Polyethylene terephthalate (PET)-degrading bacteria in the pelagic deep-sea sediments of the Pacific Ocean.

Polyethylene terephthalate (PET) plastic pollution is widely found in deep-sea sediments. Despite being an international environmental issue, it remains unclear whether PET can be degraded through bioremediation in the deep sea. Pelagic sediments obtained from 19 sites across a wide geographic range in the Pacific Ocean were used to screen for bacteria with PET degrading potential. Bacterial consortia that could grow on PET as the sole carbon and energy source were found in 10 of the 19 sites. These bacterial consortia showed PET removal rate of 1.8%-16.2% within two months, which was further confirmed by the decrease of carbonyl and aliphatic hydrocarbon groups using attenuated total reflectance-Fourier-transform infrared analysis (ATR-FTIR). Analysis of microbial diversity revealed that Alcanivorax and Pseudomonas were predominant in all 10 PET degrading consortia. Meanwhile, Thalassospira, Nitratireductor, Nocardioides, Muricauda, and Owenweeksia were also found to possess PET degradation potential. Metabolomic analysis showed that Alcanivorax sp. A02-7 and Pseudomonas sp. A09-2 could turn PET into mono-(2-hydroxyethyl) terephthalate (MHET) even in situ stimulation (40 MPa, 10 °C) conditions. These findings widen the currently knowledge of deep-sea PET biodegrading process with bacteria isolates and degrading mechanisms, and indicating that the marine environment is a source of biotechnologically promising bacterial isolates and enzymes.

Comparative Assessment of In Vitro Xanthine Oxidase and α-Glucosidase Inhibitory Activities of Cultured Cambial Meristematic Cells, Adventitious Roots, and Field-Cultivated Ginseng.

Panax ginseng, a traditional Chinese medicine with a history spanning thousands of years, faces overexploitation and challenges related to extended growth periods. Tissue-cultured adventitious roots and stem cells are alternatives to wild and field-cultivated ginseng. In this study, we assessed the in vitro xanthine oxidase and α-glucosidase inhibitory activities of saponin extracts among cultured cambial meristematic cells (CMC), adventitious ginseng roots (AGR), and field-cultivated ginseng roots (CGR). The xanthine oxidase (XO) and α-glucosidase inhibitory activities were determined by uric acid estimation and the p-NPG method, respectively. Spectrophotometry and the Folin-Ciocalteu, aluminum nitrate, and Bradford methods were employed to ascertain the total saponins and phenolic, flavonoid, and protein contents. The calculated IC50 values for total saponin extracts against XO and α-glucosidase were 0.665, 0.844, and >1.6 mg/mL and 0.332, 0.745, and 0.042 mg/mL for AGR, CMC, CGR, respectively. Comparing the total saponin, crude protein, and total phenolic contents revealed that AGR > CMC > CGR. To the best of our knowledge, this study presents the first report on the in vitro comparison of xanthine oxidase and α-glucosidase inhibitory activities among AGR, CMC, and CGR. The findings offer valuable insights into the development of hypoglycemic and antihyperuricemic medicinal, nutraceutical, and functional products utilizing AGR and CMC.

Biotransformation of American Ginseng Stems and Leaves by an Endophytic Fungus Umbelopsis sp. and Its Effect on Alzheimer's Disease Control.

BACKGROUND: Common ginsenosides can be transformed into rare ginsenosides through microbial fermentation, and some rare ginsenosides can prevent Alzheimer's disease (AD). This study aimed to transform common ginsenosides into rare ginsenosides through solid-state fermentation of American ginseng stems and leaves (AGSL) by an endophytic fungus and to explore whether fermented saponin extracts prevent AD. METHODS: The powders of AGSL were fermented in a solid state by endophytic fungus. Total saponins were extracted from fermentation products using the methanol extraction method. The types of saponins were analyzed by liquid chromatography mass spectrometry (LC/MS). The Aß42 concentration and ß-secretase activity were measured by ELISA for the prevention of AD. RESULTS: After AGSL was fermented by an endophytic fungus NSJG, the total saponin concentration of the fermented extract G-SL was higher than the unfermented CK-SL. Rare ginsenoside Rh1 was newly produced and the yield of compound K (561.79%), Rh2 (77.48%), and F2 (40.89%) was increased in G-SL. G-SL had a higher inhibition rate on Aß42 concentration (42.75%) and ß-secretase activity (42.22%) than CK-SL, possibly because the rare ginsenoside Rh1, Rh2, F2, and compound K included in it have a strong inhibitory effect on AD. CONCLUSION: The fermented saponin extracts of AGSL show more inhibition effects on AD and may be promising therapeutic drugs or nutrients for AD.

