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An agar-degrading bacterium, strain S1, was isolated from the coastal seawater of Jeju Island, Korea, and identified as a novel species of the genus Vibrio. The isolate, Vibrio sp. S1, produced at least five kinds of extracellular agarases in artificial sea water broth containing yeast extract and bacto peptone, and two of them were purified to homogeneity. Both agarases, AgaA33 and AgaA29, with apparent molecular weights of 33 kDa and 29 kDa, respectively, exhibited an optimum temperature and pH of 45°C and 7.0, respectively. AgaA33 and AgaA29 showed acidophilic properties and maintained 93% and 87% of the maximum agarase activity at 50°C, respectively, displaying their thermostability. Moreover, more than 80% activity was retained after heat treatment at 45°C for 1 h. Their agarase activities were inhibited by the presence of EDTA and remarkably stimulated by the presence of Mn2+ in a concentration-dependent manner, indicating that both agarases required the Mn2+ ion as a cofactor. The AgaA33 enzyme exhibited Km and Vmax values of 4.02 mg/mL and 27 U/mg, respectively. AgaA29 exhibited Km and Vmax values of 3.26 mg/mL and 200 U/mg, respectively. The instrumental analysis demonstrated that both are new β-agarases that can hydrolyze agarose and agaro-oligomers into neoagarotetraose and neoagarohexaose. In addition, AgaA33 coproduced neoagarooctaose as the major final product. Both thermostable enzymes are expected to be useful for the industrial application of agar.

Although many β-agarases that hydrolyze the β-1,4 linkages of agarose have been biochemically characterized, only three α-agarases that hydrolyze the α-1,3 linkages are reported to date. In this study, a new α-agarase, AgaWS5, from Catenovulum sediminis WS1-A, a new agar-degrading marine bacterium, was biochemically characterized. AgaWS5 belongs to the glycoside hydrolase (GH) 96 family. AgaWS5 consists of 1295 amino acids (140 kDa) and has the 65% identity to an α-agarase, AgaA33, obtained from an agar-degrading bacterium Thalassomonas agarivorans JAMB-A33. AgaWS5 showed the maximum activity at a pH and temperature of 8 and 40 °C, respectively. AgaWS5 showed a cold-tolerance, and it retained more than 40% of its maximum enzymatic activity at 10 °C. AgaWS5 is predicted to have several calcium-binding sites. Thus, its activity was slightly enhanced in the presence of Ca2+, and was strongly inhibited by EDTA. The Km and Vmax of AgaWS5 for agarose were 10.6 mg/mL and 714.3 U/mg, respectively. Agarose-liquefication, thin layer chromatography, and mass and NMR spectroscopic analyses demonstrated that AgaWS5 is an endo-type α-agarase that degrades agarose and mainly produces agarotetraose. Thus, in this study, a novel cold-adapted GH96 agarotetraose-producing α-agarase was identified.

Agar, a major polysaccharide of red algal cells, is degraded by β-agarases into neoagarobiose, which is further hydrolyzed into the monomers, d-galactose and 3,6-anhydro-l-galactose, by 1,3-α-3,6-anhydro-l-galactosidases including α-1,3-l-neoagarooligasaccharide hydrolase (α-NAOSH). A novel cold-adapted alkaline α-NAOSH, Ahg558, consisting of 359 amino acids (40.8 kDa) was identified from Gayadomonas joobiniege G7. It was annotated as a glycosyl hydrolase family 43 based on genomic sequence analysis, showing 84% and 74% identities with the characterized α-NAOSHs from Agarivorans gilvus WH0801 and Saccharophagus degradans 2–40, respectively. The recombinant Ahg558 (rAhg558) purified from Escherichia coli formed dimers and cleaved α-1,3 glycosidic bonds at the non-reducing ends of the neoagarobiose, neoagarotetraose, and neoagarohexaose, which was confirmed by thin-layer chromatography and mass spectrometry. The optimum pH and temperature for rAhg558 activity were 9.0 and 30 °C, respectively. Unusually, it retained over 93% activity in a broad range of temperatures between 0 and 40 °C and over 73% in a broad range of pH between pH 6.0 and pH 9.0, indicating it is a unique cold-adapted alkaline exo-acting α-NAOSH. Its enzymatic activity was dependent on Mn2+ ions. Km and Vmax values toward neoagarobiose were 2.6 mg/mL (8.01 mM) and 133.33 U/mg, respectively.

