Blue Biotechnology: Marine Bacteria Bioproducts

The ocean is the habitat of a great number of organisms with different characteristics. Compared to terrestrial microorganisms, marine microorganisms also represent a vast and largely unexplored reservoir of bioactive compounds with diverse industrial applications like terrestrial microorganisms. This review examines the properties and potential applications of products derived from marine microorganisms, including bacteriocins, enzymes, exopolysaccharides, and pigments, juxtaposing them in some cases against their terrestrial counterparts. We discuss the distinct characteristics that set marine-derived products apart, including enhanced stability and unique structural features such as the amount of uronic acid and sulfate groups in exopolysaccharides. Further, we explore the uses of these marine-derived compounds across various industries, ranging from food and pharmaceuticals to cosmetics and biotechnology. This review also presents a broad description of biotechnologically important compounds produced by bacteria isolated from marine environments, some of them with different qualities compared to their terrestrial counterparts.

Fluctibacter corallii gen. nov., sp. nov., isolated from the coral Montipora capitata on a reef in Kāne'ohe Bay, O'ahu, Hawai'i, reclassification of Aestuariibacter halophilus as Fluctibacter halophilus comb. nov., and Paraglaciecola oceanifecundans as a later heterotypic synonym of Paraglaciecola agarilytica

Strain AA17T was isolated from an apparently healthy fragment of Montipora capitata coral from the reef surrounding Moku o Lo'e in Kāne'ohe Bay, O'ahu, Hawai'i, USA, and was taxonomically evaluated using a polyphasic approach. Comparison of a partial 16S rRNA gene sequence found that strain AA17T shared the greatest similarity with Aestuariibacter halophilus JC2043T (96.6%), and phylogenies based on 16S rRNA gene sequences grouped strain AA17T with members of the Aliiglaciecola, Aestuariibacter, Lacimicrobium, Marisediminitalea, Planctobacterium, and Saliniradius genera. To more precisely infer the taxonomy of strain AA17T, a phylogenomic analysis was conducted and indicated that strain AA17T formed a monophyletic clade with A. halophilus JC2043T, divergent from Aestuariibacter salexigens JC2042T and other related genera. As a result of monophyly and multiple genomic metrics of genus demarcation, strain AA17T and A. halophilus JC2043T comprise a distinct genus for which the name Fluctibacter gen. nov. is proposed. Based on a polyphasic characterisation and identifying differences in genomic and taxonomic data, strain AA17T represents a novel species, for which the name Fluctibacter corallii sp. nov. is proposed. The type strain is AA17T (= LMG 32603 T = NCTC 14664T). This work also supports the reclassification of A. halophilus as Fluctibacter halophilus comb. nov., which is the type species of the Fluctibacter genus. Genomic analyses also support the reclassification of Paraglaciecola oceanifecundans as a later heterotypic synonym of Paraglaciecola agarilytica.

Alteromonas arenosi sp. nov., a novel bioflocculant-producing bacterium, isolated from intertidal sand

A novel Gram-stain-negative, strictly aerobic and bioflocculant-producing bacterium, designated as ASW11-36T, was isolated from an intertidal sand collected from coastal areas of Qingdao, PR China. Growth occurred at 15-40 °C (optimum, 30 °C), pH 7.0-9.0 (optimum, pH 7.5) and with 1.5-7.0% (w/v) NaCl (optimum, 2.5-3.0%). In the whole-cell fatty acid pattern prevailed C16:0 and summed feature 3 (C16:1 ω7c and/or C16:1 ω6c). The major isoprenoid quinone was determined to be Q-8 and the major polar lipids were phosphatidylethanolamine (PE) and phosphatidylglycerol (PG), one unidentified aminolipid (AL), one unidentified glycolipid (GL), and two lipids (L1, L2). Based on the phylogenetic analyses of 16S rRNA gene sequences and 618 single-copy orthologous clusters, strain ASW11-36T could represent a novel member of the genus Alteromonas and was closely related to Alteromonas flava P0211T (98.4%) and Alteromonas facilis P0213T (98.3%). The pairwise average nucleotide identity and digital DNA-DNA hybridization values of the ASW11-36T genome assembly against the closely related species genomes were 71.8% and 21.7%, respectively, that clearly lower than the proposed thresholds for species. Based on phenotypic, phylogenetic, and chemotaxonomic analyses, strain ASW11-36T is considered to represent a novel species of the genus Alteromonas, for which the name Alteromonas arenosi sp. nov. is proposed. The type strain is ASW11-36T (= KCTC 82496T = MCCC 1K05585T). In addition, the strain yielded 65% of flocculating efficiency in kaolin suspension with CaCl2 addition. The draft genome of ASW11-36T shared abundant putative CAZy family related genes, especially involved in the biosynthesis of exopolysaccharides, implying its potential environmental and biological applications.

