Unrevealing variation of microbial communities and correlation with environmental variables in a full culture-cycle of Undaria pinnatifida

Bacteria are the most abundant organisms in natural environment and dominant drivers of multiple geochemical functions. Drawing a global picture of microbial community structure and understanding their ecological status remain a grand challenge. As a typical artificial process, aquaculture provides a large amount of foods and creates great economic benefits for human beings. However, few studies are aimed at the microbial community in the aquaculture environment of aquatic plants. We analyzed microbial communities from 21 water samples in a coastal aquaculture area during the whole cultural process of Undaria pinnatifida by using high-throughout sequencing of 16S rRNA gene. The progression of U. pinnatifida aquaculture can be divided into three stages, named Seeding, Growth, and Maturity, respectively. Microbial community structures in water of the aquaculture area were significantly changed during the progression of U. pinnatifida aquaculture. The relative abundance of Flavobacteriia and Thaumarchaeota classes increased in Growth stage, and β-proteobacteria and Acidimirobiia classes decreased with the growth of U. pinnatifida. Meanwhile, environmental factors shaping the microbial community structures were uncovered during the U. pinnatifida aquaculture by using canonical correspondence analysis and Mantel test, in which temperature, dissolved oxygen, pH and nitrogen could be the major influencing factors. In addition, the microbial functions based on KEGG pathways were predicted from the microbial community compositions by PICRUSt. The comparison of predicted functions suggested that Environmental Information Processing and Genetic Information Processing were the functional categories with the most obvious shift in abundance among different stages of U. pinnatifida aquaculture. The findings of this study allowed us to better understand the microbial community in coastal aquaculture systems and the impact of seaweed cultivation on coastal ecosystems.

Protective Effects of Mekabu Aqueous Solution Fermented by Lactobacillus plantarum Sanriku-SU7 on Human Enterocyte-Like HT-29-luc Cells and DSS-Induced Murine IBD Model

Most wakame Undaria pinnatifida, a brown algae, products are made from the frond portion. In this study, the polysaccharide content and antioxidant property of aqueous extract solutions (AESs) of the four parts (frond: wakame, stem of the frond: kuki-wakame, sporophyll: mekabu, and kuki-mekabu) of wakame were investigated. Polysaccharide content was high in both the wakame and mekabu. Superoxide anion (O2-) radical-scavenging capacities were high in the mekabu. These AESs could be fermented by Lactobacillus plantarum Sanriku-SU7. The O2- radical-scavenging activity of the kuki-wakame, mekabu, and kuki-mekabu were increased by the fermentation. Fermented mekabu clearly showed a protective effect on human enterocyte-like HT-29-luc cells and in a mouse model of dextran sodium sulphate-induced inflammatory bowel disease (IBD). These results suggest that the mekabu fermented by L. plantarum Sanriku-SU7 has anti-IBD effect related to O2- radical-scavenging.

Maribacter chungangensis sp. nov., isolated from a green seaweed, and emended descriptions of the genus Maribacter and Maribacter arcticus

A Gram-stain-negative, non-spore-forming, strictly aerobic, orange-pigmented bacterial strain, motile by gliding, designated CAU 1044(T), was isolated from a green seaweed and its taxonomic position was investigated using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CAU 1044(T) formed a distinct lineage within the genus Maribacter and was most closely related to Maribacter antarcticus JCM 15445(T) and Maribacter arcticus KOPRI 20941(T) (96.3 and 95.7 % similarity, respectively). Strain CAU 1044(T) contained menaquinone 6 as the only isoprenoid quinone and iso-C15 : 0, summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c and/or iso-C15 : 0 2-OH), iso-C17 : 0 3-OH and iso-C15 : 1 G as the major fatty acids. The cell wall peptidoglycan of strain CAU 1044(T) contained meso-diaminopimelic acid and the major whole-cell sugars were glucose and ribose. The polar lipids were composed of phosphatidylethanolamine, one unidentified phospholipid, six unidentified aminolipids and four unidentified lipids. The DNA G+C content was 40.2 mol%. On the basis of phenotypic data and phylogenetic inference, strain CAU 1044(T) should be classified as a representative of a novel species in the genus Maribacter for which the name Maribacter chungangensis sp. nov. is proposed. The type strain is CAU 1044(T) ( = KCTC 23735(T) = CCUG 61948(T)). Emended descriptions of the genus Maribacter and the species M. arcticus KCTC 22053(T) are also proposed.