Isolation and Optimization of Aflatoxin B1 Degradation by Uniform Design and Complete Genome Sequencing of Novel Deep-Sea Kocuria rosea Strain 13.

Aflatoxin B1 is a natural carcinogenic mycotoxin. The biological detoxification of aflatoxin could result in less environmental pollution, more moderate conditions, and less impact on food and feed, and be more convenient than physical and chemical methods. In this study, strain 13 with aflatoxin B1 degradation activity (67.47 ± 1.44%) was isolated and identified as Kocuria rosea. A uniform design was applied to optimize the degradation activity using a software Data Processing System, and a quadratic polynomial stepwise regression model was selected to investigate the relationships between the degradation rate and five independent variables. Furthermore, the optimal degradation conditions (culture temperature of 30 °C, culture time of 4.2 days, seawater ratio of 100%, pH of 7.11, and inoculation dosage of 0.09%) were verified with a degradation rate of 88 ± 0.03%, which was well matched with the predicted value (92.97%) of the model. Complete genome sequencing of Kocuria rosea, conducted with a combination of Illumina and single-molecule real-time sequencing, was used to analyze the genomic features and functions of the strain, which were predicted by the annotation based on seven databases, and may provide insights into the potential of Kocuria rosea, as well as providing a reference for degradation gene and protein mining. These results indicate that Kocuria rosea strain 13 has the ability to degrade aflatoxin B1 efficiently, and it also has the potential to provide aflatoxin-degrading enzymes.

Optimization of Fermentation Conditions and Product Identification of a Saponin-Producing Endophytic Fungus.

BACKGROUND: Some fungal endophytes isolated from P. ginseng may present a new method of obtaining saponins. This experiment aimed to optimize the total saponin yield produced through in vitro fermentation by an endophytic fungus and analyze its saponin species in the fermented extract. METHODS: Fermentation protocols were optimized with a uniform design and verified through regression analysis to maximize the total saponin yield. The saponin types under optimal fermentation conditions were then identified and analyzed using Liquid Chromatography-Mass Spectrometry. RESULTS: The Trametes versicolor strain NSJ105 (gene accession number: OR144428) isolated from wild ginseng could produce total saponins. The total saponin yield could be increased more than two-fold through the optimization of fermentation conditions. The concentration of the total saponins achieved by the verified protocol 105-DP was close to the predicted value. The fermentation conditions of the 105-DP protocol were as follows: potato concentration 97.3 mg/mL, glucose concentration 20.6 mg/mL, inoculum volume 2.1%, fermentation broth pH 2.1, fermentation temperature 29.2 °C, and fermentation time 6 d. It was detected and analyzed that the fermented extract of 105-DP contained the ginsenosides Rf and Rb3. CONCLUSION: The endophytic fungus Trametes versicolor strain NSJ105 has potential application value in saponin production.

Effect of rhizosphere microorganisms on aflatoxin contamination of maize.

The continued large consumption of maize makes it one of the most important food crops worldwide. However, the yield and quality of maize are greatly affected by global warming, and mycotoxin pollution keeps increasing. The effect of environmental factors, especially rhizosphere microorganisms, on mycotoxin pollution of maize is not completely clear, so we carried out relevant studies. In this study, we found that microbial communities inhabiting the maize rhizosphere, which consists of soil particles firmly attached to roots, as well as the soil, have a significant influence on the aflatoxin pollution of maize. The ecoregion and soil properties also had considerable effects on the microbial structure and diversity. The bacterial communities from the rhizosphere soil were profiled using a high-throughput next-generation sequencing method. The ecoregion and soil properties had considerable effects on the microbial structure and diversity. A comparison of the aflatoxin high concentration group with the low concentration group found that bacteria of the phylum Gemmatimonadetes and order Burkholderiales were significantly more abundant in the high concentration samples. Furthermore, these bacteria were significantly correlated with aflatoxin contamination and could aggravate its contamination of maize. The results of these analyses showed that seeding location could cause significant shifts in the root microbiota of maize, and the bacteria enriched in high aflatoxin contamination area soils should attract special concern. These findings will support strategies for improving maize yield and aflatoxin contamination control.