Alteromonas gilva sp. nov. and Erythrobacter fulvus sp. nov., isolated from a tidal mudflat

Strains chi3T and sf7T were collected from a tidal mudflat around Dongmak beach in Ganghwa, Republic of Korea. Both strains were Gram-stain-negative, aerobic or facultatively anaerobic, and rod-shaped. Results of phylogenetic tree analysis based on 16S rRNA and whole-genome sequences suggested that strains chi3T and sf7T belong to the genera Alteromonas and Erythrobacter, respectively. The cells of strain chi3T were non-motile and grew at 15-45 °C (optimum, 38 °C), at pH 6.0-10.0 (optimum, pH 8.0) and in the presence of 0-9.0 % (w/v) NaCl (optimum, 2.0 %). The cells of strain sf7T were motile as they had flagella and grew at 20-48 °C (optimum, 38 °C), at pH 6.0-10.0 (optimum, pH 9.0) and in the presence of 0-5.0 % (w/v) NaCl (optimum, 1.0 %). Strains chi3T and sf7T have average nucleotide identity values (70.0-70.4% and 78.9-81.7 %) and digital DNA-DNA hybridization values (21.8-22.3% and 21.0-25.6 %) with reference strains in the genera Alteromonas and Erythrobacter, respectively. Data from digital DNA-DNA hybridization, as well as phylogenetic, biochemical and physiological analyses, indicated the distinction of the two strains from the genera Alteromonas and Erythrobacter, respectively, and we thus propose the names Alteromonas gilva sp. nov. (type strain chi3T=KACC 22866T=TBRC 16612T) and Erythrobacter fulvus sp. nov. (type strain sf7T=KACC 22865T=TBRC 16611T).

Alteromonas salexigens sp. nov., isolated from coastal seawater

A Gram-negative, aerobic, short rod-shaped bacterium, designated ASW11-19T, was isolated from a coastal seawater sample of the Yellow Sea, PR China. Strain ASW11-19T grew optimally at 37 °C, 3.0-5.0% (w/v) NaCl and pH 7.5. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that strain ASW11-19T belonged to the genus Alteromonas and most closely related to Alteromonas profundi 345S023T and Alteromonas fortis 1T (98.4%, both). The draft genome was 3.55 Mb with 3150 protein-coding genes, 18 contigs, and a DNA G+C content was 44.4%. The digital DNA-DNA hybridization and average nucleotide identity values were below the species-delineating thresholds. The major fatty acids were summed feature 3 (C16:1ω7c/C16:1ω6c), summed feature 8 (C18:1ω7c/C18:1ω6c), and C16:0. The sole respiratory quinone was ubiquinone 8. The polar lipids were phosphatidylethanolamine, phosphatidylglycerol, phospholipid, and two unidentified lipids. Based on these genomic data, phenotypic and chemotaxonomic properties, strain ASW11-19T is considered to represent a novel species of the genus Alteromonas. The name Alteromonas salexigens sp.nov. is proposed for ASW11-19T (=MCCC 1K07239T=KCTC 92247T).

