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An ultrasensitive label-free electrochemical immunosensor of okadaic acid (OA) was studied based on electrodimerization of p-aminobenzoic acid (p-ABA)-modified gold three-dimensional nanoelectrode ensembles (3DNEEs) which were prepared by electroless gold plating and etching using polycarbonate as template. Staphylococcus protein A (SPA) was introduced to immobilize okadaic acid antibody (anti-OA). The morphology and composition of 3DNEEs were analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometer (EDX). The polydimer (p-aminobenzoic acid) (pPABA) film was measured by Fourier transform infrared spectrometer (FTIR). The concentration of OA was measured by EIS and SWV. The detection limit of EIS is lower than that of SWV (6.47 × 10−3 ng mL−1 vs. 9.15 × 10−3 ng mL−1), but the linear OA detection range of the latter is wider (0.01–1.0 ng mL−1 vs. 0.01–0.8 ng mL−1). The average recovery of OA in oyster samples is 99.81%. The OA recovery test in oyster samples demonstrated potential application value of the electrochemical immunosensor.

Nitrification is a key step in the global nitrogen cycle. Compared with autotrophic nitrification, heterotrophic nitrification remains poorly understood. In this study, Halomonas venusta MA-ZP17-13, isolated from seawater in shrimp aquaculture (Penaeus vannamei), could simultaneously undertake nitrification and denitrification. With the initial ammonium concentration at 100 mg/L, the maximum ammonium-nitrogen removal rate reached 98.7% under the optimal conditions including C/N concentration ratio at 5.95, pH at 8.93, and NaCl at 2.33%. The corresponding average removal rate was 1.37 mg/(L·h) (according to nitrogen) in 3 d at 11.2°C. By whole genome sequencing and analysis, nitrification- and denitrification-related genes were identified, including ammonia monooxygenase, nitrate reductase, nitrite reductase, nitric oxide dioxygenase and nitric oxide synthase; while no gene encoding hydroxylamine oxidase was identified, it implied the existence of a novel nitrification pathway from hydroxylamine to nitrate. These results indicate heterotrophic bacterium H. venusta MA-ZP17-13 can undertake simultaneous nitrification and denitrification at low temperature and has potential for NH 4 + -N/NH3-N removal in marine aquaculture systems.

Plastics pollution poses a new threat to marine ecosystems. Mangrove locating at estuary worldwide is probably the most heavily polluted area trapping various plastics transported from terrestrial and nearby marine aquaculture. Expanded polystyrene (EPS) is one of most common plastic debris therein and even in the plastic garbage. Here we showed the bacterial diversity of the polystyrene-degrading microbial community from EPS waste sites from a subtropical mangrove area. After enrichment with EPS, the degradation consortia were obtained. They shared a similar community structure dominated by bacteria of Sphingomonadaceae, Rhodanobacteraceae, Rhizobiaceae, Dermacoccaceae, Rhodocyclaceae, Hyphomicrobiaceae, and Methyloligellaceae. Diverse bacteria standing for the first member of the genera of Novosphingobium, Gordonia, Stappia, Mesobacillus, Alcanivorax, Flexivirga, Cytobacillus, Thioclava, and Thalassospira showed PS degradation capability as a pure culture. Further, PS biodegradation of Gordonia sp. and Novosphingobium sp. was quantified by weight loss, in addition to obvious morphological and structural changes of the PS films observed by SEM, ATR-FTIR, and contact angle analysis. The formation of new oxygen-containing functional groups implied the degradation pathway of oxidation. Although the degradation rates ranged from 2.7% to 7.7% after one month in lab and possibly lower in situ, their role in EPS removal is unneglectable.

A novel marine bacterium, designated strain 216LB-ZA1-12T, was isolated from a Penaeus vannamei aquaculture seawater sample. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain 216LB-ZA1-12T belonged to the genus Sneathiella , with the highest sequence similarity to Sneathiella glossodoripedis MKT133T (97.7 %), followed by Sneathiella limimaris GH1-24T (97.0 %), Sneathiella chungangensis CAU 1294T (96.6 %) and Sneathiella chinensis LMG 23452T (96.1 %). The average nucleotide identity and the DNA–DNA hybridization estimate values between strain 216LB-ZA1-12T and four close type strains were between 69.2–71.3% and 16.7–17.8 %, respectively. The bacterium was Gram-stain-negative, facultatively anaerobic, oxidase and catalase positive, oval- to rod-shaped, and motile. Growth was observed at pH 7–9, salinities of 1–15% and temperatures of 4–42 °C. The G+C content of the chromosomal DNA was 48.50 mol%. The major respiratory quinone was determined to be Q-10. The principal fatty acids were summed feature 8 (C18 : 1 ω7c/ω6c) and C16 : 0. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine and aminophospholipid. The combined genotypic and phenotypic data show that strain 216LB-ZA1-12T represents a novel species within the genus Sneathiella , for which the name Sneathiella aquimaris sp. nov. is proposed, with the type strain 216LB-ZA1-12T (=MCCC 1A14570T=KCTC 72144T).

