Studies on the role of marine bacteria in the upwelling ecosystem——Ⅰ.Bacterial biomass in the upwelling regions

-Six cruises were carried out off the south bank of Fujian - Taiwan during the period of December 21, 1987 to November 15, 1988 to estimate the contribution of bacterial biomass carbon (BBC) to the totai particulate organic pools using epifluorescent microscopic technique. The results show that the standing crop of bacteria fluctuated from 0. 95 to 66. 60 mg /m3 (dry weight). Upwelling phenomena appeared in the region around Nanpeng Island in summer while in the region of Waixie in all seasons. The average value of BBC was 27. 60(±6. 08)mg/m3and 21. 32 (±2. 34) mg/m3 respectively. The seasonal and spatial distribution is discussed in relation to environmental factors as well as upwelling phenomena. The role of bacteria in the flow of material and energy in the upwelling ecosystem is emphasized.

Growth of marine bacteria and ammonium regeneration from substrates in different C:N ratios

Natural assemblages of marine bacteria were chosen in a batch culture experiments. The impact of varying nitrogen substrate concentrations and the substrate C：N ratios （C：Ns） on the bacterial C：N ratio （C：NB）, the bacterial growth efficiency （BGE） and ammonium regeneration was mainly examined. The C：Ns ratios varied from 5：1 （carbon limitation） to 40：1 （nitrogen limitation） with varying combinations of glucose and NO3. The C：NB ratio had positive relationship with the C：Ns ratio （r=0.93, n=8）, whose value was 3.77 when the C：Ns ratio was 5：1 but increased to 6.47 when the C：Ns ratio was 40：1. These results indicate that the C：NB ratio is a potential diagnostic tool for determining the bacterial growth in natural waters controlled by either, carbon or nitrogen. BGE decreased with the declining nitrate concentration and negatively related to C：N8 （r=-0.51, n=8）. The average value of BGE was 0.20. This value was a little lower than other reports, which could be induced by the nitrogen source used in our experiments. Finally, regeneration time of ammonium delayed with the increasing C：Ns ratio, which indicates that there were different metabolism mechanisms when bacterial growth was limited by carbon source and nitrogen source.

Phylogenetic analysis and biological characteristic tests of marine bacteria isolated from Southern Ocean(Indian sector)water

Fifty-seven bacteria were isolated from Southern Ocean （Indian sector） water samples which were collected from different latitude and longitude of the ocean. All the isolates were able to grow at 4℃, 20℃, 37℃ and tolerable NaCI concentration up to 13.5% （w/v）. 29 out of 57 isolates were identified using 16S rDNA amplification and the sequences were submitted to National Center for Biotechnology Information （NCBI）. All the isolates were classified by using Ribosomal Database Project （RDP） and found that isolates belongs to Proteobacteria and Bacteriodes. The average G＋C content was 56.4%. The isolates were screened for the presence of extracellular enzymes, viz. amylase, catalase, urease, esterase, lipase and protease. The disc diffusion method is used to screen antibiotic production by the isolates against four pathogenic bacteria, viz. Salmonella typhimurium （NCIM 2501）, Staphylococcus aureus （NCIM 2122）, Bacillus subtilis （NCIM 2193）, and Pseudomonas aeruginosa （NCIM 2036）. Nine out of 29 were found to be antibiotic producer.

Antibacterial activity of marine bacteria isolated from sponge Xestospongia testudinaria from Sorong,Papua

Objective:To explore secondary metabolite of bacteria-associated Xestospongia testudinaria from Tanjung Kasuari,Sorong,Papua.Methods:The antimicrobial activities of extracts against two Gram-positive bacteria(Staphylococcus aureus) and three Gram-negative bacteria(Pseudomonas aeruginosa,Eschericia coli and Salmonella typhi) were determined by disk diffusion dilution method.Results:The test showed that of 15 isolates of symbiont bacteria,6 isolates were successfully isolated and coded,namely,Xp 4.1,Xp 4.2,Xp 4.3,Xp 4.4,Xp 4.5 and Xp 4.6.Of the six bacterial isolates,isolated Xp 4.2 was found to have more powerful antibacterial activity than any other isolates of symbiont bacteria.Antibacterial activity assay for the n-hexane soluble fractions,ethyl-acetate soluble fractions,and n-buthanol soluble fractions revealed more powerful anti-bacterial activity than any other soluble fractions.Phytochemical screening showed alkaloid and steroid/triterpenoid,while identification for isolate of Xp 4.2 bacterial showed bacteria.Conclusions:Metabolites of bacterial associated with marine sponge Xestospongia testudinaria promise to be developed into antibacterial agents.

