotenoid pigment. The enhancement of zeaxanthin biosynthesis by applying different light-irradiation, variations in pH and temperature, and adding carbon and nitrogen supplies to the growth medium. A significant increase in intracellular zeaxanthin concentrations was also recorded during fed-batch fermentation achieving a maximum of 16.69 ± 0.71 mg/l, corresponding to a product yield of 4.05 ± 0.15 mg zeaxanthin per gram cell dry weight. Batch and fed-batch culture extracts exhibit significant antioxidant activity. The results demonstrated that the JSWR-1 strain can potentially serve as a source for zeaxanthin biosynthesis.

Symbiodiniaceae photophysiology and stress resilience is enhanced by microbial associations

Symbiodiniaceae form associations with extra- and intracellular bacterial symbionts, both in culture and in symbiosis with corals. Bacterial associates can regulate Symbiodiniaceae fitness in terms of growth, calcification and photophysiology. However, the influence of these bacteria on interactive stressors, such as temperature and light, which are known to influence Symbiodiniaceae physiology, remains unclear. Here, we examined the photophysiological response of two Symbiodiniaceae species (Symbiodinium microadriaticum and Breviolum minutum) cultured under acute temperature and light stress with specific bacterial partners from their microbiome (Labrenzia (Roseibium) alexandrii, Marinobacter adhaerens or Muricauda aquimarina). Overall, bacterial presence positively impacted Symbiodiniaceae core photosynthetic health (photosystem II [PSII] quantum yield) and photoprotective capacity (non-photochemical quenching; NPQ) compared to cultures with all extracellular bacteria removed, although specific benefits were variable across Symbiodiniaceae genera and growth phase. Symbiodiniaceae co-cultured with M. aquimarina displayed an inverse NPQ response under high temperatures and light, and those with L. alexandrii demonstrated a lowered threshold for induction of NPQ, potentially through the provision of antioxidant compounds such as zeaxanthin (produced by Muricauda spp.) and dimethylsulfoniopropionate (DMSP; produced by this strain of L. alexandrii). Our co-culture approach empirically demonstrates the benefits bacteria can deliver to Symbiodiniaceae photochemical performance, providing evidence that bacterial associates can play important functional roles for Symbiodiniaceae.

Muricauda chongwuensis sp. nov., isolated from coastal seawater of China

In the course of screening for bacterial predators, a Gram-stain-negative, non-flagellated, gliding, long rod-shaped, and yellow-pigmented bacterium, designated strain HICW^T, was isolated from coastal seawater of China. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain HICW^T represented a member of the genus Muricauda and showed the highest sequence similarity to M. aquimarina JCM11811^T (98.8%) and M. ruestringensis DSM13258^T (98.1%). The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain HICW^T and M. aquimarina JCM11811^T were 79.2% and 34.1%, respectively. NaCl was required for growth. Optimum growth occurred at 25-30 °C, 2.0-3.0% (w/v) NaCl with pH 7.0. Strain HICW^T showed some similar characteristics to the nonobligate bacterial predators, and the cells can attach to the prey cells. Strain HICW^T contained MK-6 as the predominant respiratory quinone and had iso-C_15:0, iso-C_15:1 G, and iso-C_17:0 3-OH as the major cellular fatty acids. The polar lipids contained phosphatidylethanolamine (PE), three unidentified phospholipids (PL1-PL3), one unidentified amino lipids (AL), and three unidentified polar lipids (L1-L3). The genome size of strain HICW^T was approximately 3.8 Mbp, with a G + C content of 41.4%. Based on the polyphasic evidence, strain HICW^T is proposed as representing a new species of the genus Muricauda, for which the name Muricauda chongwuensis sp. nov. is proposed. The type strain is HICW^T (= JCM 33643 ^T = MCCC 1K03769^T).

