Vibrio xiamenensis sp. nov., a cellulase-producing bacterium isolated from mangrove soil

Functional and Genomic Insights into the Biotechnological Potential of Vibrio spp. Isolated from Deeply Polluted and Pristine Environments

Vibrio spp. are remarkably diverse bacteria, being worthy of investigation not only for their antibiotic resistance and virulence, but also for their biotechnological potential. Indeed, there is increasing evidence that these bacteria display industrially relevant traits, particularly as producers of antimicrobial substances, tensioactive/emulsifying compounds, and enzymes. Here, our aim was to investigate the potential of Vibrio strains isolated from two different marine sources to produce such biotechnologically applicable substances. From the eighteen analyzed strains, five were isolated from plastic particles from a heavily polluted urban estuary and 13 from calcareous sponges inhabiting submarine caves in an isolated volcanic archipelago in the Atlantic Ocean. Enzymatic screening revealed that most strains were agarolytic and cellulolytic. Overall, six strains showed antimicrobial activity against Staphylococcus aureus ATCC 29,213, with four of them active towards Escherichia coli ATCC 25,922 as well. Additionally, eight strains were positive for the production of bioemulsifiers. Genomic analyses of four strains further revealed insights regarding the enzymatic arsenal, as shown by the detection of several key gene clusters pertaining to the chitin degradation pathway, and also encoding diverse classes of antimicrobial-active metabolites. Our findings highlight the biotechnological potential of Vibrio spp., evidencing their functional diversity and the need for continued and sustained prospecting of this bacterial genus to uncover its potential high-value-added bioproducts.

Emerging Research Topics in the Vibrionaceae and the Squid-Vibrio Symbiosis

The Vibrionaceae encompasses a cosmopolitan group that is mostly aquatic and possesses tremendous metabolic and genetic diversity. Given the importance of this taxon, it deserves continued and deeper research in a multitude of areas. This review outlines emerging topics of interest within the Vibrionaceae. Moreover, previously understudied research areas are highlighted that merit further exploration, including affiliations with marine plants (seagrasses), microbial predators, intracellular niches, and resistance to heavy metal toxicity. Agarases, phototrophy, phage shock protein response, and microbial experimental evolution are also fields discussed. The squid-Vibrio symbiosis is a stellar model system, which can be a useful guiding light on deeper expeditions and voyages traversing these "seas of interest". Where appropriate, the squid-Vibrio mutualism is mentioned in how it has or could facilitate the illumination of these various subjects. Additional research is warranted on the topics specified herein, since they have critical relevance for biomedical science, pharmaceuticals, and health care. There are also practical applications in agriculture, zymology, food science, and culinary use. The tractability of microbial experimental evolution is explained. Examples are given of how microbial selection studies can be used to examine the roles of chance, contingency, and determinism (natural selection) in shaping Earth's natural history.

Microbial diversity and ecological interactions of microorganisms in the mangrove ecosystem: Threats, vulnerability, and adaptations

Mangroves are among the world's most productive ecosystems and a part of the "blue carbon" sink. They act as a connection between the terrestrial and marine ecosystems, providing habitat to countless organisms. Among these, microorganisms (e.g., bacteria, archaea, fungi, phytoplankton, and protozoa) play a crucial role in this ecosystem. Microbial cycling of major nutrients (carbon, nitrogen, phosphorus, and sulfur) helps maintain the high productivity of this ecosystem. However, mangrove ecosystems are being disturbed by the increasing concentration of greenhouse gases within the atmosphere. Both the anthropogenic and natural factors contribute to the upsurge of greenhouse gas concentration, resulting in global warming. Changing climate due to global warming and the increasing rate of human interferences such as pollution and deforestation are significant concerns for the mangrove ecosystem. Mangroves are susceptible to such environmental perturbations. Global warming, human interventions, and its consequences are destroying the ecosystem, and the dreadful impacts are experienced worldwide. Therefore, the conservation of mangrove ecosystems is necessary for protecting them from the changing environment-a step toward preserving the globe for better living. This review highlights the importance of mangroves and their microbial components on a global scale and the degree of vulnerability of the ecosystems toward anthropic and climate change factors. The future scenario of the mangrove ecosystem and the resilience of plants and microbes have also been discussed.