Design of Copper Oxide Nanosheets-Loaded Zeolite with Efficient Inhibition of Marine Bacteria

Copper oxide-loaded zeolite 4A nanocomposites(CuO-zeolite NCs)were successfully prepared by modifying zeolite 4A with CuSO_(4)aqueous solution as the copper source.Zeolite 4A showed an important role in hosting copper oxide,and CuO-zeolite NCs exhibited a controlled release of copper ions.XRD patterns confirmed the appearance of new diffraction peaks of copper oxide at 35.83°and 38.83°.CuO nanosheets formed on the surface of zeolite 4A were about 30–40 nm thick over a width of 200–300 nm.CuO-zeolite NCs were primarily composed of Cu,Si,Al and O,as measured by XPS.Cu 2p_(3/2) and Cu 2p_(1/2) peaks were fitted into two main peaks centered at 934.7 eV and 954.6 eV,which were attributed to Cu(II).Zeolite 4A and CuO-zeolite NC displayed reversible Langmuir isotherm(type-I)characteristics and showed maximum adsorption quantities of almost 200 cm^(3) g^(−1) at a relative pressure of 1.0 by CO_(2)adsorption-desorption experiments.The antibacterial efficiencies of the CuO-zeolite NC were 99.4%,96.7%,and 96.8%against Pseudoalteromonas tetraodonis(P.tetraodonis),Micrococcus luteus(M.luteus),and Shewanella putrefaciens(S.putrefaciens),respectively.These values showed that nano CuO-loaded zeolite 4A acted as a strong bactericide against marine bacteria.CuO-zeolite NCs can be further applied to marine antifouling coating.

Characterisation of the Bacteria and Archaea Community Associated with Wild Oysters, At Three Possible Restoration Sites in the North Sea

With 85% of the global oyster reefs destroyed, there is an urgent need for large scale restoration to benefit from the ecosystem services provided by biogenic oyster reefs and their associated biodiversity, including microorganisms that drive marine biogeochemical cycles. This experiment established a baseline for the monitoring of the bacterial and archaeal community associated with wild oysters, using samples from their immediate environment of the Voordelta, with cohabiting Crassostrea gigas and Ostrea edulis, Duikplaats with only C. gigas attached to rocks, and the Dansk Skaldyrcentre, with no onsite oysters. The microbial profiling was carried out through DNA analysis of samples collected from the surfaces of oyster shells and their substrate, the sediment and seawater. Following 16S rRNA amplicon sequencing and bioinformatics, alpha indices implied high species abundance and diversity in sediment but low abundance in seawater. As expected, Proteobacteria, Bacteroidetes, Firmicutes and Thaumarchaeota dominated the top 20 OTUs. In the Voordelta, OTUs related to Colwellia, Shewanella and Psychrobium differentiated the oysters collected from a reef with those attached to rocks. Duikplaats were distinct for sulfur-oxidizers Sulfurimonas and sulfate-reducers from the Sva 0081 sediment group. Archaea were found mainly in sediments and the oyster associated microbiome, with greater abundance at the reef site, consisting mostly of Thaumarchaeota from the family Nitrosopumilaceae. The oyster free site displayed archaea in sediments only, and algal bloom indicator microorganisms from the Rhodobacteraceae, Flavobacteriaceae family and genus [Polaribacter] huanghezhanensis, in addition to the ascidian symbiotic partner, Synechococcus. This study suggests site specific microbiome shifts, influenced by the presence of oysters and the type of substrate.

