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Enterococcus and Lactobacillus contamination of raw milk in a farm dairy environment.

Enterococci and lactobacilli are ubiquitously found in the intestinal microflora of humans and animals. The aim of the present study was to determine the importance of bovine faeces as a source of these organisms in raw milk. One hundred and fifty six putative enterococci and 362 lactobacilli were isolated from bovine faeces (n=26), cows' teats, raw milk, the milking machine and the milking environment on one farm. The clonal relationships of each group were investigated using Pulsed-Field Gel Electrophoresis and representatives of the different clusters were identified by repetitive DNA element (rep)-PCR fingerprinting, protein profiling, phenylalanyl-tRNA synthase (pheS) sequence analysis or 16S rDNA gene sequencing. Lactobacilli were present at approximately 3 orders of magnitude greater than enterococci in the bovine faeces. The majority of the bovine faecal enterococcal isolates were identified as Aerococcus viridans. Seven teat isolates belonged to a potential novel Aerococcus sp. and one bovine faecal isolate to a potential second novel Aerococcus sp. The lactobacilli present in the bovine faeces were predominantly Lactobacillus mucosae and Lactobacillus brevis, with small numbers of Lactobacillus plantarum. Only one Enterococcus (a strain of E. casseliflavus) out of 76 and one Lactobacillus (a strain of L. parabuchneri/kefir) out of 247 of the bovine faecal isolates was found in the milk. The major source of these bacteria in the milk was the milking equipment.

Animals↗

Intestinal protozoa and associated bacteria in captive houbara bustards (Chlamydotis undulata) in the United Arab Emirates.

A protozoal survey was carried out in 114 captive houbara bustards (Chlamydotis undulata) in the United Arab Emirates. Trichomonas gallinarum, Chilomastix gallinarum, Giardia spp. and Lophomonas spp. were detected from faecal samples of 49 (43%) captive houbara bustards. Culture and identification studies were carried out to assess associated bacteria. The bacteria isolated from birds negative to protozoa included Enterococcus spp., Aerococcus spp., Micrococci spp., Proteus spp., Enterobacter spp., Escherichia coli and Klebsiella spp., while Enterococcus spp., Micrococci kristinae, Aerococcus spp., Staphylococcus sciuri, Staphylococcus aureus, E. coli, Klebsiella spp. and Alcaligenes faecalis were isolated from protozoa positive birds. Proteus spp., Enterobacter spp., E. coli , Klebsiella spp., Aerococcus spp. and Enterococcus spp. are considered part of the normal intestinal bacterial flora of captive bustards and they were also isolated from the food items used to feed the captive bustards. S. sciuri possibly originated from ingested mice; Alcaligenes faecalis and Micrococcus spp. are contaminants from soil or water.

Journal Article↗

Culture media for non-sporulating gram-positive food spoilage bacteria.

The spoilage association especially of protein-rich foods can be dominated by Gram-positive bacteria, notably lactic acid bacteria (LAB) which affect vacuum packaged refrigerated processed meats and some dairy products. New food ecosystems are being created by novel packaging and processing technologies, resulting in spoilage associations differing from those previously reported. In addition, improvement in identification methods, allow the detection and isolation of 'novel' bacterial groups, e.g., Carnobacterium spp. This review considers the genera Aerococcus, Brevibacterium, Brochothrix, Carnobacterium, Kurthia, Lactobacillus, Leuconostoc, Microbacterium, Micrococcus, Pediococcus and Propionibacterium. Strictly selective procedures, including incubation temperature and atmosphere, are not yet available for the genera Aerococcus, Brevibacterium, Microbacterium and Micrococcus, and only with some limitations for Kurthia and Propionibacterium. On the other hand, a causative role in food spoilage has not been established clearly for all those groups, some of which may be 'opportunistic' in their behaviour. The LAB groups Lactobacillus, Leuconostoc and Pediococcus ('LLP-Group') often share similar habitats and show similar physiological behaviour on a number of elective and selective media. Modifications to increase selectivity have been based mainly on de Man, Rogosa and Sharpe (MRS) or Rogosa agar, and include pH reduction, supplementation with chemical preservatives (e.g., sorbic acid and nitrate) and the use of reduced atmospheres or suboptimal incubation temperatures. Carnobacteria differ from other LAB in their non-aciduric nature, and selective plating procedures use high-pH media (pH 8-9) by which competitors (mainly lactobacilli) are eliminated.

Animals↗

Identification of mouse submaxillary gland protein in mouse saliva and its binding to mouse oral bacteria.

