1.Insights into mutualism mechanism and versatile metabolism of Ketogulonicigenium vulgare Hbe602 based on comparative genomics and metabolomics studies.
Jia N1,2, Ding MZ1,2, Du J1,2, Pan CH1,2, Tian G3, Lang JD3, Fang JH3, Gao F1,2,4, Yuan YJ1,2. Sci Rep. 2016 Mar 16;6:23068. doi: 10.1038/srep23068.
Ketogulonicigenium vulgare has been widely used in vitamin C two steps fermentation and requires companion strain for optimal growth. However, the understanding of K. vulgare as well as its companion strain is still preliminary. Here, the complete genome of K. vulgare Hbe602 was deciphered to provide insight into the symbiosis mechanism and the versatile metabolism. K. vulgare contains the LuxR family proteins, chemokine proteins, flagellar structure proteins, peptides and transporters for symbiosis consortium. Besides, the growth state and metabolite variation of K. vulgare were observed when five carbohydrates (D-sorbitol, L-sorbose, D-glucose, D-fructose and D-mannitol) were used as carbon source. The growth increased by 40.72% and 62.97% respectively when K. vulgare was cultured on D-mannitol/D-sorbitol than on L-sorbose. The insufficient metabolism of carbohydrates, amino acids and vitamins is the main reason for the slow growth of K.
2.Synthesis of 3-Deoxy-l-ketohexoses through Group Transfer.
Lu TN1, Chang CC1. J Org Chem. 2016 Jan 15;81(2):469-75. doi: 10.1021/acs.joc.5b02257. Epub 2015 Dec 30.
A practical method for the synthesis of 3-deoxy-l-ketohexoses is described. Both d- and l-ketohexoses can be transformed into rare 3-deoxy-l-ketohexoses in six steps through a group transfer process. The key step involves a radical cyclized onto a carbonyl group, followed by a fragmentation reaction, eventually resulting in the group transfer of an α-oxy carbonyl group. The process involves tin-free and environmentally benign radical conditions (TTMSS/AIBN/toluene). The acyclic form of 3-deoxy-l-fructose was prepared in only three steps from the inexpensive starting material, d-fructose. A further modification by preparing a dithioacetal derivative was accomplished, which could serve as a convenient sugar synthon for further synthetic applications. Removal of the dithioacetal protecting group results in the formation of the rare 3-deoxy-l-fructose in a total yield of 42%. This methodology could be further extended to the synthesis of other deoxy-l-ketohesoses, such as 3-deoxy-l-sorbose.
3.Genomic identification of nitrogen-fixing Klebsiella variicola, K. pneumoniae and K. quasipneumoniae.
Chen M1, Li Y1, Li S1, Tang L1, Zheng J1, An Q1. J Basic Microbiol. 2016 Jan;56(1):78-84. doi: 10.1002/jobm.201500415. Epub 2015 Oct 16.
It was difficult to differentiate Klebsiella pneumoniae, K. quasipneumoniae and K. variicola by biochemical and phenotypic tests. Genomics increase the resolution and credibility of taxonomy for closely-related species. Here, we obtained the complete genome sequence of the K. variicola type strain DSM 15968(T) (=F2R9(T) ). The genome of the type strain is a circular chromosome of 5,521,203 bp with 57.56% GC content. From 540 Klebsiella strains whose genomes had been publicly available as at 3 March 2015, we identified 21 strains belonging to K. variicola and 8 strains belonging to K. quasipneumoniae based on the genome average nucleotide identities (ANI). All the K. variicola strains, one K. pneumoniae strain and five K. quasipneumoniae strains contained nitrogen-fixing genes. A phylogenomic analysis showed clear species demarcations for these nitrogen-fixing bacteria. In accordance with the key biochemical characteristics of K. variicola, the idnO gene encoding 5-keto-D-gluconate 5-reductase for utilization of 5-keto-D-gluconate and the sorCDFBAME operon for catabolism of L-sorbose were present whereas the rbtRDKT operon for catabolism of adonitol was absent in the genomes of K.
4.Comparative genome analysis of the candidate functional starter culture strains Lactobacillus fermentum 222 and Lactobacillus plantarum 80 for controlled cocoa bean fermentation processes.
Illeghems K1, De Vuyst L2, Weckx S3. BMC Genomics. 2015 Oct 12;16(1):766. doi: 10.1186/s12864-015-1927-0.
BACKGROUND: Lactobacillus fermentum 222 and Lactobacillus plantarum 80, isolates from a spontaneous Ghanaian cocoa bean fermentation process, proved to be interesting functional starter culture strains for cocoa bean fermentations. Lactobacillus fermentum 222 is a thermotolerant strain, able to dominate the fermentation process, thereby converting citrate and producing mannitol. Lactobacillus plantarum 80 is an acid-tolerant and facultative heterofermentative strain that is competitive during cocoa bean fermentation processes. In this study, whole-genome sequencing and comparative genome analysis was used to investigate the mechanisms of these strains to dominate the cocoa bean fermentation process.