Synthesis and Pharmacological Studies on a Cyclooligopeptide from Marine Bacteria

A natural proline-rich tetrapeptide cyclo-prolyl-leucyl-prolyl-phenylalanyl was prepared employing solu- tion-phase method of peptide synthesis through coupling of dipeptide fragments Boc-l-Pro-l-Leu-OH and 1-Pro-l-Phe-OMe which utilizes diisopropylcarbodiimide （DIPC） as coupling agent and N-methylmorpholine （NMM） as the base. Deprotection of linear tetrapeptide unit followed by its cyclization provided a cyclopeptide, identical in all aspects to the natural molecule. Pharmacological evaluation showed cytotoxic, antifungal and antihelmintic po- tential of synthesized peptide against Dalton＇s Lymphoma Ascites （DLA） and Ehrlich＇s Ascites Carcinoma （EAC） cell lines, pathogenic dermatophytes and earthworms.

Identification of a marine agarolytic bacterium Agarivorans albus QM38 and cloning and sequencing its beta-agarase genes

A total of 117 agar-decomposing cultures were isolated from coastal seawater around Qingdao, China. The phenotypic and agarolytic features of an agarolytic isolate, QM38, were investigated. The strain was gram negative, strictly aerobic, curved rod and polar flagellum. On the basis of several phenotypic characters, biochemical and morphological characters and phylogenetic analysis of the gene coding for the 16S rRNA, the strain was identified as Agarivorans albus strain QM38. This strain can liquefy the agar on the solid agar plate. An excellular agarase activity was determined in liquid culture. The enzyme exhibited maximal activity at 40 ℃, pH 7.6. Its activity was greatly affected by different concentrations of agarose. The highest activity 32 U/ml was achieved in the culture supernatant. The hydrolytic product was analyzed by fluorophore-assisted carbohydrate electrophoresis （FACE）. After complete hydrolysis of agarose, a series of agaro-oligosaccharides were produced. The main products of the enzymes were oligosaccharides in the degree of polymerization （DP） of 2, 4, 6 and 8. Three genes agaD01, agaD02 and agaD03, encodingβ-agarases, had been cloned from genomic DNA of Agarivorans albus strain QM38. The open reading frame of agaDOl, consisted of 2 988 bp, and shared 95.5%-98.9% identity to the β-agarase genes of some strains of Vibrio and Agarivorans. Gene agaD02 comprised 2 868 bp and encoded a 955- amino-acid protein. It showed 97.4% and 98.7~0 identity to the β-agarase genes of strain Vibrio sp. PO-303 and strain Vibrio sp. JT0107, respectively. Only partial sequence of agaD03 gene has been cloned. It showed 96.5% identity to β-agarase gene （agaB） of Pseudoalteromonas sp. CY24, and shared 96.8% identity to β-agarase-c gene of Vibrio sp. PO-303.

Biological characteristics of marine bacterium S-9801 strain and its culture conditions of pigment production

Strain of Flavobacterium sp.(S-9801),was screened from 207 strains of marine bacteria isolated from the Bohai Sea continental shelf and the Zhujiang Estuary,for its red pigment production.The biological characteristics of strain S-9801 and culture conditions of pigment production have been checked out in this study. The color of the bacterial colony on 2216E medium was from coccineus to rose bengal. Optimum culture conditions were sodium chloride concentration(g/dm3),10～30;pH,3～8;temperature,25～28℃;tryptone and yeast extract as nitrogen sources and glucose as carbon source. Under optimum conditions,pigment accumulation started after 12 h,reaching a maximum rate of synthesis at 36 h.

Characterization of some bacterial strains isolated from the Egyptian eastern and northern coastlines with antimicrobial activity of Bacillus zhangzhouensis OMER4

Marine microorganisms were considered to be important sources of marine bioactive compounds.The major objective of the study was to isolate and characterize bacteria with antimicrobial activities from the various marine environment of Egypt.In this respect,thirty-five bacterial isolates were recovered from sediment samples collected from different spots along the Egyptian Red Sea coastline and Alexandria coastline during the summer season of 2017 and 2018.According to the morphological,physiological,and biochemical characteristics,the bacterial isolates were clustered into 13 groups designated as A,B,…,M.And,14 Gram-negative and 21 Grampositive bacteria were determined.The isolated bacterial strains were screened for their potentiality for antimicrobial agent(s)production against ten indicator strains.Strain Mo13 was showed high antimicrobial activity against all empirical strains.Subsequently,the most promising marine bacterial isolate with code MO13 was identified as Bacillus zhangzhouensis OMER4 according to the phenotypic characterization through morphological,physiological,and biochemical tests as well as genotypic characterization through the 16 S rDNA technique.The bioactive components were extracted with ethyl acetate,then analyzed using GC-MS and the substantial component was recognized as phenol,2,4-bis(1,1-dimethyl ethyl).

