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A one-pot synthesis of benzimidazoles by condensing naphthyl or quinoline aldehyde with benzene- 1,2-diamine has been reported. IR, ¹H and [sup.13]C NMR, mass spectral, and CHN analyses were used to elucidate the structures of the products. The molecular structural correlation in the optical properties of the quinoline and naphthalene benzimidazoles was explored. The fluorescence quantum yield ([φ.sub.f]) and time-resolved fluorescent lifetime of the quinoline benzimidazoles derivatives were estimated. The influence of solvent polarity and pH on the optical property of quinoline derivatives was illustrated. To explore the bioanalytical applicability, the thermal stability by TG-DTA analysis and the cytogenetic analysis of 3-(1H-benzoimidazol-2-yl)-2-chloro-8-methyl-quinoline (1b) compound were carried out. The fluorescent staining ability of 1b was analyzed and also compared with the normal Gram staining in the bacterium. Key words: benzimidazole quinolines, optical property, fluorescence quantum yield, cytogenetic analysis, fluorescence staining. On a realise une synthese monotope de benzimidazoles par condensation de naphtyl- et de quinoleinealdehydes avec de la benzene-1,2-diamine. On a fait appel aux analyses CHN et aux spectroscopies IR, RMN ¹H et [sup.13]C et de masse pour elucider la structure des produits. On a explore la correlation de la structure moleculaire dans les proprietes optiques des benzimidazolylquinoleines et des benzimidazolylnaphtalenes. On a evalue le rendement quantique de fluorescence ([φ.sub.f]) et le temps de vie fluorescent resolu en fonction du temps des derives benzimidazolylquinoleines. On a aussi illustre l'influence de la polarite du solvant et du pH sur les proprietes optiques de ces derives de la quinoleine. Afin de pouvoir evaluer les possibilites de l'utiliser dans le domaine des analyses biologiques, on a aussi effectue une analyse cytogenetique et on a evalue la stabilite thermique de la 3-(1H-benzimidazol-2-yl)-2-chloro-8-methylquinoleine (1b) par analyse thermogravimetrique (TG) et analyse thermique differentielle (ATD). On a analyse la capacite du compose 1b a agir comme colorant fluorescent et on a compare ses proprietes a celles de la coloration Gram normale dans les bacteries. Mots-cles : benzimidazolylquinoleines, propriete optique, rendement quantique de fluorescence, analyse cytogenetique, coloration de fluorescence. [Traduit par la Redaction], Introduction Rapid advances in optical technologies have recently led to significant progress in medical diagnostics, drug discovery, and (bio)chemical analysis, in particular for methods that use fluorescence detection in microscopy, [...]

Nowadays, demand for natural pigments has increased dramatically due to the awareness of the toxicity of some synthetic pigments. Because of the high cost of growth medium for natural pigment production, various studies have been carried out to explore medium which are less costly, such as agricultural waste. This study highlight on the application of firefly algorithm (FA) and bat algorithm (BA) in optimizing yellowish-orange pigment production (flexirubin) from the agricultural waste material. At present, response surface methodology (RSM) is the most preferred statistical method in optimizing pigment production. However, in the last two decades, nature-inspired metaheuristics approach has been used extensively in the fermentation process and have continually improve the efficiency in the optimization problem especially in pigment production. This study compared the analytics studies of RSM, FA and BA in the estimation of fermentation parameters (Lactose, Ltryptophan, and KH2PO4) in flexirubin production from Chryseobacterium artocarpi CECT8497T. All models provided similar quality predictions for the above three independent variables in term of flexirubin production with bat algorithm showing more accurate in estimation, with the coefficient value of 98.87% compare to RSM 98.20% and FA 98.38%. [ABSTRACT FROM AUTHOR]

Violacein, violet pigment produced by Chromobacterium violaceum, has attracted much attention recently due to its pharmacological properties including antibacterial activity. The present study investigated possible antibacterial mode of action of violacein from C. violaceum UTM5 against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) strains. Violet fraction was obtained by cultivating C. violaceum UTM5 in liquid pineapple waste medium, extracted, and fractionated using ethyl acetate and vacuum liquid chromatography technique. Violacein was quantified as major compound in violet fraction using HPLC analysis. Violet fraction displayed bacteriostatic activity against S. aureus ATCC 29213 and methicillin-resistant S. aureus ATCC 43300 with minimum inhibitory concentration (MIC) of 3.9 μg/mL. Fluorescence dyes for membrane damage and scanning electron microscopic analysis confirmed the inhibitory effect by disruption on membrane integrity, morphological alternations, and rupture of the cell membranes of both strains. Transmission electron microscopic analysis showed membrane damage, mesosome formation, and leakage of intracellular constituents of both bacterial strains. Mode of action of violet fraction on the cell membrane integrity of both strains was shown by release of protein, K+, and extracellular adenosine 5′-triphosphate (ATP) with 110.5 μg/mL, 2.34 μg/mL, and 87.24 ng/μL, respectively, at 48 h of incubation. Violet fraction was toxic to human embryonic kidney (HEK293) and human fetal lung fibroblast (IMR90) cell lines with LC50 value of 0.998 ± 0.058 and 0.387 ± 0.002 μg/mL, respectively. Thus, violet fraction showed a strong antibacterial property by disrupting the membrane integrity of S. aureus and MRSA strains. This is the first report on the possible mode of antibacterial action of violet fraction from C. violaceum UTM5 on S. aureus and MRSA strains. [ABSTRACT FROM AUTHOR]

Microbial oddities such as versatile pigments are gaining more attention in current research due to their widely perceived applications as natural food colorants, textiles, antimicrobial activities, and cytotoxic activities. This indicates that the future generation will depend on microbial pigments over synthetic colorants for sustainable livelihood. Although several reviews have detailed the comprehensive applications of microbial pigments extensively, knowledge on several aspects of pigmented microbes is apparently missing and not properly reviewed anywhere. Thus, this review has been made to provide overall knowledge on biodiversity, distribution, pathogenicity, and ecological and industrial applications of microbial pigments as well as their challenges and future directions for food, industrial, and biomedical applications. Meticulously, this compendious review treatise on the pigments from bacteria, fungi, yeasts, and microalgae includes reports from the 1970s to 2018. A total of 261 pigment compounds produced by about 500 different microbial species are included, and their bioactive nature is described. [ABSTRACT FROM AUTHOR]

For production of protease by a new strain, Serratia marcescens SB08, optimization of the fermentation medium and environmental conditions, were carried out by applying factorial design and response surface methodology. The results of factorial design showed that pH, agitation, incubation time and yeast extract were the key factors affecting protease production. The optimal cultural conditions for protease production obtained with response surface methodology were pH 6.0, agitation 100 rpm, incubation time 51.0 h and yeast extract 3.0 g/l. This model was also validated by repeating the experiments under the optimized conditions, which resulted in the maximum protease production of 281.23 U/ml (Predicted response 275.66 U/ml), thus proving the validity of the model. Unexplored Serratia marcescens SB08 strain isolated from enteric gut of sulphur butterfly (Kricogonia lyside) was taken up for this study. This study demonstrates the ability of the new strain, Serratia marcescens SB08, for protease production and also that smaller and less time consuming statistical experimental designs are adequate for the optimization of fermentation processes for maximum protease production.