Exogenous production of cold-active cellulase from polar Nocardiopsis sp. with increased cellulose hydrolysis efficiency.

The present work was designed to isolate and characterise the actinobacteria in the Polar Front region of the Southern Ocean waters and species of Nocardiopsis and Streptomyces were identified. Among those, the psychrophilic actinobacterium, Nocardiopsis dassonvillei PSY13 was found to have good cellulolytic activity and it was further studied for the production and characterisation of cold-active cellulase enzyme. The latter was found to have a specific activity of 6.36 U/mg and a molar mass of 48 kDa with a 22.9-fold purification and 5% recovery at an optimum pH of 7.5 and a temperature of 10 °C. Given the importance of psychrophilic actinobacteria, N. dassonvillei PSY13 can be further exploited for its benefits, meaning that the Southern Ocean harbours biotechnologically important microorganisms that can be further explored for versatile biotechnological and industrial applications.

Bioinformatics delimitation of the psychrophilic and psychrotolerant actinobacteria isolated from the Polar Frontal waters of the Southern Ocean.

Identification of microorganisms plays a key role in the determination of the composition of microbial diversity for bioprospecting of biotechnologically important biomolecules. Digitalization is the process that solve discrepancies in microbial identification and cataloguing their diversity in distinct ecological habitats. In view of this connection, the psychrophilic and psychrotolerant actinobacteria were isolated from the water samples of the Polar Frontal region of the Southern Ocean. 16S rRNA gene sequencing for identification of psychrophiles was carried out and sequences were deposited in NCBI GeneBank. 16S rRNA gene sequences were used to create QR codes, CGR, FCGR and GC plot. This generated digital data help to relate the diversity amongst the isolated actinobacterial strains. The digital data showed considerable divergence among the actinobacterial strains. This generated bioinformatics data is helpful in the delimitation of the psychrophilic and psychrotolerant actinobacteria. Thus, the present study is a robust and accurate method for the identification of Polar microorganisms in a fixed boundary. Hence, this work will help to assign a unique digital identity to microorganisms in near future [9-19].

Characterization, antimicrobial and antioxidant property of exopolysaccharide mediated silver nanoparticles synthesized by Streptomyces violaceus MM72.

Green synthesis of silver nanoparticle (SNPs) has gained considerable attention in nano-biotechnology and nano-medicine owing their potency and eco-friendliness. In this, we account the exopolysaccharide and its mediated synthesis of SNPs and their biological activities. Exopolysaccharide of the Streptomyces violaceus composed of total carbohydrate (61.4%), ash (16.1%), moisture content (1.8%) and NMR confirmed their structural composition. SNPs synthesized by the exopolysaccharide, confirmed using UV-vis spectral analysis and characterized by TEM and XRD analyses. Further, the SNPs evaluated for its antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis using disc diffusion method. The SNPs has shown promising antibacterial activity were evaluated for MIC. Furthermore, the SNPs were tested for antioxidant activities and was found to have promising antioxidant activity over the standards. The above results prove that SNPs can be considered as a potent antibacterial and antioxidant drug in future.

Actinobacteria mediated synthesis of nanoparticles and their biological properties: A review.

Nanotechnology is gaining tremendous attention in the present century due to its expected impact on many important areas such as medicine, energy, electronics, and space industries. In this context, actinobacterial biosynthesis of nanoparticles is a reliable, eco-friendly, and important aspect of green chemistry approach that interconnects microbial biotechnology and nanobiotechnology. Antibiotics produced by actinobacteria are popular in almost all the therapeutic measures and it is known that these microbes are also helpful in the biosynthesis of nanoparticles with good surface and size characteristics. In fact, actinobacteria are efficient producers of nanoparticles that show a range of biological properties, namely, antibacterial, antifungal, anticancer, anti-biofouling, anti-malarial, anti-parasitic, antioxidant, etc. This review describes the potential use of the actinobacteria as the novel sources for the biosynthesis of nanoparticles with improved biomedical applications.

