In Vitro Detoxification Studies of p-Cresol by Intestinal Bacteria Isolated from Human Feces.

p-Cresol is a neurotoxic and nephrotoxic carcinogenic aromatic substance produced as a result of microbial fermentation in the intestine. The derivatives of p-cresol (p-cresyl sulphate or p-cresyl glucuronide) have a deleterious effect on renal failure patients undergoing hemodialysis. Human gut seems to be inhabited with a diverse microbial population capable of detoxifying many aromatic compounds. However, the knowledge on the role of gut microbes in metabolizing p-cresol is limited. Hence, the present study aims to investigate p-cresol detoxification by intestinal bacteria isolated from human feces. Three potential p-cresol tolerant isolates were selected and identified as Enterococcus faecalis strains (UTD-1, UTD-2 and UTD-3) by 16SrRNA gene sequencing. All three E. faecalis isolates decreased the p-cresol concentration (30 µg/ml) at a higher rate with extracellular extracts (2.58-9.53 µg/ml) as compared to intracellular (0.55-5.28 µg/ml) extract. These three potential isolates also exhibited tolerance to gastrointestinal conditions for up to 60 min. Added to its potential, the expression of virulent genes (esp, gelE, and cyl) was found to be suppressed when subjected to bile stress under in vitro conditions. HPLC analysis displayed transformed products from extracellular extract treated samples were comparable to the metabolite standard of the p-cresol degradation pathway. Infrared spectral analysis too showed the spectrum similarity with metabolite standard. Thus, conclusively, intestinal isolates E. faecalis (UTD-1, UTD-2 and UTD-3) might be a promising candidate for mitigating p-cresol detoxification in uremic patients.

Evaluation of Pterin, a Promising Drug Candidate from Cyanide Degrading Bacteria.

Pterin is a member of the compounds known as pteridines. They have the same nucleus of 2-amino-4-hydroxypteridine (pterin); however, the side-chain is different at the position 6, and the state of oxidation of the ring may exist in different form viz. tetrahydro, dihydro, or a fully oxidized form. In the present study, the microorganisms able to utilize cyanide, and heavy metals have been tested for the efficient production of pterin compound. The soil samples contaminated with cyanide and heavy metals were collected from Salem steel industries, Tamil Nadu, India. Out of 77 isolated strains, 40 isolates were found to utilize sodium cyanate as nitrogen source at different concentrations. However, only 13 isolates were able to tolerate maximum concentration (60 mM) of sodium cyanate and were screened for pterin production. Among the 13 isolates, only 1 organism showed maximum production of pterin, and the same was identified as Bacillus pumilus SVD06. The compound was extracted and purified by preparative high-performance liquid chromatography and analyzed by UV/visible, FTIR, and fluorescent spectrum. The antioxidant property of the purified pterin compound was determined by cyclic voltammetry. In addition, antimicrobial activity of pterin was also studied which was substantiated by antagonistic activity against Escherichia coli, and Pseudomonas aeruginosa. Besides that the pterin compound was proved to inhibit the formation of biofilm. The extracted pterin compounds could be proposed further not only for antioxidant and antimicrobial but also for its potency to aid as anticancer and psychotic drugs in future.