N-terminal amino acid sequences of the subunits of the Na+-translocating F1F0 ATPase from Propionigenium modestum

AbstractWe report here the N-terminal protein sequences of the subunits of the ATPase from Propionigenium modestum. Subunits c, b, δ, α and β start with an N-terminal methionine residue, the γ and ε subunits have an alanine N-terminus, from which N-formylmethionine was hydrolyzed by posttranslational modification, and subunit a contains a blocked N-terminus. Each of the N-terminal sequences exactly matches a portion of the DNA sequence in the gene encoding the respective subunit protein on the unc operon. Thus, the exact translational start for each subunit protein can be identified and the primary structures of the protein transcripts can be clearly defined. Based on these data the putative size of the open reading frame that was envisaged from the DNA sequence had to be revised for the α and δ subunits

Use of a Packed-Column Bioreactor for Isolation of Diverse Protease-Producing Bacteria from Antarctic Soil

Seventy-five aerobic heterotrophs have been isolated from a packed-column bioreactor inoculated with soil from Antarctica. The column was maintained at 10°C and continuously fed with a casein-containing medium to enrich protease producers. Twenty-eight isolates were selected for further characterization on the basis of morphology and production of clearing zones on skim milk plates. Phenotypic tests indicated that the strains were mainly psychrotrophs and presented a high morphological and metabolical diversity. The extracellular protease activities tested were optimal at neutral pH and between 30 and 45°C. 16S ribosomal DNA sequence analyses showed that the bioreactor was colonized by a wide variety of taxons, belonging to various bacterial divisions: α-, β-, and γ-Proteobacteria; the Flexibacter-Cytophaga-Bacteroides group; and high G+C gram-positive bacteria and low G+C gram-positive bacteria. Some strains represent candidates for new species of the genera Chryseobacterium and Massilia. This diversity demonstrates that the bioreactor is an efficient enrichment tool compared to traditional isolation strategies