Biodegradation of polystyrene (PS) by marine bacteria in mangrove ecosystem.

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.

Mesonia hitae sp. nov., isolated from the seawater of the South Atlantic Ocean.

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).

Croceimicrobium hydrocarbonivorans gen. nov., sp. nov., a novel marine bacterium isolated from a bacterial consortium that degrades polyethylene terephthalate.

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).

Diversity and Antiaflatoxigenic Activities of Culturable Filamentous Fungi from Deep-Sea Sediments of the South Atlantic Ocean.

Despite recent studies, relatively few are known about the diversity of fungal communities in the deep Atlantic Ocean. In this study, we investigated the diversity of fungal communities in 15 different deep-sea sediments from the South Atlantic Ocean with a culture-dependent approach followed by phylogenetic analysis of ITS sequences. A total of 29 fungal strains were isolated from the 15 deep-sea sediments. These strains belong to four fungal genera, including Aspergillus, Cladosporium, Penicillium, and Alternaria. Penicillium, accounting for 44.8% of the total fungal isolates, was a dominant genus. The antiaflatoxigenic activity of these deep-sea fungal isolates was studied. Surprisingly, most of the strains showed moderate to strong antiaflatoxigenic activity. Four isolates, belonging to species of Penicillium polonicum, Penicillium chrysogenum, Aspergillus versicolor, and Cladosporium cladosporioides, could completely inhibit not only the mycelial growth of Aspergillus parasiticus mutant strain NFRI-95, but also the aflatoxin production. To our knowledge, this is the first report to investigate the antiaflatoxigenic activity of culturable deep-sea fungi. Our results provide new insights into the community composition of fungi in the deep South Atlantic Ocean. The high proportion of strains that displayed antiaflatoxigenic activity demonstrates that deep-sea fungi from the Atlantic Ocean are valuable resources for mining bioactive compounds.

Novel Pathway for Chloramphenicol Catabolism in the Activated Sludge Bacterial Isolate Sphingobium sp. CAP-1.

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.

Sneathiella aquimaris sp. nov., isolated from aquaculture seawater.

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).

Roseovarius amoyensis sp. nov. and Muricauda amoyensis sp. nov., isolated from the Xiamen coast.

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).

Isolation of a novel deep-sea Bacillus circulus strain and uniform design for optimization of its anti-aflatoxigenic bioactive metabolites production.

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.

Characterization of an efficient chloramphenicol-mineralizing bacterial consortium.

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 ±â€¯2.63% of CAP was mineralized and Cl- recovery efficiency was 90.80 ±â€¯7.34%. Interestingly, the CAP degradation efficiency obviously decreased to 18.22 ±â€¯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-1p-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.

Identification and Functional Mechanism of Novel Angiotensin I Converting Enzyme Inhibitory Dipeptides from Xerocomus badius Cultured in Shrimp Processing Waste Medium.

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.

Screening of alginate lyase-excreting microorganisms from the surface of brown algae.

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.

Isolation of a novel alginate lyase-producing Bacillus litoralis strain and its potential to ferment Sargassum horneri for biofertilizer.

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.

Optimization of Cultural Conditions for Antioxidant Exopolysaccharides from Xerocomus badius Grown in Shrimp Byproduct.

To optimize the production conditions for exopolysaccharides with higher antioxidant activities from Xerocomus badius cultured 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 of 4.588 ± 0.346 g/L and a total antioxidant activity of 2.956 ± 0.105 U/mg. These values are consistent with the values predicted by the corresponding regression models (RSD < 5%).

Roseovarius atlanticus sp. nov., isolated from surface seawater.

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).