Abundance of general aerobic heterotrophic bacteria in the Bering Sea and Chukchi Sea and their adaptation to temperature

The abundance of general aerobic heterotrophic bacteria(GAB) from the water and sediment in the Bering Sea and the Chukchi Sea was determined by using petri dish cultivation and counting method. The abundance of GAB among the different sea areas, sampling sites, layers of sediments surveyed and adaptability to differential temperatures was studied. The result obtained showed that: the occurrence percentage of GAB in the surface water was higher than that in sediment, but the abundance was only 0.17% of sediment. The occurrence percentage of GAB in surficial layer of sediment was higher than that in the other layers. The occurrence percentage of GAB in surficial layer of sediment was higher than that in the other layers. The occurrence percentage, abundance and its variation of GAB in the Bering Sea were higher than that in the Chukchi Sea respectively. The average value of the abundance in the all sediment surveyed was 3166.3×10 2 CFU·g -1(wet.). The abundance of GAB in sediment showed a trend: roughly higher in the lower latitudinal area than higher latitude. The results from temperature test mean that: the majority of bacteria tested were cold-adapted ones, minority might be mesophilic bacteria. The results indicated that, Arctic ocean bacteria had a stronger adaptability to environmental temperature.

Short‑chain fatty acids(SCFAs)as potential resuscitation factors that promote the isolation and culture of uncultured bacteria in marine sediments

Many marine bacteria are difcult to culture because they are dormant,rare or found in low-abundances.Enrichment culturing has been widely tested as an important strategy to isolate rare or dormant microbes.However,many more mechanisms remain uncertain.Here,based on 16S rRNA gene high-throughput sequencing and metabolomics technology,it was found that the short-chain fatty acids(SCFAs)in metabolites were signifcantly correlated with uncultured bacterial groups during enrichment cultures.A pure culture analysis showed that the addition of SCFAs to media also resulted in high efciency for the isolation of uncultured strains from marine sediments.As a result,238 strains belonging to 10 phyla,26 families and 82 species were successfully isolated.Some uncultured rare taxa within Chlorobi and Kiritimatiellaeota were successfully cultured.Amongst the newly isolated uncultured microbes,most genomes,e.g.bacteria,possess SCFA oxidative degradation genes,and these features might aid these microbes in better adapting to the culture media.A further resuscitation analysis of a viable but non-culturable(VBNC)Marinilabiliales strain verifed that the addition of SCFAs could break the dormancy of Marinilabiliales in 5 days,and the growth curve test showed that the SCFAs could shorten the lag phase and increase the growth rate.Overall,this study provides new insights into SCFAs,which were frst studied as resuscitation factors in uncultured marine bacteria.Thus,this study can help improve the utilisation and excavation of marine microbial resources,especially for the most-wanted or key players.

Structure and Potential Application of Konjac Glucomannan Nano Microfibril Aerogel

An ultra-light and high porosity nano microfibril aerogel was prepared from konjac glucomannan（KGM） by the electrospinning and freeze-drying. The structure of aerogel was analyzed by scanning electron microscopy（SEM） and X-ray diffraction（XRD） while the density and compressive strength of the samples were studied separately. Results reveal that porous network structure of the KGM nano microfibril aerogel is constructed by intermolecular hydrogen bonds in random and interpenetrate way. The nano microfibril structure presents in the KGM aerogel,which is an important reason of its high density and compressive strength. There is a potential application for this unique nano microfibril aerogel in the absorption of biodegradation bacteria to solve problems in marine oil spill pollution.

