Functional characterization of sll0659 from Synechocystis sp PCC 6803

Synchocystis sp. PCC 6803 lacks a gene for the any known types of lycopene cyclase. Recently, we reported that sll0659 (unknown for its function) from Synechocystis sp. PCC6803 shows similarity in sequence to a lycopene cyclase gene-CruA from Chlorobium tepidum. To test, whether Sll0659 encoded protein serves as lycopene cyclase, in this study, we investigated the carotenoids of the wild types ans mutants, In the sll0659 deleted mutant, there is no blockage at the lycopene cyclization step. Our results demonstrate that sll0659 does not affect lycopene cyclization. However, the ultrastructure of mutants suggests the involvement or necessity of sll0659 in the cell division.

Substrate induction and statistical optimization for the production of chitosanase from Microbacterium sp OU01

The chitosanase production was markedly enhanced by substrate induction, statistical optimization of medium composition and culture conditions by Microbacteritan sp. OU01 in shake-flask. A significant influence of (NH4)(2)SO4, MgSO4 center dot 7H(2)O and initial pH on chitosanase production was noted with Plackett-Burman design. It was then revealed with the method of steepest ascent and response surface methodology (RSM) that 19.0 g/L (NH4)(2)SO4, 1.3 g/L MgSO4 and an initial pH of 2.0 were optimum for the production of chitosanase; colloidal chitosan appeared to be the best inducer for chitosanase production by Microbacterium sp. OU01. This optimization strategy led to the enhancement of chitosanase from 3.6 U/mL to 118 U/mL. (c) 2006 Elsevier Ltd. All rights reserved.

Molecular cloning, expression and characterization of a chitosanase from Microbacterium sp.

A gene encoding a chitosanase (mschito) was cloned from Microbacterium, sp. OU01. The ORF consists of 801 bp which encoded a polypeptide of 266 amino acid residues. The deduced amino acid sequence shows 98% identity to that of the chitosanase reported in Pseudomonas sp. A-01. In addition, the fusion protein containing MSCHITO was expressed in E. coli and purified using Ni-NTA affinity chromatography. The purified rMSCHITO protein degraded the chitosan (the degree of deacetylation of 99%) and produced a mixture of chitooligosaccharides. The MSCHITO is thus an endo-chitosanase.

5,7-Dihydroxy-5,6,7,8-tetrahydro-1H-azocin-2-one from a marine-derived Streptomyces sp.

In the course of a screening program, we have isolated the new natural product, 5,7-dihydroxy-5,6,7,8-tetrahydroazocin-2(IH)-one (1), from the staurosporine producing marine-derived Streptomyces sp. strain QD518. Here we report the isolation and structure elucidation of 1 and the artifacts 3 and 4 resulting from I by acid catalyzed intra- and inter-molecular reactions.

Heterologous expression and purification of recombinant allophycocyanin in marine Streptomyces sp isolate M097

Allophycocyanin is one of the most important marine active peptides. Previous studies suggested that recombinant allophycocyanin (rAPC) could remarkably inhibit the S-180 carcinoma in mice, indicating its potential pharmaceutical uses. Based on intergeneric conjugal transfer, heterologous expression of rAPC was first achieved in marine Streptomyces sp. isolate M097 through inserting the apc gene into the thiostrepton-induced vector pIJ8600. The transformation frequency for this system was approximately 10(-4) exconjugants/recipient. In the transformed Streptomyces sp. isolate M097, the yield of purified rAPC could amount to about 38 mg/l using a simple purification protocol, and HPLC analysis showed that the purity of the protein reached about 91.5%. In vitro activity tests also revealed that the purified rAPC had effective scavenging abilities on superoxide and hydroxyl radicals. This would widen the usefulness of the marine Streptomyces as a host to express the rAPC and to offer industrial strain for the production of rAPC.

Purification and characterization of two types of chitosanase from a Microbacterium sp.

Two extracellular chitosanases (ChiX and ChiN) were extracted from Microbacterium sp. OU01 with Mr values of 81 kDa (ChiX) and 30 kDa (ChiN). ChiN was optimally active at pH 6.2 and 50 degrees C and ChiX at pH 6.6 and 60 degrees C (assayed over 15 min). Both the activities increased with the degree of deacetylation (DDA) of chitosan. ChiN hydrolyzed oligomers of glucosamine (GlcN) larger than chitopentaose, and chitosan with 62-100% DDA; but ChiX acted on chitosan and released GlcN. Hydrolysis of chitosan with 99% DDA by ChiN released chitobiose, chitotriose and chitotetraose as the major products.