bluuebunny/crossref_metadata_2025 huggingface dataset:
Competition for hydrogen between sulphate‐reducing bacteria and methanogenic bacteria from the human large intestine
Authors: Gibson G.R. , Cummings J.H. , Macfarlane G.T.
Published: March 2008

Sulphate‐reducing activity in human faecal slurries was followed by measuring sulphide production. Sulphate‐reducing bacteria (SRB) were found to outcompete methanogenic bacteria (MB) for the mutual substrate hydrogen in faecal slurries from methane‐ and non‐methane‐producing individuals mixed together. When molybdate (20mmol/l) was added to these slurries, sulphate reduction was inhibited and methanogenesis became the major route of electron disposal. Sulphide production was stimulated by the addition of 20 mmol/1 sulphate in non‐methanogenic but not in methanogenic slurries. In methanogenic slurries that contained the methanogen inhibitor 2‐bromoethanesulphonic acid (BES), hydrogen accumulated whilst sulphide levels were unaffected, confirming the absence of SRB in methanogenic faeces. The addition of nitrate (10 mmol/l) to faecal slurries completely inhibited methanogenesis but only slightly reduced sulphate reduction. The sulphated mucopolysaccharides, chondroitin sulphate and mucin, strongly stimulated sulphide production in non‐methanogenic faecal slurries only, suggesting that these substances may be a potential source of sulphate in the large gut.
Purification, characterization and antimicrobial spectrum of a bacteriocin produced by Pediococcus acidilactici
Authors: Bhunia A.K. , Johnson M. C. , Ray B.
Published: March 2008

An antimicrobial peptide designated pediocin AcH was isolated from Pediococcus acidilactici strain H. The pediocin AcH was purified by ion exchange chromatography. The molecular weight of pediocin AcH was determined by SDS‐PAGE to be about 2700 daltons. Pediocin AcH was sensitive to proteolytic enzymes, resistant to heat and organic solvents, and active over a wide range of pH. Pediocin AcH exhibited inhibition against several food spoilage bacteria and foodborne pathogens including Staphylococcus aureus, Clostridium perfringens and Listeria monocytogenes. It was bactericidal to sensitive cells and acted very rapidly. The bactericidal effect was not produced by either cell lysis or apparent loss of membrane permeability.
Prediction of the shelf‐life of pasteurized milk at different storage temperatures
Authors: Griffiths M.W. , Phillips J.D.
Published: March 2008

Initial psychrotroph counts determined by a Most Probable Number technique were correlated with shelf‐lives of pasteurized milk determined at a number of storage temperatures. The initial psychrotroph count was also correlated with a bacterial count carried out on milk agar containing crystal violet penicillin and nisin after previous incubation of the milk at 15°C for 25 h.

Pre‐incubation counts carried out at a variety of temperatures and on a variety of media were examined for their relation to shelf‐life. Shelf‐lives at four pre‐set temperatures (2, 6, 10 and 14°C) could best be predicted by pre‐incubation of pasteurized milk at 15°C before inoculation on milk agar.

An equation which allows prediction of shelf‐life of pasteurized milk at any storage temperature is described.
Quantitative and qualitative studies of the microflora of barley malt production
Authors: Petters H.I. , Flannigan B. , Austin B.
Published: March 2008

Populations of aerobic heterotrophic bacteria, mycelial fungi and yeasts occurring in malting barley were estimated by a plate technique and scanning electron microscopy. There was an increase in the total number of micro‐organisms during germination, although populations declined after kilning. Bacteria dominated on all samples, with progressively lower populations of yeasts and filamentous fungi. There was no obvious spatial distribution of micro‐organisms on the samples although there appeared to be high populations of bacteria and fungal hyphae on the inner surface of the kernels. The dominant groups of aerobic heterotrophic bacteria were presumptively identified as Alcaligenes sp., Arthrobacter globiformis, Clavibacter iranicum, Erwinia herbicola, Lactobacillus spp. and Pseudomonas fluorescens. The principal filamentous fungi were identified as Aiternaria alternata, Aspergillus glaucus (group), Cladosporium macrocarpum, Epicoccum purpurascens, Fusarium avenaceum, Geotrichum candidum and Penicillium spp. The yeasts isolated most frequently were Candida catenulata, C. vini, Debaryomyces hansenii, Hansenula polymorpha, Kloeckera apiculata, Rhodotorula mucilaginosa, Sporobolomyces roseus and Trichosporon beigelii.
Bacterial fermentation of soya bean for ‘daddawa’ production
Authors: Ogbadu Lucy , Okagbue R.N.
Published: March 2008

The fermentation of soya bean for ‘daddawa’ production in Nigeria is carried out by bacteria. Bacillus subtilis and Bacillus pumilus were consistently isolated in fermentations lasting 48 h.
Production of extracellular enzymes by Thermomonospora curvata during growth on protein‐extracted lucerne fibres
Authors: Bernier R. , Kopp M. , Trakas B. , Stutzenberger F.
Published: March 2008

After extraction of food protein from lucerne, the residual fibre was used as a carbon and energy source by the thermophilic actinomycete, Thermomonospora curvata. Induction of catabolic exoenzymes during growth for 7 d on the fibre at 53°C in a mineral salts minimal medium was compared with that on a variety of other inductive substrates. A fibre concentration of 1.5% (w/v) was optimal for total protein secretion. The fibre was a poor substrate for amylase production due to lack of inducer rather than to catabolite repression by soluble sugars released during degradation. β‐Glucosidase release during growth on the fibre was about 10 times that observed in cultures grown on cellobiose or cellulose, but production of other cellulolytic enzymes was about one‐half that produced on cellulose. Pectinolytic activity (measured as polygalacturonate lyase) was equal to that produced on pectin. Cells grown on the fibre released about eight times as much proteinase as those grown on cellulose, but proteolytic activity was transient and decreased rapidly during later growth. Xylanase appeared to be co‐ordinately induced with cellulolytic enzymes; comparable maximal activities, observed during growth on either the fibre or cellulose, were three times that produced on xylan or xylose.
The mechanisms of inhibition of Desulfovibrio and Desulfotomaculum species by selenate and molybdate
Authors: Newport P.J. , Nedwell D. B.
Published: March 2008

