A bacterially induced crystal particle is formed by a composite shell that encloses a hollow space. The composite shell layer includes a biomaterial and a metallic material. The biomaterial includes cell wall or cell membrane of a bacterium. The metallic material includes oxides, sulfides, selenides, acid salt compounds of a transition metal, or any combination thereof. When the bacterially induced crystal particle is spheric, the composite shell is formed by two dome-shaped portions, and a thickness of each of the dome-shaped portions is not less than 1/73 of a diameter of the bacterially induced crystal particle. Alternatively, when the bacterially induced crystal particle is rod-shaped, the thickness of the dome-shaped portions is not less than 1/73 of a width of the bacterially induced crystal particle, and a thickness of the cylindrical portion is not less than 1/37 of the width of the bacterially induced crystal particle.

A recombinant microorganism including a genetic modification that increases activity of nitric oxide reductase in the recombinant microorganism, a composition for reducing a concentration of nitric oxide in a sample, the composition including the recombinant microorganism, and a method of reducing a concentration of nitric oxide in a sample, are disclosed.

The invention is directed to a process to prepare elemental sulphur by (i) contacting an aqueous solution comprising bisulphide with oxidised sulphide-oxidising bacteria under anaerobic conditions wherein elemental sulphur is produced and a reduced sulphide-oxidising bacteria is obtained and (ii) wherein the reduced sulphide-oxidising bacteria are oxidised by transfer of electrons to an anode of an electrochemical cell to obtain the oxidised sulphide-oxidising bacteria.

The invention is directed to a process to prepare elemental sulphur by (i) contacting an aqueous solution comprising bisulphide with oxidised sulphide-oxidising bacteria under anaerobic conditions wherein elemental sulphur is produced and a reduced sulphide-oxidising bacteria is obtained and (ii) wherein the reduced sulphide-oxidising bacteria are oxidised by transfer of electrons to an anode of an electrochemical cell to obtain the oxidised sulphide-oxidising bacteria.

This invention relates to a method of in-situ remediation of arsenic-contaminated soil, comprising the following steps: inoculating a bacterial strain, Pseudomonas putida MnB1 in a culture medium where an addition amount of the bacterial strain accounts for 2-10% (v/v) of the culture medium; shaking the culture medium with the bacterial strain at a rotation speed of 100-180 rpm at 15-35° C. for 1-5 days under an aerobic condition, thereby yielding an enriched bacterial strain; and adding manganese carbonate, ammonium ferrous sulfate, sodium citrate, a yeast extract and the enriched bacterial strain to arsenic contaminated soil; adding water to the soil until the soil has a moisture content of 50-70%, stirring the soil for 5-30 minutes, and culturing the bacterial strain in the soil under an aerobic/microaerobic condition at 10-40° C. for 2-6 weeks.

This invention relates to a method of in-situ remediation of arsenic-contaminated soil, comprising the following steps: inoculating a bacterial strain, Pseudomonas putida MnB1 in a culture medium where an addition amount of the bacterial strain accounts for 2-10% (v/v) of the culture medium; shaking the culture medium with the bacterial strain at a rotation speed of 100-180 rpm at 15-35° C. for 1-5 days under an aerobic condition, thereby yielding an enriched bacterial strain; and adding manganese carbonate, ammonium ferrous sulfate, sodium citrate, a yeast extract and the enriched bacterial strain to arsenic contaminated soil; adding water to the soil until the soil has a moisture content of 50-70%, stirring the soil for 5-30 minutes, and culturing the bacterial strain in the soil under an aerobic/microaerobic condition at 10-40° C. for 2-6 weeks.

Disclosed is a method for producing a carbon black pigment from a microbial biomass. In certain aspects, the method involves providing a microbial biomass solution with a plurality microbial cells in an aqueous solvent; nucleating the plurality of microbial cells by adding a first soluble ion to the microbial biomass solution; initiating crystal formation in and/or on the plurality of microbial cells by adding a second soluble ion to the microbial biomass solution, forming a plurality of crystal encrusted microbial cells, where the charge of the first soluble ion is the opposite of the charge of the second soluble ion and where the crystals are formed from precipitation of the first and second ions; and performing thermal processing of the plurality of crystal encrusted microbial cells to form a charred biomass; washing the charred biomass to form a microbechar.

Disclosed is a method for producing a carbon black pigment from a microbial biomass. In certain aspects, the method involves providing a microbial biomass solution with a plurality microbial cells in an aqueous solvent; nucleating the plurality of microbial cells by adding a first soluble ion to the microbial biomass solution; initiating crystal formation in and/or on the plurality of microbial cells by adding a second soluble ion to the microbial biomass solution, forming a plurality of crystal encrusted microbial cells, where the charge of the first soluble ion is the opposite of the charge of the second soluble ion and where the crystals are formed from precipitation of the first and second ions; and performing thermal processing of the plurality of crystal encrusted microbial cells to form a charred biomass; washing the charred biomass to form a microbechar.

A method of reducing a concentration of N.sub.2O, NO, or a combination thereof in a medium, the method comprising: culturing a microorganism of the genus Paracoccus, a microorganism of the genus Pseudomonas, or a combination thereof in a liquid medium comprising Mg.sup.2+ ions and Fe(II)(L)-NO, N.sub.2O, or a combination thereof, wherein L is a chelating agent; and reducing NO to N.sub.2O or N.sub.2, or reducing N.sub.2O to N.sub.2.

This disclosure describes methods that allow for the uncoupling of microbial growth from product formation, which allows for maximal use of raw material and optimal end-product formation.