Abstract: The disclosure relates to a sucrose phosphorylase mutant with improved enzyme activity, and construction method thereof and use thereof, and belongs to the technical field of genetic engineering. The amino acid sequence of the mutant of the disclosure is as shown in SEQ ID NO: 1. The mutant of the disclosure is based on sucrose phosphorylase derived from Leuconostoc mesenteroides, and subjected to site-directed mutagenesis to improve the enzyme activity of sucrose phosphorylase. The mutant is expressed in Corynebacterium glutamicum and used as a whole cell catalyst to produce 2-O-?-D-glycerol glucoside. At a 5 L fermentation tank level, a large quantity of 2-O-?-D-glycerol glucoside can be produced efficiently in a short time, which is conducive to expanding the prospect of industrial application of sucrose phosphorylase for the production of 2-O-?-D-glycerol glucoside and realizing its large-scale industrial application.

Abstract: The disclosure discloses 17?-hydroxysteroid dehydrogenase mutants and application thereof, and belongs to the technical field of biology. The disclosure provides 17?-hydroxysteroid dehydrogenase mutants V107A, T155N, H164Y and V107A/T155N/H164Y with high specific enzyme activities, and the specific enzyme activities of the 17?-hydroxysteroid dehydrogenase mutants V107A, T155N, H164Y and V107A/T155N/H164Y are as high as 1.85, 1.93, 2.06 and 5.15 U/mg, respectively, which are 1.11, 1.16, 1.24 and 3.10 times larger than that of wild-type 17?-hydroxysteroid dehydrogenase (1.66 U/mg).

Abstract: The disclosure relates to a sucrose phosphorylase mutant with improved enzyme activity, and construction method thereof and use thereof, and belongs to the technical field of genetic engineering. The amino acid sequence of the mutant of the disclosure is as shown in SEQ ID NO: 1. The mutant of the disclosure is based on sucrose phosphorylase derived from Leuconostoc mesenteroides, and subjected to site-directed mutagenesis to improve the enzyme activity of sucrose phosphorylase. The mutant is expressed in Corynebacterium glutamicum and used as a whole cell catalyst to produce 2-O-?-D-glycerol glucoside. At a 5L fermentation tank level, a large quantity of 2-O-?-D-glycerol glucoside can be produced efficiently in a short time, which is conducive to expanding the prospect of industrial application of sucrose phosphorylase for the production of 2-O-?-D-glycerol glucoside and realizing its large-scale industrial application.

Abstract: The disclosure discloses 17?-hydroxysteroid dehydrogenase mutants and application thereof, and belongs to the technical field of biology. The disclosure provides 17?-hydroxysteroid dehydrogenase mutants V107A, T155N, H164Y and V107A/T155N/H164Y with high specific enzyme activities, and the specific enzyme activities of the 17?-hydroxysteroid dehydrogenase mutants V107A, T155N, H164Y and V107A/T155N/H164Y are as high as 1.85, 1.93, 2.06 and 5.15 U/mg, respectively, which are 1.11, 1.16, 1.24 and 3.10 times larger than that of wild-type 17?-hydroxysteroid dehydrogenase (1.66 U/mg).

Abstract: The present invention provides an aspartase mutant, a recombinant expression vector and recombinant bacterium containing the aspartase mutant, and the use thereof, and belongs to the technical field of genetic engineering. The amino acid sequence of the aspartase mutant is as set forth in SEQ ID NO: 1. In the aspartase mutant of the present invention, on the basis of wild type aspartase (with an amino acid sequence as set out in SEQ ID NO: 3), glutamic acid at position 427 is mutated into glutamine. In the present invention, by mutating the amino acid residue at position 427 into glutamine, the polar environment near an active site is changed, and thus ammonia supply during substrate reaction is further facilitated, thereby improving an enzyme activity, enhancing the ability of the enzyme in synthesizing a ?-amino acid, and providing a practical and effective strategy for industrial production of the ?-amino acid.

Abstract: The present invention discloses a Mycobacterium neoaurum-derived steroid C27-monooxygenase and an application thereof, which belong to the technical fields of genetic engineering and enzyme engineering. By the method of gene knockout and intensive expression, the present invention screens out three isoenzymes of a key enzyme SMO in the process of degrading sterol side chains from Mycobacterium neoaurum. The three isoenzymes are intensively expressed respectively in the Mycobacterium neoaurum for the high yield of androsta-1,4-diene-3,17-dione (ADD), the yield of ADD is increased remarkably, wherein the effect of SMO2 is most remarkable. By overexpressing SMO2, the final ADD yield is increased from 5.2 g·L?1 to 7.3 g·L?1. The present invention provides a helpful guidance for the industrialization of the microbial fermentation method for increasing the ADD yield.

Abstract: The present invention discloses a Mycobacterium neoaurum-derived steroid C27-monooxygenase and an application thereof, which belong to the technical fields of genetic engineering and enzyme engineering. By the method of gene knockout and intensive expression, the present invention screens out three isoenzymes of a key enzyme SMO in the process of degrading sterol side chains from Mycobacterium neoaurum. The three isoenzymes are intensively expressed respectively in the Mycobacterium neoaurum for the high yield of androsta-1,4-diene-3,17-dione (ADD), the yield of ADD is increased remarkably, wherein the effect of SMO2 is most remarkable. By overexpressing SMO2, the final ADD yield is increased from 5.2 g·L.?1 to 7.3 g·L.?1. The present invention provides a helpful guidance for the industrialization of the microbial fermentation method for increasing the ADD yield.

