Regulation of the tricarboxylic acid cycle in gram-positive, facultatively anaerobic bacilli.

The facultative anaerobes Bacillus polymyxa Hino G, B. polymyxa Hino J, and B.macerans were observed to have imcomplete tricarboxylic acid cycles. They were devoid of malate dehydrogenase and all had very low levels of alpha-ketoglutarate dehydrogenase. B. polymyxa Hino J was devoid of alpha-ketoglutarate dehydrogenase when grown aerobically and anerobically. Citrate synthase from B. polymyxa was inhibited by adenosine triphosphate but not reduced nicotinamide adenine dinucleotide and resembled enzymes from other gram-positive bacteria in this respect. Like the citrate synthases from gram-negative, facultative anaerobes and chemolithotrophs, the enzyme from B. polymyxa was inhibited by alpha-ketoglutarate. Inhibition by adenosine triphosphate was shown to be competitive with acetyl-coenzyme A and alpha-ketoglutarate inhibition was competitive with oxaloacetate.     

Heat shock proteins in bacilli.

Five strains of bacilli, including a nonsporulating strain, when heat shocked, accelerated the synthesis of a specific subset of proteins. The major heat shock protein in all bacilli had a molecular weight of 66,000. The response persisted for at least 40 min and could be eliminated upon a shift down to 37 degrees C.     

Regulation of spo0H, an early sporulation gene in bacilli.

The construction of lacZ fusions in frame with the spo0H gene of Bacillus licheniformis enabled us to study the expression of this gene under various growth conditions and in various genetic backgrounds. spo0H was expressed during vegetative growth, but the levels increased during early stationary phase and then decreased several hours later. Expression of the gene was not repressed by glucose, but was induced by decoyinine, an inhibitor of guanine nucleotide biosynthesis, which can induce sporulation. Of those tested, the only spo0 gene required for the expression of spo0H was spo0A, and this requirement was eliminated by the abrB mutation, a partial suppressor of spo0A function. spo0H-lacZ expression was much higher in a strain with a deletion in the spo0H gene.     

Mode of cell wall synthesis in gram-positive bacilli.

Ultrastructural experiments on plasmolyzed cells suggested that the information for the position and orderly synthesis of septa is not determined by the attachment of cell membrane to previously formed wall. These experiments, in conjunction with others on cells disrupted by the freeze-fracture technique, are most consistent with wall growth over the entire surface of the rods, with wall material gradually moving from a position next to the cell membrane to a position at the outer surface of the cell.     

Potential virulence factors of Proteus bacilli.

The object of this review is the genus Proteus, which contains bacteria considered now to belong to the opportunistic pathogens. Widely distributed in nature (in soil, water, and sewage), Proteus species play a significant ecological role. When present in the niches of higher macroorganisms, these species are able to evoke pathological events in different regions of the human body. The invaders (Proteus mirabilis, P. vulgaris, and P. penneri) have numerous factors including fimbriae, flagella, outer membrane proteins, lipopolysaccharide, capsule antigen, urease, immunoglobulin A proteases, hemolysins, amino acid deaminases, and, finally, the most characteristic attribute of Proteus, swarming growth, enabling them to colonize and survive in higher organisms. All these features and factors are described and commented on in detail. The questions important for future investigation of these facultatively pathogenic microorganisms are also discussed.     

Conjugation in bacilli

The review considers experimental data on the conjugal transfer of plasmids in the Bacillus cereus and Bacillus subtilis groups (the transfer of large self-transmissible plasmids and the mobilization of small plasmids). Conjugation in bacilli is compared with conjugation in E. coli dependent on the F factor. Conjugation of bacilli in their natural habitats is also discussed.