Leuconostoc miyukkimchii sp. nov., isolated from brown algae (Undaria pinnatifida) kimchi

A Gram-staining-positive, non-motile and non-spore-forming lactic acid bacterium, designated strain M2(T), was isolated from fermented brown algae (Undaria pinnatifida) kimchi in South Korea. Cells of the isolate were facultatively anaerobic ovoids and showed catalase- and oxidase-negative reactions. Growth of strain M2(T) was observed at 4-35 °C and at pH 5.0-9.0. The G+C content of the genomic DNA was 42.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain M2(T) belonged to the genus Leuconostoc and was most closely related to Leuconostoc inhae IH003(T), Leuconostoc kimchii IH25(T), Leuconostoc gasicomitatum LMG 18811(T), Leuconostoc gelidum DSM 5578(T), Leuconostoc palmae TMW2.694(T) and Leuconostoc holzapfelii BFE 7000(T) with 98.9 %, 98.8 %, 98.8 %, 98.7 %, 98.5 % and 98.2 % sequence similarity, respectively. DNA-DNA hybridization values between strain M2(T) and Leuconostoc inhae KACC 12281(T), Leuconostoc kimchii IH25(T), Leuconostoc gelidum KACC 12256(T), Leuconostoc gasicomitatum KACC 13854(T), Leuconostoc palmae DSM 21144(T) and Leuconostoc holzapfelii DSM 21478(T) were 13.8±3.2 %, 14.3±3.4 %, 9.9±1.0 %, 13.2±0.8 %, 22.4±4.9 % and 16.2±4.6 %, respectively, which allowed differentiation of strain M2(T) from the closely related species of the genus Leuconostoc. On the basis of phenotypic and molecular properties, strain M2(T) represents a novel species in the genus Leuconostoc, for which the name Leuconostoc miyukkimchii sp. nov. is proposed. The type strain is M2(T) ( = KACC 15353(T)  = JCM 17445(T)).

Bioactive metabolites from Guignardia sp., an endophytic fungus residing in Undaria pinnatifida

AIM

To isolate new and/or bioactive constituents from EtOAc extract of liquid culture of endophyte Guignardia sp. from the leaves of Undaria pinnatifida (Harv.) Sur.

METHODS

Isolation and purification were performed through silica gel column chromatograph, Sephadex LH-20 and reversed-phase ODS column and the structures of the compounds obtained were identified through a combination of spectral and chemical methods (IR, MS, (1)H and (13)C NMR). In vitro bioactive assays including antifungal activity against three human pathogenic fungi Microsporum canis, Tricophyton rubrum and Epidermophyton floccosom and cytotoxic activity against the human nasopharyngeal epidermoid tumor KB cell line were evaluated.

RESULTS

Seven compounds have been obtained from the liquid culture of the title endophyte: ergosterol peroxide (6, 22-diene-5, 8-epidioxyergosta-3-ol) (1), ergosterol (2), cyclo-(Tyr-Leu) (3), cyclo-(Phe-Phe) (4), cyclo-(Val-Leu) (5), cyclo-(Phe-Pro) (6) and cyclo-(Leu-Ile) (7). Compounds 1-3 and 6 inhibited the growth of M. canis with MICs of 10.0, 20.0, 50.0 and 5.0 μg·mL(-1), respectively and compounds 1, 2 and 6 against T. rubrum with MICs of 15.0, 20.0 and 10.0 μg·mL(-1), respectively and 1 and 6 against E. floccosom with MICs of 20.0 and 50.0 μg·mL(-1), respectively. In addition, compounds 1, 3 and 6 exhibited cytotoxic activity against KB cell line with IC(50) of 20.0, 10.0, 10.0 μg·mL(-1), respectively.

CONCLUSION

Compounds 1-7 were obtained from Guignardia sp. of U. pinnatifida for the first time, and compounds 1 and 6 had potent cytotoxic and antifungal activity.

