Construction of Whole Cell Bacterial Biosensors as an Alternative Environmental Monitoring Technology to Detect Naphthenic Acids in Oil Sands Process-Affected Water.

After extraction of bitumen from oil sands deposits, the oil sand process-affected water (OSPW) is stored in tailings ponds. Naphthenic acids (NA) in tailings ponds have been identified as the primary contributor to toxicity to aquatic life. As an alternative to other analytical methods, here we identify bacterial genes induced after growth in naphthenic acids and use synthetic biology approaches to construct a panel of candidate biosensors for NA detection in water. The main promoters of interest were the atuAR promoters from a naphthenic acid degradation operon and upstream TetR regulator, the marR operon which includes a MarR regulator and downstream naphthenic acid resistance genes, and a hypothetical gene with a possible role in fatty acid biology. Promoters were printed and cloned as transcriptional lux reporter plasmids that were introduced into a tailings pond-derived Pseudomonas species. All candidate biosensor strains were tested for transcriptional responses to naphthenic acid mixtures and individual compounds. The three priority promoters respond in a dose-dependent manner to simple, acyclic, and complex NA mixtures, and each promoter has unique NA specificities. The limits of NA detection from the various NA mixtures ranged between 1.5 and 15 mg/L. The atuA and marR promoters also detected NA in small volumes of OSPW samples and were induced by extracts of the panel of OSPW samples. While biosensors have been constructed for other hydrocarbons, here we describe a biosensor approach that could be employed in environmental monitoring of naphthenic acids in oil sands mining wastewater.

Draft genome sequences of six bacterial strains isolated from Cannabis rhizosphere soil.

Although bacterial isolates from Cannabis flowers were reported and sequenced, few from its rhizosphere have been characterized. Here we report the draft genomes of six bacterial strains isolated from Cannabis rhizosphere soil samples. These sequences may shed light on plant-microbe interactions in the Cannabis rhizosphere at the molecular level.

Draft genome sequences of six Pseudomonas spp. and one Rheinheimera sp. isolated from oil sands process-affected water from Alberta, Canada.

We report the draft genomes of seven bacterial strains (six Pseudomonas spp. and one Rheinheimera sp.) isolated from environmental water samples from oil sands tailings ponds that have accumulated a wide variety of organic compounds, salts and metals.

Biosensor-guided detection of outer membrane-specific antimicrobial activity against Pseudomonas aeruginosa from fungal cultures and medicinal plant extracts.

IMPORTANCE: New approaches are needed to discover novel antimicrobials, particularly antibiotics that target the Gram-negative outer membrane. By exploiting bacterial sensing and responses to outer membrane (OM) damage, we used a biosensor approach consisting of polymyxin resistance gene transcriptional reporters to screen natural products and a small drug library for biosensor activity that indicates damage to the OM. The diverse antimicrobial compounds that cause induction of the polymyxin resistance genes, which correlates with outer membrane damage, suggest that these LPS and surface modifications also function in short-term repair to sublethal exposure and are required against broad membrane stress conditions.