AbstractBiosurfactants are surface-active metabolites produced by microorganisms. Biosurfactants tend to solubilize hydrocarbons in the surrounding environment, by reducing surface tension and increasing carbon uptake. In this study, isolation of biosurfactant producing bacteria and effect of renewable, non-fossil fuel based carbon sources on production were assessed. Oil field produced water was collected from Potwar oil fields and thirteen strains were isolated. Strains were screened for biosurfactant production by hemolysis test, emulsification index test, emulsification assay, oil displacement test, drop collapse test, tilted glass slide test and oil coated agar emulsification test. Strains were further screened for maximum production on cost effective renewable carbon source e.g. glucose, waste glycerol and animal fat. Promising strains were identified as Bacillus subtilis (MH142143), Pseudomonas aeruginosa (MH142144), Bacillus tequilensis (MH142145) and Bacillus safensis (MH142146) by 16S rRNA gene sequencing. Among all isolates, highest biosurfactant production on glucose (37%), glycerol (48%) and animal fat oil (49%), after 24 h cultivation was by Pseudomonas aeruginosa. Biosurfactant showed similarity to rhamnolipids by Thin Layer Chromatography (TLC). Assessment of bioactive propertiaes of rhamnolipid showed strong antimicrobial activity against Bacillus spp. Future investigations can be focused on application of these strains in environmental as well as industrial sectors.

AbstractOil reservoirs contain large amounts of hydrocarbon rich produced water, trapped in underground channels. Focus of this study was isolation of PHA producers from produced water concomitant with optimization of production using animal fat and glycerol as carbon source. Bacterial strains were identified as Bacillus subtilis (PWA), Pseudomonas aeruginosa (PWC), Bacillus tequilensis (PWF), and Bacillus safensis (PWG) based on 16S rRNA gene sequencing. Similar amounts of PHA were obtained using animal fat and glycerol in comparison to glucose. After 24 h, high PHA production on glycerol and animal fat was shown by strain PWC (5.2 g/ L, 6.9 g/ L) and strain PWF (12.4 g/ L, 14.2 g/ L) among all test strains. FTIR analysis of PHA showed 3-hydroxybutyrate units. The capability to produce PHA in the strains was corroborated by PhaC synthase gene sequencing. Focus of future studies can be the use of lipids and glycerol on industrial scale.

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Biodegradable biopolymers such as polyhydroxyalkanoates (PHA) and polylactide (PLA) have wide range of applications in almost all sectors. Degradation of these polymers, however efficient, still creates a paradox with green chemistry principles. Blending of these polymers can potentially decrease plastic pollution due to their increased biodegradability. During this study, PHAwas produced using bacterial strains DL3; Bacillus subtilis (MT043898), PWA; Bacillus subtilis (MH142143), PWC; Pseudomonas aeruginosa (MH142144), PWF; Bacillus tequilensis (MH142145) and PWG; Bacillus safensis (MH142146). Corn-based PLA was produced chemically and physically blendedwith PHA (PHA-PLA blends). During molecular studies, PHA, PLA and PHA-PLA blendswere characterized via FT-IR analysis, SEM, and light microscopy indicating successful blending of PHA-PLA samples. FTIR results indicated PHA produced by strain PWF and mixed culture wasmcl-PHA. Degradation of polymers and copolymer blends was studied by bacteria for 12 weeks and in different environmental systems i.e. in soil, water, air, and heat for 20 weeks. Degradation analysis indicated highest degradation of PLA, followed by PHA-PLA blends. Among these systems, degradation was favored in soil (80%), followed by water (78%) and air (78%). Least degradation (76%) was observed on heat exposure. Sample degradation observed using light microscope and SEM showed fungal and bacterial colonization amidst cracks, crevices, bumps, and fractures after 20 weeks. Understanding the role of ambient microbial population during degradation and its impact on natural soil environment can be the focus of future studies.