The effects of two specific inhibitors of sulphate‐reducing bacteria, selenate and molybdate, have been studied by measurement of sulphate uptake and by measurement of the effects of these compounds on growth of the bacteria on a variety of media. The results obtained with selenate are consistent with the view that it acts as a competitive inhibitor of sulphate transport. The results obtained with molybdate show that there is more than one site of action and suggest that the primary effect is also on sulphate transport.
The growth of potential food poisoning organisms on chicken and pork muscle surfaces
Authors: Mattila Tiina , Frost A.J.
Published: March 2008

Muscle surfaces of pork were inoculated with a mixture of Yersinia enterocolitica and Staphylococcus aureus, and chicken muscle with Campylobacter jejuni or a mixture of Salmonella typhimurium and Staph. aureus. The surface growth at 20°C was followed microscopically. Organisms grew as discrete colonies bound together by a glycocalyx which differed between bacterial species. On prolonged incubation colonies spread peripherally and tended to coalesce, while still retaining their colony structure. Staphlycoccus aureus colonies were very small and remained so. The glycocalyx was considered critical in maintaining the dense populations of bacteria on the meat surfaces.
Campylobacter and salmonella contamination of unpasteurized cows' milk on sale to the public
Authors: Humphrey T.J. , Hart R.J.C.
Published: March 2008

Campylobacters and salmonellas were isolated respectively from 6 and 0.2% of samples of unpasteurized cow's milk on sale to the public. There was a significant association between the presence of Escherichia coli and that of Campylobacter jejuni. The mean E. coli count was also higher in campylobacter‐positive samples. Enumeration of E. coli would seem to have value as an indicator of faecal contamination and thus potential hazard in raw milk.
The effect of potassium sorbate on the structural integrity of Alteromonas putrefaciens
Authors: Statham J.A. , McMeekin T.A.
Published: March 2008

Treatment of Alteromonas putrefaciens with potassium sorbate at pH 7.0 resulted in increased hydrophobicity of the cell wall and lysis on exposure to lysozyme. These effects could be overcome to some extent by the addition of magnesium ions to the incubation medium. Transmission and scanning electron microscopy provided evidence of outer membrane damage in sorbate‐treated cells. Dissociated sorbate ion was shown to have an inhibitory effect on A. putrefaciens.
Properties of two pectin lyases produced by Aureobasidium pullulans LV 10
Authors: Parini C. , Fortina Maria Grazia , Manachini P.L.
Published: March 2008

Two pectic lyases, L1 and L2, from culture liquids of Aureobasidium pullulans LV 10 were partially purified by ultrafiltration, CM‐Sepharose 6B, DEAE‐cellulose and/or Sephadex G 100 column chromatography, and characterized. L1 and L2 showed optimum activity at pH 5 and 7.5 respectively, and at 40°C. The molecular weights of the enzymes determined by gel filtration were estimated to be 89000 1000 and 55000 1000 for L1 and L2 respectively. Both lyases were activated by Ca2+ ions. L1 attacked highly esterified pectins, L2 attacked low methoxy‐pectins in preference to polygalacturonic acid.
Inhibition of adhesion of viridans streptococci to fibronectin‐coated hydroxyapatite beads by lipoteichoic acid
Authors: Hogg S.D. , Manning J.E.
Published: March 2008

Fibronectin‐coated hydroxyapatite (FnHA) beads were used in a model adhesion assay to isolate the lipoteichoic acid (LTA) mediated adhesion of oral streptococci. Representative strains of the commonly isolated viridans streptococci were incubated with FnHA beads in the presence and absence of exogenous LTA. The LTA inhibited the adhesion of all strains to a greater or lesser extent, but only a very few strains were inhibited by more than 90%. Strains of Streptococcus sanguis Type II and Streptococcus mitis which synthesize an amphiphile other than LTA were also inhibited. The findings provided circumstantial evidence for the involvement of LTA in the adhesion of this group of oral bacteria.
Contribution of the microflora to proteolysis in the human large intestine
Authors: Macfarlane G. T. , Allison C. , Gibson S. A. W. , Cummings J. H.
Published: March 2008

Protease activities in human ileal effluent were approximately 20‐fold greater than in normal faeces. Comparative studies with faeces from a person who did not have a pancreas suggested that a substantial proportion of the proteolytic activity in normal faeces was of bacterial origin. Thimerosal, iodoacetate, EDTA and cysteine significantly inhibited proteolysis in faeces, but not in small intestinal contents, showing that cysteine and metalloproteases were produced by bacteria in the large gut. These results, together with results from studies using p‐nitroanilide substrates, demonstrated that faecal proteolysis was both qualitatively and quantitatively different from that in the small intestine. Studies with pure cultures of proteolytic gut bacteria indicated that the cell‐bound proteases of Bacteroides fragilis‐type organisms were likely to contribute significantly towards proteolytic activity associated with the washed cell fraction and washed particulate fraction of faeces. Extracellular proteases were formed by Streptococcus faecalis ST6, Propionibacterium acnes P6, Clostridium perfringens C16, Cl. bifermentans C21 and Cl. sporogenes C25. Inhibition results suggested that these bacteria, and similar organisms, may be partly responsible for the extracellular proteolytic activity found in the cell‐free supernatant fraction of faeces.
The effect of growth‐promoting antibiotics on the faecal enterococci of healthy young chickens
Authors: Kaukas Anne , Hinton M. , Linton A. H.
Published: March 2008