An Overview on Industrial and Medical Applications of Bio-Pigments Synthesized by Marine Bacteria

Marine bacterial species contribute to a significant part of the oceanic population, which substantially produces biologically effectual moieties having various medical and industrial applications. The use of marine-derived bacterial pigments displays a snowballing effect in recent times, being natural, environmentally safe, and health beneficial compounds. Although isolating marine bacteria is a strenuous task, these are still a compelling subject for researchers, due to their promising avenues for numerous applications. Marine-derived bacterial pigments serve as valuable products in the food, pharmaceutical, textile, and cosmetic industries due to their beneficial attributes, including anticancer, antimicrobial, antioxidant, and cytotoxic activities. Biodegradability and higher environmental compatibility further strengthen the use of marine bio-pigments over artificially acquired colored molecules. Besides that, hazardous effects associated with the consumption of synthetic colors further substantiated the use of marine dyes as color additives in industries as well. This review sheds light on marine bacterial sources of pigmented compounds along with their industrial applicability and therapeutic insights based on the data available in the literature. It also encompasses the need for introducing bacterial bio-pigments in global pigment industry, highlighting their future potential, aiming to contribute to the worldwide economy.

Ameliorating process parameters for zeaxanthin yield in Arthrobacter gandavensis MTCC 25325

The present study aims to escalate the production of prophylactic agent zeaxanthin using a screened potential bacterial isolate. For this purpose, a freshwater bacterium capable of producing zeaxanthin was isolated from Bor Talav, Bhavnagar. The 16S rRNA sequence confirmed the isolate as Arthrobacter gandavensis. The bacterium was also submitted to Microbial Type Culture Collection, CSIR-Institute of Microbial Technology, Chandigarh, India, with the accession number MTCC 25325. The chemo-metric tools were employed to optimise the influencing factors such as pH, temperature, inoculum size, agitation speed, carbon source and harvest time on zeaxanthin yield. Thereafter, six parameters were narrowed down to three factors and were optimised using the central composite design (CCD) matrix. Maximum zeaxanthin (1.51 mg/g) was derived when A. gandavensis MTCC 25325 was grown under pH 6.0, 1.5% (w/v) glucose and 10% (v/v) inoculum size. A high regression coefficient (R²= 0.92) of the developed model indicated the accurateness of the tested parameters. To the best of our knowledge, this is the first report on tailoring the process parameters using chemo-metric optimisation for escalating the zeaxanthin production by A. gandavensis MTCC 25325.

A Zeaxanthin-Producing Bacterium Isolated from the Algal Phycosphere Protects Coral Endosymbionts from Environmental Stress

Occupying less than 1% of the seas, coral reefs are estimated to harbor ∼25% of all marine species. However, the destruction of coral reefs has intensified in the face of global climate changes, such as rising seawater temperatures, which induce the overproduction of reactive oxygen species harmful to corals. Although reef-building corals form complex consortia with bacteria and photosynthetic endosymbiotic algae of the family Symbiodiniaceae, the functional roles of coral-associated bacteria remain largely elusive. By manipulating the Symbiodiniaceae bacterial community, we demonstrated that a bacterium that produces an antioxidant carotenoid could mitigate thermal and light stresses in cultured Symbiodiniaceae isolated from a reef-building coral. Therefore, this study illuminates the unexplored roles of coral-associated bacteria under stressful conditions.

Reef-building corals form a complex consortium with photosynthetic algae in the family Symbiodiniaceae and bacteria, collectively termed the coral holobiont. These bacteria are hypothesized to be involved in the stress resistance of the coral holobiont, but their functional roles remain largely elusive. Here, we show that cultured Symbiodiniaceae algae isolated from the reef-building coral Galaxea fascicularis are associated with novel bacteria affiliated with the family Flavobacteriaceae. Antibiotic treatment eliminated the bacteria from cultured Symbiodiniaceae, resulting in a decreased maximum quantum yield of PSII (variable fluorescence divided by maximum fluorescence [F_v/F_m]) and an increased production of reactive oxygen species (ROS) under thermal and light stresses. We then isolated this bacterial strain, named GF1. GF1 inoculation in the antibiotic-treated Symbiodiniaceae cultures restored the F_v/F_m and reduced the ROS production. Furthermore, we found that GF1 produces the carotenoid zeaxanthin, which possesses potent antioxidant activity. Zeaxanthin supplementation to cultured Symbiodiniaceae ameliorated the F_v/F_m and ROS production, suggesting that GF1 mitigates thermal and light stresses in cultured Symbiodiniaceae via zeaxanthin production. These findings could advance our understanding of the roles of bacteria in Symbiodiniaceae and the coral holobiont, thereby contributing to the development of novel approaches toward coral protection through the use of symbiotic bacteria and their metabolites.