A novel ultrasensitive and label-free electrochemical immunosensor was developed and used in combination with electrochemical impedance spectroscopy (EIS) or square wave voltammetry (SWV) for okadaic acid (OA) detection. The prepared immunosensor is primarily composed of polythionine-modified three-dimensional gold nanoelectrode ensembles (3DGNEEs). These ensembles were fabricated by combining electroless and electrochemical deposition. The deposition potential and time of the electrodeposition were optimized to enhance the properties of the 3DGNEEs. OA antibodies (anti-OA) were fixed on the PTh-modified ensembles by glutaraldehyde (GA). The fabrication process of immunosensor was characterized by EIS. The EIS responses were simulated using a newly constructed model of the recognition interface, and the detection limit of SWV is lower than that of EIS (3.20 × 10−15 vs. 2.65 × 10−12 g mL−1), and the linear OA detection range of the former is wider (1 × 10−12–1 × 10−7 vs. 5 × 10−12–1 × 10−9 g mL−1).

Strain GCL-8T and GCL-11T were isolated from Guanyinshan, a sandy beach on the Xiamen coast. Cells of the two strains were Gram-stain-negative, catalase-positive, oxidase-positive, rod-shaped and non-motile. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strains GCL-8T and GCL-11T belonged to the genera Roseovarius and Muricauda, with the highest sequence similarities to Roseovarius indicus B108T (96.5%) and Muricauda antarctica CGMCC 1.12174T (97.3%), respectively. The major fatty acids of strain GCL-8T were summed feature 8 (C18:1ω7c/ω6c), C19:0cyclo ω8c, C16:0 and C17:0, while the major fatty acids of strain GCL-11T were iso-C15:1 G, iso-C15:0 and iso-C17:0 3-OH. The G+C contents of the chromosomal DNA of strains GCL-8Tand GCL-11T were 64.1 mol% and 45.67 mol%, respectively. The respiratory quinones of strains GCL-8T and GCL-11T were Q-10 and MK-6, respectively. The polar lipids of strain GCL-8T were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, one unidentified aminophospholipid, one unidentified aminolipid, three unidentified phospholipids and three unidentified polar lipids. The polar lipids of strain GCL-11Twere phosphatidylethanolamine, seven unidentified phospholipids and four unidentified polar lipids. The combined genotypic and phenotypic data show that strains GCL-8T and GCL-11T represent two novel species within genera Roseovarius and Muricauda, for which the names Roseovariu samoyensis sp. nov. and Muricauda amoyensis sp. nov. are proposed, with type strains GCL-8T (=MCCC 1A11651T = KCTC 52430T) and GCL-11T (=MCCC 1A11649T=KCTC 52432T).

A Gram-negative, non-motile, non-spore-forming, aerobic and short rod-shaped bacterial strain R32T, was isolated from seawater of the South Atlantic Ocean. Strain R32T grew at 10–40 °C (optimum 28 °C), at pH 6.0–8.0 (optimum 7.0), and in the presence of 3–8 % NaCl (w/v) (optimum 5 %). Cells were oxidase- and catalase-positive. The 16S rRNA gene sequence of strain R32T shared the highest similarities with Mesonia oceanica (98.3 %), followed by Salegentibacter salarius (93.0 %), Salegentibacter mishustinae (92.8 %), Salegentibacter salegens (92.5 %) and Mesonia maritima (92.4 %). The dominant fatty acids were iso-C15 : 0 (32.7 %) and iso-C17 : 0 3-OH (21.1 %). Menaquinone-6 (MK-6) was detected as the sole respiratory quinone. The polar lipids found were phosphatidylethanolamine, three aminolipids and three unidentified lipids. The DNA G+C content was 35.0 mol%. The ANI value and dDDH value between strain R32T and the Salegentibacter and Mesonia species were 70.5–85.8 % and 18.7–30.5 %, respectively. Based on the results of the polyphasic characterization, strain R32T is considered to represent a novel species of the genus Mesonia , for which the name Mesonia hitae sp. nov. is proposed. The type strain is R32T (=MCCC 1A09780T=KCTC 72004T).