Our study investigated the biological functions of three neoagarooligosaccharides (NAOs), neoagarobiose (NA2), neoagarotetraose (NA4), and neoagarohexaose (NA6). NAOs were prepared by hydrolyzing agar with the recombinant β-agarases, DagA and DagB, from Streptomyces coelicolor A3(2). An in vitro DPPH (diphenyl-2,4,6-trinitrophenyliminoazanium) radical scavenging assay revealed that none of the NAOs had any significant antioxidative activity. We also assessed the antibacterial activity of each NAO against several gram-negative and gram-positive bacteria. This revealed weak effects against four of the seven tested strains. NAO treatment resulted in significant inhibition of α-glucosidase, with the strongest effect observed in a NA4 and NA6 mixture, and a decreasing effect was observed in the order NA2>NA4>NA6. Little inhibition was observed against α-amylase, with an effect significantly lower than that of acarbose. No observable cytotoxicity was found in immortalized Melan-a mouse melanocytes by NAO treatment up to a concentration of 2,000 μg/mL. However, melanin synthesis was significantly reduced by NAO treatment, with the strongest effect observed in a NA4 and NA6 mixture and decreasing effects observed in the order NA6>NA4>NA2. The tyrosinase activity of Melan-a cells was also consistently decreased by NAO treatment. Among the tested factors, treatment of NA4 and NA6 mixture showed the highest inhibition effects against α-glucosidase and tyrosinase, and melanin biosynthesis. Further in vivo study to investigate the role of NAO in these biological functions will be necessary for future biotechnological applications.

New structural designs of antibody fragments have considerable biotechnological and therapeutic potential. In this study, we describe the construction and functional expression of a cetuximab-based antibody fragment (scFv-CH3, minibody) that exhibits activity against human colon cancer. Heterologous expression in Escherichia coli (E. coli) was improved by optimizing the host cells, signal peptides, induction conditions, and culture media. The recombinant minibody was expressed successfully in the periplasm of E. coli BL21(DE3) and purified by immobilized metal affinity chromatography using a Ni2+-NTA resin. The purified minibody showed high binding affinity to cell-surface epidermal growth factor receptor (EGFR) and exhibited inhibition of EGFR-mediated signal transduction in the human colon cancer cell line HT29 in a similar way by the cetuximab. The minibody also showed significant level of anti-cancer ability in the HT29 colorectal cancer xenograft model, which was lower than that by the cetuximab.

A xylan-degrading bacterium, designated as MS5(T) strain, was isolated from soil collected from the Jeju Island, Republic of Korea. Strain MS5(T) was Gram-stain-positive, aerobic, and motile by polar flagellum. The major fatty acids identified in this bacterium were iso-C15:0 (32.3%), C16:0 (27.3%), and anteiso-C15:0 (10.2%). A similarity search based on the 16S rRNA gene sequence revealed that the strain belongs to the class Bacilli and shared the highest similarity with the type strains Bacillus beringensis BR035(T) (98.7%) and Bacillus korlensis ZLC-26(T) (98.6%) which form a coherent cluster in a neighbor-joining phylogenetic tree. The DNA G+C content of strain MS5(T) was 43.0 mol%. The major menaquinone was MK-7 and the diagnostic diamino acid in the cell-wall peptidoglycan was meso-diaminopimelic acid. The DNADNA relatedness values between strain MS5(T) and two closely related species, B. beringensis BR035(T) and B. korlensis ZLC-26(T), were less than 70%. DNA-DNA relatedness analysis and 16S rRNA sequence similarity, as well as phenotypic and chemotaxonomic characteristics suggest that the strain MS5(T) constitutes a novel Bacillus species, for which the name Bacillus coreaensis sp. nov. is proposed. The type strain is MS5(T) (=DSM25506(T) =KCTC13895(T)).

