Functional and Structural Characterization of Melanin from Brevibacillus invocatus Strain IBA

Melanin is a polyphenol or indolic dark brown to black pigment of macromolecules that has a variety of biological functions including UV defence, desiccation, and oxidation. The pigment is classified as a heterogenic polymer. Analytical characterization of melanin can be difficult due to its heterogeneity. In this study, a newly isolated strain of Brevibacillus invocatus strain IBA capable of extracellular melanin production was grown on nutrient agar and the bacteria were molecularly identified. Chemical and physical methods were used to characterize melanin. The solubility of melanin in organic and inorganic solvents was used to characterise it chemically. According to the UV-visible wavelength scan, physical characterization revealed absorption in the UV region 200 to 300 nm, but declining towards the visible region. Functional group identification of extracted melanin was carried out by FTIR with different stretching vibrations at 3226, 2920, 2849, 1628, 1555, 1340 cm^-1 and weak absorption bands at 1104 and 1015 cm^-1. Structural characterization was carried by SEM of extracted melanin which showed irregular shape and size at different magnifications. The crystallinity of melanin was studied using X-ray crystallography, with a lattice parameter of approximately a = 8.54. The XRD spectrum of the extracted melanin crystallographic pattern revealed peaks at 2θ = 27.32, 31.66, 45.41, 53.84, 53.84, 56.44, 66.18, 73.10, 75.26, and 83.94, which correspond to reflections (111), (200), (220), (311), (222), (400), (331), (420), and (422), respectively. The analytical methods available for melanin analysis are largely complementary, providing detailed knowledge required to draw reliable conclusions about the sample under investigation.

Molecular strain typing of Trichophyton mentagrophytes (T. mentagrophytes var. interdigitale) using non-transcribed spacer region as a molecular marker

Background & objectives:

Dermatophytes are keratinophilic fungi that infect keratinized tissues of human and animal origin. Trichophyton mentagrophytes is considered to be a species complex composed of several strains, which include both anthropophiles and zoophiles. Accurate discrimination is critical for comprehensive understanding of the clinical and epidemiological implications of the genetic heterogeneity of this complex. Molecular strain typing renders an effective way to discriminate each strain. The objective of the study was to characterize T. mentagrophytes clinical isolates to sub-species level using molecular techniques and non-transcribed spacer (NTS) region as marker.

Methods:

Sixty four T. mentagrophytes clinical isolates were identified by phenotypic methods. These were subjected to polymerase chain reaction targeting three sub-repeat elements (SREs), TmiS0, TmiS1 and TmiS2 of the NTS region. Sequence analysis of internal transcribed spacer (ITS) region of different types was also done.

Results:

Strain-specific polymorphism was observed in all three loci. Totally, 13 different PCR types were obtained on combining all the three SREs loci. No variation was observed in the ITS region.

Interpretation & conclusions:

The study described the usefulness of molecular strain typing technique for the discrimination of the T. mentagrophytes isolates. This will help for the future explorations into the epidemiology of T. mentagrophytes and its complex.

Isolation and Characterization of "Terrein" an Antimicrobial and Antitumor Compound from Endophytic Fungus Aspergillus terreus (JAS-2) Associated from Achyranthus aspera Varanasi, India

The present study aimed at characterizing biological potentials of endophyte Aspergillus terreus JAS-2 isolated from Achyranthus aspera. Crude extracted from endophytic fungus JAS-2 was purified and chemically characterized by chromatographic and spectroscopic studies respectively. Spectral assignment of NMR (nuclear magnetic resonance) data, ¹H proton and ¹³C carbon analysis along with FTIR data elucidated the structure of compound as 4,5-Dihydroxy-3-(1-propenyl)-2-cyclopenten-1-one. After purification and identification a set of experiment was conducted to explore efficacy of compound. Results revealed that on accessing the antifungal activity of compound, growth diameter of tested phytopathogenic fungi was reduced to 50% at higher concentration taken (10 μgμl⁻¹). Compound exhibited in-vitro bacterial cell inhibition at 20 μgml⁻¹ concentration along with moderate antioxidant behavior. Evaluation of anticancer activity against human lung cancer cell line (A-549) exhibited its IC₅₀ value to be 121.9 ± 4.821 μgml⁻¹. Further cell cycle phase distribution were analyzed on the basis of DNA content and evaluated by FACS (Fluorescence Activated Cell Sorting) and it was revealed that at 150 μgml⁻¹ of compound maximum cells were found in sub G1 phase which represents apoptotic dead cells. Terrein (4, 5-Dihydroxy-3-(1-propenyl)-2-cyclopenten-1-one) a multi-potential was isolated from endophytic fungus JAS-2, from well recognized medicinal herb A. aspera. To best of our knowledge, this is the first report of “Terrein” from endophytic derived fungus. This compound had also exhibited anticancer and antifungal activity against human lung cancer cell line A-549 and Bipolaris sorokiniana respectively which is causal organism of many plants disease. Hence endophytes are serving as alternative sources of drug molecules.