A novel Gram-stain-negative, aerobic, gliding, rod-shaped and carotenoid-pigmented bacterium, designated A20-9T, was isolated from a microbial consortium of polyethylene terephthalate enriched from a deep-sea sediment sample from the Western Pacific. Growth was observed at salinities of 1–8 %, at pH 6.5–8 and at temperatures of 10–40 °C. The results of phylogenetic analyses based on the genome indicated that A20-9T formed a monophyletic branch affiliated to the family Schleiferiaceae , and the 16S rRNA gene sequences exhibited the maximum sequence similarity of 93.8 % with Owenweeksia hongkongensis DSM 17368T, followed by similarities of 90.4, 90.1 and 88.8 % with Phaeocystidibacter luteus MCCC 1F01079T, Vicingus serpentipes DSM 103558T and Salibacter halophilus MCCC 1K02288T, respectively. Its complete genome size was 4 035 598 bp, the genomic DNA G+C content was 43.2 mol%. Whole genome comparisons indicated that A20-9T and O. hongkongensis DSM 17368T shared 67.8 % average nucleotide identity, 62.7 % average amino acid identity value, 46.6% of conserved proteins and 17.8 % digital DNA–DNA hybridization identity. A20-9T contained MK-7 as the major respiratory quinone. Its major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phospatidylcholine; and the major fatty acids were iso-C15 : 0 (37.5 %), iso-C16 : 0 3-OH (12.4 %), and summed feature 3 (C16 : 1ω7c /C16 : 1ω6c, 11.6 %). Combining the genotypic and phenotypic data, A20-9T could be distinguished from the members of other genera within the family Schleiferiaceae and represents a novel genus, for which the name Croceimicrobium hydrocarbonivorans gen. nov., sp. nov. is proposed. The type strain is A20-9T (=MCCC 1A17358T =KCTC 72878T).

The chlorinated nitroaromatic antibiotic chloramphenicol (CAP) is a refractory contaminant that is widely present in various environments. However, few CAP-mineralizing bacteria have been documented, and a complete CAP catabolism pathway has yet to be identified. In this study, the bacterial strain

The deep-sea bacterium strain FA13 was isolated from the sediment of the South Atlantic Ocean and identified as Bacillus circulans based on 16S ribosomal DNA sequence. Through liquid fermentation with five media, the cell-free supernatant fermented with ISP2 showed the highest inhibition activities against mycelial growth of Aspergillus parasiticus mutant strain NFRI-95 and accumulation of norsolorinic acid, a precursor for aflatoxin production. Based on ISP2, uniform design was used to optimize medium formula and fermentation conditions. After optimization, the inhibition efficacy of the 20-time diluted supernatant against A. parasiticus NFRI-95 mycelial growth and aflatoxin production was increased from 0–23.1% to 100%. Moreover, compared to the original protocol, medium cost and fermentation temperature were significantly reduced, and dependence on seawater was completely relieved, thus preventing the fermentor from corrosion. This is the first report of a deep-sea microorganism which can inhibit A. parasiticus NFRI-95 mycelial growth and aflatoxin production.

Numerous studies have reported soil damage from chemical fertilizer application and an obvious promotional effect of seaweed fertilizer fermented with Sargassum horneri on the growth of tomato roots and seedlings due to its alginate oligosaccharide. However, few studies have assessed the effects of the fermented seaweed fertilizer on ecological environment and microorganisms in soil. Herein, our objective is to uncover microbial and soil environmental responses to Sargassum horneri-fermented seaweed fertilizer. After treated tomato-planting plots with Sargassum horneri fermented seaweed fertilizer, soil bacterial community compositions based on 16S rRNA gene amplicon sequencing, enzyme activities in soil and crop yield were analyzed. The bacterial α-diversity was strongly influenced by seaweed fertilizer amendment after 60 days. Non-metric multidimensional scaling (NMDS) analysis showed that a difference in bacterial community compositions between day 0 and day 60 was obvious for soil treated with seaweed fertilizer. The community variation could be caused by invertase activity and dehydrogenase activity in canonical correlation analysis (CCA). Protease activity, polyphenol oxidase activity and urease activity showed an obvious correlation with community variation in the Mantel test. The fertilization increased tomato yield by 1.48–1.83 times, Vc content by 1.24–4.55 times and lycopene content by 1.20–2.33 times. In the present study, a possible reason for bacterial community variation was discovered, which will provide an economical dilution rate of seaweed fertilizer for optimal crop yield and quality. Meanwhile, our study will be beneficial for developing a possible substitute for chemical fertilizer and an improved understanding of soil microbial functions and soil sustainability.