A Gram-negative, aerobic, motile, rod-shaped, agarolytic bacterium, designated as H7, was isolated from a coastal seawater sample. This strain grows at pH 6.0–8.0, temperature of 15–40 °C, and at an NaCl concentration of 1–7 % (w/v). Ubiquinone-8 was the predominant respiratory quinone, and the DNA G+C content was 45.82 mol%. Analysis of the 16S rRNA sequence suggests that strain H7 belongs to the genus Pseudoalteromonas. DNA-DNA hybridization analysis showed DNA relatedness of as low as 55.42 and 40.27 % with its nearest phylogenetic neighbors Pseudoalteromonas atlantica IAM12927T and Pseudoalteromonas espejiana NCIMB2127T, respectively, which led us to name H7 Pseudoalteromonas hodoensis sp. nov. The type strain is H7T (=DSM25967T = KCTC23887T). An agarase (AgaA7) was purified to homogeneity from the cell-free culture broth of H7 through many steps of chromatography. Purified AgaA7 had an apparent molecular weight of 35 kDa, with a distinct NH2-terminal sequence of Ala-Asp-Ala-Thr-X-Pro (X, any amino acid) from the reported proteins, implying that it is a novel enzyme. The optimum pH and temperature for agarase activity were 7.0 and 45 °C, respectively. Thin-layer chromatography analysis, mass spectrometry, and enzyme assay using p-nitrophenyl-α/β-D-galactopyranoside revealed that AgaA7 is both an exo- and endo-type β-agarase that degrades agarose into neoagarotetraose, neoagarohexaose, and neoagarooctaose (minor).

Alteromonas sp. GNUM-1 is known to degrade agar, the main cell wall component of red macroalgae, for their growth. A putative agarase gene (agaG1) was identified from the mini-library of GNUM-1, when extracellular agarase activity was detected in a bacterial transformant. The nucleotide sequence revealed that AgaG1 had significant homology to GH16 agarases. agaG1 encodes a primary translation product (34.7 kDa) of 301 amino acids, including a 19-amino-acid signal peptide. For intracellular expression, a gene fragment encoding only the mature form (282 amino acids) was cloned into pGEX-5X-1 in Escherichia coli, where AgaG1 was expressed as a fusion protein with GST attached to its N-terminal (GST-AgaG1). GST-AgaG1 purified on a glutathione sepharose column had an apparent molecular weight of 59 kDa on SDS-PAGE, and this weight matched with the estimated molecular weight (58.7 kDa). The agarase activity of the purified protein was confirmed by the zymogram assay. GST-AgaG1 could hydrolyze the artificial chromogenic substrate, p-nitrophenyl-β-d-galactopyranoside but not p-nitrophenyl-α-d-galactopyranoside. The optimum pH and temperature for GST-AgaG1 activity were identified as 7.0 and 40 °C, respectively. GST-AgaG1 was stable up to 40 °C (100 %), and it retained more than 70 % of its initial activity at 45 °C after heat treatment for 30 min. The K m and V max for agarose were 3.74 mg/ml and 23.8 U/mg, respectively. GST-AgaG1 did not require metal ions for its activity. Thin layer chromatography analysis, mass spectrometry, and 13C-nuclear magnetic resonance spectrometry of the GST-AgaG1 hydrolysis products revealed that GST-AgaG1 is an endo-type β-agarase that hydrolyzes agarose and neoagarotetraose into neoagarobiose.

Two genes from Zymomonas mobilis that are responsible for ethanol production, pyruvate decarboxylase (pdc) and alcohol dehydrogenase II (adhII), were heterologously expressed in the Gram-positive bacterium Streptomyces lividans TK24. An examination of carbon distribution revealed that a significant portion of carbon metabolism was switched from biomass and organic acid biosynthesis to ethanol production upon the expression of pdc and adhII. The recombinant S. lividans TK24 produced ethanol from glucose with a yield of 23.7 % based on the carbohydrate consumed. The recombinant was able to produce ethanol from xylose, l-arabinose, mannose, l-rhamnose, galactose, ribose, and cellobiose with yields of 16.0, 25.6, 21.5, 33.6, 30.6, 14.6, and 33.3 %, respectively. Polymeric substances such as starch and xylan were directly converted to ethanol by the recombinant with ethanol yields of 18.9 and 8.8 %, respectively. The recombinant S. lividans TK24/Tpet developed in this study is potentially a useful microbial resource for ethanol production from various sources of biomasses, especially microalgae.