Isolation and enzyme bioprospection of bacteria associated to Bruguiera cylindrica, a mangrove plant of North Sumatra, Indonesia

Mangrove-associated bacteria are of industrial interest due to their diverse and versatile enzyme properties. This study investigates the culturable bacteria from a wide range of habitat in a Bruguiera cylindrica mangrove ecosystem in North Sumatra. Screening of extracellular hydrolytic enzymes showed multiple potential traits in amylase, cellulase, chitinase, phosphatase, protease, and urease production by bacterial isolates. Molecular identification based on 16S rDNA region of a potential strain, Vibrio alginolyticus Jme3-20 is then reported as a newly proteolytic agent. The strain also showed a stable growth under salinity (NaCl) stress with considerable phosphate solubilization activities. Protease activity was enhanced by optimizing the 0.5 % (w/v) sucrose and soy peptone in the fermentation medium. SDS-PAGE and zymogram analysis showed the presence of a 35-kDa MW protease. Hence, our study revealed important insights into the bacterial diversity and activity in mangrove ecosystems, evidencing the importance of microbial exploration in this ecosystem.

Kaustia mangrovi gen. nov., sp. nov. isolated from Red Sea mangrove sediments belongs to the recently proposed Parvibaculaceae family within the order Rhizobiales

We isolated a novel strain, R1DC25T, described as Kaustia mangrovi gen. nov. sp. nov. from the sediments of a mangrove forest on the coast of the Red Sea in Saudi Arabia. This isolate is a moderately halophilic, aerobic/facultatively anaerobic Gram-stain-negative bacterium showing optimum growth at between 30 and 40 °C, at a pH of 8.5 and with 3-5 % NaCl. The genome of R1DC25T comprises a circular chromosome that is 4 630 536 bp in length, with a DNA G+C content of 67.3 mol%. Phylogenetic analyses based on the 16S rRNA gene sequence and whole-genome multilocus sequence analysis of 120 concatenated single-copy genes revealed that R1DC25T represents a distinct lineage within the family Parvibaculaceae in the order Rhizobiales within the class Alphaproteobacteria. R1DC25T showing 95.8, 95.3 and 94.5 % 16S rRNA gene sequence identity with Rhodoligotrophos appendicifer, Rhodoligotrophos jinshengii and Rhodoligotrophos defluvii, respectively. The predominant quinone was Q-10, and the polar lipids were phosphatidylglycerol, phosphatidylcholine, diphosphatidylglycerol, as well as several distinct aminolipids and lipids. The predominant cellular fatty acids were C19 : 0 cyclo ω8c, a combination of C18 : 1ω7c and/or C18 : 1ω6c and C16 : 0. On the basis of the differences in the phenotypic, physiological and biochemical characteristics from its known relatives and the results of our phylogenetic analyses, R1DC25T (=KCTC 72348T;=JCM 33619T;=NCCB 100699T) is proposed to represent a novel species in a novel genus, and we propose the name Kaustia mangrovi gen. nov., sp. nov. (Kaustia, subjective name derived from the abbreviation KAUST for King Abdullah University of Science and Technology; mangrovi, of a mangrove).

Genome-Wide Identification and Functional Characterization of β-Agarases in Vibrio astriarenae Strain HN897

The genus Vibrio is a genetically and metabolically versatile group of heterotrophic bacteria that are important contributors to carbon cycling within marine and estuarine ecosystems. HN897, a Vibrio strain isolated from the coastal seawater of South China, was shown to be agarolytic and capable of catabolizing D-galactose. Herein, we used Illumina and PacBio sequencing to assemble the whole genome sequence for the strain HN897, which was comprised of two circular chromosomes (Vas1 and Vas2). Genome-wide phylogenetic analysis with 140 other Vibrio sequences firmly placed the strain HN897 into the Marisflavi clade, with Vibrio astriarenae strain C7 being the closest relative. Of all types of carbohydrate-active enzyme classes, glycoside hydrolases (GH) were the most common in the HN897 genome. These included eight GHs identified as putative β-agarases belonging to GH16 and GH50 families in equal proportions. Synteny analysis showed that GH16 and GH50 genes were tandemly arrayed on two different chromosomes consistent with gene duplication. Gene knockout and complementation studies and phenotypic assays confirmed that Vas1_1339, a GH16_16 subfamily gene, exhibits an agarolytic phenotype of the strain. Collectively, these findings explained the agar-decomposing of strain HN897, but also provided valuable resources to gain more detailed insights into the evolution and physiological capability of the strain HN897, which was a presumptive member of the species V. astriarenae.