Production of α-amylase for the biosynthesis of gold nanoparticles using Streptomyces sp. MBRC-82.

Marine actinobacterial synthesis of gold nanoparticles has good potential to develop simple, cost-effective and eco-friendly methods for production of important biomaterials. In this context, gold nanoparticles have attracted considerable attention in recent years, owing to their various applications. In this paper, we report on the production of α-amylase for the extracellular synthesis of gold nanoparticles using Streptomyces sp. MBRC-82. Medium composition and culture conditions for α-amylase production were statistically optimized. Plackett-Burman design was employed to find out the optimal medium constituents and culture conditions to enhance α-amylase production. Box-Behnken design revealed that three independent variables namely soluble starch (5.8484 g), peptone (3.5191 g), and NaCl (0.3829) significantly influenced α-amylase production. The gold nanoparticles were characterized by ultraviolet-visible (UV-vis) spectrometer, X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDXA), and transmission electron microscopy (TEM). The particles synthesized using the optimized enzyme activity ranged from 20 to 80 nm with an average particle size of 40 nm and therefore can be extended to various medicinal applications.

Actinobacterial enzyme inhibitors--a review.

Actinobacteria have potential as important new sources of enzyme inhibitors. Enzyme inhibitors have great demand in medicine, agriculture and biotechnology. In medicine, enzyme inhibitors can be used as therapeutic agents for bacterial, fungal, viral and parasitic diseases as well as treating cancer, neurodegenerative, immunological and cardiovascular diseases. Enzyme inhibitors are also valuable for the control of carbohydrate-dependent diseases such as diabetes, obesity and hyperlipidemia and melanogenesis in skin. They can be also involved in crop protection against plant pathogens, herbivorous pests and abiotic stresses such as drought. In this review, we discuss about several actinobacterial enzyme inhibitors with various industrial uses and biotechnological applications.

Marine actinobacteria: an important source of bioactive natural products.

Marine environment is largely an untapped source for deriving actinobacteria, having potential to produce novel, bioactive natural products. Actinobacteria are the prolific producers of pharmaceutically active secondary metabolites, accounting for about 70% of the naturally derived compounds that are currently in clinical use. Among the various actinobacterial genera, Actinomadura, Actinoplanes, Amycolatopsis, Marinispora, Micromonospora, Nocardiopsis, Saccharopolyspora, Salinispora, Streptomyces and Verrucosispora are the major potential producers of commercially important bioactive natural products. In this respect, Streptomyces ranks first with a large number of bioactive natural products. Marine actinobacteria are unique enhancing quite different biological properties including antimicrobial, anticancer, antiviral, insecticidal and enzyme inhibitory activities. They have attracted global in the last ten years for their ability to produce pharmaceutically active compounds. In this review, we have focused attention on the bioactive natural products isolated from marine actinobacteria, possessing unique chemical structures that may form the basis for synthesis of novel drugs that could be used to combat resistant pathogenic microorganisms.

Optimization, production and characterization of glycolipid biosurfactant from the marine actinobacterium, Streptomyces sp. MAB36.

A potential glycolipid biosurfactant producer Streptomyces sp. MAB36 was isolated from marine sediment samples. Medium composition and culture conditions for the glycolipid biosurfactant production by Streptomyces sp. MAB36 were optimized, using two statistical methods: Plackett-Burman design was applied to find out the key ingredients and conditions for the best yield of glycolipid biosurfactant production and central composite design was used to optimize the concentration of the four significant variables, starch, casein, crude oil and incubation time. Fructose and yeast extract were the best carbon and nitrogen sources for the production of the glycolipid biosurfactant. Biochemical characterizations including FTIR and MS studies suggested the glycolipid nature of the biosurfactant. The isolated glycolipid biosurfactant reduced the surface tension of water from 73.2 to 32.4 mN/m. The purified glycolipid biosurfactant showed critical micelle concentrations of 36 mg/l. The glycolipid biosurfactant was effective at very low concentrations over a wide range of temperature, pH, and NaCl concentration. The purified glycolipid biosurfactant showed strong antimicrobial activity. Thus, the strain Streptomyces sp. MAB36 has proved to be a potential source of glycolipid biosurfactant that could be used for the bioremediation processes in the marine environment.