Molecular Strain Typing of Clinical Isolates, Trichophyton rubrum using Non Transcribed Spacer (NTS) Region as a Molecular Marker

INTRODUCTION

Dermatophytes are a group of fungi which infect keratinized tissues and causes superficial mycoses in humans and animals. The group comprises of three major genera, Trichophyton, Microsporum and Epidermophyton. Among them Trichophyton rubrum is a predominant anthropophilic fungi which causes chronic infections. Although, the infection is superficial and treatable, reinfection/coinfection causes inflation in the treatment cost. Identifying the source and mode of transmission is essential to prevent its transmission. Accurate discrimination is required to understand the clinical (relapse or reinfection) and epidemiological implications of the genetic heterogeneity of this species. Polymorphism in the Non Transcribed Spacer (NTS) region of ribosomal DNA (rDNA) clusters renders an effective way to discriminate strains among T. rubrum.

AIM

To carry out the strain typing of the clinical isolates, Trichophyton rubrum using NTS as a molecular marker.

MATERIALS AND METHODS

Seventy T.rubrum clinical isolates obtained from April-2011-March 2013, from Sri Ramachandra Medical Centre, Chennai, Tamil Nadu, India, were identified by conventional phenotypic methods and included in this prospective study. The isolates were then subjected to Polymerase Chain Reaction (PCR) targeting two subrepeat elements (SREs), TRS-1 and TRS-2 of the NTS region.

RESULTS

Strain-specific polymorphism was observed in both subrepeat loci. Total, nine different strains were obtained on combining both TRS-1 and TRS-2, SREs.

CONCLUSION

The outcome has given a strong representation for using NTS region amplification in discriminating the T. rubrum clinical isolates. The method can be adapted as a tool for conducting epidemiology and population based study in T. rubrum infections. This will help in future exploration of the epidemiology of T. rubrum.

Broad spectrum antimicrobial compounds from the bacterium Exiguobacterium mexicanum MSSRFS9

Clinical bacterial pathogens front a major challenge for the clinical researchers and physicians. In particular microbial pathogens like Escherichia coli, Shigella flexneri, Klebsiella pneumonia and Salmonella enterica are apparelled with systemic machineries to bring down the human immune system as well as proliferate dramatically in a short period which in turn cause a pronounced ailment to the human health. In vitro evaluation of four purified compounds isolated from rhizosphere bacterium Exiguobacterium mexicanum tested against clinical pathogens mentioned above by disc diffusion method showed the two compounds viz., 3,6,18-trione, 9,10-dihydro-12'-hydroxyl-2methyl-5-(phenyl methyl) (5'-alpha, 10-alpha)-dihydroergotamine (C3) and dipropyl - S-propyl ester (C4) exhibit antibacterial property against all the tested pathogens. Among the four clinical pathogens tested, compound C3 has shown higher zone of inhibition against S. enterica with 17±0 mm, followed by S. flexneri with 16.5±0.7 mm, E. coli with 15±0 mm and K. pneumoniae with 14±0 mm, respectively. The compound C4 has shown higher antimicrobial activity against S. enterica with 21.5±0.7 mm zone of inhibition, followed by S. flexneri with 19.5±0.7 mm, E. coli with 17±0 mm and K. pneumoniae with 16±0 mm, these two compounds were found to be safer when subjected to rat haematological and enzymatic analysis.