Vibrio zhugei sp. nov., a moderately halophilic bacterium isolated from pickling sauce

Strain HBUAS61001^T was isolated from the pickling sauce used to make a traditional fermented food product, datoucai, in China. The strain belonged to the genus Vibrio, but was placed in a clade separate from any known Vibrio species based on the 16S rRNA gene and MLSA results. The genome consisted of two chromosomes: chromosome I was 2 901 449 bp long with a G+C content of 45.4 mol%; and chromosome II was 1 107 930 bp long with a G+C content of 45.5 mol%. The most abundant fatty acids were C16 : 0 (28.1 %), summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c, 29.4 %) and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c, 10.1 %). The isoprenoid quinones detected were Q7 and Q8. The predominant polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. Strain HBUAS61001^T could grow in the presence of up to 17 % NaCl. The calculated average nucleotide identity and in silico DNA-DNA hybridization (GGDC) values of the strain against the closest related type strains were all lower than 95 and 70 %, respectively. Putative genes in the genome associated with survival under high salinity stress were identified. Based on whole genome sequence analysis and phenotypic characteristics, strain HBUAS61001^T is a new species in the genus Vibrio, and the name Vibrio zhugei (=GDMCC 1.1416^T=KCTC 62784^T) is proposed.

Microbial cellulases - Diversity & biotechnology with reference to mangrove environment: A review

Cellulose is an abundant natural biopolymer on earth, found as a major constituent of plant cell wall in lignocellulosic form. Unlike other compounds cellulose is not easily soluble in water hence enzymatic conversion of cellulose has become a key technology for biodegradation of lignocellulosic materials. Microorganisms such as aerobic bacteria, fungi, yeast and actinomycetes produce cellulase that degrade cellulose by hydrolysing the β-1, 4-glycosidic linkages of cellulose. In contrast to aerobic bacteria, anaerobic bacteria lack the ability to effectively penetrate into the cellulosic material which leads to the development of complexed cellulase systems called cellulosome. Among the different environments, the sediments of mangrove forests are suitable for exploring cellulose degrading microorganisms because of continuous input of cellulosic carbon in the form of litter which then acts as a substrate for decomposition by microbe. Understanding the importance of cellulase, the present article overviews the diversity of cellulolytic microbes from different mangrove environments around the world. The molecular mechanism related to cellulase gene regulation, expression and various biotechnological application of cellulase is also discussed.

Vibrio oceanisediminis sp. nov., a nitrogen-fixing bacterium isolated from an artificial oil-spill marine sediment

A Gram-staining-negative, halophilic, facultatively anaerobic, motile, rod-shaped and nitrogen-fixing bacterium, designated strain S37T, was isolated from an artificial oil-spill sediment sample from the coast of Taean, South Korea. Cells grew at 10–37 °C and pH 5.0–9.0, with optimal growth at 28 °C and pH 6.0–8.0. Growth was observed with 1–9 % (w/v) NaCl in marine broth, with optimal growth with 3–5 % NaCl, but no growth was observed in the absence of NaCl. According to the results of 16S rRNA gene sequence analysis, strain S37T represents a member of the genus Vibrio of the class Gammaproteobacteria and forms a clade with Vibrio plantisponsor MSSRF60T (97.38 %), Vibrio diazotrophicus ATCC 33466T (97.31 %), Vibrio aestuarianus ATCC 35048T (97.07 %) Vibrio areninigrae J74T (96.76 %) and Vibrio hispanicus LMG 13240T (96.76 %). The major fatty acids were C16 : 0, C16 : 1ω7c/C16 : 1ω6c and C18 : 1ω7c/C18 : 1ω6c. The DNA G+C content was 41.9 %. The DNA–DNA hybridization analysis results showed a 30.2 % association value with the closely related type strain V. plantisponsor DSM 21026T. On the basis of phenotypic and chemotaxonomic characteristics, strain S37T represents a novel species of the genus Vibrio, for which the name Vibrio oceanisediminis sp. nov., is proposed with the type strain S37T ( = KEMB 2255-005T = JCM 30409T).