ACE inhibitory dipeptides from Xerocomus badius fermented shrimp processing waste were isolated with ethanol, macroporous resin, chloroform, and Sephadex G-10 in sequence and identified by LC-MS/MS system coupled with electrospray ionization source. Molecular docking was performed for exploring the mechanism of their inhibitions. The results showed that the identified ACE inhibitory dipeptides were Cys-Cys and Cys-Arg with IC50 values of 4.37 ± 0.07 and 475.95 ± 0.11 μM, respectively. The difference between ACE inhibitor potency of Cys-Cys and Cys-Arg could be explained by results of molecular docking. Cys-Cys formed crucial coordination between carboxyl oxygen and Zn(II), hydrogen bonds with residues Ala354(O), Ala356(HN), and Tyr523(OH), and a bump with the residue His387(NE2) at the active site of ACE. There was no coordination, except for 5 hydrogen bonds (at residues His353, Ala354, Glu384, Glu403, and Arg522) and a bump (Glu411) between Cys-Arg and active site of ACE. These findings highlighted that Cys-Cys could be considered as a novel potent ACE inhibitor, and coordination between its carboxyl oxygen and Zn(II) played significant role in defining its ACE inhibitor potency.

A novel label-free impedimetric immunosensor for the quantitative detection of aflatoxin B1 (AFB1) was developed based on orientated staphylococcus protein A (SPA) modified gold three dimensional nanotube ensembles (3DTNEEs) which consisted of gold nanotubes fabricated by combining the technologies of template synthesis and controlled chemical etching of track-etched polycarbonate membrane. The structure and morphology of 3DTNEEs were evaluated by scanning electron microscopy. The diffusion characteristic and local current distribution on 3DTNEEs were simulated via the COMSOL Multiphysics 4.4 simulative software. The SPA self-assembly modified 3DTNEEs (SPA/3DTNEEs) was assessed by X-ray photoelectron spectroscopy. Electrochemical impedance spectroscopy was employed to characterize the fabrication process and optimize working conditions. The model of the molecular recognition interface was constructed and analyzed. The detection limit of AFB1 was 1.0 × 10−12 g mL−1 (S/N = 3) with a linear AFB1 concentration range of 4.0 × 10−12 to 6.0 × 10−9 g mL−1. The AFB1 recovery test in corn samples demonstrated one potential application of the immunosensor.

The chlorinated nitroaromatic antibiotic chloramphenicol (CAP) is a refractory contaminant that is widely present in various environments. However, few CAP-mineralizing bacteria have been documented, and a complete CAP catabolism pathway has yet to be identified. In this study, the bacterial strain Sphingobium sp. CAP-1 was isolated from an activated sludge sample and was shown to be capable of aerobically subsisting on CAP as the sole carbon, nitrogen, and energy source while simultaneously and efficiently degrading CAP. p-Nitrobenzoic acid (PNBA), p-nitrobenzaldehyde (PNBD), protocatechuate (PCA), and the novel side chain C3-hydroxy-oxygenated product of CAP (O-CAP) were identified during CAP degradation. Strain CAP-1 was able to convert O-CAP to intermediate product PNBA. The putative functional genes associated with PNBA catabolism into the tricarboxylic acid cycle via PCA and floc formation were also identified by genome sequencing and comparative proteome analysis. A complete pathway for CAP catabolism was proposed. The discovery of a novel CAP oxidation/detoxification process and a complete pathway for CAP catabolism enriches the fundamental understanding of the bacterial catabolism of antibiotics, providing new insights into the microbial-mediated fate, transformation, and resistance risk of CAP in the environment. The molecular basis of CAP catabolism and floc formation in strain CAP-1 also offers theoretical guidance for the enhanced bioremediation of CAP-containing environments.