A newly isolated bacterial strain, Bacillus sp. MX47, was actively producing extracellular xylanase only in xylan-containing medium. The xylanase was purified from the culture broth by two chromatographic steps. The xylanase had an apparent molecular weight of 26.4 kDa with an NH2-terminal sequence (Gln-Gly-Gly-Asn-Phe) distinct from that of reported proteins, implying it is a novel enzyme. The optimum pH and temperature for xylanase activity were 8.0 and 40 °C, respectively. The enzyme activity was severely inhibited by many divalent metal ions and EDTA at 5 mM. The xylanase was highly specific to beechwood and oat spelt xylan, however, not active on carboxymethyl cellulose (CMC), avicel, pectin, and starch. Analysis of the xylan hydrolysis products by Bacillus sp. MX47 xylanase indicated that it is an endo-β-1,4-xylanase. It hydrolyzed xylan to xylobiose as the end product. The K m and V max values toward beechwood xylan were 3.24 mg ml−1 and 58.21 μmol min−1 mg−1 protein, respectively.

Agar is a mixture of heterogeneous galactans, mainly composed of 3,6-anhydro-L-galactoses (or L-galactose-6-sulfates) D-galactoses and L-galactoses (routinely in the forms of 3,6-anhydro-L-galactoses or L-galactose-6-sulfates) alternately linked by β-(1,4) and α-(1,3) linkages. It is a major component of the cell walls of red algae and has been used in a variety of laboratory and industrial applications, owing to its jellifying properties. Many microorganisms that can hydrolyze and metabolize agar as a carbon and energy source have been identified in seawater and marine sediments. Agarolytic microorganisms commonly produce agarases, which catalyze the hydrolysis of agar. Numerous agarases have been identified in microorganisms of various genera. They are classified according to their cleavage pattern into three types-α-agarase, β-agarase, and β-porphyranase. Although, in a broad sense, many other agarases are involved in complete hydrolysis of agar, most of those identified are β-agarases. In this article we review agarolytic microorganisms and their agar-hydrolyzing systems, covering β-agarases as well as α-agarases, α-neoagarobiose hydrolases, and β-porphyranases, with emphasis on the recent discoveries. We also present an overview of the biochemical and structural characteristics of the various types of agarases. Further, we summarize and compare the agar-hydrolyzing systems of two specific microorganisms: Gram-negative Saccharophagus degradans 2-40 and Gram-positive Streptomyces coelicolor A3(2). We conclude with a brief discussion of the importance of agarases and their possible future application in producing oligosaccharides with various nutraceutical activities and in sustainably generating stock chemicals for biorefinement and bioenergy.

Protein D (9.7 kDa) is an extracellular protein detected in the culture broth of A-factor-producing Streptomyces griseus IFO 13350, but not of the A-factor-deficient mutant strain S. griseus HH1. Comparison of the N-terminal amino acid sequence with the genomic sequencing data of S. griseus IFO 13350 identified protein D as Sgr3394, which encodes a putative secretory protein with unknown function. The premature Sgr3394 consisted of 128 amino acids (13.5 kDa), showed 87.5% identity with SACT1DRAFT-0503, from Streptomyces sp. ACT-1, and 68.8% identity with SrosN15-18634, from S. roseosporus NRRL15998, and was confirmed to be matured for secretion by a peptide cleavage between the Ala-38 and Ala-39 bond. RT-PCR analysis of Sgr3394 clearly showed that it can be transcribed in the wild-type strain, but not in the A-factor-deficient strain. However, a gel-mobility shift assay of the promoter region of sgr3394 with A-factor-dependent transcriptional regulator (AdpA) showed that AdpA could not specifically recognize the putative AdpA-binding site (5'-TCCCCCGAAT-3'). All of these data strongly suggest that the expression of sgr3394 is not directly induced by AdpA but is regulated indirectly by an A-factor dependent protein. Introduction of sgr3394 on a high-copy-numbered plasmid (pWHM3-sgr3394) into S. lividans TK21 induced massive production of actinorhodin (blue pigment) and undecylprodigiosin (red pigment). Compared to the control, production of each pigment increased by 6.1 and 2.6 times, respectively, on R2YE agar, and 3.1 and 1.4 times, respectively, in R2YE broth; there was little influence on morphogenesis. In S. coelicolor A3(2)/pWHM3-sgr3394, actinorhodin and undecylprodigiosin productions were enhanced to 1.8 and 1.1 times those observed in the control, respectively, suggesting that overexpression of sgr3394 can stimulate secondary metabolism, especially actinorhodin biosynthesis, in S. lividans and S. coelicolor.

