Microbios最新文献

Bacillus species 11089 and alkalophilic Bacillus species 11203 were both capable of growth in continuous culture on macromolecular substrates, starch, soybean flour, casein, pectin, polypectate, polygalacturonate and carboxymethylcellulose (CMC) when these were used as the carbon-energy source in a mineral salts basal medium. High maximum specific growth rate (micronmax) and biomass values occurred when cells were grown on starch, soybean flour and casein, and low values on pectin, polypectate, polygalacturonic acid and CMC. Hydrolytic enzymes (protease, amylase, polygalacturonate lyase and alkaline phosphatase) were subject to regulation (induction and/or repression) depending on the nature of the growth substrate utilized. In general, high levels of enzymes were produced on soybean flour, casein and starch but low levels on CMC, pectin, polypectate and polygalacturonate.

In order to determine the reason for the slow growth of Mycobacterium leprae either in a host or in vitro, the growth characteristics of Mycobacterium tuberculosis were studied. The ATP content of in vitro-grown M. tuberculosis was about 520 pg/10(6) viable organisms. The ATP levels from in vivo-derived organisms obtained from liver and spleen of mice was about 130 pg (in cases of chronic infection) and about 270 pg (in cases of acute infection). When the in vivo-derived organisms were inoculated into culture medium, the growth rates for both types of organisms, acute as well as chronic infection, were the same and the maximum growth was reached during the fifth subculture. Although the maximum ATP content for both types of organism was the same, it was attained during the 4th subculture for organisms obtained during acute infection and during the 6th subculture for those obtained during chronic infection. The comparison between the ATP content of M. leprae and of M. tuberculosis indicates the reason for the slow growth of M. leprae.

The total enumeration of enterococci from the rumen content of deer, their species determination, resistance to antibiotics with the predominant importance of vancomycin resistance, and their metabolic properties, were examined. Enterococci (2.0 x 10(2) CFU per ml) encountered from the rumen of deer were phenotypically allotted to the species Enterococcus casseliflavus (26.6%), E. gallinarum (26.6%) and E. faecium (6.6%). The other isolates were not phenotypically specified. Although the resistance to the other antibiotics was recorded, the emergence of vancomycin-resistant enterococci in a high percentage (60%) was revealed. The majority of strains (80%) were multiresistant with the predominant resistance shown by vancomycin. These strains produced lactic acid in the range from 0.258 mol l-1 up to 0.489 mol l-1, and most of the isolates (53.3%) manifested medium urease activity. Vancomycin-resistant enterococci were selected for other studies such as plasmid determination and bacteriocin production, and to assess their value as indicators of faecal contamination.

Products of 1-methyladenosine, 2'-O-methyladenosine, 2'-O-methylcytidine, and 5-methylcytidine catabolism by resting cells of Staphylococcus aureus and Staphylococcus intermedius were chromatographically separated. The methyl group in 1-methyladenosine protected the adenosine derivative from deamination by S. intermedius but it did not protect N-glycosidic bond from cleavage by S. intermedius and S. aureus. The methyl group in 2'-O-methyladenosine and 2'-O-methylcytidine protected the N-glycosidic bond from cleavage by S. aureus and S. intermedius but it did not protect the adenosine and cytidine derivatives from deamination by S. intermedius. 5-Methylcytidine was converted by the common route in which 5-methylcytidine was first deaminated to ribothymidine which was cleaved to yield thymine. S. intermedius deaminated the purine and pyrimidine ribonucleosides adenosine, 2'-O-methyladenosine, cytidine, and 5-methylcytidine. Pyrimidine ribonucleosides (cytidine, 5-methyl-cytidine) were deaminated only slowly and purine ribonucleosides (adenosine, 2'-O-methyladenosine) not at all by S. aureus.

In order to evaluate hepatitis C virus-RNA (HCV-RNA), immunoglobulin M (IgM) anti-HCV and risk factors in haemodialysis patients, 180 subjects (45 HCV negative and 135 HCV positive) were studied. Sex, age, duration of dialysis, number of transfusions and ALT were also considered. HCV-RNA was determined by the Amplicor HCV test, and IgM anti-HCV by the Abbott HCV IgM EIA. These markers were present in 40% and 30.4% of anti-HCV positive subjects. The agreement between the two tests employed was 77%. The results showed a close association between HCV-RNA and IgM anti-HCV with abnormal ALT levels and between HCV-RNA and the number of transfusions. Both of these markers were different when correlated with age and time on dialysis, respectively. Therefore, IgM anti-HCV may also serve as a serological marker of HCV infection and a complementary marker of virus replication.

