RESUMEN
In the emerging scenario of increasing antibiotic resistance and pathogen transmission channels, the grave danger posed by bacterial endospores in critical fields like food industry, health and medicine highlights the urgent need to develop efficient probes for their detection; their sturdy and impermeable multilayer coat makes desirable methods like fluorescence imaging extremely difficult. Selective imaging of the endospores in the presence of the bacteria is even more challenging. Furthermore, it is preferable to maintain the dormant state of endospores through the imaging process, if extended monitoring is required; many of the available techniques involve lethal germination or destruction of the endospores. We show that simple zwitterionic diaminodicyanoquinodimethane (DADQ) molecules with selected functionalities are efficient dyes for fluorescence imaging due to their dipolar structure that facilitates the penetration into the endospore system, and the enhanced fluorescence in their rigid/aggregated state. The facile structural tailorability allows DADQs with various appendage moieties to be synthesized; a derivative with ionic substituents (BT2), and another with optimally long alkyl chains and the resultant hydrophobic character (BHADQ) are shown to be excellent fluorescent probes for endospores. Nanomolar amounts of dyes provide effective staining; while BT2 stains bacteria and endospores, most significantly, BHADQ stains endospores selectively. To the best of our knowledge, this is the first example of selective fluorescence imaging of endospores in their dormant state. A range of spectroscopy, microscopy and calorimetry studies provide insight into the molecular level interactions that enable efficient staining and bright images. DADQ fluorophores are photostable and non-cytotoxic, hence useful in practical applications. The versatile structural tailorability of these dye molecules holds great promise for targeted imaging.
Asunto(s)
Colorantes Fluorescentes/química , Halobacillus/química , Imagen Óptica , Esporas Bacterianas/química , Estructura Molecular , Tamaño de la Partícula , Espectrometría Raman , Propiedades de SuperficieRESUMEN
In the present study, an attempt has been made to explore the antifouling potential of bioactive compound isolated from sponge associated bacterium Halobacillus kuroshimensis SNSAB01. The crude extract of SNSAB01 strongly inhibited the growth of fouling bacterial strains with least minimal inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The bioactive compound was characterized through FT-IR, HPLC, GCMS and NMR predicted as 'pyrrolo". From the mass spectral library, structure was elucidated as pyrrolo [1, 2-a] pyrazine-1, 4-dione, hexahydro. The in silico studies provided encouraging docking scores with two interactions by GLN 200 and GLU 304. The extract inhibited 89% diatom adhesion at 350 µg/ml concentration against Amphora sp. An EC50 value of 150 µg/ml for 50% inhibition of byssal thread of Perna viridis and LC50 was found to be 500 µg/ml. The LC50/EC50 ratio of 3.0 indicated nontoxic to nature. The result suggested that pyrrolo[1,2-a]pyrazine-1,4-dione can be used for antifouling coating.
Asunto(s)
Antiinfecciosos/farmacología , Bivalvos/efectos de los fármacos , Diatomeas/efectos de los fármacos , Halobacillus/química , Pirazinas/farmacología , Pirroles/farmacología , Acetilglucosamina/análogos & derivados , Acetilglucosamina/metabolismo , Animales , Antiinfecciosos/química , Antiinfecciosos/aislamiento & purificación , Sitios de Unión , Bivalvos/crecimiento & desarrollo , Mezclas Complejas/química , Diatomeas/crecimiento & desarrollo , Matriz Extracelular/química , Halobacillus/clasificación , Pruebas de Sensibilidad Microbiana , Simulación del Acoplamiento Molecular , Filogenia , Poríferos/microbiología , Pirazinas/química , Pirazinas/aislamiento & purificación , Pirroles/química , Pirroles/aislamiento & purificación , Simbiosis/fisiologíaRESUMEN
moderately halophilic spore forming, motile, Gram-positive, rod-shaped bacterial strain designated as KGW1T was isolated from water sample of Chilika Lake and characterized taxonomically using polyphasic approach. The strain grew in the presence of 0-25% (w/v) NaCl in marine salt agar media, hydrolyzes casein, and gelatin and shows presence of alkaline proteases. The major cell wall menaquinone was MK7 and major cellular fatty acids were anteiso-C15:0 (44.89%), anteiso-C17:0 (6.18%), isoC15:0 (19.38%), and iso-C16:0 (7.39%). Several chemotaxonomic features conform the isolate be a member of genus Halobacillus. The isolate KGW1T contained A1γ meso-Dpm-direct type of peptidoglycan which is different from its phylogenetically closest neighbours. The 16S rRNA gene sequence based phylogenetic analysis also revealed the strain KGW1T was affiliated to the genus Halobacillus and sequence similarity between the isolated strain and the type strains of Halobacillus species were found closest to, H. dabanensis D-8 DSM 18199T (99.08%) and H. faecis IGA7-4 DSM 21559T (99.01%), H. trueperi SL-5 DSM 10404T (98.94%). The in silico DDH showed that the values in a range of 14.2-17.5% with the most closest strain H. dabanensis D-8 DSM 18199T and other type strains of the genus Halobacillus for which whole genome sequence is reported. DNA-DNA relatedness between strain KGW1T and the closest type strain Halobacillus trueperi DSM 10404T was 11.75% (± 1.15). The draft genome sequence includes 3,683,819 bases and comprises of 3898 predicted coding sequences with a G + C content of 46.98%. Thus, the significant distinctiveness supported by phenotypic and genotypic data with its closest neighbors and other closely related species confirm the strain KGW1T to be classified as a novel species within the genus Halobacillus, for which the name Halobacillus marinus sp. nov. is proposed. The type strain is KGW1T (= DSM 29522 = JCM 30443).