Marine Bacteria versus Microalgae: Who Is the Best for Biotechnological Production of Bioactive Compounds with Antioxidant Properties and Other Biological Applications?

Natural bioactive compounds with antioxidant activity play remarkable roles in the prevention of reactive oxygen species (ROS) formation. ROS, which are formed by different pathways, have various pathological influences such as DNA damage, carcinogenesis, and cellular degeneration. Incremental demands have prompted the search for newer and alternative resources of natural bioactive compounds with antioxidant properties. The marine environment encompasses almost three-quarters of our planet and is home to many eukaryotic and prokaryotic microorganisms. Because of extreme physical and chemical conditions, the marine environment is a rich source of chemical and biological diversity, and marine microorganisms have high potential as a source of commercially interesting compounds with various pharmaceutical, nutraceutical, and cosmeceutical applications. Bacteria and microalgae are the most important producers of valuable molecules including antioxidant enzymes (such as superoxide dismutase and catalase) and antioxidant substances (such as carotenoids, exopolysaccharides, and bioactive peptides) with various valuable biological properties and applications. Here, we review the current knowledge of these bioactive compounds while highlighting their antioxidant properties, production yield, health-related benefits, and potential applications in various biological and industrial fields.

Draft Genome Sequences of Two Bacterial Strains, Muricauda sp. 72 and NH166, Isolated from the South China Sea and West Pacific Ocean

Here, we report the whole-genome sequences of two bacterial strains, Muricauda sp. 72 and NH166, isolated from the South China Sea and West Pacific Ocean, respectively. These two strains may represent a novel species of the genus Muricauda, and the features of their genome sequences will enrich our understandings of strains in the genus Muricauda.

Here, we report the whole-genome sequences of two bacterial strains, Muricauda sp. 72 and NH166, isolated from the South China Sea and West Pacific Ocean, respectively. These two strains may represent a novel species of the genus Muricauda, and the features of their genome sequences will enrich our understandings of strains in the genus Muricauda.

Carotenoid Distribution in Nature

Carotenoids are naturally occurring red, orange and yellow pigments that are synthesized by plants and some microorganisms and fulfill many important physiological functions. This chapter describes the distribution of carotenoid in microorganisms, including bacteria, archaea, microalgae, filamentous fungi and yeasts. We will also focus on their functional aspects and applications, such as their nutritional value, their benefits for human and animal health and their potential protection against free radicals. The central metabolic pathway leading to the synthesis of carotenoids is described as the three following principal steps: (i) the synthesis of isopentenyl pyrophosphate and the formation of dimethylallyl pyrophosphate, (ii) the synthesis of geranylgeranyl pyrophosphate and (iii) the synthesis of carotenoids per se, highlighting the differences that have been found in several carotenogenic organisms and providing an evolutionary perspective. Finally, as an example, the synthesis of the xanthophyll astaxanthin is discussed.

