Occurrence of hydrocarbon-utilising bacteria in oil-polluted arid soils in Sudan

Aims@#This study aimed to isolate and identify hydrocarbon-utilising bacteria from oil- polluted sites and to develop a microbial consortium for use in pilot trial and commercial scale bioremediation treatment systems in the future.@*Methodology and results@#Ten hydrocarbon-utilising bacterial strains were isolated using enrichment culture technique from oil-polluted sites using crude oil as sole carbon source. The strains were tentatively identified on the basis of colony morphology, microscopic examination and biochemical characteristics. The growth of each strain was assessed by growing the bacteria in mineral salt medium amended with diesel oil as sole carbon source. The isolates exhibited differences in growth with the order of biomass production being Enterobacter sp. (OD620=1.283)> Bacillus subtilis subsp. subtilis (OD620=1.245) > Aerococcus sp. (OD620=1.100) > Bacillus firmus (OD620=0.970) > Corynebacterium sp. (OD620=0.886) > Bacillus lentus (OD620=0.743) > Micrococcus luteus (OD620=0.656) > Bacillus subtilis (OD620=0.367) > Bacillus cereus (OD620=0.110) > Kocuria flavus (OD620=0.065). @*Conclusion, significance and impact of study@#This study is a prerequisite for the design of future full-scale bioremediation treatment of oil-polluted sites using hydrocarbon-utilising bacteria. An efficient consortium was developed comprising the best three hydrocarbon-utilising strains, which include Enterobacter sp., Bacillus subtilis subsp. subtilis and Aerococcus sp. This efficient microbial consortium is suggested to be used in future to rehabilitate oil-polluted sites in Sudan.

Subeutectic growth of single-crystal silicon nanowires grown on and wrapped with graphene nanosheets: high-performance anode material for lithium-ion battery.

A novel one-pot synthesis for the subeutectic growth of (111) oriented Si nanowires on an in situ formed nickel nanoparticle catalyst prepared from an inexpensive nickel nitrate precursor is developed. Additionally, anchoring the nickel nanoparticles to a simultaneously reduced graphene oxide support created synergy between the individual components of the c-SiNW-G composite, which greatly improved the reversible charge capacity and it is retention at high current density when applied as an anode for a Li-ion battery. The c-SiNW-G electrodes for Li-ion battery achieved excellent high-rate performance, producing a stable reversible capacity of 550 mAh g(-1) after 100 cycles at 6.8 A g(-1) (78% of that at 0.1 A g(-1)). Thus, with further development this process creates an important building block for a new wave of low-cost silicon nanowire materials and a promising avenue for high rate Li-ion batteries.

Engineered Si electrode nanoarchitecture: a scalable postfabrication treatment for the production of next-generation Li-ion batteries.

A novel, economical flash heat treatment of the fabricated silicon based electrodes is introduced to boost the performance and cycle capability of Li-ion batteries. The treatment reveals a high mass fraction of Si, improved interfacial contact, synergistic SiO2/C coating, and a conductive cellular network for improved conductivity, as well as flexibility for stress compensation. The enhanced electrodes achieve a first cycle efficiency of ∼84% and a maximum charge capacity of 3525 mA h g(-1), almost 84% of silicon's theoretical maximum. Further, a stable reversible charge capacity of 1150 mA h g(-1) at 1.2 A g(-1) can be achieved over 500 cycles. Thus, the flash heat treatment method introduces a promising avenue for the production of industrially viable, next-generation Li-ion batteries.