Pharmaceutically active secondary metabolites of marine actinobacteria.

Marine actinobacteria are one of the most efficient groups of secondary metabolite producers and are very important from an industrial point of view. Many representatives of the order Actinomycetales are prolific producers of thousands of biologically active secondary metabolites. Actinobacteria from terrestrial sources have been studied and screened since the 1950s, for many important antibiotics, anticancer, antitumor and immunosuppressive agents. However, frequent rediscovery of the same compounds from the terrestrial actinobacteria has made them less attractive for screening programs in the recent years. At the same time, actinobacteria isolated from the marine environment have currently received considerable attention due to the structural diversity and unique biological activities of their secondary metabolites. They are efficient producers of new secondary metabolites that show a range of biological activities including antibacterial, antifungal, anticancer, antitumor, cytotoxic, cytostatic, anti-inflammatory, anti-parasitic, anti-malaria, antiviral, antioxidant, anti-angiogenesis, etc. In this review, an evaluation is made on the current status of research on marine actinobacteria yielding pharmaceutically active secondary metabolites. Bioactive compounds from marine actinobacteria possess distinct chemical structures that may form the basis for synthesis of new drugs that could be used to combat resistant pathogens. With the increasing advancement in science and technology, there would be a greater demand for new bioactive compounds synthesized by actinobacteria from various marine sources in future.

Biosynthesis, antimicrobial and cytotoxic effect of silver nanoparticles using a novel Nocardiopsis sp. MBRC-1.

The biosynthesis of nanoparticles has been proposed as a cost effective environmental friendly alternative to chemical and physical methods. Microbial synthesis of nanoparticles is under exploration due to wide biomedical applications, research interest in nanotechnology and microbial biotechnology. In the present study, an ecofriendly process for the synthesis of nanoparticles using a novel Nocardiopsis sp. MBRC-1 has been attempted. We used culture supernatant of Nocardiopsis sp. MBRC-1 for the simple and cost effective green synthesis of silver nanoparticles. The reduction of silver ions occurred when silver nitrate solution was treated with the Nocardiopsis sp. MBRC-1 culture supernatant at room temperature. The nanoparticles were characterized by UV-visible, TEM, FE-SEM, EDX, FTIR, and XRD spectroscopy. The nanoparticles exhibited an absorption peak around 420 nm, a characteristic surface plasmon resonance band of silver nanoparticles. They were spherical in shape with an average particle size of 45 ± 0.15 nm. The EDX analysis showed the presence of elemental silver signal in the synthesized nanoparticles. The FTIR analysis revealed that the protein component in the form of enzyme nitrate reductase produced by the isolate in the culture supernatant may be responsible for reduction and as capping agents. The XRD spectrum showed the characteristic Bragg peaks of 1 2 3, 2 0 4, 0 4 3, 1 4 4, and 3 1 1 facets of the face centered cubic silver nanoparticles and confirms that these nanoparticles are crystalline in nature. The prepared silver nanoparticles exhibited strong antimicrobial activity against bacteria and fungi. Cytotoxicity of biosynthesized AgNPs against in vitro human cervical cancer cell line (HeLa) showed a dose-response activity. IC50 value was found to be 200 µg/mL of AgNPs against HeLa cancer cells. Further studies are needed to elucidate the toxicity and the mechanism involved with antimicrobial and anticancer activity of the synthesized AgNPs as nanomedicine.

Marininema halotolerans sp. nov., a novel thermoactinomycete isolated from a sediment sample, and emended description of the genus Marininema Li et al. 2012.

