Project description:Petrocodon rubiginosus Y.G. Wei & R.L. Zhang, sp. nov., from Guangxi of South China, is described and illustrated with photographs. The new species is morphologically similar to Pet. hechiensis, but can be easily distinguished by a combination of characters, especially in its petioles, peduncles and pedicels covered with densely ferruginous pilose hairs.
Project description:The food enzyme is a d-xylose aldose-ketose-isomerase (EC 5.3.1.5) produced with the genetically modified Streptomyces rubiginosus strain DP-Pzn37 by Danisco US Inc. Although the production strain contains antibiotic resistance genes, the food enzyme was shown to be free from viable cells of the production organism and its DNA. The food enzyme is intended to be used in an immobilised form for the isomerisation of glucose for the production of high fructose syrups. Residual amounts of total organic solids (TOS) are eliminated by the use of an immobilised food enzyme and further removed by the purification steps applied during the production of high fructose syrups using the immobilised enzyme; consequently, dietary exposure was not calculated. Genotoxicity tests did not raise safety concerns. The systemic toxicity was assessed by a repeated dose 90-day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 85.2 mg TOS/kg body weight (bw) per day, the highest dose tested. Similarity of the amino acid sequence to those of known allergens was searched and no match was found. The Panel considered that, under the intended conditions of use, the risk of allergic sensitisation and elicitation reactions by dietary exposure cannot be excluded, but the likelihood is considered to be low. Based on the data provided, the immobilisation process and the removal of total organic solids during the production of high fructose syrups, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.
Project description:The xylose isomerase (xylA) and the xylulose kinase (xylB) genes from Streptomyces rubiginosus were isolated, and their nucleotide sequences were determined. The xylA and xylB genes encode proteins of 388 and 481 amino acids, respectively. These two genes are transcribed divergently from within a 114-nucleotide sequence separating the coding regions. Regulation of the xyl genes in S. rubiginosus was examined by fusing their promoters to the Pseudomonas putida catechol dioxygenase gene and integrating the fusions into the minicircle integration site on the S. rubiginosus chromosome. The expression of catechol dioxygenase was then measured under a variety of conditions. The results indicated that transcription of the xyl genes was induced by D-xylose and repressed by glucose. Data from quantitative S1 mapping were consistent with this conclusion and suggested that xylA had one and xylB had two transcription initiation sites. The transcription initiation site of xylA was 40 bp upstream of the coding region. The two transcription initiation sites of xylB were 20 and 41 bp 5' of its translation initiation codon. Under control of appropriate regulatory elements, the cloned xyl genes are capable of complementing either Escherichia coli xylose isomerase- or xylulose kinase-deficient strains. The deduced amino acid sequence of the S. rubiginosus xylA protein is highly homologous to sequences of other microbial xylose isomerases.