The agar degrading bacterial strain GNUM-08124 was isolated from Enteromorpha compressa collected in the East Sea of Korea by using a selective artificial sea water (ASW) agar plate containing agar as the sole carbon source. GNUM-08124 grows to produce a circular, smooth, yellow-colored, and raised colony. Its ability to hydrolyze agar was confirmed by staining the ASW agar plate with Lugol’s solution. In liquid culture, the cell density (A600) increased exponentially and reached a maximum level on the third day of cultivation. The specific agarase activity also increased in proportion to the cell density and reached maximum agarolytic activity on the third day. The 16S rRNA sequence of GNUM-08124 showed a close relationship to Micrococcus luteus (99.65%) and Micrococcus endophyticus (99.15%), which led us to assign it to the genus Micrococcus. Physiological studies indicated that optimal growth conditions were between 30 and 40°C, pH 4 and 7, using media containing between 5 and 10% NaCl (w/v), respectively. The GNUM-08124 strain was a grampositive, urease-positive, and catalase-positive bacterium. It could not hydrolyze gelatin, cellulose, xylan, or starch, but fermented a broader range of substrates, including Dglucose, D-galactose, D-fructose, D-lactose, D-trehalose, D-mannitol, D-melibiose, D-raffinose, D-xylose, methyl-α-D-glucopyranoside, N-acetyl-glucosamine, and xylitol, than those fermented by M. luteus or M. endophyticus, suggesting GNUM-08124 is a novel agar hydrolyzing microorganism belonging to Genus Micrococcus. Micrococcus sp. GNUM-08124 showed the highest agarase activity when it was cultured in ASW-YP medium supplemented with 0.4% glucose, but demonstrated lower activity in rich media (LB or TSB), in spite of superior cell growth, implying that agarase production is tightly regulated in an agar-dependent manner and repressed in rich conditions.

Production of proteins in secretary form is one of the important factors affecting fermentation. The Tat (twin arginine translocation) protein secretion system, which includes the proteins TatA, TatB, and TatC, was identified in the genomic sequence of Streptomyces griseus IFO13350. The tatA and tatC genes were organized into a polycistronic operon, whereas tatB was located separately on the chromosome. Comparison of amino acid sequences suggested that TatC was a membrane-spanning protein, whereas TatA and TatB were found to be cytoplasmic proteins. Analysis of extracellular proteins and N-terminal amino acid sequencing revealed that secretion of SGR5556 was significantly enhanced by overexpression of TatAC in S. griseus HH1. Further, enzymatic study showed that SGR5556 encoded a glycerophosphoryl diester phosphodiesterase. In addition, other hydrolase activities, such as those of amylase, total protease, metalloprotease, trypsin, chymotrypsin, and Leuaminopeptidase, were also enhanced by 3, 3, 2.6, 2.3, 5.4, and 2.5 fold, respectively, in S. griseus upon TatAC overexpression. Overexpression of TatAC induced the production of a greenish-yellow pigment in S. griseus HH1 as well as more abundant sporulation at an earlier stage in Streptomyces coelicolor A3(2). In silico analysis by TatFIND, SignalP, and TMHMM identified 19 binding proteins, 28 enzymatic proteins, and 27 other proteins with unknown functions as putative TatAC-dependent secretary proteins. These results clearly indicate that TatA and TatC constitute a functional Tat system in S. griseus. Additionally, the S. griseus Tat system can be useful for the production of valuable proteins, including many hydrolytic enzymes and candidates of Tat-dependent secretary proteins, under industrial conditions.