Small groups of chickens were given feed containing either avoparcin, nitrovin, vir‐giniamycin or zinc bacitracin from the day of their purchase as day‐olds. Differences between the birds receiving growth promoters and the untreated controls were observed during the last third of the 23 d survey period. The enterococcal population of the ‘dosed’ birds contained a greater proportion of Enterococcus faecium than did that of the control birds while the converse was true for Ent. gallinarum. This apparent selection of Ent. faecium by the growth‐promoting antibiotics had an influence on the incidence of resistance to therapeutic antibiotics among the enterococcal population as a whole. This was because this species was generally more resistant than Ent. gallinarum to cephalothin, the MLS antibiotics (erythromycin, lincomycin and tylosin) and tetracycline.
Demonstration of capsule in a strain of Staphylococcus hyicus by an electron microscope
Authors: Yoshida K. , Ichiman Y. , Umeda A. , Takeuchi S.
Published: March 2008

A compact type variant designated as strain ST67V was isolated by a high‐temperature subculture method from strain ST67P of Staphylococcus hyicus, which was a diffuse type in serum‐soft agar. The parent strain was relatively virulent in mice and resisted ingestion by mouse peritoneal cells. The variant strain, however, was avirulent in mice and no antiphagocytic activity was observed in the peritoneal cavity. In ultra‐thin sections of the organisms treated with anti‐ST67P rabbit anti‐serum conjugated with ferritin, the outermost layer of the cell wall of the parent strain was covered with a well‐defined capsule while no capsule was shown in the variant strain.
Azelaic acid: its uptake and mode of action in Staphylococcus epidermidis NCTC 11047
Authors: Bojar R.A. , Holland K.T. , Leeming J.P. , Cunliffe W.J.
Published: March 2008

In vitro tests using Staphylococcus epidermidis as a model have shown that at pH 5.6 the micro‐organisms are sensitive to azelaic acid, whilst at pH 6.0 and 7.0 the cells become progressively resistant, especially with nutrients present. In a simple defined medium the growth rate was reduced at 1 mmol/l and growth inhibited at 25 mmol/l. The uptake of azelaic acid was pH dependant, higher transport at lower pH values, and required viable cells. Azelaic acid, 457 μmol/l gave 50% inhibition of protein synthesis and this mechanism could account for the bactericidal and bacteristatic effects. DNA and RNA were affected slightly by 100 mmol/l azelaic acid, and respiration by 500 mmol/l
Behaviour of Staphylococcus aureus strains, producers of enterotoxins C1 or C2, during the manufacture and storage of Burgos cheese
Authors: Otero A. , García M.C. , García M.L. , Prieto M. , Moreno B.
Published: March 2008

Burgos cheese was manufactured from pasteurized ewes milk inoculated with Staphylococcus aureus strains FRI 137 and FRI 361, at levels of ca 103 and 105 cfu/ml and stored at 4°, 10° and 15°C and at room temperature (10°‐15°C). Populations of Staph. aureus and mesophilic aerobes, pH, and production of thermonuclease and enterotoxins C1 and C2 were investigated. Aerobic counts increased during cheese‐making and storage. With both test strains, important growth was observed only during the storage period, the larger levels corresponding to the higher temperatures. Although Staph. aureus strains attained populations of over 108 cfu/g, no enterotoxin was detected. Strain FRI 361 reached 107 cfu/g without production of a detectable amount of thermonuclease. With strain FRI 137, the minimal population associated with enzyme activity was influenced by the inoculum size. Staphylococcus aureus counts are better indicators of staphylococcal growth in Burgos cheese than the thermonuclease test.
Serovars and biovars of Campylobacter strains isolated from humans and slaughterhouse animals in northern Germany
Authors: WOKATSCH R. , BOCKEMÜHL J.
Published: March 2008

A total of 318 Campylobacter strains from sporadic cases of human enteritis (109 strains) and healthy slaughterhouse animals in northern Germany (209 strains) were bio‐ and serotyped according to the Lior typing schemes. Three hundred strains were typable (94.3%) and 38 serovars were identified. Among human strains 28 serovars were identified with 30% of them belonging to serovar 4. Strains from pigs were associated with 25 serovars, the most frequent being serovar 20 (21.2%). Fourteen serovars were identified in the ovine strains of which 31.1% were of serovar 49, and 22.2% of serovar 4. All of the strains from one chicken farm were of serovar 11, whereas in those from another serovar 1 was predominant (85.4%). Twenty‐five of the 38 serovars identified were associated with at least two different biovars. Campylobacter jejuni biovar I was predominant in humans, sheep and chickens and Campylobacter coli biovar I in pigs. The results suggest that the combined use of bio‐ and serotyping according to the Lior typing schemes would be of use in studies on the epidemiology of human campylobacteriosis in Germany.
Limitations of the enzyme‐linked immunosorbent assay for routine determination of legume inoculant quality
Authors: Lochner H.H. , Strijdom B.W. , Kishinevsky B. , Steyn P.L.
Published: March 2008

