Biological activated carbon process for biotransformation of azo dye Carmoisine by Klebsiella spp.

The feasibility of employing the biological activated carbon (BAC) process to debilitate azo dye Carmoisine by Klebsiella spp. was investigated. Plate assay revealed the capability of Klebsiella spp. for removal of Carmoisine via degradation. Kinetic parameters were measured for Carmoisine debilitation by Klebsiella spp. using the suspended anaerobic process. Two types of granular and rod-shaped activated carbon were used to form the biological beds in order to study the Carmoisine debilitation in batch processes. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were used to indicate the colonization and biofilm formation of bacteria grown on activated carbon particles (ACPs). Thin-layer chromatography (TLC), liquid chromatography-mass spectrometry (LC-MS), high-pressure liquid chromatography (HPLC) and biosorption studies demonstrated biotransformation of Carmoisine into its constituent aromatic amines during the Carmoisine debilitation in suspended anaerobic and BAC processes. The porosity of activated carbons, inoculation size and age of biological beds were the important factors affecting the viability of bacterial cells grown on ACPs and, consequently, the rate and efficiency of the Carmoisine debilitation process determined through spectrophotometry. The reusability of biological beds was demonstrated by conducting sequential batch experiments. In conclusion, the BAC process proved to be an efficient method for anaerobic dye degradation.

Structural characterization and surface activities of biogenic rhamnolipid surfactants from Pseudomonas aeruginosa isolate MN1 and synergistic effects against methicillin-resistant Staphylococcus aureus.

The aim of present work was to study chemical structures and biological activities of rhamnolipid biosurfactants produced by Pseudomonas aeruginosa MN1 isolated from oil-contaminated soil. The results of liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis revealed that total rhamnolipids (RLs) contained 16 rhamnolipid homologues. Di-lipid RLs containing C(10)-C(10) moieties were by far the most predominant congeners among mono-rhamnose (53.29 %) and di-rhamnose (23.52 %) homologues. Mono-rhamnolipids form 68.35 % of the total congeners in the RLs. Two major fractions were revealed in the thin layer chromatogram of produced RLs which were then purified by column chromatography. The retardation factors (R (f)) of the two rhamnolipid purple spots were 0.71 for RL1 and 0.46 for RL2. LC-MS/MS analysis proved that RL1 was composed of mono-RLs and RL2 consisted of di-RLs. RL1 was more surface-active with the critical micelle concentration (CMC) value of 15 mg/L and the surface tension of 25 mN/m at CMC. The results of biological assay showed that RL1 is a more potent antibacterial agent than RL2. All methicillin-resistant Staphylococcus aureus (MRSA) strains were inhibited by RLs that were independent of their antibiotic susceptibility patterns. RLs remarkably enhanced the activity of oxacillin against MRSA strains and lowered the minimum inhibitory concentrations of oxacillin to the range of 3.12-6.25 µg/mL.

Intra/extracellular biosynthesis of silver nanoparticles by an autochthonous strain of Proteus mirabilis isolated from photographic waste.

There is an enormous interest in developing green synthesis procedures for production of nanoparticles by using biomimetic approaches. In our research focus has been given to the development of an efficient and eco-friendly viable process for the synthesis of nanoscale silver particles using Proteus mirabilis PTCC 1710, a bacterial strain that was isolated during a screening program from photographic waste. A significant result of this study is our observation that silver nanoparticles could be induced to synthesis intra and extracellulary. The silver nanoparticles were characterized by means of UV-Vis spectroscopy, transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS) and atomic absorption spectrometer (AAS). The nanoparticles exhibited maximum absorbance at 400-410 nm in UV-Vis spectroscopy. TEM images showed formation of stable silver nanoparticles of spherical shape with most of the particles in the size range of 10-20 nm. It was found that incubation of bacterial cells in Muller-Hinton broth medium resulted in higher extracellular synthesis of silver nanoparticles, whereas intracellular synthesis of silver nanoparticles effectively increased in tryptic soy broth. The method of extraction of intracellular silver nanoparticles was inexpensive, simple and effective in large scale with no need to complex instruments. The bacteria work as a bionanofactory which continued to grow after synthesis of silver nanoparticles. The silver reduction by this strain is occurred through energy-dependent processes that lead to the high output of this reaction. Hence this new approach of using a non-pathogenic bacterial strain for the successful synthesis of nanosized silvers could be easily scaled up which establishes its commercial viability.

Biotransformation of hydrocortisone by a natural isolate of Nostoc muscorum.

Hydrocortisone was converted in the culture of an isolated strain of the cyanobacterium Nostoc muscorum PTCC 1636 into some androstane and pregnane derivatives. The microorganism was, isolated during a screening program from soil samples collected from paddy fields of north of Iran. The bioproducts obtained were purified using chromatographic methods and identified as 11beta-hydroxytestosterone, 11beta-hydroxyandrost-4-en-3,17-dione and 11beta,17alpha,20beta,21-tetrahydroxypregn-4-en-3-one on the basis of their spectroscopic features.