We assessed the ability of aPseudonocardia sp. from soil samples to bioconvert vitamin D3. The optimal culture conditions for the bioconversion of vitamin D3 to active 1α,25-dihydroxyvitamin D3 were investigated by varying the carbon and nitrogen sources, the metal salt concentrations, the initial pH, and the temperature. Microbial transformations were carried out with the addition of vitamin D3 dissolved in ethanol. They were sampled by extraction with methanol-dichloromethane and the samples were examined by HPLC. Optimum culture conditions were found to be 0.4% yeast extract, 1% glucose, 3% starch, 1% fish meal, 0.2% NaCl, 0.01% K2HPO4, 0.2% CaCO3, 0.01% NaF, and pH 7.0 at 28°C. The optimal timing of the addition of vitamin D3 for the production of calcitriol byPseudonocardia autotrophica ID 9302 was concurrent with the inoculation of seed culture broth. Maximum calcitriol productivity and the yield of bioconversion reached a value of 10.4 mg/L and 10.4% respectively on the 7th day in a 75 L fermenter jar under the above conditions.

Background Environmental signals usually enhance secondary metabolite production in Streptomycetes by initiating complex signal transduction system. It is known that different sigma factors respond to different types of stresses, respectively in Streptomyces strains, which have a number of unique signal transduction mechanisms depending on the types of environmental shock. In this study, we wanted to know how a pH shock would affect the expression of various sigma factors and shock-related proteins in S. coelicolor A3(2). Results According to the results of transcriptional and proteomic analyses, the major number of sigma factor genes were upregulated by an acidic pH shock. Well-studied sigma factor genes of sigH (heat shock), sigR (oxidative stress), sigB (osmotic shock), and hrdD that play a major role in the secondary metabolism, were all strongly upregulated by the pH shock. A number of heat shock proteins including the DnaK family and chaperones such as GroEL2 were also observed to be upregulated by the pH shock, while their repressor of hspR was strongly downregulated. Oxidative stress-related proteins such as thioredoxin, catalase, superoxide dismutase, peroxidase, and osmotic shock-related protein such as vesicle synthases were also upregulated in overall. Conclusion From these observations, an acidic pH shock was considered to be one of the strongest stresses to influence a wide range of sigma factors and shock-related proteins including general stress response proteins. The upregulation of the sigma factors and shock proteins already found to be related to actinorhodin biosynthesis was considered to have contributed to enhanced actinorhodin productivity by mediating the pH shock signal to regulators or biosynthesis genes for actinorhodin production.

A new anthracycline ID6105 (11-hydroxyaclacinomycin X, Hyrubicin), which has potent antitumor activities against a broad range of cancer cell lines, was produced by hybrid biosynthetic approach. We investigated ID6105-induced apoptosis and in vivo efficacy on experimental tumors, and also defined its optimal dosing schedule. From PARP cleavage assay and caspase-3 activation assay, we found that ID6105 can induce apoptosis in tumor cells and its ability was superior to doxorubicin. In human tumor xenograft models, ID6105 showed greater antitumor effects on SW620 and NCI-H23 than doxorubicin. The 1 mg/kg of ID6105 treatment reduced size of tumor by 93% in NCI-H23 model whereas doxorubicin (2 mg/kg) showed only 39% inhibition rate. In SW620 model, 0.3 mg/kg of ID6105 proved to be comparable to 2 mg/kg of doxorubicin. Testing with several dosing schedule such as qd10, qd5, and q4d3, we decided intravenous qd5 treatment was an optimal schedule as a dose regimen of ID6105. In conclusion, ID6105 is a potent apoptosis-inducing anthracycline and effective in treatment of tumors with qd5 dosing schedule.