Peat inoculants containing strains of either Rhizobium or Bradyrhizobium spp. were used to determine correlations between cell numbers and A405 values obtained with double antibody sandwich enzyme‐linked immunosorbent assay (DAS ELISA) and indirect ELISA. ELISA values of inoculants containing strains of Rhizobium were weak and non‐specific; with Bradyrhizobium spp. strains, readings were higher and cross‐reactions negligible when heated inoculant suspensions were allowed to stand for 3 h before ELISA determinations were made. With soybean inoculant, correlation coefficients of r = 0.93 and 0.83 were obtained with DAS and indirect ELISA, respectively. A linear curve relating log cell numbers to A405 values was used to determine the reliability of DAS ELISA values obtained over 2 years with tests on commercially produced soybean inoculants. In the range 5 times 108‐ca 3 times 109 cells/g inoculant, DAS ELISA estimates closely followed plate counts but no significant correlation was found when inoculants contained >ca 3 times 109 cells/g. With a minimum requirement of 1 times 109 cells/g inoculant, discrepancies between DAS ELISA estimates and plate counts obtained with inoculants produced with gamma‐irradiated peat would have resulted in the erroneous rejection or acceptance of 14.5% of all inoculants tested, based on DAS ELISA estimates. With inoculants produced with steam‐sterilized peat, which was unfavourable for survival of strain WB1, 70.0% of the inoculants rejected because of low plate counts would have been acceptable on the basis of DAS ELISA estimates.
Effect of extracts obtained from olive oil mill waste waters on Bacillus megaterium ATCC 33085
Authors: Rodriguez Ma. M. , Perez J. , Ramos‐Cormenzana A. , Martinez J.
Published: March 2008

n‐Propanol was the most effective solvent for extracting antibacterial substances from olive oil mill waste water (‘alpechines’). Several phenolics were detected in propanol extracts that had bactericidal effects on Bacillus megaterium ATCC 33085, inhibiting sporulation and germination at 5.6 mmol/l total phenolics (expressed as syringic acid). The biological effect was increased in the presence of high glucose and NaCl concentrations and after β‐glucosidase hydrolysis.
Response of Campylobacter jejuni to combinations of ferrous sulphate and cadmium chloride
Authors: Stern N.J. , Kazmi S.U. , Roberson B.S. , Ono K. , Juven B.J.
Published: March 2008

On Mueller Hinton (MH) agar, Campylobacter jejuni showed 20.0 and 30.9mm zones of inhibition surrounding discs impregnated with 2.5 and 20 μg CdCl2 respectively. The minimal inhibitory concentration (MIC) ranged from 0.64 to 3.2 μg CdCl2/ml of MH agar for four C. jejuni strains. In the presence of 23 μg FeSO4/ml of MH the MIC increased to a range of 1.5–5.4 μg CdCl2/ml of MH. Moreover, the numbers of colonies present on MH supplemented with FeSO4 were greater than on MH without iron. The growth response of C. jejuni in the presence of 0.025% (w/v) FeSO4 in MH broth was increased about 10000 fold in three of four strains when compared with the growth in unsupplemented MH broth. Zones of inhibition surrounding 20 μg discs of CdCl2 were 50.6 and 24.4 mm on MH and Campy‐BAP media respectively, with cells grown on MH. These results suggest that the blood‐containing medium ‘neutralized’ the biocidal influence of the CdCl2. In comparison, C. jejuni inoculum from fluid thioglycollate (FT) medium showed smaller zones of inhibition. These decreased from 34.9 mm on MH agar to 19.6 mm on Campy‐BAP agar, suggesting that components in the FT growth medium ameliorated the toxic influence of CdCl2. Atomic absorption spectroscopy analysis indicated mean values (mg/100 g dry weight) of selected metals bound by C. jejuni as: Cu, 10.4; Mg, 146; Na, 2385; Fe, 45.1; Zn, 13.0; and K, 172.
Biodegradation of substituted benzenes
Authors: Goulding Claire , Gillen C.J. , Bolton E.
Published: March 2008

The ability of an association of micro‐organisms to degrade a range of substituted aromatic compounds was assessed. Compounds were provided as sources of carbon and energy, and degradation rates monitored. The effect of the presence of other aromatic compounds and of rapidly metabolizable substrates was also investigated. The significance of bioaugmentation of waste‐treatment processes with such an inoculum is discussed.
Growth of psychrotrophic bacteria in raw and UHT‐treated goats'milk
Authors: Cox J.M. , Rae I.C. Mac
Published: March 2008

The growth of six strains of Pseudomonas fluorescens, two of Ps. fragi, and one of Serratia liquefaciens was followed in raw and UHT‐treated goats'milk, held at 4°C. Generation times for Ps. fluorescens in UHT milk ranged from 5.19 to 5.81 h, increasing markedly in raw milk (8.34–21.49 h). Growth of Ps. fragi did not differ significantly between raw (4.56, 4.65 h) and UHT (5.04, 7.24 h) milk. Generation times for S. liquefaciens were 6.63 and 14.07 h, for UHT and raw milk respectively.
Vibrio parahaemolyticus and other halophilic vibrios associated with seafood in Hong Kong
Authors: Chan Kwong‐Yu , Woo M.L. , Lam L.Y. , French G.L.
Published: March 2008