Muricauda pacifica sp. nov., isolated from seawater of the South Pacific Gyre

A Gram-stain-negative, strictly aerobic, non-flagellated, non-gliding, oxidase- and catalase-positive, rod-shaped and orange-pigmented bacterium with appendages, designated strain SW027T, was isolated from a surface seawater sample collected from the South Pacific Gyre (26° 29′ S 137° 56′ W) during the Integrated Ocean Drilling Program (IODP) Expedition 329. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SW027T shared the highest sequence similarity with members of the genus Muricauda (94.3–92.7 %), exhibiting 94.3 % sequence similarity to Muricauda flavescens SW-62T. Optimal growth occurred in the presence of 3 % (w/v) NaCl, at pH 7.0 and at 37 °C. The DNA G+C content of strain SW027T was 42.7 mol%. The major fatty acids were iso-C15 : 0, iso-C15 : 1 G and iso-C17 : 0 3-OH. The major respiratory quinone was menaquinone-6. The major polar lipids were phosphatidylethanolamine and two unidentified lipids. Enzymic activity profiles, cell morphology and DNA G+C content differentiated the novel bacterium from the most closely related members of the genus Muricauda. On the basis of the polyphasic analyses, strain SW027T is considered to represent a novel species of the genus Muricauda, for which the name Muricauda pacifica sp. nov. is proposed. The type strain is SW027T ( = JCM 17861T = LMG 26637T).

Gramella oceani sp. nov., a zeaxanthin-producing bacterium of the family Flavobacteriaceae isolated from marine sediment

A Gram-staining-negative, yellow-pigmented, strictly aerobic, zeaxanthin-producing, rod-shaped, non-endospore-forming, appendaged bacterial strain that exhibits gliding motility, designated CC-AMSZ-TT, was isolated from marine sediment off coastal Kending, Taiwan. Strain CC-AMSZ-TT shared 94.9 % and 96.7–94.1 % 16S rRNA gene sequence similarities with Gramella echinicola KMM 6050T and other species of the genus Gramella , respectively, and formed a distinct phyletic lineage in phylogenetic trees. The major (≥5 % of the total) fatty acids were C16 : 0, iso-C15 : 0, anteiso-C15 : 0, C16 : 1ω6c and/or C16 : 1ω7c and iso-C17 : 1ω9c and/or C16 : 0 10-methyl. Phosphatidylethanolamine, six unidentified lipids and three unidentified aminolipids were the polar lipid components. The DNA G+C content was 38.6 mol%. The predominant respiratory quinone was menaquinone-6 (MK-6). Based on the phylogenetic distinctiveness and distinguishing phenotypic characteristics, strain CC-AMSZ-TT represents a novel species of the genus Gramella , for which the name Gramella oceani sp. nov. is proposed. The type strain is CC-AMSZ-TT ( = JCM 18809T = BCRC 80547T).

Gramella planctonica sp. nov., a zeaxanthin-producing bacterium isolated from surface seawater, and emended descriptions of Gramella aestuarii and Gramella echinicola

A Gram-stain negative, strictly aerobic, zeaxanthin-producing, rod-shaped, non-spore-forming bacterial strain which is motile by gliding, designated CC-AMWZ-3(T), was isolated from surface seawater off coastal Kending, Taiwan. Strain CC-AMWZ-3(T) was found to share 93.3 % and 96.0-92.4 % pairwise 16S rRNA gene sequence similarity to Gramella echinicola KMM 6050(T) and other Gramella species, respectively, and formed distinct phyletic lineage during phylogenetic analysis. The major fatty acids were identified as C16:0, iso-C15:0, anteiso-C15:0, C16:1 ω6c and/or C16:1 ω7c and iso-C17:1 ω9c and/or C16:0 10-methyl. Polar lipids were found to include phosphatidylethanolamine, six unidentified lipids and three unidentified aminolipids. The DNA G+C content was determined to be 40.6 mol%. Menaquinone-6 was the sole respiratory quinone identified and triamine-sym-homospermidine was the predominant polyamine. Based on the polyphasic characteristics that are in line with those of Gramella species, in addition to distinguishing phylogenetic and phenotypic features, strain CC-AMWZ-3(T) appears to represent a novel species of the genus Gramella, for which the name Gramella planctonica sp. nov. (type strain CC-AMWZ-3(T) = JCM 18807(T) = BCRC 80553(T)) is proposed. In addition, emended descriptions of the species Gramella aestuarii and Gramella echinicola are also proposed.

