Stress proteins, nonribosomal peptide synthetases, and polyketide synthases regulate carbon sources-mediated bio-demulsifying mechanisms of nitrate-reducing bacterium Gordonia sp. TD-4

Rapid and efficient oil removal from O/W emulsions by hydrophobic porous polystyrene microspheres embedded with hydrophilic surface micro-regions

Inspired by Namib Desert beetle's back which is patterned with different wetting properties, hydrophobic porous polystyrene microspheres embedded with hydrophilic surface micro-regions (HPHs) were designed and fabricated by the radical copolymerization in the W₁/O/W₂ double Pickering emulsions with high internal water phase. The synergistic effect of the hydrophobic surface and the hydrophilic surface micro-regions results in HPHs exhibiting superior performances for separating both surfactant-free and surfactant-stabilized O/W emulsions. After 60 s hand-shaking, the oil was absorbed and stored within HPHs which could be separated from the water using a 600-mesh sieve, and the TOC values of purified water could be reduced to 2.06 ± 0.06-67.38 ± 2.02 ppm when the initial oil content was 1 vol%. Meanwhile, HPHs could be recovered and reused through a simple treatment. The excellent oil removal efficiency was kept even after 50 cycles. High oil removal efficiency, general applicability, easy operation and excellent recyclability endow HPHs with great potential for practical applications. And this work provides a facile and general way to prepare porous polymer microspheres with wettability contrast surfaces.

Bio-augmentation with dissimilatory nitrate reduction to ammonium (DNRA) driven sulfide-oxidizing bacteria enhances the durability of nitrate-mediated souring control

Biological souring (producing sulfide) is a global challenge facing anaerobic water bodies, especially the oil reservoir fluids. Nitrate injection has demonstrated great potential in souring control, and dissimilatory nitrate reduction to ammonium (DNRA) bacteria was proposed to play crucial roles in the process. How to durably control souring with nitrate amendment, however, remains undiscovered. Herein, Gordonia sp. TD-4, a DNRA-driven sulfide-oxidizing bacterium, was used to elucidate the effects of bio-augmentation with DNRA bacteria on the durability of nitrate-mediated souring control. The results revealed that nitrate amendment combined with bio-augmentation with TD-4 after souring could effectively control souring and enhance the durability of nitrate-mediated souring control, while nitrate amendment before souring failed to persistently control souring. Nitrate amendment before and after souring resulted in different evolution dynamics of nitrate-reducing bacteria. Denitrifying bacteria were enriched in reactors amended with nitrate before souring or in dissolved sulfide exhausted reactors amended with nitrate after souring. The heterotrophic denitrifying activity of denitrifying bacteria, however, decreased the durability of nitrate-mediated souring control. Comparative and functional genomics analysis identified potential niche adaptation mechanisms (autotrophic and heterotrophic nitrate/nitrite reduction, including DNRA and denitrification) of predominant SRB in nitrate-amended environments, which were responsible for the rapid resumption of sulfide accumulation after the depletion of nitrate and nitrite. Pulsed injection of nitrate combined with bio-augmentation with DNRA-driven sulfide-oxidizing bacteria was proposed as a potential method to enhance the durability of nitrate-mediated souring control. The findings were innovatively applied to simultaneous bio-demulsification and souring control of emulsified and sour produced water from the petroleum industry.

Gordonia crocea sp. nov. Isolated from Wound Infection After Pacemaker Implantation: Case Report and Literature Review

Gordonia is a recognized pathogen in patients with immunodeficiency and a normal immune response, which can cause bacteremia, endocarditis, peritonitis and pulmonary infection. We report a case of wound infection after pacemaker implantation caused by Gordonia crocea. Matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF MS) was routinely used to identify the pathogen, and the results showed that the pathogen could not be accurately identified in the MALDI-TOF database at present. The 16S rRNA gene of the pathogen was further sequenced, and the result was Gordonia crocea. To the best of our knowledge, this is the first reported case of human infection caused by Gordonia crocea.