Algae have long been used to augment plant productivity through their beneficial effects. Alginate oligosaccharide is believed to be one of the important components to enhance growth and crop yield. In this study, we isolated and characterized a Bacillus litoralis strain, named Bacillus M3, from decayed kelps. We further demonstrated that the M3 strain could secrete alginate lyase to degrade alginate. The crude enzyme exhibited the highest activity (33.74 U/mg) at pH 7.0 and 50°C. The M3 strain was also able to ferment the brown alga Sargassum horneri. Fermentation results revealed that a fermentation period of 8–12 hr was the best harvest time with the highest level of alginate oligosaccharides. Plant growth assay showed that the seaweed fermentation extract had an obvious promotion effect on root and seedling growth of Lycopersicon eseulentum L. Our results suggest that fermentation extract of Sargassum horneri by the novel strain of Bacillus litoralis M3 has significant development potential for biofertilizer production and agriculture application.

Obtaining efficient antibiotic-mineralizing consortium or pure cultures is a central issue for the deep elimination of antibiotic-contaminated environments. However, the antibiotic chloramphenicol (CAP) mineralizing consortium has not yet been reported. In this study, an efficient CAP-mineralizing consortium was successfully obtained with municipal activated sludge as the initial inoculum. This consortium is capable of aerobically subsisting on CAP as the sole carbon, nitrogen and energy sources and completely degrading 50 mg L−1 CAP within 24 h. After 5 d, 71.50 ± 2.63% of CAP was mineralized and Cl− recovery efficiency was 90.80 ± 7.34%. Interestingly, the CAP degradation efficiency obviously decreased to 18.22 ± 3.52% within 12 h with co-metabolic carbon source glucose. p-nitrobenzoic acid (p-NBA) was identified as an intermediate product during CAP biodegradation. The consortium is also able to utilize p-NBA as the sole carbon and nitrogen sources and almost completely degrade 25 mg L−1 p-NBA within 24 h. Microbial community analysis indicated that the dominant genera in the CAP-mineralizing consortium all belong to Proteobacteria (especially Sphingobium with the relative abundance over 63%), and most bacteria could degrade aromatics including p-NBA, suggesting these genera involved in the upstream and downstream pathway of CAP degradation. Although the acclimated consortium has been successively passaged 152 times, the microbial community structure and core genera were not obviously changed, which was consistent with the stable CAP degradation efficiency observed under different generations. This is the first report that the acclimated consortium is able to mineralize CAP through an oxidative pathway with p-NBA as an intermediate product.

A taxonomic study was carried out on strain R12BT, which was isolated from surface seawater of the Atlantic Ocean. The bacterium was observed to be rod-shaped, Gram-stain-negative, oxidase-positive and weakly positive for catalase. Growth was observed at salinities of 0.5–15 % and at temperatures of 4–45 °C. The isolate was incapable of nitrate reduction and hydrolysis of gelatin, Tween 80 and aesculin. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain R12BT belonged to the genus Roseovarius, with highest sequence similarity to Roseovarius indicus B108T (97.2 % 16S rRNA gene sequence similarity), followed by Roseovarius halotolerans HJ50T (96.8 %); other species of genus Roseovarius shared 93.0–96.2 % sequence similarities. The DNA–DNA hybridization estimate value between strain R12BT and R. indicus B108T was 23.2 ± 2.4 %. The average nucleotide identity between strain R12BT and R. indicus B108T was 77.1 %. The principal fatty acids were summed feature 8 (C18 : 1ω7c/ω6c) and C16 : 0. The G+C content of the chromosomal DNA was 63.6 mol%. The respiratory quinone was determined to be Q-10. Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, two aminolipids, two phospholipids and some unidentified lipids were present. The combined genotypic and phenotypic data show that strain R12BT represents a novel species of the genus Roseovarius, for which the name Roseovarius atlanticus sp. nov. is proposed, with the type strain R12BT ( = MCCC 1A09786T = KCTC 42506T).

A liquid fermentation process to bioconvert shrimp by-products was developed with two species of fungi, Boletus edulis and Suillus bovinus. Angiotensin I-converting enzyme (ACE) inhibitory, antioxidant activities of bioconverted products and the deodorization effect of fungal bioconversion were determined. Two species of fungi could grow quickly in shrimp by-products medium and deodorize shrimp by-products. Bioconverted products had higher ACE inhibitory and antioxidant activities than control medium. Water extracts without crude polysaccharides from mycelia of B. edulis had the highest ACE inhibitory activity (IC50 = 0.084 ± 0.011 mg/mL). Crude exopolysaccharides of B. edulis had higher antioxidant activity. Bioconversion with the fungus was proven to be a novel, practicable way to recycle shrimp by-products.