A novel Gram-stain-positive bacterium, designated strain YIM M11385(T), was isolated from a marine sediment sample collected from the South Bay, Little Andaman Island, India with a salinity of 35 p.p.m., pH 8.5. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain YIM M11385(T) belongs to the genus Marininema, supported by a bootstrap value of 100 %. The taxonomic position of this organism was further established by using a polyphasic approach. Strain YIM M11385(T) grew optimally at 28 °C, pH 7.0 and in the presence of 0-5 % (w/v) NaCl. The 16S rRNA gene sequence similarity between strain YIM M11385(T) and Marininema mesophilum SCSIO 10219(T) was 98.3 %. Strain YIM M11385(T) exhibited a quinone system with only MK-7, the polar lipid profile included diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine as major components, and the major fatty acids were anteiso-C15 : 0, iso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. The level of DNA-DNA relatedness between strain YIM M11385(T) and M. mesophilum SCSIO 10219(T) was 59.36 %. On the basis of genotypic and phenotypic data, it is apparent that strain YIM M11385(T) represents a novel species of the genus Marininema, for which the name Marininema halotolerans sp. nov. is proposed. The type strain is YIM M11385(T) ( = CCTCC AB 2012052(T) = DSM 45789(T)). In addition, we propose that the description of the genus Marininema should be further emended based on the results of the present study.

Statistical optimization and anticancer activity of a red pigment isolated from Streptomyces sp. PM4.

OBJECTIVE: To enhance the pigment production by Streptomyces sp. PM4 for evaluating its anticancer activity. METHODS: Response surface methodology was employed to enhance the production of red pigment from Streptomyces sp. PM4. Optimized pigment was purified and evaluated for the anticancer activity against HT1080, Hep2, HeLa and MCF7 cell lines by MTT assay. RESULTS: Based on the response surface methodology, it could be concluded that maltose (4.06 g), peptone (7.34 g), yeast extract (4.34 g) and tyrosine (2.89 g) were required for the maximum production of pigment (1.68 g/L) by the Streptomyces sp. PM4. Optimization of the medium with the above tested features increased the pigment yield by 4.6 fold. Pigment showed the potential anticancer activity against HT1080, HEp-2, HeLa and MCF-7 cell lines with the IC50 value of 18.5, 15.3, 9.6 and 8.5 respectively. CONCLUSIONS: The study revealed that the maximum amount of pigment could be produced to treat cancer.

Production, characterization and antioxidant potential of protease from Streptomyces sp. MAB18 using poultry wastes.

Poultry waste is an abundant renewable source for the recovery of several value-added metabolites with potential industrial applications. This study describes the production of protease on poultry waste, with the subsequent use of the same poultry waste for the extraction of antioxidants. An extracellular protease-producing strain was isolated from Cuddalore coast, India, and identified as Streptomyces sp. MAB18. Its protease was purified 17.13-fold with 21.62% yield with a specific activity of 2398.36 U/mg and the molecular weight was estimated as 43 kDa. The enzyme was optimally active at pH 8-10 and temperature 50-60 ° C and it was most stable up to pH 12 and 6-12% of NaCl concentration. The enzyme activity was reduced when treated with Hg(2+), Pb(2+), and SDS and stimulated by Fe(2+), Mg(2+), Triton X-100, DMSO (dimethyl sulfoxide), sodium sulphite, and ß-mercaptoethanol. Furthermore, the antioxidant activities of protease were evaluated using in vitro antioxidant assays, such as DPPH radical-scavenging activity, O2 scavenging activity, NO scavenging activity, Fe(2+) chelating activity, and reducing power. The enzyme showed important antioxidant potential with an IC50 value of 78 ± 0.28 mg/mL. Results of the present study indicate that the poultry waste-derived protease may be useful as supplementary protein and antioxidant in the animal feed formulations.

Isolation and characterization of biologically active melanin from Actinoalloteichus sp. MA-32.