The endotoxins from two recently-classified subspecies of Fusobacterium, namely F. necrophorum subsp. necrophorum and F. necrophorum subsp. funduliforme, were compared. Chemical analysis of the isolated endotoxins revealed that they were clearly different. Distinct levels of polysaccharides were demonstrated. The endotoxins isolated were devoid of heptose and 3-deoxy-D-manno-octulosonate (KDO). The endotoxins of F. n. necrophorum and F. n. funduliforme contained lipid A in a ratio of 4:1 which may account for the variations in their virulence.

The effects of Fusobacterium necrophorum subsp. necrophorum on cellular actin were investigated using tissue-cultured bovine portal cells. Fluorescence studies revealed the appearance of intense fluorescent spots on the cellular actin and the spots increased in a time dependent manner. Sodium dodecyl sulphate polyacrylamide gel electrophoresis profiles manifested partial or complete degradation of actin preparation after treatment with the bacterial cells. These findings suggest that the bacterial cell wall may contribute to the degradation of the cellular actin during the initial stage of the infection caused by F. necrophorum subsp. necrophorum.

The antibacterial activities of twelve species of anthozoans (4 gorgonians, 5 soft corals and 3 antipatharians) collected off the east coast of India were assayed against four dominant marine fouling bacterial strains isolated from the biofilm of fouled aluminium panels. Of the 48 combinations (12 corals x 4 bacteria) eighteen interactions showed antibacterial activity (37.5%). Such activity was most apparent in gorgonians, which inhibited bacterial growth in ten out of sixteen interactions (62.5%) compared with that of five out of twenty interactions (25%) among soft corals and three out of twelve interactions (25%) among antipatharians. The activity scores varied with different extracts and test organisms used, and was highest in antipatharians. Among the four bacterial strains Vibrio sp. was the least sensitive (2/12) when compared with Flavobacterium sp. (6/12). This is the first report of antibacterial activities of antipatharian colonies against marine microfoulers. The results imply that anthozoan corals harbour potent agents which could be exploited for the development of antifouling technology.

The purpose of this study was to ascertain whether viable bacteria could be transferred from gloves to laboratory cards in dental records and, if so, to determine whether bacteria could survive on the paper. The thumbs and forefingers of two types of glove (Biogel D and Microtouch) were inoculated with Streptococcus sanguis and left for various periods of time. A sterile dental laboratory card was then held with the gloves and the number of bacteria surviving on the card determined after various periods of incubation of the card at room temperature. Bacteria were transferred to the laboratory cards and remained viable for up to 72 h. More viable bacteria were transferred from the Microtouch gloves than from the Biogel D gloves, and this was attributable, in part, to the latter gloves exerting a bactericidal effect. The results demonstrated that bacteria can be transferred from gloves to laboratory cards and that these organisms can remain viable for long periods of time. Dental records may, therefore, represent a possible route of cross-infection.

Two Escherichia coli strains in which alpha-amylase production differed were used to study in depth some characteristics related to beta-glucuronidase induction by starch. The beta-glucuronidase background activity in Luria broth medium was comparable for the two isolates, but only amylase positive S1 was able to grow on starch molecules supplied as the sole carbon source. In this case growth resulted at higher beta-glucuronidase levels (p < 0.01) with respect to basal activity and the induced expression was maximal (6.1-fold) when cultures reached the stationary phase. Growth in the presence of a protein synthesis inhibitor (chloramphenicol) was associated with a marked reduction of activity. The beta-glucuronidase activity of amylase negative M94 remained unchanged during starvation on starch medium, but an induced response was observed with methylumbelliferyl-glucuronide. These results further support the hypothesis that starch metabolism is involved in the complex beta-glucuronidase regulation of E. coli strains. This is relevant not only for basic research but also to investigating gut microbial enzymology.