The summer prevalence of Vibrio parahaemolyticus and other halophilic vibrios in seafood from Hong Kong markets was investigated. Halophilic vibrios were isolated from all seven types of seafood examined, and comprised 9.1%, 8% and 6.1% of contaminating aerobic heterotrophic bacteria from mussels, clams and oysters respectively. Sucrose‐positive vibrios were more common than sucrose‐negative varieties. Vibrio alginolyticus was the most frequently isolated species, followed by V. parahaemolyticus, V. harveyi, V.fluvialis, V. vulnificus, V. pelagius, V. campbellii, V. spendidus and V. marinus. Mussels contained the highest concentration of V. parahaemolyticus (4.6×103/g); oysters and clams contained 3.4×104/g and 6.5×103/g respectively. The ubiquity and relatively high concentrations of V. parahaemolyticus and other pathogenic vibrios in shellfish is a potential public health hazard in Hong Kong and other subtropical Asian countries.
Survival of soft rot coliforms, Erwinia carotovora subsp. carotovora and E. carotovora subsp. atroseptica in soil in Scotland
Authors: Perombelon M.C.M. , Hyman L.J.
Published: March 2008

An enrichment method was used to monitor Erwinia carotovora in soil or the rhizosphere of different crops and weeds in 17 fields with different cropping histories on three farms. The bacteria were detected in all fields not cropped with potatoes, although not consistently, and the mean annual frequency of detection was generally low (< 10%). Fields in which potatoes were grown were extensively contaminated after harvest in September but contamination declined over the winter to very low levels by early summer in the following year. Contamination level tended to rise in some fields without potatoes regardless of their cropping history but for only a short time during autumn and winter. The bacteria were no more frequent in rhizosphere soil of any of the weeds or crops examined, with the exception of brassicas, than in bare soil. In fields where more than 16 months had elapsed since cropping with potatoes, 91% of erwinia isolates obtained were E. carotovora subsp. carotovora, the remainder being E. carotovora subsp. atroseptica. The bacteria were shortlived in soil and in the rhizospheres of inoculated field and pot grown crop and weed plants. Longevity was greater in dry (10% moisture) than in wet (21% moisture) soil and decreased as temperatures rose, particularly above 25°C. Survival was best in association with brassica plants, moderate on grasses and cereals, and least on potatoes and weeds. E.c. carotovora survived better than E.c. atroseptica. Because survival of the bacteria in soil is apparently restricted, their presence in fields could be attributed to recurrent introductions from different sources.
A laser‐light pulse counting method for automatic and sensitive counting of bacteria stained with acridine orange
Authors: Kroll R.G. , Pinder A.C. , Purdy P.W. , Rodrigues Ubaldina M.
Published: March 2008

A laser‐light pulse counting method was developed and investigated for its ability automatically to count acridine orange‐stained bacteria and microcolonies of bacteria on the surface of polycarbonate membrane filters. The system consisted of an Argon laser which delivered a 5 μm diameter spot of coherent 488 nm wavelength light which was raster scanned across a 5×2 mm area of the membrane. Fluorescence pulses of orange light (ca 650 nm) were detected via a dichroic mirror and barrier filter with a photomultiplier tube. For microcolony preparations a good relationship between the number of light pulses and cell density down to below 102/ml was observed, but at lower cell densities counting was not reliable, probably because of fluorescent debris. The method was also able to count single cells, but background auto‐fluorescence and photo‐bleaching produced a high and variable background signal in some samples.
Growth and fumitremorgin production by Neosartorya fischeri as affected by food preservatives and organic acids
Authors: NIELSEN P.V. , BEUCHAT L.R. , FRISVAD J.C.
Published: March 2008

The effects of potassium sorbate, sodium benzoate, sulphur dioxide and citric, malic and tartaric acids on growth and fumitremorgin production by a heat‐resistant mould, Neosartorya fischeri, cultured on Czapek yeast autolysate agar (CYA) were studied over a 32‐day incubation period. Colonies were examined, and extracts of agar and mycelia were analyzed for mycotoxin content using high performance liquid chromatography (HPLC). Growth of N. fischeri always resulted in production of the fumitremorgins verruculogen and fumitremorgin A and C. Growth on CYA (pH 3.5) was highly repressed by potassium sorbate and sodium benzoate; 75 mg/1 completely inhibited germination of ascospores. Sulphur dioxide was less inhibitory; growth occurred on CYA containing 100 but not 200 mg/1. Growth of N. fischeri was significantly reduced when the pH of CYA was reduced from 7.0 to 4.5 to 3.5 to 2.5. Citric, malic and tartaric acids promoted growth and fumitremorgin production when supplemented to CYA (pH 2.5). These observations indicate that growth and fumitremorgin production by N. fischeri are influenced by pH and type of acid present and can be controlled by small amounts of preservatives.
Purification and properties of a BT‐glucosidase of Hanseniaspora vineae Van der Walt and Tscheuschner with the view to its utilization in fruit aroma liberation
Authors: VASSEROT Y. , CHRISTIAENS H. , CHEMARDIN P. , ARNAUD A. , GALZY P.
Published: March 2008

The β‐glucosidase of Hanseniaspora vineae was purified by ion‐exchange chromatography and gel filtration. Its molecular weight was 295000 PT 15000, its optimum pH was between 6 and 6–5, and its optimum temperature was 55°C. The enzyme was active against different soluble glucosides with β(1–2), β(1–3), β(1–4), β(1–6) and even aP(1–4) configurations. A glucosyltransferase activity appeared in the presence of ethanol. The enzyme was constitutive but its synthesis was repressed by glucose.
Volatile compounds associated with microbial growth on normal and high pH beef stored at chill temperatures
Authors: DAINTY R.H. , EDWARDS R.A. , HIBBARD C.M. , MARNEWICK J.J.
Published: March 2008