An ultrasensitive label free impedimetric immunosensor for AFB1 detection was fabricated based on poly(o-phenylenediamine) (PoPD) electropolymerized film modified gold three dimensional nanoelectrode ensembles (3DNEEs). The nanoelectrode ensembles were fabricated by template synthesis in track etched polycarbonate (PC) membranes. Scanning electron microscopy and X-ray diffraction were used for the evaluation of the properties of 3DNEEs. Anti-AFB1 was directionally immobilized on Staphylococcus protein A (SpA) with orientation functions. Cyclic voltammetry and electrochemical impedance spectroscopy were employed to characterize the fabrication process and optimize working conditions. The interface model of molecular recognition was constructed and reasonably interpreted. The detection limit was 0.019 ng mL−1 (S/N = 3). The linear detection concentration range of AFB1 was from 0.04 to 8.0 ng mL−1.

Alginate lyase is a biocatalyst that degrades alginate to produce oligosaccharides, which have many bioactive functions and could be used as renewable biofuels. Here we report a simple and sensitive plate assay for screening alginate lyase-excreting microorganisms from brown algae. Brown algae Laminaria japonica, Sargassum horneri and Sargassum siliquatrum were cultured in sterile water. Bacteria growing on the surface of seaweeds were identified and their capacity of excreting alginate lyase was analyzed. A total of 196 strains were recovered from the three different algae samples and 12 different bacterial strains were identified capable of excreting alginate lyases. Sequence analysis of the 16S rRNA gene revealed that these alginate lyase-excreting strains belong to eight genera: Paenibacillus (4/12), Bacillus (2/12), Leclercia (1/12), Isoptericola (1/12), Planomicrobium (1/12), Pseudomonas (1/12), Lysinibacillus (1/12) and Sphingomonas (1/12). Further analysis showed that the LJ-3 strain (Bacillus halosaccharovorans) had the highest enzyme activity. To our best knowledge, this is the first report regarding alginate lyase-excreting strains in Paenibacillus, Planomicrobium and Leclercia. We believe that our method used in this study is relatively easy and reliable for large-scale screening of alginate lyase-excreting microorganisms. Electronic supplementary material The online version of this article (doi:10.1186/s13568-017-0361-x) contains supplementary material, which is available to authorized users.

Ten actinomycete strains isolated from the Yellow Sea off China’s coasts were identified as belonging to two genera by 16S rDNA phylogenetic analysis: Streptomyces and Nocardiopsis. Six Streptomyces strains (MA10, 2SHXF01-3, MA35, MA05-2, MA05-2-1 and MA08-1) and one Nocardiopsis strain (MA03) were predicted to have the potential to produce aromatic polyketides based on the analysis of the KSα (ketoacyl-synthase) gene in the type II PKS (polyketides synthase) gene cluster. Four strains (MA03, MA01, MA10 and MA05-2) exhibited significant inhibitory effects on mycelia growth (inhibition rate >50%) and subsequent aflatoxin production (inhibition rate >75%) of the mutant aflatoxigenic Aspergillus parasiticus NFRI-95. The ethyl acetate extracts of the broth of these four strains displayed significant inhibitory effects on mycelia growth, and the IC50 values were calculated (MA03: 0.275 mg mL−1, MA01: 0.106 mg mL−1, MA10: 1.345 mg mL−1 and MA05-2: 1.362 mg mL−1). Five strains (2SHXF01-3, MA03, MA05-2, MA01 and MA08-1) were selected based on their high cytotoxic activities. The ethyl acetate extract of the Nocardiopsis strain MA03 was particularly noted for its high antitumor activity against human carcinomas of the cervix (HeLa), lung (A549), kidney (Caki-1) and liver (HepG2) (IC50: 2.890, 1.981, 3.032 and 2.603 μg mL−1, respectively). The extract also remarkably inhibited colony formation of HeLa cells at an extremely low concentration (0.5 μg mL−1). This study highlights that marine-derived actinomycetes are a huge resource of compounds for the biological control of aflatoxin contamination and the development of novel drugs for human carcinomas.