Description of three new Alteromonas species Alteromonas antoniana sp. nov., Alteromonas lipotrueae sp. nov. and Alteromonas lipotrueiana sp. nov. isolated from marine environments, and proposal for reclassification of the genus Salinimonas as Alteromonas

In the course of a bioprospective study of marine prokaryotes for cosmetic purposes, four strains, MD_567^T, MD_652^T, MD_674 and PS_109^T, were isolated that 16S rRNA gene affiliation indicated could represent three new species within the family Alteromonadaceae. A thorough phylogenetic, genomic and phenotypic taxonomic study confirmed that the isolates could be classified as three new taxa for which we propose the names Alteromonas antoniana sp. nov., Alteromonas lipotrueae sp. nov. and Alteromonas lipotrueiana sp. nov. In addition, the consistent monophyletic nature of the members of the genera Alteromonas and Salinimonas showed that both taxa should be unified, and therefore we also propose the reclassification of the genus Salinimonas within Alteromonas, as well as new combinations for the species of the former. As the specific epithets profundi and sediminis are already used for Alteromonas species, we created the nomina nova "Alteromonas alteriprofundi" nom. nov. and Alteromonas alterisediminis nom. nov. to accommodate the new names for "Salinimonas profundi" and Salinimonas sediminis. Whole genome comparisons also allowed us to detect the unexpected codification of aromatic hydrocarbon biodegradative compounds, such as benzoate and catechol, whose activity was then demonstrated phenotypically. Finally, the high genomic identity between the type strains of Alteromonas stellipolaris and Alteromonas addita indicated that the latter is a junior heterotypic synonym of Alteromonas stellipolaris.

A Novel Broad Host Range Phage Infecting Alteromonas

Bacteriophages substantially contribute to bacterial mortality in the ocean and play critical roles in global biogeochemical processes. Alteromonas is a ubiquitous bacterial genus in global tropical and temperate waters, which can cross-protect marine cyanobacteria and thus has important ecological benefits. However, little is known about the biological and ecological features of Alteromonas phages (alterophages). Here, we describe a novel alterophage vB_AmeP-R8W (R8W), which belongs to the Autographiviridae family and infects the deep-clade Alteromonas mediterranea. R8W has an equidistant and icosahedral head (65 ± 1 nm in diameter) and a short tail (12 ± 2 nm in length). The genome size of R8W is 48,825 bp, with a G + C content of 40.55%. R8W possesses three putative auxiliary metabolic genes encoding proteins involved in nucleotide metabolism and DNA binding: thymidylate synthase, nucleoside triphosphate pyrophosphohydrolase, and PhoB. R8W has a rapid lytic cycle with a burst size of 88 plaque-forming units/cell. Notably, R8W has a wide host range, such that it can infect 35 Alteromonas strains; it exhibits a strong specificity for strains isolated from deep waters. R8W has two specific receptor binding proteins and a compatible holin-endolysin system, which contribute to its wide host range. The isolation of R8W will contribute to the understanding of alterophage evolution, as well as the phage-host interactions and ecological importance of alterophages.

Alteromonas ponticola sp. nov., a gammaproteobacterium isolated from seawater

A Gram-stain-negative, aerobic, non-spore-forming, non-motile and ovoid or rod-shaped bacterial strain, MYP5T, was isolated from seawater in Jeju island of South Korea. MYP5T grew optimally at 30–35 °C and in the presence of 2.0 % (w/v) NaCl. A neighbour-joining phylogenetic tree based on 16S rRNA gene sequences revealed that MYP5T fell within the clade enclosed by the type strains of species of the genus Alteromonas , clustering with the type strains of Alteromonas confluentis and Alteromonas halophila . MYP5T exhibited the highest 16S rRNA gene sequence similarity value (98.0 %) to the type strain of A. confluentis and similarities of 95.1–97.9 % to the type strains of the other species of the genus Alteromonas . ANI and dDDH values of genomic sequences between MYP5T and the type strains of 22 species of the genus Alteromonas were 66.8–70.5 % and 18.6–27.5 %, respectively. The DNA G+C content of MYP5T, determined from the genome sequence, was 46.1 %. MYP5T contained Q-8 as the predominant ubiquinone and C18 : 1 ω7c, summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), C16 : 0 and 10-methyl C17 : 0 as the major fatty acids. The major polar lipids of MYP5T were phosphatidylethanolamine and phosphatidylglycerol. Distinguishing phenotypic properties, along with the phylogenetic and genetic distinctiveness, revealed that MYP5T is separated from species of the genus Alteromonas . On the basis of the data presented, MYP5T is considered to represent a novel species of the genus Alteromonas , for which the name Alteromonas ponticola sp. nov. is proposed. The type strain is MYP5T (=KCTC 82144T=NBRC 114354T).