Volatile compounds produced by Pseudomonas fragi and mixed, natural floras on beef of normal pH (5–5–5–8; glucose < 1500 μg/g) and high pH (6–3–6–8; glucose < 10 μg/g) included a range of alkyl esters and a number of sulphur‐containing compounds including dimethylsulphide but not hydrogen sulphide. Production of the last was a property common to the other Gram‐negative organisms tested viz. Hafnia alvei, Enterobacter agglomerans, Serratia liquefaciens, Alteromonas putrefaciens and Aeromonas hydrophila, all of which produced similar off‐odours and, with the exception of E. agglomerans, ‘greening’on high pH meat. Serratia liquefaciens also produced greening of normal pH meat. Acetoin and diacetyl were major end products of Brochothrix thermosphacta but the related 2,3‐butanediol was formed only on normal pH meat. The Enterobacteriaceae produced the same compounds but only on normal pH meat and together with Br. thermosphacta were probable sources of these compounds and of the free and esterified branched‐chain alcohols detected in the naturally contaminated samples.
Detecting aberrant strains in bacterial groups as an aid to constructing databases for computer identification
Authors: LANGHAM C.D. , SNEATH P.H.A. , WILLIAMS S.T. , MORTIMER A.M.
Published: March 2008

Computer assisted identification systems require that databases on the test results of the species are of high quality. One reason for poor quality is the inadvertent inclusion of strains that do not belong to a taxon; this can readily occur in groups where ancillary criteria (e.g. serology) are not available. A possible strategy is to exclude strains that are very atypical in their properties, i.e. that are very outlying, provided an objective criterion can be used.

A computer program, OUTLIER, for the detection of outlying strains in bacterial clusters was evaluated. A brief description of the theory and operation of the program is given. The program uses as an objective criterion the degree to which the strain data fits a chi‐square. This allows easy identification of aberrant strains that should be excluded in constructing a database.

The program utilizes 1,0 data and calculations are based upon a choice of one of four identification coefficients. The relative merits of these four coefficients were examined for eight sets of bacterial data. Two of the coefficients, ‐log10 Willcox likelihood and Taxonomic distance squared appear to show little significant differences and we recommend these for routine work, with the first being the more useful. The Pattern distance squared was useful in indicating where atypical strains may be metabolically less active or slow‐growing members of a cluster rather than true outliers. The Variance‐weighted Taxonomic distance squared behaved anomalously and we do not recommend it.
Evaluation of different plating media used in the isolation of salmonellas from environmental samples
Authors: MORINCIGO M.A. , MARTINEZ‐MANZANARES E. , MUNCOZ A. , CORNAX R. , ROMERO P. , BORREGO J.J.
Published: March 2008

Different serotypes of salmonellas were compared for selectivity and efficiency of recovery using 11 plating media. No optimal growth was obtained after 24h incubation in any of the media, but after 48h, brilliant green, brilliant green‐phenol red‐lactose‐sucrose, bismuth sulphite, xylose‐lysine‐deoxycholate and Hektoen enteric agars showed optimal recovery of all the salmonella serotypes.

Xylose‐lysine‐deoxycholate and brilliant green‐phenol red‐lactose‐sucrose agars were the most selective media for all salmonella serotypes. Addition of 10 μg/ml of sodium novobiocin to the tryptic soy‐xylose‐lysine and tryptic soy‐brilliant green agars significantly improved their selectivity but reduced or inhibited the growth of some salmonella serotypes, including Salmonella typhi. Xylose‐lysine‐deoxycholate agar gave the highest recovery percentage of stressed salmonellas with a double‐agar layer technique. Good recovery was also obtained on brilliant green‐phenol red‐lactose‐sucrose, tryptic soy‐brilliant green, tryptic soy‐brilliant green‐novobiocin, tryptic, soy‐xylose‐lysine and tryptic soy‐xylose‐lysine‐novobiocin agars. Salmonella‐shigella agar was the least efficient medium for the recovery of salmonellas under stress‐induced or non‐stressed conditions.
The mycoflora of gari
Authors: Sanni M. Olayinka
Published: March 2008

Mycological studies have been carried out on market samples of gari, a ready‐to‐use staple fermentation product of cassava (Manihot esculenta cranz). Commercial and industrial samples were analysed. The moisture contents of samples varied from 7% to 17% while the water activity (aw) varied from 0·52 to 0·85 and the pH of samples ranged from 3·9 to 7·26. Several fungi were isolated from the commercial samples while the industrial packaged samples were relatively mould‐free. Moulds isolated were mainly Aspergillus spp., Penicillium spp., and several Mucorales, e.g. Rhizopus sp., Syncephalastrum sp., Mucor sp. and Circinella sp.
Factors affecting the production of hydrogen sulphide by Lactobacillus sake L13 growing on vacuum‐packaged beef
Authors: Egan A. F. , Shay B. J. , Rogers P. J.
Published: March 2008

Lactobacillus sake L13 produced hydrogen sulphide during growth at 0°C on vacuum‐packaged beef of normal pH (5·6–5·8) when the packaging films used had oxygen permeabilities as high as 200 ml/m2/24 h/atm (measured at 25°C and 98% relative humidity. No hydrogen sulphide was detected when the film permeability was 300 ml/m2/24 h/atm. Sulphmyoglobin was formed whenever hydrogen sulphide was present except when the film permeability was very low (1 ml of oxygen/m2/24 h/atm). Lactobacillus sake L13 also produced hydrogen sulphide when grown on beef under anaerobic conditions at 5°C. When meat pH was high (6·4–6·6) hydrogen sulphide was first detected after incubation for 9 d. When 250 μg of glucose was added to each g of high pH meat, or when meat pH was normal (5·6–5·8), hydrogen sulphide was first detected after incubation for 18 d. The spoilage of beef by hydrogen sulphide‐producing lactobacilli is more rapid when the pH of the meat is high because high‐pH meat contains less glucose. Sulphmyoglobin formation and greening can be prevented by the use of packaging films of very low oxygen permeability.
Performance profiles of topical antimicrobials in vitro
Authors: Hart A. P. , McColl K. , Thomas C. , Orr N. A.
Published: March 2008