The mouse submaxillary gland protein (mSMGP) is highly expressed in the submandibular gland of the adult mouse and rat. It shares 51% identity at the amino-acid level with a human protein, the prolactin-inducible protein (PIP)/gross cystic disease fluid protein 15 (GCDFP-15), which has been found in saliva, tears, sweat, seminal plasma, submucosal glands of the lung and amniotic fluid. More recently, the human PIP has been reported to bind to bacterial strains normally found in the mouth, ear canal and human skin. Sequence analysis of mSMGP/PIP earlier identified the presence of a signal peptide, suggesting that it is a secreted protein. Here, by Western blotting, mSMGP/PIP has been identified in mouse saliva. To investigate further the role of this secreted protein, its ability to bind specifically to oral bacteria was examined; the hypothesis was that mSMGP/PIP is involved in non-immune host defence by binding to bacteria. Several bacterial strains, found to belong to the genera Streptococcus, Aerococcus, Pseudomonas, Staphylococcus, Sphingomonas, Vibrio and Aeromonas, were isolated from the mouse oral cavity. Following incubation of these bacteria with (35)S-labeled, in vitro-translated mSMGP/PIP, the protein was found to bind specifically and selectively to several but not all strains tested, showing the highest affinity for the streptococci. The protein also bound specifically to an Aerococcus sp., and a low binding interaction with the Pseudomonas and Staphylococcus spp. was observed. The conservation of SMGP sequences among several animal species suggests that this protein may play an important part in the biology of the submandibular gland. As the function of the mSMGP/PIP is still undetermined, these findings provide insight into a possible involvement of this protein in host defence.

Animals↗

Airborne bacteria in an urban environment.

Samples were taken at random intervals over a 2-year period from urban air and tested for viable bacteria. The number of bacteria in each sample was determined, and each organism isolated was identified by its morphological and biochemical characteristics. The number of bacteria found ranged from 0.013 to 1.88 organisms per liter of air sampled. Representatives of 19 different genera were found in 21 samples. The most frequently isolated organisms and their percent of occurence were Micrococcus (41%), Staphylococcus (11%), and Aerococcus (8%). The bacteria isolated were correlated with various weather and air pollution parameters using the Pearson product-moment correlation coefficient method. Statistically significant correlations were found between the number of viable bacteria isolated and the concentrations of nitric oxide (-0.45), nitrogen dioxide (+0.43), and suspended particulate pollutants (+0.56). Calculated individually, the total number of Micrococcus, Aerococcus, and Staphylococcus, number of rods, and number of cocci isolated showed negative correlations with nitric oxide and positive correlations with nitrogen dioxide and particulates. Statistically significant positive correlations were found between the total number of rods isolated and the concentration of nitrogen dioxide (+0.54) and the percent relative humidity (+0.43). The other parameters tested, sulfur dioxide, hydrocarbons, and temperature, showed no significant correlations.

Air Microbiology↗

Phenotypic characterization, cellular fatty acid composition, and DNA relatedness of aerococci and comparison to related genera.

Aerococci can be misidentified as streptococci, enterococci, pediococci, lactococci, or leuconostocs. To distinguish the genus and determine if another species is needed in the present taxon, we analyzed 37 aerococci for cellular fatty acids and compared them with 377 strains of gram-positive cocci, including the species type strains from each of the related genera. The cellular fatty acid profile of aerococci was distinguishable from other genera. Two relatively novel fatty acids found in the aerococci were identified as C16:1 omega 9c and C16:1 omega 9t. Eleven strains of aerococci (including a strain originally identified as "Gaffkya" species) were chosen for DNA-DNA reassociation studies with the type strain Aerococcus viridans ATCC 11563; DNAs from eight of these strains were more than 75% related to the type strain and had 1 to 4% divergence in related sequences. The remaining three strains were 60 to 70% related to the type strain, had 7 to 11.5% divergence, and may represent a second species, Aerococcus genospecies 2. beta-Glucuronidase, alpha-galactosidase, and beta-galactosidase were useful in characterizing the aerococci.

Chloramphenicol O-Acetyltransferase↗

Atmospheric growth requirements for Alloiococcus species and related gram-positive cocci.