Strategies for culturing active/dormant marine microbes

Microorganisms are ubiquitous in the ocean environment and they play key roles in marine ecosystem function and service.However,many of their functions and phenotypes remain unknown because indigenous marine bacteria are mostly difficult to culture.Although many novel techniques have brought previously uncultured microbes into laboratory culture,there are still many most-wanted or key players that need to be cultured from marine environments.This review discusses possible reasons for‘unculturable microbes’and categorizes uncultured bacteria into three groups:dominant active bacteria,rare active bacteria,and dormant bacteria.This review also summarizes advances in cultivation techniques for culturing each group of unculturable bacteria.Simulating the natural environment is an effective strategy for isolating dominant active bacteria,whereas culturomics and enrichment culture methods are proposed for isolating rare active bacteria.For dormant bacteria,resuscitation culture is an appropriate strategy.Furthermore,the review provides a list of the most-wanted bacteria and proposes potential strategies for culturing these bacteria in marine environments.The review provides new insight into the development of strategies for the cultivation of specific groups of uncultured bacteria and therefore paves the way for the detection of novel microbes and their functions in marine ecosystems.

Microbial electrosynthesis of acetate from CO_(2)under hypersaline conditions

Microbial electrosynthesis(MES)enables the bioproduction of multicarbon compounds from CO_(2)using electricity as the driver.Although high salinity can improve the energetic performance of bioelectrochemical systems,acetogenic processes under elevated salinity are poorly known.Here MES under 35e60 g L^(-1)salinity was evaluated.Acetate production in two-chamber MES systems at 35 g L^(-1)salinity(seawater composition)gradually decreased within 60 days,both under-1.2 V cathode potential(vs.Ag/AgCl)and^(-1).56 A m^(-2)reductive current.Carbonate precipitation on cathodes(mostly CaCO3)likely declined the production through inhibiting CO_(2)supply,the direct electrode contact for acetogens and H2 production.Upon decreasing Ca2t and Mg2t levels in three-chamber reactors,acetate was stably produced over 137 days along with a low cathode apparent resistance at 1.9±0.6 mU m^(2)and an average production rate at 3.80±0.21 g m^(-2)d^(-1).Increasing the salinity step-wise from 35 to 60 g L^(-1)gave the most efficient acetate production at 40 g L^(-1)salinity with average rates of acetate production and CO_(2)consumption at 4.56±3.09 and 7.02±4.75 g m^(-2)d^(-1),respectively.The instantaneous coulombic efficiency for VFA averaged 55.1±31.4%.Acetate production dropped at higher salinity likely due to the inhibited CO_(2)dissolution and acetogenic metabolism.Acetobacterium up to 78%was enriched on cathodes as the main acetogen at 35 g L^(-1).Under high-salinity selection,96.5%Acetobacterium dominated on the cathode along with 34.0%Sphaerochaeta in catholyte.This research provides a first proof of concept that MES starting from CO_(2)reduction can be achieved at elevated salinity.

Novel Anti-fouling Strategies of Live and Dead Soft Corals(Sarcophyton trocheliophorum):Combined Physical and Chemical Mechanisms

At present,biomimetic antifouling research objects are mostly concentrated on the fast-moving marine organism,but the anti-fouling effect of the low-speed or static marine equipment is not obvious.This paper describes the anti-fouling mechanism of soft coral(Sarcophyton trocheliophorum),including the physical defense mechanism and the bactericidal ability of mucus and coral powder.As a sessile organisms,soft coral lacks escape mechanism.Therefore,the study on its antibacterial strategy is significant because it can provide theoretical guidance for static antifouling.Results showed that the live soft coral would molt in unfriendly environment,and the secreted mucus could defend themselves against fouling microorganism.Then,Liquid Chromatography-Mass Spectrometry(LC-MS)analysis was conducted to identify the bioactive compounds of the coral powder and mucus.Results revealed that both powder and mucus contained a wide variety of toxic components,which had bactericidal effects.Moreover,at the same concentration,the inhibitory effect of the main components on Gram-negative bacteria was stronger than that on positive bacteria.These findings enhance the understanding about the antifouling mechanism of soft coral and provide new ideas for design and prepare novel antifouling strategy to combat biofouling under static condition.