The in‐vitro efficacy of commercially available topical antimicrobial products against control strains and those from clinical material are compared with an agar diffusion model. The MICs of the constituent antimicrobial compounds have been determined for the same organisms. Plotting the inhibition zone diameters produced by the topical products against the log10 MICs of their constituent antimicrobial compound(s) gives overall product performance profiles for a range of organisms. These profiles confirm that the formulation of a topical product clearly modifies the response obtained with a specific antimicrobial compound.
Lactobacillus plantarum; a deleterious contaminant of plant tissue cultures
Authors: Leifert C. , Waites W.M. , Camotta Helen , Nicholas J.R.
Published: March 2008

Lactobacillus plantarum was isolated from in vitro plant cultures of Hemerocallis Stella d'ora, Catherine Woodbury and Stafford. Infected cultures deteriorated rapidly during three subcultures (15 weeks) when grown in vitro, showing chlorotic white shoots and grey calli. Weaned plants developed normally when transferred to the soil. The drop in multiplication rate of plant cultures coincided with a decrease in pH of the growth media. Uninfected plants of Hemerocallis Stella d'ora showed the same symptoms after inoculation with L. plantarum. Lactobacillus plantarum was reisolated from inoculated plant cultures that showed symptoms, thus fulfilling Koch's postulates. In plants inoculated with L. plantarum both the amount of dl‐lactic acid formed and the number of plants showing symptoms increased with increasing numbers of bacteria in the inoculum, wheras plant multiplication rate and pH decreased. These effects could be reproduced by adding dl‐lactic acid to the multiplication medium of plants free from L. plantarum, suggesting that the bacterial production of lactic acid was responsible for the changes in infected plants.
The faecal flora of the giant panda (Ailuropoda melanoleuca)
Authors: Hirayama K. , Kawamura S. , Mitsuoka T. , Tashiro K.
Published: March 2008

The faecal floras of two adult (male and female) and one infant (male) giant panda kept at the Ueno Zoo, Tokyo, Japan were examined and shown to be quite different from those of other animals. The predominant bacteria in the adults were Streptococcus (including Enterococcus) and Enterobacteriaceae, while obligate anaerobes had minor populations. Fastidious anaerobes were not detected. The predominant bacteria in the suckling infant were Lactobacillus and Streptococcus, followed by Bifidobacterium. After the infant began to eat bamboo leaves the number of Lactobacillus decreased and Bifidobacterium became undetectable, whereas Enterobacteriaceae became one of the most predominant flora. The most dominant streptococcus isolated from the female panda was identified as Streptococcus bovis, but those from the male adult and the weaned infant were not identified as any known species.
In vitro studies of haemolysis by some staphylococci grown in chemically defined media
Authors: Jassim S. , Salt W.G. , Stretton R.J.
Published: March 2008

Staphylococcus aureus (five strains) and Staph. epidermidis (one strain) have been evaluated for comparative growth and haemolysin titre in both brain heart infusion (BHI) and in developed, nutritionally adequate, chemically defined media (CDMs) varying only in amino acid composition. The ability to show a particular haemolytic profile was strain‐dependent and the haemolytic titre (HU50/ml) was both strain‐ and medium‐dependent. Highest titres of both alpha and beta type haemolysins were obtained in BHI. Maximum titres were in general detected in the late exponential phase in both CDMs and BHI. Titres declined during the stationary phase in CDMs. Staphylococcus epidermidis produced a delta‐type haemolysis profile on BHI‐based blood agars, but only rabbit blood was sensitive in agars based on a developed, chemically defined medium (CDM/A; 13 amino acids) in which all six staphylococci grew. The addition of yeast extract to CDM/A increased alpha haemolysin titre, but suppressed beta haemolysin formation; beta haemolysin was, however, detected in yeast extract/phosphate‐buffered saline. Strain Wood 46 degraded haemoglobin, but only in (initially) whole blood; red blood cell‐free haemoglobin‐rich plates (BHI) were unaffected during growth. A novel haemolytic profile is described for Staph. aureus NCTC 8532 growing on blood agars based on CDM/A and may relate to the production of methaemoglobin during haemolysis.
Complexing of copper in drinking water samples to enhance recovery of Aeromonas and other bacteria
Authors: Versteegh J.F.M. , Havelaar A.H. , Hoekstra A.C. , Visser A.
Published: March 2008

The presence of copper in drinking water samples at concentrations as low as 10 μg/l resulted in a rapid die‐off of aeromonads. Coliform bacteria, heterotrophic plate count bacteria and faecal streptococci were also sensitive to copper but to a lesser degree than aeromonads. The effect was particularly noticeable in soft water (<3 meq/l Ca + Mg) and at pH‐values below 8.0. The toxic effect of copper concentrations up to 500 μg/l could be neutralized for a period of up to 24 h by the addition to samples of 50 mg/l of disodium‐ethylene‐diamino‐tetraacetate (Na2EDTA) and keeping the samples on melting ice.
Use of antibiotic resistance mutations to track strains of obligately anaerobic bacteria introduced into the rumen of sheep
Authors: Flint H.J. , Bisset Jacqueline , Webb Jeanette
Published: March 2008