Vibrio salilacus sp. nov., a new member of the Anguillarum clade with six alleles of the 16S rRNA gene from a saline lake

A Gram-stain-negative, catalase- and oxidase-positive, facultatively aerobic bacterium, strain DSG-S6T, was isolated from Dasugan Lake (salinity 3.1 %, w/w), China. Its taxonomic position was determined by using a polyphasic approach. Cells of strain DSG-S6T were non-spore-forming, slightly bent rods, and motile by means of a single polar flagellum. Growth occurred in the presence of 0–7.0  % (w/v) NaCl (optimum, 2.0  %), at 4–35 °C (optimum, 30 °C) and at pH 6.0–10.5 (optimum, pH 8.0–8.5). C16 : 0, C18 : 1ω7c and C16 : 1ω7c and/or C16 : 1ω6c were the major fatty acids. Six alleles of the 16S rRNA gene sharing 98.9–99.9  % similarity were detected in strain DSG-S6T, which showed highest 16S rRNA gene sequence similarity to Vibrio aestuarianus ATCC 35048T (97.7  %), then to Vibrio pacinii LMG 19999T (97.6  %) and Vibrio metschnikovii CIP 69.14T (96.8  %). Multilocus sequence analysis of four housekeeping genes and 16S rRNA genes clearly clustered it as a member of the Anguillarum clade. Mean DNA–DNA relatedness between strain DSG-S6T and V. aestuarianus NBRC 15629T, V. pacinii CGMCC 1.12557T and V. metschnikovii JCM 21189T was 20.6 ± 2.3, 38.1 ± 3.5 and 24.2 ± 2.8  %, respectively. The DNA G+C content was 46.8 mol% (T m). Based on the data, it is concluded that strain DSG-S6T represents a novel species of the genus Vibrio, for which the name Vibrio salilacus sp. nov. is proposed. The type strain is DSG-S6T ( = CGMCC 1.12427T = JCM 19265T).

Vibrio olivae sp. nov., isolated from Spanish-style green-olive fermentations

Three isolates originating from Spanish-style green-olive fermentations in a manufacturing company in the province of Seville, Spain, were taxonomically characterized by a polyphasic approach. This included a phylogenetic analysis based on 16S rRNA gene sequences and multi-locus sequence analysis (MLSA) based on pyrH, recA, rpoA, gyrB and mreB genes. The isolates shared 98.0 % 16S rRNA gene sequence similarity with Vibrio xiamenensis G21T. Phylogenetic analysis based on 16S rRNA gene sequences using the neighbour-joining and maximum-likelihood methods showed that the isolates fell within the genus Vibrio and formed an independent branch close to V. xiamenensis G21T. The maximum-parsimony method grouped the isolates to V. xiamenensis G21T but forming two clearly separated branches. Phylogenetic trees based on individual pyrH, recA, rpoA, gyrB and mreB gene sequences revealed that strain IGJ1.11T formed a clade alone or with V. xiamenensis G21T. Sequence similarities of the pyrH, recA, rpoA, gyrB and mreB genes between strain IGJ1.11T and V. xiamenensis G21T were 86.7, 85.7, 97.3, 87.6 and 84.8 %, respectively. MLSA of concatenated sequences showed that strain IGJ1.11T and V. xiamenensis G21T are two clearly separated species that form a clade, which we named Clade Xiamenensis, that presented 89.7 % concatenated gene sequence similarity, i.e. less than 92 %. The major cellular fatty acids (>5 %) of strain IGJ1.11T were summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16 : 0 and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c). Enzymic activity profiles, sugar fermentation patterns and DNA G+C content (52.9 mol%) differentiated the novel strains from the closest related members of the genus Vibrio. The name Vibrio olivae sp. nov. is proposed for the novel species. The type strain is IGJ1.11T ( = CECT 8064T = DSM 25438T).

Viscosity dictates metabolic activity of Vibrio ruber

Little is known about metabolic activity of bacteria, when viscosity of their environment changes. In this work, bacterial metabolic activity in media with viscosity ranging from 0.8 to 29.4 mPas was studied. Viscosities up to 2.4 mPas did not affect metabolic activity of Vibrio ruber. On the other hand, at 29.4 mPas respiration rate and total dehydrogenase activity increased 8 and 4-fold, respectively. The activity of glucose-6-phosphate dehydrogenase (GPD) increased up to 13-fold at higher viscosities. However, intensified metabolic activity did not result in faster growth rate. Increased viscosity delayed the onset as well as the duration of biosynthesis of prodigiosin. As an adaptation to viscous environment V. ruber increased metabolic flux through the pentose phosphate pathway and reduced synthesis of a secondary metabolite. In addition, V. ruber was able to modify the viscosity of its environment.