Melanins are enigmatic pigments and biological macromolecules that are produced by a wide variety of microorganisms including several species of bacteria and fungi. The present study was carried out on isolation and characterization of melanin from marine actinobacteria, Actinoalloteichus sp. MA-32. Medium composition and culture conditions for the melanin production by Actinoalloteichus sp. MA-32 were optimized using two statistical methods: Plackett-Burman design applied to find the key ingredients and conditions for the best yield of melanin production and central composite design used to optimize the concentration of the four significant variables: glycerol, L-tyrosine, NaCl and trace salt solution. The melanin was optimally active at pH 7-9 and temperature 45-60°C and it was most stable up to pH 11 and 4% of NaCl concentration. Melanin was examined by UV-vis absorption spectroscopy and infrared spectrometry. Melanin has potential antibacterial activity as it showed greater antagonistic and it has a strong antioxidant potential observed in the in vitro evaluation of its DPPH radical-scavenging activity, superoxide radical-scavenging activity, nitric oxide-scavenging activity, reducing power and metal chelating activity. The observed activities indicate that melanin might be a novel potential antioxidant. This study suggested that the melanin could potentially be used as a natural antioxidant in the food, cosmetic and pharmaceutical industries.

Saccharomonospora oceani sp. nov. isolated from marine sediments in Little Andaman, India.

Two actinomycete strains, designated YIM M11168(T) and YIM M11177, were isolated from marine sediment samples from Little Andaman, Indian Ocean, and their taxonomic position was determined by a polyphasic approach. The two Gram-positive, aerobic strains were observed to produce branched substrate mycelium and aerial hyphae but did not fragment, and no diffusible pigment was produced on the media tested. At maturity, spores were formed singly or in pairs on aerial hyphae and substrate mycelium, and occasionally the single ones were borne on long sporophores. The optimum growth was determined to occur at 28 °C, 0-4 % (w/v) NaCl and pH 7.0-8.0. Whole-cell hydrolysates of both strains contained meso-diaminopimelic acid and the diagnostic sugars were determined to be galactose, glucose and arabinose. Their predominant menaquinone was found to be MK-9(H4). The polar lipids detected in the two strains were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol mannoside, phosphatidylinositol, phosphatidylmethylethanolamine, phosphatidylethanolamine and two unknown phosphoglycolipids. The major fatty acids (>10 %) identified were iso-C16:0, iso-C16:1 H, iso-C16:0, C17:1 ω6c for strain YIM M11168(T), iso-C16:0 and Summed Feature 3 for strain YIM M11177. The G + C contents of the genomic DNAs of both strains were determined to be 71.4 %. DNA-DNA hybridization relatedness values (78.4 ± 3.7 %) of these two isolates supported the conclusion that they belong to the same species. Based on phylogenetic analysis, phenotypic and genotypic data, it is concluded that the two isolates belong to a novel species of the genus Saccharomonospora of the family Pseudonocardiaceae. The name Saccharomonospora oceani sp. nov. (Type strain YIM M11168(T) = DSM 45700(T) = JCM 18128(T)) is proposed for the novel species.

Actinobacterial melanins: current status and perspective for the future.

Melanins are enigmatic pigments that are produced by a wide variety of microorganisms including several species of bacteria and fungi. Melanins are biological macromolecules with multiple important functions, yet their structures are not well understood. Melanins are frequently used in medicine, pharmacology, and cosmetics preparations. Melanins also have great application potential in agriculture industry. They have several biological functions including photoprotection, thermoregulation, action as free radical sinks, cation chelators, and antibiotics. Plants and insects incorporate melanins as cell wall and cuticle strengtheners, respectively. Actinobacteria are the most economically as well as biotechnologically valuable prokaryotes. However, the melanin properties are, in general, poorly understood. In this review an evaluation is made on the present state of research on actinobacterial melanins and its perspectives. The highlights include the production and biotechnological applications of melanins in agriculture, food, cosmetic and medicinal fields. With increasing advancement in science and technology, there would be greater demands in the future for melanins produced by actinobacteria from various sources.