Asunto(s)
Genoma Bacteriano , Halobacillus/clasificación , Halobacillus/genética , Lagos/microbiología , Microbiología del Agua , Técnicas de Tipificación Bacteriana , Composición de Base , ADN Bacteriano/genética , ADN Ribosómico/genética , Ácidos Grasos/análisis , Genotipo , Halobacillus/química , Halobacillus/aislamiento & purificación , India , Fenotipo , Filogenia , ARN Ribosómico 16S/genética , Salinidad , Análisis de Secuencia de ADNRESUMEN
We reported earlier on the bioflocculant production potential of Halobacillus sp. Mvuyo, a marine bacteria isolated from Algoa Bay sediment samples. In this paper we report on the detailed characterization of the purified bioflocculant composed of polysaccharide and protein. The optimum dose of the purified bioflocculant for the clarification of 4 g l(-1) kaolin clay suspension was 0.2 mg ml(-1) at neutral pH. Scanning electron micrograph (SEM) revealed the bioflocculant to have an amorphous structure. The Fourier transform infrared (FTIR) spectrum exhibited the presence of hydroxyl, carboxyl and amino groups in its structure. The bioflocculant was thermostable with relative bioflocculant activity residue of 74.4% after heat treatment at 100 degrees C. Moreover thermogravimetric analysis (TGA) exhibited a degradation temperature (Td) of - 140 degrees C. The flocculation efficiency of the bioflocculant was 86.2% compared with 82.6%, 74.5% and 70.9% for polyethylimine, ferric chloride and alum, respectively. This bioflocculant has immense promise as a substitute to inorganic and synthetic flocculants in view of their hazard implications.
Asunto(s)
Proteínas Bacterianas/química , Halobacillus/química , Polisacáridos Bacterianos/química , Proteínas Bacterianas/aislamiento & purificación , Floculación , Caolín/química , Polisacáridos Bacterianos/aislamiento & purificaciónRESUMEN
Salt acclimation in moderately halophilic bacteria is the result of action of a grand interplay orchestrated by signals perceived from the environment. To elucidate the cellular players involved in sensing and responding to changing salinities we have determined the genome sequence of Halobacillus halophilus, a Gram-positive moderate halophilic bacterium that has a strict requirement for the anion chloride. Halobacillus halophilus synthesizes a multitude of different compatible solutes and switches its osmolyte strategy with the external salinity and growth phase. Based on the emerging genome sequence, the compatible solutes glutamate, glutamine, proline and ectoine have already been experimentally studied. The biosynthetic routes for acetyl ornithine and acetyl lysine are also delineated from the genome sequence. Halobacillus halophilus is nutritionally very versatile and most compatible solutes cannot only be produced but also used as carbon and energy sources. The genome sequence unravelled isogenes for many pathways indicating a fine regulation of metabolism. Halobacillus halophilus is unique in integrating the concept of compatible solutes with the second fundamental principle to cope with salt stress, the accumulation of molar concentrations of salt (Cl(-)) in the cytoplasm. Extremely halophilic bacteria/archaea, which exclusively rely on the salt-in strategy, have a high percentage of acidic proteins compared with non-halophiles with a low percentage. Halobacillus halophilus has an intermediate position which is consistent with its ability to integrate both principles.