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Biomedical subjects

W M Waites

Publications and source records attributed to W M Waites.

At least 37 records · Page 2Linked to original sources
PubMed1994

Small, acid-soluble proteins bound to DNA protect Bacillus subtilis spores from being killed by freeze-drying.

Wild-type spores of Bacillus subtilis were resistant to eight cycles of freeze-drying, whereas about 90% of spores lacking the two major DNA-binding proteins (small, acid-soluble proteins alpha and beta) were killed by three to four cycles of freeze-dryings, with significant mutagenesis and DNA damage accompanying the killing. This role for alpha/beta-type small, acid-soluble proteins in spore resistance to freeze-drying may be important in spore survival in the environment.

Bacillus subtilis↗
PubMed1993

The application of laser diffractometry to study the water content of spores of Bacillus sphaericus with different heat resistances.

The distribution of water in the protoplast and integument of three populations of Bacillus sphaericus spores was determined by laser diffractometry together with the sizes of their integuments and protoplasts. The spores were produced at 15, 20 and 30 degrees C. Spores grown at 15 degrees C had protoplast and integument water contents similar to those produced at 20 degrees C, while those grown at 30 degrees C had significantly lower water contents than the other two populations. The inner (or protoplast) radii of the spores produced at 15, 20 and 30 degrees C were 0.41 +/- 0.02 microns, 0.42 +/- 0.01 microns and 0.38 +/- 0.02 microns whilst the outer (or whole spore) radii were 0.56 +/- 0.01 microns, 0.58 +/- 0.01 microns and 0.52 +/- 0.02 microns respectively. The ratios of integument to protoplast radius were 0.40 +/- 0.02, 0.43 +/- 0.07 and 0.41 +/- 0.03 respectively.

Bacillus↗
PubMed1989

Dynamic light-scattering studies on the effect of heat and disinfectants on spores of Bacillus cereus.

The relative stability of spores of Bacillus cereus grown at three different temperatures was examined by using quasi-elastic light scattering (q.l.s.) in conjunction with turbidity and scanning electron microscopy (s.e.m.). Cultures grown at 20, 30 and 40 degrees C (BC20, BC30 and BC40 respectively) were compared in terms of (i) their effective hydrodynamic radius, rH, as determined from q.l.s. and (ii) their gross morphology, as determined from s.e.m. The effects of autoclaving at 121.1 degrees C on both these properties was also examined. We observed (1) that cultures BC20 and BC30 appeared to have similar values for rH, whereas that of BC40 appeared some 50% higher, and (2) BC40 had a correspondingly much lower heat resistance (its structural integrity was lost after about 20 min autoclaving, whereas that of BC20 and BC30 was retained even after 80 min autoclaving). These data were in good agreement with independent measurements of heat-resistance coefficients. Changes in the hydrodynamic radius, polydispersity (both using q.l.s.) and turbidity were monitored with time on addition of the disinfectants sodium hypochlorite and peracetic acid; again BC40 appeared to have a lower resistance.

Bacillus cereus↗
PubMed1989

Purification and amino acid sequence of two small, acid-soluble proteins from Clostridium bifermentans spores.

Clostridium bifermentans spores contain two major small, acid-soluble, proteins (SASP) termed SASP-alpha and beta. The amino acid sequences of SASP-alpha and beta are almost identical, and are very similar to those of alpha/beta-type SASP from spores of C. perfringens and various Bacillus species. However, the C. bifermentans proteins contain an extra five amino acids in the middle of their sequence. Surprisingly, no gamma-type SASP were found in C. bifermentans or C. perfringens spores, although these are the most prominent SASP in spores of Bacillus species.

Amino Acid Sequence↗
PubMed1988

Plasmid profiles as indicators of the source of contamination of Staphylococcus aureus endemic within poultry processing plants.

