APPLICATION OF MICROBIAL TECHNOLOGY TO MINERAL PROCESSING

The application of microbial technology to mineral processing hasbeen reviewed with respect to the bioleaching of metals fromminerals, the influence of biotreatment on flotation, the biobeneficication of nonmetallic minerals, and the biotreatment for minewaste reclamation. The application of microbial technology to mineralprocess- ing has shown the advantages of high efficiency, low en-Ergy and reagent consumption, low capital and operating Costs, andlow pollution of the environment.

Recent progress in microbial cell surface display systems and their application on biosensors

Microbial cell surface display technology is a recombinant technology to express target proteins on the cell membrane,which can be used to redesign the cell surface with functional proteins and peptides.Bacterial and yeast surface display systems are the most common cell surface display systems of prokaryotic and eukaryotic proteins,that are widely applied as the core elements in the field of biosensors due to their advantages,including enhanced stability,high yield,good safety,expression of larger and more complex proteins.To further promote the performance of biosensors,the biomineralized microbial surface display technology was proposed.This review summarized the different microbial surface display systems and the biomineralized surface display systems,where the mechanisms of surface display and biomineralization were introduced.Then we described the recent progress of their applications on biosensors for different types of detection targets.Finally,the outlooks and tendencies were discussed and forecasted with the expectation to provide some general functions and enlightenments to this aspect of research.

Current Research and Strategy on the Biosurfactants Used in the Remediation of Petrochemical Polluted Environment

Biosurfactants are biologically active metabolites, and the efficiency of direct screening of new biosurfactants from nature using traditional methods is low, which should be enhanced in the following studies by adopting advanced biotechnologies. Rapid development and wide application of microbial culture independent methods, such as metagenomics, metatranscriptomics, metaproteomics and metabonomics, etc., contributes to quickly and precisely screening of novel biological surfactants. We mainly represented the current status of research and applications of biosurfactants in the remediation of petrochemical polluted environment, and also prospected avenues for future research.

Direct ammonium oxidation to nitrogen gas (Dirammox) in Alcaligenes strain HO-1: The electrode role

It has been recently suggested that Alcaligenes use a previously unknown pathway to convert ammonium into dinitrogen gas(Dirammox)via hydroxylamine(NH2OH).This fact alone already implies a significant decrease in the aeration requirements for the process,but the process would still be dependent on external aeration.This work studied the potential use of a polarised electrode as an electron acceptor for ammonium oxidation using the recently described Alcaligenes strain HO-1 as a model heterotrophic nitrifier.Results indicated that Alcaligenes strain HO-1 requires aeration for metabolism,a requirement that cannot be replaced for a polarised electrode alone.However,concomitant elimination of succinate and ammonium was observed when operating a previously grown Alcaligenes strain HO-1 culture in the presence of a polarised electrode and without aeration.The usage of a polarised electrode together with aeration did not increase the succinate nor the nitrogen removal rates observed with aeration alone.However,current density generation was observed along a feeding batch test representing an electron share of 3%of the ammonium removed in the presence of aeration and 16%without aeration.Additional tests suggested that hydroxylamine oxidation to dinitrogen gas could have a relevant role in the electron discharge onto the anode.Therefore,the presence of a polarised electrode supported the metabolic functions of Alcaligenes strain HO-1 on the simultaneous oxidation of succinate and ammonium.

Monitoring stratification of anode biofilms in bioelectrochemical laminar flow reactors using flow cytometry

A laminar flow bioelectrochemical systems(BES)was designed and benchmarked using microbial anodes dominated with Geobacter spp.The reactor architecture was based on modeled flow fields,the resulting structure was 3D printed and used for BES manufacturing.Stratification of the substrate availability within the reactor channels led to heterogeneous biomass distribution,with the maximum biomass found mainly in the initial/middle channels.The anode performance was assessed for different hydraulic retention times while coulombic efficiencies of up to 100%(including also hydrogen recycling from the cathode)and current densities of up to 75 μA cm^(-2) at an anode surface to volume ratio of 1770 cm^(2) L^(-1) after 35 days were achieved.This low current density can be clearly attributed to the heterogeneous distributions of biomass and the stratification of the microbial community structure.Further,it was shown that time and space resolved analysis of the reactor microbiomes per channel is feasible using flow cytometry.

Preparation and characterization of a novel microorganism embedding material for simultaneous nitrification and denitrification

A novel microorganism embedding material was prepared to enhance the biological nitrogen removal through simultaneous nitrification and denitrification. Polyvinyl alcohol （PVA）, sodium alginate （SA） and cyclodextrin （CD） were used to compose gel bead with embedded activated sludge. The effects of temperature, CD addition and concentrations of PYA and SA on nitrogen removal were evaluated. Results show that the gel bead with CD addition at 30℃contributed to the highest nitrogen removal efficiency and nitrogen removal rate of 85.4% and 2.08 mg·（L·h）^-1, respectively. Meanwhile, negligible NO3^- and NO2^- were observed, proving the occurrence of simultaneous nitrification and denitrification. The High-Throughput Sequencing confirms that the microbial community mainly contained Comamonadaceae in the proportion of 61.3%. Overall, CD increased gel bead＇s porosity and resulted in the high specific endogenous respiration rate and high nitrogen removal efficiency, which is a favorable additional agent to the traditional embedding material.