Alteromonas portus sp. nov., an alginate lyase-excreting marine bacterium

An alginate lyase-excreting bacterium, designated strain HB161718T, was isolated from coastal sand collected from Tanmen Port in Hainan, PR China. Cells were Gram-stain-negative rods and motile with a single polar flagellum. Its major isoprenoid quinone was ubiquinone 8 (Q-8), and its cellular fatty acid profile mainly consisted of C16 : 1 ω7c and/or C16 : 1 ω6c, C18 : 1 ω6c and/or C18 : 1 ω7c, C16 : 0, C17 : 0 10-methyl and C16 : 0 N alcohol. The G+C content of the genomic DNA was 44.1 mol%. 16S rRNA gene sequence analysis suggested that strain HB161718T belonged to the genus Alteromonas , sharing 99.5, 99.4, 99.2, 98.9 and 98.5 % sequence similarities to its closest relatives, Alteromonas macleodii JCM 20772T, Alteromonas gracilis 9a2T, Alteromonas australica H17T, Alteromonas marina SW-47T and Alteromonas mediterranea DET, respectively. The low values of DNA–DNA hybridization and average nucleotide identity showed that it formed a distinct genomic species. The combined phenotypic and molecular features supported the conclusion that strain HB161718T represents a novel species of the genus Alteromonas , for which the name Alteromonas portus sp. nov. is proposed. The type strain is HB161718T (=CGMCC 1.13585T=JCM 32687T).

Marisediminitalea mangrovi gen. nov., sp. nov., isolated from marine mangrove sediment, and reclassification of Aestuariibacter aggregatus as Marisediminitalea aggregata comb. nov

Strain GS-14^T was isolated from a mangrove sediment sample collected at Beilun Estuary National Nature Reserve, Guangxi Province, PR China. Cells were Gram-stain-negative, strictly aerobic and rod-shaped with a polar flagellum. Optimal growth occurred in the presence of 3-6 % (w/v) NaCl, at pH 6-8 and at a temperature of 37 °C. The predominant polar lipids were phosphatidylglycerol and phosphatidylethanolamine. Ubiquinone 8 (Q-8) was the sole respiratory quinone. The major fatty acids (>10 % of the total fatty acids) were summed feature 3 (C_16 : 1ω7c and/or C_16 : 1ω6c) and C_16 : 0. The DNA G+C content was 47.6 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain GS-14^T had the highest sequence similarity to Aestuariibacter aggregatus WH169^T (96.63 %), Aliiglaciecola coringensis AK49^T (96.56 %) and Alteromonas lipolytica JW12^T (96.22 %). In addition, the OrthoANIu value and dDDH values calculated from the genomes of strain GS-14^T and A. aggregatus WH169^T were 79.5 and 21.9 %, respectively. Based on the polyphasic taxonomic results, strain GS-14^T is considered to represent a novel species in a new genus, for which the name Marisediminitalea mangrovi gen. nov., sp. nov. is proposed. The type strain of Marisediminitalea mangrovi is GS-14^T (=KCTC 72401^T=MCCC 1K03622^T). Because Aestuariibacter aggregatus WH169^T clustered with strain GS-14^T in the phylogenetic trees and was clearly separated from the two species within the genus Aestuariibacter, it is reclassified as a member of the genus Marisediminitalea as Marisediminitalea aggregata comb. nov. (type strain WH169^T=CGMCC 1.8995^T=LMG 25283^T). The type species of the genus Marisediminitalea is Marisediminitalea aggregata gen. nov., comb. nov.