Selective plating procedures were used to follow the fate of rifampicin‐resistant mutant strains of the obligately anaerobic species Bacteroides multiacidus and Selenomonas ruminantium after their introduction at numbers around 107/ml into the rumen of sheep. Bacteroides multiacidus strain F100 showed an initially rapid rate of loss (49%/h) but subsequently numbers declined more gradually approaching the limits of detection (103/ml) after 100 h. Viable cell numbers also decreased in vitro upon addition of F100 cells to whole rumen contents, but remained stable upon addition to cell‐free rumen fluid, suggesting protozoal predation. F100 cells were able to grow in vitro in whole rumen contents in the presence of an added utilizable substrate such as sorbitol, but addition of sorbitol to the rumen failed to enhance survival in vivo. In the case of S. ruminantium, introduced rifR strains persisted in the rumen at levels around 106 ml for at least 30 days.
Adhesion of Desulfovibrio desulfuricans and Pseudomonas fluorescens to mild steel surfaces
Authors: Beech Iwona B. , Gaylarde Christine C.
Published: March 2008

The adhesion of micro‐organisms to metal surfaces has been shown to be important in the corrosion process, but the cell surface structures participating in this adhesion have not previously been identified. Evidence is presented that a bacterial substance taking part in the initial adhesion of Pseudomonas fluorescens and Desulfovibrio desulfuricans (New Jersey) to mild steel is polysaccharide in nature. It is likely that this is present in the outer membrane of the bacterial cells as lipopolysaccharide.
Effect of the ethanol content of beer on the heat resistance of a spoilage Lactobacillus
Authors: ADAMS M. R. , O'BRIEN P. J. , TAYLOR G. T.
Published: March 2008

D‐values of a heterofermentative beer spoilage lactobacillus were measured at 55°C, 60°C and 65°C in beers containing <0·05% to 4·4% v/v ethanol. Z‐values for the different beers varied between 9·17 and 12·13°C. At each temperature an increase in ethanol reduced the measured D‐value. The maximum, 5·01 min was observed in alcohol‐free beer (<0·05%) at 55°C and the minimum, 0·31 min, at 60°C and 65°C in beer containing 4·4% ethanol. D‐values could be increased by prior growth in the presence of ethanol. They could be reduced by adding ethanol to alcohol‐free beer or by increasing its hop extract content. The implications for the pasteurization of low‐alcohol beers are discussed.
The effect of incubation temperature and magnesium chloride concentration on growth of salmonella in home‐made and in commercially available dehydrated Rappaport‐Vassiliadis broths
Authors: PETERZ M. , WIBERG C. , NORBERG P.
Published: March 2008

Growth rate of salmonellas in Rappaport‐Vassiliadis broth (RV) decreased with higher temperature when incubated at 40, 42 and 43°C. Home‐made RV and RV‐Merck were less inhibitory than RV‐Oxoid and RV‐lab m. At 43°C growth of all strains of Salmonella dublin were almost completely inhibited in all types of RV. In home‐made RV and RV‐Merck incubated at 42°C, Salm, dublin was not inhibited any more than other serotypes tested. Variations in growth rate between different types of RV could be explained by differences in concentration of MgCl2. RV with higher MgCl2‐concentration were most inhibitory. It is proposed that RV should be incubated at 41.5 ± 0.5°C (42.0 ± 0.1°C in a waterbath) and that the amount of MgCl2. 6H2O should be approximately 28.6 g/1 of the ready‐to‐use medium, which corresponds to the formula in the original description.
Survival and activity of Salmonella typhimurium and Escherichia coli in tropical freshwater
Authors: Jiménez L. , Muñiz I. , Toranzos G.A. , Hazen T.C.
Published: March 2008

The survival of Salmonella typhimurium LT2 and Escherichia coli was studied in situ in a tropical rain forest watershed using membrane diffusion chambers. Numbers were determined by acridine orange staining and a Coulter counter. Population activity was determined by microautoradiography, cell respiration, frequency of dividing cells, and by nucleic acid composition. Numbers of Salm. typhimurium and E. coli decreased less than 1 log unit after 105 h as measured by direct count methods. Activity as measured by respiration, acridine orange activity, frequency of dividing cells, and microautoradiography indicated that both bacteria remained moderately active during the entire study. After 24 h, E. coli was more active than Salm. typhimurium, as measured by nucleic acid composition, and frequency of dividing cells. Both E. coli and Salm. typhimurium survived and remained active in this tropical rain forest watershed for more than 5 d, suggesting that Salm. typhimurium may be of prolonged public health significance once it is introduced into tropical surface waters. As E. coli was active and survived for a long time in this natural environment, it would seem to be unsuitable as an indicator of recent faecal contamination in tropical waters.
Seasonal variation of thermophilic campylobacters in sewage sludge
Authors: Jones K. , Betaieb M. , Telford D.R.
Published: March 2008

The seasonal variation of thermophilic campylobacters in Lancaster's sewage sludge was studied over a 21 month period. The numbers in fresh sludge (from primary sedimentation) vary between approximately 200 and 5000/100 ml for most of the year but there was a large increase in May and June (in May 1988 there were 42100 campylobacters/100 ml which is 17 times more than in the preceding April). In 1989 there was a similar May/June peak but with lower numbers. This seasonal variation, measured by environmental monitoring, reflects the incidence of infections in the community. The same pattern was found in 2‐d old sludge but the numbers were substantially lower (40% lower over the experimental period).

Thermophilic campylobacters were virtually absent from digested sludge and sludge prior to land distribution. Survival experiments confirm that campylobacters survive for only a few hours in both sterile and unsterile digested and undigested sludge. These results suggest that it is safe to dispose of Lancaster's digested sludge on land but there is still uncertainty about the ability of campylobacters to survive in sludge in the viable but non‐culturable form.