Abstract: A distributed object store in a network storage system uses location-independent global object identifiers (IDs) for stored data objects. The global object ID enables a data object to be seamlessly moved from one location to another without affecting clients of the storage system, i.e., “transparent migration”. The global object ID can be part of a multilevel object handle, which also can include a location ID indicating the specific location at which the data object is stored, and a policy ID identifying a set of data management policies associated with the data object. The policy ID may be associated with the data object by a client of the storage system, for example when the client creates the object, thus allowing “inline” policy management. An object location subsystem (OLS) can be used to locate an object when a client request does not contain a valid location ID for the object.

Abstract: A method of performing a global deduplication may include: collecting a data chunk to be written to a backing storage of a storage system at a staging area in the storage system; generating a data fingerprint of the data chunk; sending the data fingerprint in batch along with other data fingerprints corresponding to data chunks collected at different times to a metadata server system in the storage system; receiving an indication, at the staging area, of whether the data fingerprint is unique in the storage system from the metadata server system; and discarding the data chunk when committing a data object containing the data chunk to the backing storage, when the indication indicates that the data chunk is not unique.

Abstract: A distributed object store in a network storage system uses location-independent global object identifiers (IDs) for stored data objects. The global object ID enables a data object to be seamlessly moved from one location to another without affecting clients of the storage system, i.e., “transparent migration”. The global object ID can be part of a multilevel object handle, which also can include a location ID indicating the specific location at which the data object is stored, and a policy ID identifying a set of data management policies associated with the data object. The policy ID may be associated with the data object by a client of the storage system, for example when the client creates the object, thus allowing “inline” policy management. An object location subsystem (OLS) can be used to locate an object when a client request does not contain a valid location ID for the object.

Abstract: A hierarchically tagged cache provides abstraction between access requests for data and the cached data. The cache is managed by hierarchical layers of indexes including reference to the data. Access requests indicate a header for the requested data, which is associated with one of the layers. Cache management determines what layer is associated with the header, and can traverse the indexes, beginning at the layer associated with the header, to access the data. If the header does not exist at the index of that layer, it can be created. Indexes can be appropriately updated with indexes at each layer being referenced by one or more indexes of the layer higher up in the hierarchy.

Abstract: A distributed object store in a network storage system uses location-independent global object identifiers (IDs) for stored data objects. The global object ID enables a data object to be seamlessly moved from one location to another without affecting clients of the storage system, i.e., “transparent migration”. The global object ID can be part of a multilevel object handle, which also can include a location ID indicating the specific location at which the data object is stored, and a policy ID identifying a set of data management policies associated with the data object. The policy ID may be associated with the data object by a client of the storage system, for example when the client creates the object, thus allowing “inline” policy management. An object location subsystem (OLS) can be used to locate an object when a client request does not contain a valid location ID for the object.

Abstract: A data storage system includes a processor, a system memory, and logical extents. Blocks of storage in one or more physical storage devices are allocated to each of the logical extents. The processor maintains a logical container for data objects and the volume includes one or more of the logical extents. The processor stores data objects that are uniquely identified by object identifiers in the logical extents. The processor also maintains a first index that is stored in the system memory and maps a range of the object identifiers to a second index. The second index is also stored in a logical extent and indicates storage locations of the data objects associated with the range of the object identifiers.

Abstract: A data storage system includes a processor, a system memory, and logical extents. Blocks of storage in one or more physical storage devices are allocated to each of the logical extents. The processor maintains a logical container for data objects and the volume includes one or more of the logical extents. The processor stores data objects that are uniquely identified by object identifiers in the logical extents. The processor also maintains a first index that is stored in the system memory and maps a range of the object identifiers to a second index. The second index is also stored in a logical extent and indicates storage locations of the data objects associated with the range of the object identifiers.

Abstract: Example embodiments provide various techniques for fast and efficient search of attributes stored in data structures. The attributes are organized following a hierarchical structure of the file system and, in an example, the attributes are stored in a data structure where the hierarchical structure is maintained. As a result, a search within such data structure may follow one or more paths along the hierarchical structure of the file system. Attributes associated with directories and files outside of the path can be excluded from the search. Example embodiments also provide various techniques for updating signatures associated with the attributes. In an example, updates to the signatures can be made incrementally. For example, signatures can be updated when the attributes change.

Abstract: Embodiments of the present invention provide mechanisms that overcome limitations of existing indexes by creating two-dimensional (2D) spatial indexes to quickly locate data containers that match two or more predicates. This is accomplished by representing metadata attributes describing a data container as dimensions in a 2D space so that a data container can be expressed as a point or a cell in a 2D space with coordinates being a pair of values of the selected attributes. A space filling curve is used to traverse the 2D space and convert each pair of the 2D coordinates to a single space filling curve value. A 2D spatial index is then created based on the computed space filling curve values so that one value can be associated with one or more points (data containers) in the index. Advantageously, the created spatial index provides for searching and processing fewer metadata entries, thereby decreasing the time typically used to search for data.

Abstract: A method is disclosed for executing a predetermined query plan, the method comprising: executing a portion of the query plan; providing a reordered query plan; comparing ranking metrics for the query plans; and executing the query plan having the lower ranking metric.

Abstract: A method is disclosed for executing a predetermined query plan, the method comprising: executing a portion of the query plan; providing a reordered query plan; comparing ranking metrics for the query plans; and executing the query plan having the lower ranking metric.