Characterization of Pseudomonas fluorescens polyhydroxyalkanoate produced from molasses as a carbon source

Abstract

Polyhydroxyalkanoate (PHA) is a biopolymer produced by various types of bacteria under conditions of unbalanced growth. One of the bacteria generating PHA is Pseudomonas fluorescens with a carbon source in the form of molasses. This study aim ed to determine the effect of molasses concentration and incubation period on biomass and PHA characteristics. This study utili s ed two factor s , such as molasses concentration of 40, 60, 80 g/L, and incubation period for 3, 5, 7 days. The research result indicated the highest biomass yield was obtained from the treatment of 40 g/L molasses concentration and in 7-day incubation period , with dry cell weight values of 1 , 955 g/L, PHA weight of 0.756 g/L, dry cell yield of 2.036%, and PHA yield of 39.06% , respectively . The visual characteristics of PHA samples were indicated with brownish and granular state , while the melting point and functional group s were identical to pure polyhydroxybutyrate (PHB). The characteristics of the PHB structure obtained from Fourier Transform Infrared Spectroscopy (FTIR) analysis, depicting: C = O esters, CH 3 , CH 2 , -C-O-, -C-O-C Polymers, and C-C. The melting point of PHA samples , using Differential Scanning Calorimetry (DSC) analysis, was 166.4 o C and an enthalpy of -13.885 J/g with 9.5% degree of crystalli s ation.