Isolation and characterization of marine bacterial strain degrading fucoidan from Korean Undaria pinnatifida Sporophylls

In spite of an increasing interest in fucoidans as biologically active compounds, no convenient commercial sources with fucoidanase activity are yet available. A marine bacterial strain that showed confluent growth on a minimal medium containing fucoidan, prepared from Korean Undaria pinnatifida sporophylls, as the sole carbon source was isolated and identified based on a 16S rDNA sequence analysis as a strain of Sphingomonas paucimobilis, and named Sphingomonas paucimobilis PF-1. The strain depolymerized fucoidan into more than 7 distinct lowmolecular- mass fucose-containing oligosaccharides, ranging from 305 to 3,749 Da. The enzyme activity was shown to be associated with the whole cell, suggesting the possibility of a surface display of the enzyme. However, a whole-cell enzyme preparation neither released the monomer Lfucose from the fucoidan nor hydrolyzed the chromogenic substrate p-nitrophenyl-alpha-L-fucoside, indicating that the enzyme may be an endo-acting fucoidanase rather than an alpha-L-fucosidase. Therefore, this would appear to be the first report on fucoidanolytic activity by a Sphingomonas species and also the first report on the enzymatic degradation of the Korean Undaria pinnatifida sporophyll fucoidan. Moreover, this enzyme activity may be very useful for structural analyses of fucose-containing polysaccharides and the production of bioactive fucooligosaccharides.

Degradation of the seaweed wakame (Undaria pinnatifida) by a composting process with the inoculation of Bacillus sp. HR6

Disposal of the seaweed wakame (Undaria pinnatifida) by inoculating the halotolerant bacterium Bacillus sp. HR6 was examined in an experimental scale composting system. Strain HR6 was effective in initiating the composting process of wakame, and there was a rapid increase in temperature to over 54.9-55.7 degrees C after 18-20 h. The composting process of wakame could be carried out despite a high NaCl content, 28.2 mg/g, although lower salinity resulted in a shorter lag time and higher weight reduction. In a larger scale composting process with aeration, two peaks of temperature change were found which corresponded well to oxygen consumption and CO2 emission during the process. The pH increased to 8.83 and organic materials were reduced to 93.4% after 72 h. The initial N and C contents were 3.9 and 34.0%, respectively, both of which decreased during the composting process. The changes in the viable cell numbers suggested that strain HR6 predominated before 24 h and other microorganisms including HR6 were present in a mixed state during the later period of composting. The total content of alginate (TA), 32.2% in the initial stage, decreased to 29.2% after 72 h, while water soluble alginate (WSA) increased, indicating that the solubilization and decomposition of alginate had occurred during the composting process.

Marine bacteria associated with the Korean brown alga, Undaria pinnatifida

Several marine bacterial strains were isolated from Undaria pinnatifida (Miyok in Korean). Sixty-six strains were isolated on R2A agar media at 10 degrees and identified by a phylogenetic analysis of the 16S rRNA gene sequences. They were grouped into 10 different sequence types based on the initial sequence analysis of the 5' domain of the gene (approximately 500 bp). Full sequences of 16S rRNA gene were obtained from one strain in each sequence type and the species-affiliation was determined using phylogenetic and sequence similarity analyses. The results of the analyses indicated that they were closely related to Psychrobacter aquimaris, P. celer, P. nivimaris, P. pulmonis, Psychromonas arctica or Bacillus psychrodurans. These bacteria are marine or psychrotrophic bacteria. Because the sporophytes of U.pinnatifida are cultured on the costal area during winter, the U. pinnatifida-associated bacteria appeared to grow at low temperatures. U. pinnatifida sporophytes can be a good source for the isolation of psychrotrophic bacteria.

Purification and characterization of an alginate lyase from marine Bacterium Vibrio sp. mutant strain 510-64

Marine Vibrio sp. 510 was chosen as a parent strain for screening high producers of alginate lyase using the complex mutagenesis of Ethyl Methanesulphonate and UV radiation treatments. The mutant strain Vibrio sp. 510-64 was selected and its alginate lyase activity was increased by 3.87-fold (reaching 46.12 EU/mg) over that of the parent strain. An extracellular alginate lyase was purified from Vibrio sp. 510-64 cultural supernatant by successive fractionation on DEAE Sepharose FF and two steps of Superdex 75. The purified enzyme yielded a single band on SDS-PAGE with the molecular weight of 34.6 kDa. Data of the N-terminal amino acid sequence indicated that this protein might be a novel alginate lyase. The substrate specificity results demonstrated that the alginate lyase had the specificity for poly G block.