Thirty-six strains of marine actinomycetes were isolated from a sample of marine sediment collected from the Yellow Sea and evaluated in terms of their inhibitory activity on the growth of Aspergillus parasiticus and the production of norsolorinic acid using dual culture plate assay and agar diffusion methods. Among them, three strains showed strong antifungal activity and were subsequently identified as Streptomyces sp. by 16S rRNA gene sequencing analysis. The supernatant from the fermentation of the MA01 strain was extracted sequentially with chloroform and ethyl acetate, and the activities of the extracts were determined by tip culture assay. The assay results show that both extracts inhibited mycelium growth and toxin production, and the inhibitory activities of the extracts increased as their concentrations increased. The results of this study suggest that marine actinomycetes are biologically important for the control of mycotoxins, and that these bacteria could be used as novel biopesticides against mycotoxins.

Chitinase is one of the most important mycolytic enzymes with industrial significance, and produced by a number of organisms. A chitinase producing isolateSerratia marcescensJPP1 was obtained from peanut hulls in Jiangsu Province, China, and exhibited antagonistic activity against aflatoxins. In this study, we describe the optimization of medium composition with increased production of chitinase for the selected bacteria using statistical methods: Plackett-Burman design was applied to find the key ingredients, and central composite design of response surface methodology was used to optimize the levels of key ingredients for the best yield of chitinase. Maximum chitinase production was predicted to be 23.09 U/mL for a 2.1-fold increase in medium containing 12.70 g/L colloidal chitin, 7.34 g/L glucose, 5.00 g/L peptone, 1.32 g/L (NH4)2SO4, 0.7 g/L K2HPO4, and 0.5 g/L MgSO4·7H2O. Polymerase chain reaction (PCR) amplification of the JPP1 chitinase gene was performed and obtained a 1,789 bp nucleotide sequence; its open reading frame encoded a protein of 499 amino acids named as ChiBjp.

Fusarium graminearum is the main causal pathogen affecting small-grain cereals, and it produces deoxynivalenol, a kind of mycotoxin, which displays a wide range of toxic effects in human and animals. Bacterial strains isolated from peanut shells were investigated for their activities against F. graminearum by dual-culture plate and tip-culture assays. Among them, twenty strains exhibited potent inhibition to the growth of F. graminearum, and the inhibition rates ranged from 41.41% to 54.55% in dual-culture plate assay and 92.70% to 100% in tip-culture assay. Furthermore, eighteen strains reduced the production of deoxynivalenol by 16.69% to 90.30% in the wheat kernels assay. Finally, the strains with the strongest inhibitory activity were identified by morphological, physiological, biochemical methods and also 16S rDNA and gyrA gene analysis as Bacillus amyloliquefaciens. The current study highlights the potential application of antagonistic microorganisms and their metabolites in the prevention of fungal growth and mycotoxin production in wheat kernels. As a biological strategy, it might avoid safety problems and nutrition loss which always caused by physical and chemical strategies.

A class of (1R,2R)-N1-alkyl, N2-(4-chlorobenzyl)cyclohexane-1,2-diamines (4) were designed and synthesized. They were used to form the corresponding copper(II) complexes, 4-Cu(OAc)2, as chiral catalysts in the asymmetric Henry reaction of benzaldehyde and nitromethane, in which the desired product was obtained with a good yield (up to 99%) and up to 96% ee. The optimized catalyst, 4g-Cu(OAc)2, was also found efficient in the asymmetric Henry reaction between different aldehydes (aromatic aldehydes or aliphatic aldehydes) and nitromethane. Upon scaling up to gram quantities, the β-nitroalcohol was obtained in good yield (91%) with excellent selectivities (93% ee). The recycled catalyst, 4g-Cu(OAc)2, worked well up to three catalytic runs with marginal loss in yield and the enantioselectivity of the product was retained. It is believed that this procedure provides an opportunity to facilely synthesize large amounts of enantiomerically enriched β-nitroalcohol. A possible catalytic transition state for the asymmetric Henry reactions with our catalyst was suggested.

Additional file 3: Table S1. Comparison of alginate lyase activities in different strains.