Saliniradius amylolyticus gen. nov., sp. nov., isolated from solar saltern sediment

A novel non-pigmented, Gram-stain-negative, motile by means of a polar flagellum, aerobic and rod-shaped bacterium, designated HMF8227^T, was isolated from solar saltern sediment sampled at Shinan, Republic of Korea. The isolate was able to grow at 15-42 °C (optimum, 37 °C), at pH 6-8 (pH 7) and with 0.5-12 % NaCl (2-5 %). Strain HMF8227^T was positive for hydrolysis of starch and dextrin. 16S rRNA gene sequence analysis revealed that strain HMF8227^T was affiliated with the family Alteromonadaceae, sharing the highest sequence similarities to the genera Salinimonas (93.0-94.4 %), Aestuariibacter (92.0-94.2 %), Alteromonas (92.0-93.6 %) and Lacimicrobium (93.6 %). In the phylogenetic trees, strain HMF8227^T formed an independent clade with Lacimicrobium alkaliphilum X13M-12^T. The major fatty acids were C_16 : 0, summed feature 3 (C_16 : 1 ω7c and/or C_16 : 1 ω6c) and summed feature 8 (C_18 : 1 ω7c and/or C_18 : 1 ω6c). The major respiratory quinone was ubiquinone-8 (Q-8). The major polar lipids are phosphatidylglycerol, phosphatidylethanolamine, one unidentified aminolipid and two unidentified glycolipids. The DNA G+C content of the genomic DNA was 52.1 mol%. On the basis of the polyphasic characterizations, strain HMF8227^T represents a novel species and genus within the family Alteromonadaceae, for which the name Saliniradius amylolyticus gen. nov., sp. nov. is proposed, with the type strain being HMF8227^T (=KCTC 62462^T =NBRC 113230^T).

The tellurite-reducing bacterium Alteromonas macleodii from a culture of the toxic dinoflagellate Prorocentrum foraminosum

The Alteromonas macleodii strain 2328 was isolated from a clonal culture of the toxic dinoflagellate Prorocentrum foraminosum. The strain exhibits a resistance to high K₂TeO₃ concentrations (2500 μg/mL). A study of the growth dynamics of the strain exposed to K₂TeO₃ has shown a longer lag phase and a reduced stationary phase compared to those during cultivation with no toxicant. The fatty acids profile is dominated by 16:1 (n-7), 16:0, 17:1, 15:0, 18:1 (n-7), and 17:0. The 2328 strain belongs to the Gammaproteobacteria and is related to the genus Alteromonas with 99-100% sequence similarity to some intra-genome allele variants (paralogues) of 16S rRNA from A. macleodii. A phylogenetic reconstruction (ML and NJ), based on HyHK amino acid sequences, has revealed that the analyzed 2328 strain forms a common cluster with A. macleodii strains. In the presented work, the ability of A. macleodii to reduce potassium tellurite to elemental tellurium has been recorded for the first time. Bacteria reduce potassium tellurite to Te (0), nanoparticles of which become distributed diffusely and in the form of electron-dense globules in cytoplasm. Large polymorphous metalloid crystals are formed in the extracellular space. Such feature of the A. macleodii strain 2328 makes it quite attractive for biotechnological application as an organism concentrating the rare metalloid.

Characterization and Genome Analysis of a Novel Alteromonas Phage JH01 Isolated from the Qingdao Coast of China

A novel Alteromonas phage JH01, with the host strain identified to be Alteromonas marina SW-47(T), was isolated from the Qingdao coast during the summer of 2017. Transmission electron microscopy analysis showed that phage JH01 can be categorized into the Siphoviridae family, with an icosahedral head of 62 ± 5 nm and a long contractile tail of 254 ± 10 nm. The bioinformatic analysis shows that this phage consists of a linear, double-stranded 46,500 bp DNA molecule with a GC content of 44.39%, and 58 ORFs with no tRNA genes. The ORFs are classified into four groups, including phage packaging, phage structure, DNA replication and regulation, and hypothetical protein. The phylogenetic tree, constructed using neighbor-joining analysis, shows that phage JH01 has altitudinal homology with some Vibrio and Pseudoalteromonas phage B8b. Comparative analysis reveals the high similarity between phage JH01 and phage B8b. Additionally, our study of phage JH01 provides useful information for further research on the interaction between Alteromonas phages and their hosts.