A total of 530 strains of Staphylococcus aureus were isolated from the defeathering machinery of a chicken processing plant and from neck skin samples of carcasses at different stages of processing in two visits 4 weeks apart. Eleven different plasmid profiles were detected in the isolates, eight being common to both visits. The plasmid profiles of the strains forming the majority of the population on the freshly slaughtered birds were rarely present in the strains isolated from the pluckers (except at the entry to the first plucker) and were present in only a small proportion of the strains isolated from carcasses after plucking. However, the profiles from the strains isolated from the pluckers on both visits were different from those forming the majority of the population on the incoming birds but formed the major part of the carcass flora after plucking, suggesting that such strains were endemic. These strains were found as a small proportion of the isolates made from the incoming birds, suggesting that this was the route by which the endemic strains were introduced into the plant. Such endemic strains exhibited a clumping growth, even in liquid shake culture, which may have made it easier for them to become established on the pluckers and to resist cleaning and disinfection. This clumping phenotype was correlated with the presence of a 7.5-megadalton plasmid.

Animals↗
PubMed1987

Comparison of populations of human faecal bacteria before and after in vitro incubation with plant cell wall substrates.

Human faecal slurries were incubated anaerobically with larchwood xylan, oat spelt xylan, wheat bran, apple cell walls or sugar beet pulp as sole carbon sources. The populations which developed during incubation were different from the inoculum, the most marked changes being an increase in the number of Bacteroides species and a decrease in the number of Fusobacterium species for all carbon sources tested. With a water-soluble preparation of larchwood xylan the population was dominated by species able to ferment this substrate, in contrast to the population which developed with the insoluble substrates. The ability to use one plant cell wall substrate appeared to be related to the ability to use others. Strains capable of using plant cell wall substrates included Bacteroides spp., Clostridium clostridiiforme, Bifidobacterium longum, Fusobacterium spp. and Escherichia coli. When incubation with two contrasting substrates (bran and larchwood xylan) was replicated, the populations which developed were reproducibly different from the inoculum and from each other.

Bacteroides↗
PubMed1987

Use of plasmid profiles to detect changes in strains of Staphylococcus aureus during poultry processing.

The plasmid profiles of Staphylococcus aureus strains isolated at different stages in three poultry processing plants have been examined. Changes in profiles were seen in two plants after the plucking stage and the appearance of these new profiles correlated with the presence of an endemic strain, as suggested previously by increases in bacterial counts and changes in biotypes at the same stage. A third plant in which such changes did not occur showed no change in profiles. Plasmid profiles are therefore a rapid and sensitive method for distinguishing endemic strains within a plant from the flora of the incoming birds. Certain profiles also appeared to correspond with particular biotypes and certain phage types.

Ampicillin Resistance↗
PubMed1979

The effect of transition metal ions on the resistance of bacterial spores to hydrogen peroxide and to heat.

The presence of 10 microM-Cu2+ increased the lethal effect of hydrogen peroxide on spores of Clostridium bifermentans but not on those of Clostridium sporogenes PA 3679, Clostridium perfringens, Bacillus cereus or Bacillus subtilis var. niger. Cu2+ at 100 muM also increased the lethal effect of heat on spores of C. bifermentans but not on those of B. sutilis var. niger. The rate and extent of Cu2+ uptake by spores of C. bifermentans and B. subtilis var. niger were similar, but examination of unstained sections of spores by electron microscopy suggested that Cu2+ is bound by the protoplasts of spores of C. bifermentans but not of B. subtilis var. niger.

Bacillus↗
PubMed1977

Biochemical properties of Clostridium bifermentans spores.

As previously found for spores of Bacillus species, dormant spores of Clostridium bifermentans contained essentially no adenosine triphosphate, a high level of adenosine monophosphate, a high level of 3-phosphoglyceric acid, and much transfer ribonucleic acid lacking a 3'-terminal adenosine monophosphate residue. As in spores of Bacillus species, germination of C. bifermentans spores was accompanied by utilization of the 3-phosphoglyceric acid, a large increase in the adenosine triphosphate level, and the disappearance of defective transfer ribonucleic acid. In contrast to spores of Bacillus species, dormant spores of C. bifermentans contained little free amino acid.

Adenine Nucleotides↗