Biosorbents based on esterified starch carrying immobilized oil-degrading microorganisms.

The complex sorbents based on hydrophobized starch, which contain oil-degrading microorganisms, have been proposed for effective sorption and utilization of petroleum-related pollutants. The sorbents were made on the base of benzoic, lauric and stearic acid esters of starch with degrees of substitution of 0.4-1.1. The esterification of starch was carried out by the reaction with acyl chlorides of the corresponding acids in an aqueous-organic medium. The structure of the esters was studied by SEM, IR and NMR spectroscopy. As a result of porous hydrophobic structure, these sorbents are capable of binding and retention of petroleum products on the water surface, and keeping the flotation for at least 30days after the petroleum products sorption. The test of biodegradability of the obtained samples revealed that the modified starches can be degraded by microscopic fungi, therefore they do not cause secondary pollution. The cultures of yeast Rhodotorula glutinis VKM Y-2993D and bacteria Pseudomonas libanensis VKM B-3041D immobilized on the sorbent facilitate the rapid utilization of accumulated petroleum products.

Studying the Mechanochemistry of Processive Cytoskeletal Motors With an Optical Trap.

Cytoskeletal motors utilize the energy stored in ATP to generate linear motion along rigid filaments. Because their enzymatic cycles are tightly coupled to the production of force and forward movement, the optical-trapping technique is uniquely suited for studying their mechanochemical cycle. Here, we discuss the practical aspects of optical trapping in connection with single-motor assays and describe three distinct experimental modes (fixed-trap, force feedback, and square wave) that are typically used to investigate the enzymatic and biophysical properties of cytoskeletal motors. The principal outstanding questions in the field involve motor regulation by cargo adaptor proteins and cargo transport by teams of motors, ensuring that the optical trap's ability to apply precise forces and measure nanometer-scale displacements will remain crucial to the study of intracellular motility in the foreseeable future.