A new insertion sequence (IS1381) was identified in the genome of Streptococcus pneumoniae R6 as an 846-bp segment containing 20-bp terminal inverted repeats and flanked by 7-bp direct repeats. The three sequenced copies of this element have two overlapping open reading frame (ORF) genes named orfA and orfB. However, significant variations between individual copies were found, suggesting that inactivating mutations have occurred in an original single ORF. Accordingly, the consensus IS1381 element derived from the comparison of the three available copies should contain a single ORF sufficient to encode a basic protein of 267 amino acids which exhibited high similarity to the putative transposases of ISL2 from Lactobacillus helveticus and of IS702 from the cyanobacterium Calothrix sp. strain PCC 7601. A minimum of five to seven copies were detected by hybridization experiments in the R6 genome. In remarkable contrast with the two previously reported pneumococcal insertion sequences, several copies of IS1381 have been detected in all of the clinical isolates tested so far. Interestingly, Streptococcus oralis NCTC 11427 (type strain), a close relative of pneumococcus, does not contain this element, but its occurrence in the type strain of Streptococcus mitis (NCTC 12261) suggests that this species has exchanged DNA with S. pneumoniae directly or through an intermediate species.
a b s t r a c tSeveral studies have dealt with the microwave-induced pyrolysis of organic residues as an effective technology for maximizing the production of syngas at the expense of the production of oily tars. This liquid fraction is composed of a complex mixture of organic compounds making it difficult to upgrade for use as a biofuel and containing hazardous compounds such as polycyclic aromatic hydrocarbons (PAH). In this study the effect of the type of residue (municipal solid wastes, sewage sludges, plastic wastes and agroresidues) and the heating mechanism on the product distribution within the oil fraction has been investigated by means of GC-MS technique. Two different approaches have been performed: direct GC-MS analysis and methanolysed-oils GC-MS analysis, the later determining the non-volatile compounds. In general, quite different distributions are attained when microwave pyrolysis is conducted, providing lighter compounds. In some cases, such as the plastic-derived oil, microwave pyrolysis lead to a potential source of chemicals such as benzene, toluene and xylenes.
The C19 steroid 1,4-androstadiene-3,17-dione (androstadienedione, ADD) is an added value product used as a synthon in the pharmaceutical industry for the commercial production of corticosteroids, mineralocorticoids, oral contraceptives, and other pharmaceutical steroids. Phytosterol biotransformation catalyzed by microbial whole cells is actually a very well-established research area in white biotechnology. The protocol below provides detailed information on ADD production by the mutant CECT 8331 of Mycobacterium smegmatis mc155 using phytosterols as raw material in a lab scale. This protocol describes the bioconversion of phytosterols into ADD in a single fermentation step.
A simple and rapid procedure to detect autolysin‐defective mutants of Streptococcus pneumoniae has been developed. The autolysin gene (lyt) can be introduced into the appropriate receptor strain by genetic transformation and the transformants are readily detected on the surface of semisynthetic medium (C medium) plates by using a membrane filter. A pneumococcal autolysin mutation (lyt‐4) behaved as a low‐efficiency marker in genetic transformation.
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