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Two strains of hydrocarbon-utilizing bacteria were isolated from soil samples of the Kuwait Burqan oil field at a temperature of 37°C. The bacteria were motile endospore-forming rods with slight differences in their metabolic patterns and 16S rRNA sequence. Vegetative cells of the strains designated as AHI and AHII had an ultrastructure typical of Gram-positive bacteria and showed Gram-positive staining. The bacteria did not show pigmentation. Best growth was observed at 37°C at neutral pH and NaCl concentrations in the range of 5–10 g per 1. Both strains were obligatory aerobic and developed on synthetic media with either Diesel fuel, n-decan or naphthalene as the sole carbon and energy source. No specific growth factors were required. On the basis of their morphological, physiological and biochemical features, as well as their 16S rRNA analysis and electron microscope study, both strains were assigned to the species of Bacillus subtilis.

The radCgene, whose product plays a role in the prokaryotic repair of DNA damage after UV and X-ray irradiation, was cloned and sequenced from the phototrophic bacterium Rhodobacter capsulatusB10. The gene codes for a protein of 214 amino acids with a molecular mass of 23,792 Da. The deduced amino acid sequence showed significant homology with the RadC proteins of Escherichia coli, Bacillus subtilisand Haemophilus influenzae. Northern blot analysis indicated that under both chemotrophic and phototrophic growth conditions the radCgene was relatively highly expressed and was induced about five-fold after UV-irradiation. Primer extension analysis revealed that transcription was initiated from the same position before and after UV treatment. Mutants (radCnegative) have a low survival rate and a slower growth rate than the wild type.

The small bacteriochlorophyll-binding polypeptide(β) of the light-harvesting complex B800-850 from the phototrophic bacterium Rhodopseudomonas capsulatawas purified from the complex and the membrane, respectively. The complete amino-acid sequence has been determined. The Mrof the polypeptide is 4597. The protein consists of 49 amino acids, 64% of which are hydrophobic. Homology with other bacteriochlorophyll-binding polypeptides is discussed.

Chromatophores (intracytoplasmic inside‐out membrane vesicles) from the mutant strain Ala+ of Rhodopseudomonascapsulatawere treated with proteinase K in order to determine the orientation of the pigment‐binding polypeptides of the photochemical reaction center and of the light‐harvesting complex B870. Nine amino acid residues of the B870α polypeptide were cleaved up to position Leu9‐Val10of the N‐terminus and 22 residues up to position Val22‐Tyr23of the β‐chain N‐terminus. From the reaction center L‐chain the N‐terminus up to position 27 (Val) was split off. The C‐termini of the B870α and β polypeptides including the hydrophobic α‐helical transmembrane portion remained intact. It is concluded that the N‐terminal region of the pigment‐binding polypeptides α and β of the B870 light‐harvesting complex and of the L‐chain of the reaction center point to the cytoplasm while the C‐termini of the B870α,β polypeptides are exposed or pointing toward the periplasmic membrane surface.

[14C]penicillin binding experiments and membrane analysis were carried out with cell envelope preparations from Escherichia coli and Proteus mirabilis. After incubation with [14C] penicillin G labeled free lipoprotein could be identified. The analysis of the isolated lipoprotein by SDS polyacrylamide gel electrophoresis indicates that there is only one protein with an apparent molecular weight of 7000. The amino acid composition of isolated labeled free lipoprotein from E. coli was identical to the lipoprotein already found in E. coli. It is a point of interest that the amino acid composition of the isolated labeled free lipoprotein from P. mirabilis D52 differs from that found in other mutants of this strain. The free form of lipoprotein from P. mirabilis D52 is composed of 61 amino acids and has glycine, phenylalanine and proline as specific components.

In the present work we report the high-level expression of foreign genes encoding the light-harvesting (LHII) membranespanning polypeptides in photosynthetic bacteria. To do this we first constructed three deletion strains of Rhodovulum (Rhv) sulfidophilumin which all or part of the puc operon, encoding the peripheral light-harvesting proteins, is missing. To investigate the heterologous expression of the light-harvesting polypeptides from Rb. capsulatusin Rhv. sulfidophilumand vice versawe have reintroduced functional foreign LH genes into these and equivalent strains of Rhodobacter (Rb.) capsulatus. In some cases very high levels of expression were obtained (85% of those observed in the wild type), while in other cases much lower expression was observed; possible reasons for these differences are discussed. The heterologously expressed proteins were shown to contain normal pigmentbinding sites and to be normally and functionally integrated within the host photosynthetic apparatus. The results indicate that heterologous proteins are able to assemble properly and enter into the same protein-protein interactions as their analogs originally present in the host strain.