Production and characterization of an extracellular polysaccharide from Streptomyces violaceus MM72.

The isolation, optimization, purification and characterization of an extracellular polysaccharide (EPS) from a marine actinobacterium, Streptomyces violaceus MM72 were investigated. Medium composition and culture conditions for the EPS production by S. violaceus MM72 were optimized using two statistical methods: Plackett-Burman design applied to find the key ingredients and conditions for the best yield of EPS production and central composite design used to optimize the concentration of the three significant variables: glucose, tryptone and NaCl. The preferable culture conditions for EPS production were pH 7.0, temperature 35°C and NaCl concentration 2.0% for 120h with fructose and yeast extract as best carbon and nitrogen sources, respectively. The results showed that S. violaceus MM72 produced a kind of EPS having molecular weight of 8.96×10(5)Da. In addition, the EPS showed strong DPPH radical-scavenging activity, superoxide scavenging and metal chelating activities while moderate inhibition of lipid peroxidation and reducing activities determined in this study. These results showed the great potential of EPS produced by S. violaceus MM72 could be used in industry in place of synthetic compounds. The EPS from S. violaceus MM72 may be a new source of natural antioxidants with potential value for health, food and therapeutics.

RETRACTED: Marine actinobacterial metabolites: current status and future perspectives.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor. Authors and Editor agreed to retract this article because substantial parts of the text were copied from the following sources without proper attribution: Lam, K.S. (2006), Discovery of novel metabolites from marine actinomycetes. Current Opinion in Microbiology 9(3), pp. 245­251; Subramani, R., Aalbersberg, W. (2012), Marine actinomycetes: An ongoing source of novel bioactive metabolites. Microbiological Research 167(10), pp. 571­580; Dharmaraj, S. (2010), Marine Streptomyces as a novel source of bioactive substances. World Journal of Microbiology and Biotechnology 26(12), pp. 2123­2139. The authors apologize for this oversight and any inconvenience caused.

Actinomadura sediminis sp. nov., a marine actinomycete isolated from mangrove sediment.

In this study, the taxonomic position of an actinobacterium, strain YIM M 10931(T), which was isolated from a mangrove sediment sample collected in Dugong Creek, Little Andaman, India, was determined by a polyphasic approach. This gram-positive, aerobic strain produced branched substrate mycelium and aerial hyphae, which differentiated into short, hooked or spiral spore chains. The organism contained meso-diaminopimelic acid as the diagnostic diamino acid in the cell-wall peptidoglycan. The whole cell sugars consisted of mannose, ribose, glucose, galactose and madurose. The cellular fatty acid profile mainly consisted of iso-C(16 : 0), 10-methyl C(18 : 0) and C(16 : 0). The quinone system was predominantly composed of MK-9(H(8)) (45.5 %) and MK-9(H(6)) (39 %). The phospholipids detected were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol mannoside, phosphatidylinositol and two unknown phospholipids. The organism showed a combination of morphological and chemotaxonomic properties typical of members of the genus Actinomadura. Moreover, phylogenetic analysis based on a 16S rRNA gene sequence generated from the strain identified its closest relatives as Actinomadura cremea DSM 43676(T) (98.4 % sequence similarity), Actinomadura rifamycini DSM 43936(T) (97.4 %) and Actinomadura apis IM17-1(T) (96.9 %). It was obvious from the resulting phylogenetic trees that strain YIM M 10931(T) belongs to a distinct subclade within the evolutionary radiation of the genus Actinomadura. DNA-DNA hybridizations of strain YIM M 10931(T) with A. cremea DSM 43676(T) and A. rifamycini DSM 43936(T) were performed and further confirmed that the isolate represents a separate genomic species. Based on the phenotypic and genotypic characteristics presented, it is proposed that strain YIM M 10931(T) represents a novel species within the genus Actinomadura, for which the name Actinomadura sediminis sp. nov. is proposed; the type strain is YIM M 10931(T) ( = CCTCC AA 2010009(T) = DSM 45500(T)).