Alteromonas sediminis sp. nov., isolated from sediment in a sea cucumber culture pond

A novel strain, U0105^T, was isolated from marine sediment of the coast of Weihai, China. The bacterium was aerobic, Gram-stain-negative, oxidase-positive, catalase-positive, rod-shaped and motile. Growth was observed at salinities of 1.0-6.0 % (w/v) NaCl (optimum with 2.0-3.0 %), temperatures of 20-40 °C (optimum at 37 °C) and pH of 6.5-9.5 (optimum at pH 7.0-7.5). The isolate could not reduce nitrate to nitrite. It could hydrolyse starch and Tweens 20, 40 and 60, but not casein or cellulose. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain U0105^T belonged to the genus Alteromonas, with highest sequence similarity to Alteromonas aestuariivivens KCTC 52655^T (97.1 %). The average nucleotide identity value and the digital DNA-DNA hybridization value between strain U0105^T and A. aestuariivivens KCTC 52655^T were 69.2 % and 21.2 %, respectively. Strain U0105^T was found to contain Q-8 as the sole menaquinone and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16 : 0 and C18 : 1ω7c as the major fatty acids. The major polar lipids were identified as phosphatidylglycerol and phosphatidylethanolamine. The G+C content of the chromosomal DNA was 45.3 mol%. The combined genotypic and phenotypic data show that strain U0105^T represents a novel species of the genus Alteromonas, for which the name Alteromonas sediminis sp. nov. is proposed. The type strain is U0105^T (=KCTC 62080^T=MCCC 1H00299^T).

Polyunsaturated fatty acids in marine bacteria and strategies to enhance their production

Polyunsaturated fatty acids (PUFAs) play an important role in human diet. Despite the wide-ranging importance and benefits from heart health to brain functions, humans and mammals cannot synthesize PUFAs de novo. The primary sources of PUFA are fish and plants. Due to the increasing concerns associated with food security as well as issues of environmental contaminants in fish oil, there has been considerable interest in the production of polyunsaturated fatty acids from alternative resources which are more sustainable, safer, and economical. For instance, marine bacteria, particularly the genus of Shewanella, Photobacterium, Colwellia, Moritella, Psychromonas, Vibrio, and Alteromonas, are found to be one among the major microbial producers of polyunsaturated fatty acids. Recent developments in the area with a focus on the production of polyunsaturated fatty acids from marine bacteria as well as the metabolic engineering strategies for the improvement of PUFA production are discussed.

Alteromonas naphthalenivorans sp. nov., a polycyclic aromatic hydrocarbon-degrading bacterium isolated from tidal-flat sediment

A Gram-staining-negative and halotolerant bacterium, designated SN2T, capable of biodegrading polycyclic aromatic hydrocarbons, was isolated from a tidal flat contaminated with crude oil in Korea. Cells were strictly aerobic, catalase- and oxidase-positive, motile rods, with a single polar flagellum. Growth was observed at 4–37 °C (optimum, 25–30 °C) at pH 6.0–9.0 (optimum, pH 7.0–7.5) and in the presence of 0.5–9.0 % (w/v) NaCl (optimum, 2.0 %). Only ubiquinone 8 was detected as the isoprenoid quinone, and summed feature 3 (comprising C16 : 1ω7c and/or iso-C15 : 0 2-OH), C16 : 0, C18 : 1ω7c and C12 : 0 were observed as the major cellular fatty acids. The major polar lipids consisted of phosphatidylethanolamine, phosphatidylglycerol, a glycolipid, an aminolipid and three unidentified lipids. The DNA G+C content was 43.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain SN2T formed a phylogenetic lineage with Alteromonas stellipolaris and Alteromonas addita within the genus Alteromonas, which was consistent with multilocus phylogenetic and MALDI-TOF MS analyses. Strain SN2T was most closely related to the type strains of A. stellipolaris, A. addita and Alteromonas macleodii, with 16S rRNA gene sequence similarities of 99.5, 99.3 and 98.4 % and DNA–DNA relatedness of 48.7 ± 6.6, 24.9 ± 7.5 and 27.9 ± 8.4 %, respectively. In conclusion, strain SN2T represents a novel species of the genus Alteromonas, for which the name Alteromonas naphthalenivorans sp. nov. is proposed. The type strain is SN2T ( = KCTC 11700BPT = JCM 17741T = KACC 18427T).