Cellular polyamines of various aerobic Gram-positive cocci and some radio-resistant eubacteria were analyzed. Staphylococcus and Micrococcus species except for some spermidine-containing or cadaverine-containing strains were lacking in polyamines. Planococcus species ubiquitously contained putrescine, spermidine and agmatine. Marinococcus were divided into two groups, one of which contains no polyamine and another putrescine, spermidine and agmatine. Polyamines were not detected in Pediococcus, Tetragenococcus, Aerococcus, Alloiococcus, Helcococcus and Kineococcus species. Spermidine was found in Stomatococcus mucilaginosus and Salinicoccus hispanicus while no polyamine was detected in Salinicoccus roseus. Sporosarcina halophila and Sporosarcina ureae ubiquitously contained spermidine, however, agmatine was found in the former and spermine in the latter. Polyamine profiles were heterogeneous within aerobic Gram-positive cocci, though each profile was specific for the genera. Different polyamine patterns found in the genera Marinococcus, Salinicoccus and Sporosarcina suggest the heterogeneity of these genera. Radio-resistant Rubrobacter radiotolerans was devoid of polyamines, whereas spermidine was detected in radio-resistant Deinobacter grandis as well as radio-tolerant Deinococcus species.
To elucidate the detailed role of the RGD (Arg-Gly-Asp) sequence of the primer protein (PP) on the protein primed DNA replication of phage M2, we introduced the site-specific mutations in the nucleotide sequence for the RGD sequence of PP. Using an in vitro DNA replication system which was composed of three indispensable components, PP, Pol (phage M2 coded DNA polymerase) and double-stranded template DNA of phage M2 with a covalently bound terminal protein (TP) at both 5′ termini (TP-DNA), the priming activity of modified PPs was tested. The modified PPs decreased in priming activity by various levels, indicating an essential role of the RGD sequence to initiate DNA replication. Then, the modified PPs were tested for their binding ability to the other components, Pol and TP. Though all the modified PPs formed heterodimers with Pol, a significant reduction of the binding ability to TP was evident. The degrees of the reduction corresponded to the decrease of the ability of each modified PP to prime DNA replication. The results strongly suggest that the RGD motif of phage M2 primer protein is a key sequence for binding TP to initiate the protein primed DNA replication.
A total of 140 strains of Mycobacterium species were studied for their ability to hydrolyze 54 different fluorogenic 4-methylumbelliferyl (4-MU)- and 2-naphthylamide (2-NA)-linked fluorogenic substrates within 6 and 24h of incubation. Enzymatic profiles were heterogeneous within the genus, and some of the tests can improve the differentiation of Mycobacterium species. However, enzymatic profiles are not sufficient for unambiguous identification and should be used in combination with other biochemical tests.
Three unfaunated cattle, fitted with a rumen fistula at the age of 9 months, were fed with hay wafer and pelleted concentrate. After two unfaunated cows were inoculated with a mixed population of protozoal species, changes of the bacterial populations as well as volatile fatty acids (VFA) and NH3 production in the rumen were followed for one month. The protozoal inoculum was prepared by using the rumen fluid obtained from a fistulated cattle given hay and concentrate ration. The third cow was kept protozoa-free as a control animal. A mixed population of protozoa established in the rumen of two cows within one month after inoculation. The number of total culturable anaerobic bacteria, amylolytic bacteria and cellulolytic bacteria decreased after the inoculation of protozoa. In contrast, the numbers of methanogenic bacteria, sulfate-reducing bacteria and anaerobic fungi increased after the inoculation of protozoa. The number of lactate utilizers decreased within 9 days after the inoculation of protozoa, and thereafter increased to the original level. Neither the number of xylanolytic bacteria nor pectinolytic bacteria changed after the inoculation of protozoa. The proportion of Ruminobacter amylophilus of total culturable bacterial population was reduced most significantly by the presence of protozoa, while that of Butyrivibrio spp., Selenomonas spp. and Clostridium spp. was increased. The NH3 and VFA production increased along with the proportion of butyrate after the inoculation of protozoa. The presence of protozoa affected markedly not only the number and constitution of bacterial populations, but also the NH3 and VFA production in the rumen.
Microorganisms, especially sulphate-reducing bacteria (SRB), have long been implicated in metal corrosion in the petroleum industry. SRB can appear in planktonic or adherent forms, interacting with surfaces to produce thick, consortial biofilms. We carried out an ultrastructural investigation of biofilms and planktonic bacteria obtained from samplers on offshore platforms operated in southeast Brazil. A great variety of Gram-negative bacteria were observed. The surface coat and extracellular matrix of these cells stained strongly with ruthenium red, indicating their anionic character. Sessile bacteria were found to be enmeshed in an extensive extracellular matrix. The inner ultrastructure of sessile bacteria was characterized by vacuoles, inclusions and internal membranes. ESI analysis revealed the presence of corrosion products associated with the surface coat of these bacteria.
A new solid medium, termed solid 2:2 medium, was developed for application to the genetic manipulation of Thiobacillus ferrooxidans. The medium contains a mixture of both ferrous iron and thiosulphate as energy sources for the growth of T. ferrooxidans at pH 4.6-4.8. Kanamycin and streptomycin could be used in the medium to select recombinants. Thousands of interspersing colonies can develop on each plate without any iron-oxidizing zones. T. ferrooxidans colonies on solid 2:2 medium have distinct morphologies, and several types of colonies were described. A new type of colony morphology variant with high mutation and reversion rates was also observed.