The growth of Alloiococcus otitis under different atmospheres and nutritional conditions was studied. The growth rates of 25 strains of gram-positive cocci representing five genera on heart infusion agar plates containing 5% rabbit blood and on brucella agar plates with and without sheep blood under aerobic, increased CO2, and anaerobic atmospheres were compared. Eight strains of alloiococci plated on heart infusion agar with rabbit blood and on brucella sheep blood agar grew under aerobic and candle jar atmospheres. Two of these strains showed poor anaerobic growth after 7 days. Strains of Aerococcus viridans, Aerococcus urinae, Helcococci kunzi, Dolosigranulum pigrum, Gemella haemolysans, and Gemella morbillorum grew well under all three atmospheres and on the three types of media and in thioglycolate broth. These results confirm all the aerobic atmospheric requirements for Alloiococcus strains and show that aerobic growth characteristics help distinguish the alloiococci from the other gram-positive cocci that are facultatively anaerobic.

Aerobiosis↗

Isolation of hexavalent chromium-reducing Cr-tolerant facultative anaerobes from tannery effluent.

Several facultative anaerobes tolerant to high levels of chromate (>400 mg/ml) were isolated from tannery effluents. These isolates displayed varying degrees of Cr(VI) reduction under aerobic and anaerobic conditions at room temperature (24+/-2 degrees C). Interestingly, eight isolates were efficient in reducing 70% Cr(VI) anaerobically. This includes 5 isolates of genus Aerococcus, two isolates of Micrococcus and single isolate of genus Aeromonas. These isolates were subjected to further characterization for possible use in Cr(VI) detoxification of industrial wastes. This is the first report of Aerococcus sp. capable of Cr(VI) reduction >70% anaerobically. These bacteria were further checked for tolerance to a variety of other heavy metals. Our study indicates the possible use of these bacteria in environmental clean up.

Journal Article↗

[Use of immobilized cells of bacteria in the process of purification of waste water containing chlorates and chromates].

Some regularities of immobilization of chlorate-reducing bacteria by various carriers and especially sewage treatment for chlorate and chromates by adhered bacteria have been studied. Most bacterial cells are immobilized during the first hour of contact with the carrier. The studied carriers, as to their ability to adsorb Aerococcus dechloraticans TGS-463 cells, may be arranged in the following sequence: porolon > claydite > glass broaches > maize stem > barley straw. The 12-24 hour culture Aerococcus dechloraticans TGS-463 expresses maximum ability to immobilization. The bacterial cell fastening on the carrier increases 2.1 times the reduction velocity for chlorates and 1.6 times that for chromates. The velocity of chlorates and chromates reduction by the culture factened on the carrier decreases in the due course of time, that requires the carrier regeneration.

Bacterial Adhesion↗

Stereoselective epoxidation of phenyl allyl ether by alkene-utilizing bacteria.

Eighteen newly isolated ethene- and propene-utilizing bacteria were screened for the ability to produce phenyl glycidyl ether, a common precursor for the synthesis of beta blockers, from phenyl allyl ether. These organisms included Aerococcus, Alcaligenes, Micrococcus and Staphylococcus spp. and a variety of Gram-negative, Gram-positive and Gram-variable mesophilic rods/coccobacilli not yet identified. The majority of ethene- and propene-grown cultures (14 strains) accumulated phenyl glycidyl ether (0.4-1.7 mM) as the sole oxidation product. The bioconversions with the three most promising ethene-utilizers (M26, M90C, M93A) were scaled-up to yield essentially optically pure (enantiomeric excess = 93%) S-(+)-phenyl glycidyl ether. This is currently under investigation for commercial production of optically pure beta blockers.

Alkenes↗

Aldolases of the lactic acid bacteria. Demonstration of immunological relationships among eight genera of Gram positive bacteria using an anti-pediococcal aldolase serum.

Reciprocal qualitative and quantitative immunological experiments employing an anti-Pediococcus cerevisiae aldolase serum confirmed many of the interspecific relationships demonstrated previously among lactic acid bacteria with antisera prepared against the Streptococcus faecalis fructose diphosphate aldolase. The extent of immunological relatedness observed between the Lactobacillus and Pediococcus aldolases was markedly gses indicating that the pediococci share closer phylogenetic ties with the rod-shaped lacotbacilli than with their spherical counterparts in the streptococci. In addition to confirming the existence of definitive, but distant, relationships between the lactic acid bacteria and certain gram positive nonsporeforming anaerobes, immunological cross-reactivity was also demonstrated between the pediococcal aldolases and those of Aerococcus viridans.

Biological Evolution↗

Ofloxacin for prevention of bacterial infections in granulocytopenic patients.