Robertkochia marina gen. nov., sp. nov., of the family Flavobacteriaceae, isolated from surface seawater, and emended descriptions of the genera Joostella and Galbibacter

A Gram-staining-negative, orange-pigmented, strictly aerobic, carotenoid-producing, rod-shaped, non-flagellated, non-spore-forming bacterium, motile by gliding, designated strain CC-AMO-30DT, was isolated from surface seawater collected near Taichung harbour, Taiwan. Strain CC-AMO-30DT shared pairwise 16S rRNA gene sequence similarities of 94.8, 93.7 and 92.5 % with the type strains of the type species of the genera Joostella , Pustulibacterium and Galbibacter , respectively, and formed a distinct monophyletic lineage in phylogenetic trees. The major fatty acids (≥5 % of total) were iso-C15 : 1 G, iso-C15 : 0, iso-C17 : 0 3-OH, iso-C15 : 0 3-OH, iso-C16 : 0 and anteiso-C15 : 0. The polar lipid profile consisted of phosphatidylethanolamine, four unidentified lipids, two unidentified aminolipids and an unidentified phospholipid. The major polyamine was the triamine sym-homospermidine. The DNA G+C content was 47.1 mol% and the predominant respiratory quinone was menaquinone-6 (MK-6). Based on the phylogenetic distinctiveness and distinguishing phenotypic characteristics, strain CC-AMO-30DT represents a novel genus and species of the family Flavobacteriaceae , for which the name Robertkochia marina gen. nov., sp. nov. is proposed; the type strain of the type species Robertkochia marina is CC-AMO-30DT ( = JCM 18552T = BCRC 80469T). Emended descriptions of the genera Joostella and Galbibacter are also proposed.

Aquibacter zeaxanthinifaciens gen. nov., sp. nov., a zeaxanthin-producing bacterium of the family Flavobacteriaceae isolated from surface seawater, and emended descriptions of the genera Aestuariibaculum and Gaetbulibacter

A Gram-stain-negative, strictly aerobic, rod-shaped, non-flagellated, non-spore-forming and gliding marine bacterium, designated strain CC-AMZ-304(T), was isolated from coastal surface seawater near Taichung harbour, Taiwan. Strain CC-AMZ-304(T) predominantly synthesized zeaxanthin and thus formed yellow colonies on marine agar. The novel strain showed an unstable phylogenetic position, although sharing high pairwise 16S rRNA gene sequence similarities of 95.9-94.9, 95.7 and 95.1-93.9 % with Gaetbulibacter species (n = 4), Aestuariibaculum suncheonense SC17(T) and Bizionia species (n = 7), respectively. The polar lipid profile of strain CC-AMZ-304(T) consisted of phosphatidylethanolamine, five unidentified lipids, one unidentified phospholipid, two unidentified aminolipids and one unidentified glycolipid. The major (>5 % of the total) fatty acids were iso-C15 : 0, iso-C15 : 1 G, iso-C17 : 0 3-OH, iso-C15 : 0 3-OH and C15 : 1ω5c. The DNA G+C content was 36.0 mol%. Menaquinone-6 (MK-6) was the sole respiratory quinone and the major polyamine was triamine sym-homospermidine. Phylogenetic distinctiveness, unique polar lipid composition, presence of significant amounts of branched hydroxyl fatty acids (iso-C17 : 0 3-OH and iso-C15 : 0 3-OH) and a low amount of anteiso-C15 : 0, and several additional distinguishing biochemical features clearly discriminated strain CC-AMZ-304(T) from the type species of the genera Aestuariibaculum and Gaetbulibacter. Thus, based on data from the present polyphasic study, strain CC-AMZ-304(T) is considered to represent a novel species of a new genus within the family Flavobacteriaceae, for which the name Aquibacter zeaxanthinifaciens gen. nov., sp. nov. is proposed; the type strain of Aquibacter zeaxanthinifaciens is CC-AMZ-304(T) ( = JCM 18557(T) = BCRC 80463(T)). Emended descriptions of the genera Aestuariibaculum and Gaetbulibacter are also proposed.