Acute viral necrosis virus (AVNV) was newly reported as one causative agent responsible for mass mortality of adult Chinese scallop Chlamys farreri , which is widely cultured on northern China coast. Unfortunately, the interaction between virus and host is largely unknown. According to these, this study was undertaken to deeply explore the immune response of haemocyte against AVNV. Two-dimensional gel electrophoresis (2-DE) was introduced to produce protein expression profiles from samples taken at 24 h post-infection (hpi) from the haemocytes of C. farreri that were either specific pathogen free or else infected with AVNV. Forty-eight protein spots, which consistently showed either a marked change (≥1.5-fold difference) in accumulated levels or else were highly expressed in haemocytes, were selected for further investigation. In-gel trypsin digestion was conducted followed by matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-TOF-MS). Matching search was subsequently performed throughout bioinformatics databases. A total of 42 proteins were identified, all of which were classified into eight categories according to their Gene Ontology annotations of biological processes and molecular functions, i.e. cytoskeleton proteins, proteins involved in metabolism, proteins related to calcium homeostasis, chaperone, proteins involved in immunity, proteins involved in transcriptional regulation, proteins related to signal transduction, and ungrouped proteins. The possible biological significance of some observed proteins in the host response to AVNV was discussed. These studies could be served as the first global analysis of differentially expressed proteins in haemocytes from AVNV-infected C. farreri , and in addition to increasing our understanding of the pathogenesis of this virus-associated scallop disease, the results presented here should be useful both for potential biomarkers identification and anti-virus approaches development as well.

3D gold brush nanoelectrode ensembles (BNEEs) consisted of gold nanowires 100 nm in diameter and 300 nm in length were fabricated by combining the technologies of template synthesis and controlled chemical etching of the membrane. The structure and morphology of the BNEEs was imaged by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The real active areas of BNEEs were found to be different when characterized by different redox species. The direct redox of daunorubicin (DNR) at the gold BNEEs exhibited absorption-controlled characteristics and high current activity. BNEEs are reliable and effective in DNR detection.

A new functionalized l -cysteine surface modified 3D gold brush nanoelectrode assembly BNEE ( l -cys/BNEEs) was prepared. The BNEEs consisted of gold nanowires 100 nm in diameter and up to 400 nm in length fabricated by template synthesis in track etched polycarbonate membranes. The nanowires were exposed by controlled chemical etching of the membrane and were then modified by coating l -cys on the surface of the exposed gold nanowires. The morphology of the BNEEs was imaged by scanning electron microscopy and the real active area of BNEEs was determined by electrochemical impedance spectroscopy. The redox of daunorubicine (DNR) at the l -cys/BNEEs exhibited absorption-controlled characteristics and higher current activity than that at l -cys surface modified 2D disk NEEs ( l -cys/DNEEs). The square wave voltammetry technique was employed to detect DNR. The detection limit was 1.0 × 10 −8 M (s/n = 3). The linear detection concentration range of DNR was from 2.5 × 10 −8 to 4.0 × 10 −7 M.

To optimize the production conditions for exopolysaccharides with higher antioxidant activities fromXerocomus badiuscultured in shrimp byproduct medium, Plackett-Burman design, path of steepest ascent, and response surface methodology were explored. Based on the results of Plackett-Burman design and path of steepest ascent, a Box-Behnken design was applied to optimization and the regression models. The optimal cultural condition for high yield and antioxidant activity of the exopolysaccharides was determined to be 10.347% of solid-to-liquid ratio, a 4.322% content of bran powder, and a 1.217% concentration of glacial acetic acid. Culturing with the optimal cultural conditions resulted in an exopolysaccharides yield of4.588±0.346 g/L and a total antioxidant activity of2.956±0.105 U/mg. These values are consistent with the values predicted by the corresponding regression models (RSD < 5%).

Gold 3D cylindrical nanoelectrode ensembles (NEEs), 100 nm in diameter and 500 nm in length were prepared by electroless template synthesis in polycarbonate filter membranes, followed by selective controlled chemical etching. The morphology of the nanowires and cylindrical NEEs was imaged by scanning electron microscopy. The protruding nanoelectrodes were in good parallel order. EDX study showed that the nanoelectrode elements consisted of pure gold. The electrochemical evaluation of the 3D electrodes was conducted using the well known [Fe(CN)6]3−/[Fe(CN)6]4− couple. Cyclic voltammgrams (CV) show a very low double layer charging current and a higher ratio of signal to background current than 2D disc NEEs. Electrochemical impedance spectroscopy (EIS) indicates that the 3D cylindrical NEEs effectively accelerate the charge transfer process, which is in consistent with the results of CV. The linear relationship with a slope of 0.5 between lg Ipc and lg v shows that linear diffusion is dominant on the 3D cylindrical NEEs at conventional scan rates.