We studied the potential value of oral ofloxacin (200 mg twice daily) for selective decontamination and infection prevention in 40 granulocytopenic patients with acute leukemia, blast crisis of chronic myelogenous leukemia, hairy cell leukemia or severe aplastic anemia. The quality of selective decontamination was acceptable with rapid elimination of Enterobacteriaceae from the alimentary tract, only a slight decrease in concentrations of anaerobes in faeces, and a small number of newly acquired transient (twelve isolates in seven patients) or colonizing (six strains with 28 isolates in four patients) aerobic gram-negative rods and Staphylococcus aureus (one isolate) recovered from 672 surveillance cultures from faeces, oral washings and urine. Two of three patients colonized with ofloxacin-resistant Pseudomonas aeruginosa strains developed Pseudomonas infections. A total of twelve acquired infections was observed. Six were microbiologically documented infections, all caused by ofloxacin-resistant bacteria (two P. aeruginosa, two Staphylococcus epidermidis, one Aerococcus viridans, one Micrococcus sp.). Tolerance was acceptable with no serious side effects observed. Mean drug concentrations in serum and saliva were comparable to those determined in healthy volunteers and were found to be higher in saliva than in serum. We conclude that ofloxacin may be studied as an effective alternative to trimethoprim-sulfamethoxazole for selective decontamination and infection prevention in severely granulocytopenic patients. Careful monitoring of colonizing Pseudomonas spp. with decreased ofloxacin sensitivity, however, seems necessary.

Adult↗

Improving the thermal stability of lactate oxidase by directed evolution.

Lactate oxidase is used in biosensors to measure the concentration of lactate in the blood and other body fluids. Increasing the thermostability of lactate oxidase can significantly prolong the lifetime of these biosensors. We have previously obtained a variant of lactate oxidase from Aerococcus viridans with two mutations (E160G/V198I) that is significantly more thermostable than the wild-type enzyme. Here we have attempted to further improve the thermostability of E160G/V198I lactate oxidase using directed evolution. We made a mutant lactate oxidase gene library by applying error-prone PCR and DNA shuffling, and screened for thermostable mutant lactate oxidase using a plate-based assay. After three rounds of screening we obtained a thermostable mutant lactate oxidase, which has six mutations (E160G/V198I/G36S/T103S/A232S/F277Y). The half-life of this lactate oxidase at 70 degrees C was about 2 times that of E160G/V198I and about 36 times that of the wild-type enzyme. The amino acid mutation process suggests that the combined neutral mutations are important in protein evolution.

Amino Acid Substitution↗

Isolation and identification of bacteria associated with adult laboratory Mexican fruit flies, Anastrepha ludens (Diptera: Tephritidae).

From the guts of new and old colonies (female and male) of Mexican fruit flies, Anastrepha ludens (Diptera: Tephritidae), we identified a total of 18 different bacterial species belonging to the family Enterobacteriaceae, Pseudomonadaceae, Vibrionaceae, Micrococcaceae, Deinococcacea, Bacillaceae, and the genus Listeria. Enterobacter, Providencia, Serratia, and Staphylococcus spp. were the most frequently isolated genera, with Citrobacter, Streptococcus, Aerococcus, and Listeria found less frequently. We found Bacillus cereus, Enterobacter sakazakii, Providencia stuartii, and Pseudomonas aeruginosa only in the new colony, Aeromonas hydrophila and Klebsiella pneumoniae spp. pneumoniae only in the old colony. We also studied resistance/sensitivity to 12 antibiotics for six bacterial isolates such as Enterobacter cloacae, E. sakazakii, K. pneumoniae spp., Providencia rettgeri, P. aeruginosa, and Bacillus cereus. Isolates on the whole were resistant to penicillin and ampicillin (five of six isolates) and sensitive to rifampin and streptomycin (six of six isolates). Antibiotic resistance profiles might be useful characteristics for distinguishing among species and strains of these bacteria, probably having ecological significance with respect to intra- and inter-specific competition within host cadavers, and could have implications for the utility of these organisms for biological control, including the alternative control strategy, paratransgenesis.

Animals↗

Molecular cloning and characterization of cDNA of penaeidin-like antimicrobial peptide from tiger shrimp (Penaeus monodon).