Muricauda antarctica sp. nov., a marine member of the Flavobacteriaceae isolated from Antarctic seawater

A Gram-stain-negative, rod-shaped bacterium with appendages, designated Ar-22T, was isolated from a seawater sample collected from the western part of Prydz Bay, near Cape Darnley, Antarctica. Strain Ar-22T grew optimally at 35 °C, at pH 7.5 and in the presence of 1–3 % (w/v) NaCl. The isolate was positive for casein, gelatin and Tween 20 decomposition and negative for H2S production and indole formation. Chemotaxonomic analysis showed that MK-6 was the major isoprenoid quinone and phosphatidylethanolamine was the major polar lipid. The major fatty acids were iso-C17 : 0 3-OH, iso-C15 : 1 G, iso-C15 : 0 and C16 : 1ω7c/iso-C15 : 0 2OH. The genomic DNA G+C content was 44.8 mol%. Comparative 16S rRNA gene sequence analysis revealed that strain Ar-22T is closely related to members of the genus Muricauda , sharing 94.2–97.3 % sequence similarity with the type strains of species of the genus Muricauda and being most closely related to the Muricauda aquimarina . Phylogenetic analysis based on the 16S rRNA gene sequence comparison confirmed that strain Ar-22T formed a deep lineage with Muricauda flavescens . Sequence similarity between strain Ar-22T and Muricauda ruestringensis DSM 13258T, the type species of the genus Muricauda , was 96.9 %. Strain Ar-22T exhibited mean DNA–DNA relatedness values of 40.1 %, 49.4 % and 25.7 % to M. aquimarina JCM 11811T, M. flavescens JCM 11812T and Muricauda lutimaris KCTC 22173T, respectively. On the basis of phenotypic and genotypic data, strain Ar-22T represents a novel species of the genus Muricauda , for which the name Muricauda antarctica sp. nov. (type strain Ar-22T = CGMCC 1.12174T = JCM 18450T) is proposed.

Zeaxanthin production by novel marine isolates from coastal sand of India and its antioxidant properties

Zeaxanthin carotenoids are class of commercially important natural products and diverse biomolecules produced by plants and many microorganisms. Bacteria often produce a cocktail of polar and nonpolar carotenoids limiting their industrial applications. Marine members of the family Flavobacteriaceae are known to produce potential carotenoids such as astaxanthin and zeaxanthin. A few bacterial species have been reported for the predominant production zeaxanthin. Here, we report the molecular identification of the zeaxanthin as a major carotenoid produced by two novel bacteria (YUAB-SO-11 and YUAB-SO-45) isolated from sandy beaches of South West Coast of India and the effect of carbon sources on the production of zeaxanthin. The strains were identified based on the 16S rRNA gene sequencing as a member of genus Muricauda. The closest relatives of YUAB-SO-11 and YUAB-SO-45 were Muricauda aquimarina (JCM 11811(T)) (98.9 %) and Muricauda olearia (JCM 15563(T)) (99.2 %), respectively, indicating that both of these strains might represent a novel species. The highest level of zeaxanthin production was achieved (YUAB-SO-11, 1.20 ± 0.11 mg g(-1)) and (YUAB-SO-45, 1.02 ± 0.13 mg g(-1)) when cultivated in marine broth supplemented with 2 % NaCl (pH 7) and incubated at 30 °C. Addition of 0.1 M glutamic acid, an intermediate of citric acid cycle, enhanced the zeaxanthin production as 18 and 14 % by the strains YUAB-SO-11 and YUAB-SO-45 respectively. The zeaxanthin showed in vitro nitric oxide scavenging, inhibition of lipid peroxidation, and 2,2-diphenyl-1-picryl hydrazyl scavenging activities higher than the commercial zeaxanthin. The results of this study suggest that two novel strains YUAB-SO-11 and YUAB-SO-45 belonging to genus Muricauda produce zeaxanthin as a predominant carotenoid, and higher production of zeaxanthin was achieved on glutamic acid supplementation. The pigment showed good in vitro antioxidant activity, which can be exploited further for commercial applications.