Purification and Characterization of Polyunsaturated Fatty Acids (PUFA) Produced by Psychrotolerant Bacteria Isolated from Different Glaciers of Pakistan

Abstract

Polyunsaturated fatty acids (EPA, DHA) are a member of Omega-3 family is essential fatty acid. Omega-3 can be isolated from various source like plants, microalgae, fungi and various fish but they all have certain problems associated with them. Human cannot synthesize omega-3 due to deficiency of enzyme Δ5 desaturase and obtain it through external source. A promising and cost effective alternative source of Omega-3 is bacterial production.. Bacteria can be easily cultured in simple medium and have short growth and production time. A total of 140 bacteria were isolated from previously collected samples of glaciers sediments, water and ice of Batura, Passu and Tirchmir of the Himaliya, Karakoram and Hindukosh regions of Pakistan. The isolates were screened through a calorimetric method 2,3,5-triphenyltetrazolium chloride (TTC) for the production of PUFA. We selected five isolates and labeled as PLPI-1, PDPI-2, PDPI-3, TSC-2 and PSC-3. The selected bacterial isolates were identified by 16S rRNA gene sequence analysis. PLPI-1 was identified as Alcaleene fecalis, PDPI-2 identified as Alcaleene fecalis PDPI-3 identified a Alcaleene fecalis, TSC-2 identified as Alcaleene fecalis and PSC-3 was identified as Alcaleene fecalis but the strain was different. Production of the PUFA by the selected bacteria was verified by Thin Layer Chromatography (TLC) and Fourier transformed infrared spectroscopy (FTIR) using EPA and DHA standards. An investigation of the effects of variables like media, incubation time, temperature and pH for the growth and optimum production of PUFA was checked, using one factor at a time approach (OFAT). It was observed that all the isolates produce maximum PUFA at lower temperature and at neutral pH. For isolates PLPI-1, pH 7, 15˚C temperature and NB medium was found best for PUFA production. Isolate PSC-3, PDPI-1 and TSC-2 showed optimum PUFA production on pH 7, 15˚C temperature and NB medium. Moreover, PDPI-1 has shown maximum PUFA production on wider pH ranging from 5 to 8. It was observed that bacteria were able to produce PUFA. PUFA producing ability in bacteria make it valuable and are better alterative of fish oil will cope the high global demand of omega-3 fatty acid. It has many advantages that heavy metals are absent in their biomass as well suitable for vegetarian. To our knowledge this is the first report of a bacterial isolate producing Omega-3 glaciers samples