We report the molecular cloning and characterization of a penaeidin-like antimicrobial peptide (AMP) complementary DNA from the hemocytes of tiger shrimp (Penaeus monodoni). A tiger shrimp AMP cDNA containing the entire coding region of the peptide, determined by rapid amplification of cDNA 5' and 3' ends and polymerase chain reaction of the messenger RNA isolated from hemocytes of the shrimp, is 683 bp in length with an open reading frame of 222 bp. The deduced amino acid sequence of this antimicrobial peptide consists of 55 amino acid residues of the mature peptide and a signal peptide of 19 amino acid residues. The mature peptide contains a proline-rich domain at the N terminus and 6 cysteine residues at the C terminus, and it shares less than 50% amino acid sequence identity with the mature penaeidins of Litopenaeus vannamei. To demonstrate the bactericidal activity of this peptide, a synthetic peptide was prepared according to the amino acid sequence deduced from the cDNA of tiger shrimp penaeidin-like AMP. By the minimal inhibitory concentration MIC assay, the synthetic peptide was shown to exert bactericidal activity against Escherichia coli, Vibrio harveyi, Vibrio alginolyticu, and Aerococcus viridans. It also inhibited the growth of 2 filamentous fungi, Fusarium pisi and Fusarium oxysporum. Tiger shrimp penaeidin-like AMP mRNA was detected in hemocytes, gills, intestines, eyestalks, hepatopancreas, and muscles of the tiger shrimp by reverse transcriptase-polymerase chain reaction assay. Although the highest level was detected in hemocytes, challenging tiger shrimp with V. harveyi did not result in a significant increase of the mRNA level in hemocytes.

Amino Acid Sequence↗

Characterization of peptidoglycan stem lengths by solid-state 13C and 15N NMR.

Lyophilized whole cells of Aerococcus viridans (Gaffkya homari) grown on a synthetic medium containing D-[2-13C, 15N]Ala, or containing both L-[1-13C]Lys and D-[15N]Ala, have been examined by double cross-polarization magic-angle spinning 13C and 15N nuclear magnetic resonance. Results from the double-labeled alanine experiment confirm the absence of metabolic scrambling of alanine by A. viridans. Results from the combined single-label experiment can be used to count directly the number of adjacent L-Lys and D-Ala units in peptide chains of cell-wall peptidoglycan. This count leads to the conclusion that there are no terminal D-Ala or D-Ala-D-Ala units in uncross-linked chains of the peptidoglycan of A. viridans.

Alanine↗

Effects of metals on the chemiluminescent response of rainbow trout (Salmo gairdneri) phagocytes.

Quantification of an induced chemiluminescent (CL) response in phagocytes is currently being evaluated as an indicator system for determining those environmental pollutants that may predispose fish to disease. A CL assay was developed using phagocytes from the pronephros of rainbow trout (Salmo gairdneri). The CL response of phagocytes to phorbol myristate acetate, a chemical inducer of CL, was shown to be dose-dependent. The response to five species of bacteria was also evaluated. Staphylococcus aureus and Aeromonas hydrophila produced the most intense CL responses and the longest duration of response (100 min.) Yersinia ruckeri induced an immediate strong CL response of short duration (20 min.) whereas Vibrio anguillarum and Aerococcus viridans failed to stimulate CL under the test conditions employed. The effect of sub-toxic levels of Cu, Al, and Cd on the CL response of phagocytes to S. aureus was examined using phagocytes exposed to the metals immediately before assay or after 1 hr or 24 hr exposure times. Copper caused a significant decrease in CL to the baseline level under all treatment conditions upon stimulation with S. aureus. Similar results were obtained with Al except that the decrease in CL, although significant, was not to the baseline level. In contrast, Cd caused a significant increase in CL when added 1 hr prior to or immediately before the assay; but, following a 24 hr exposure, the results were variable, in that either no change or a decrease was observed. The addition of Cu to phagocytes already exhibiting a strong CL response to S. aureus caused an immediate decrease in CL to that seen with the negative controls.

Aeromonas↗

Growth of Enterococcus, Lactococcus and Streptococcus strains and environmental isolates in liquid media and their reactions on BEEA.

Growth of known species of Enterococcus, Lactococcus and Streptococcus and Aerococcus viridans in selective and nonselective liquid media routinely used to enumerate faecal streptococci was measured optically at different temperatures. Growth of environmental isolates was measured in some of these media. Growth of the reference strains on Bile esculin azide agar at elevated incubation temperatures was tested. The results revealed only minor differences between media but strong influence of incubation temperature. Some media tended to yield higher cell densities than others. For many species the inoculum size affected maximum turbidity. To combine selective media with selective incubation temperatures seems to be necessary to achieve satisfactory reliability in traditional liquid enumeration methods for faecal streptococci. Because of the diversity of this group, optimal selectivity and recovery can hardly be achieved simultaneously.

Agar↗