Staphylococci in Competition: IV. Effect of Starch and Kind and Concentration of Sugar on Staphylococcal Growth in Mixed Populations

Foods containing large amounts of carbohydrate have frequently been involved in staphylococcal food poisoning. Custard has been considered to be a highly favorable culture medium for staphylococci; however, it may be a selective medium rather than an ideal one. The influence of dextrose, lactose, and sucrose in varying amounts from 0.25 to 18%, and of starch, on the growth of staphylococci in mixed populations with saprophytes was determined. The inhibitory effect of the sugars was much greater on the saprophyte population than on the staphylococci. Of the three sugars, sucrose was most inhibitory to the saprophytes. It greatly decreased their lag periods as the concentration of sugar increased. Dextrose was the least inhibitory; in fact, 0.5% dextrose gave considerable stimulus to saprophyte growth. This sharply repressed staphylococcal growth. Lactose occupied an intermediate position. Rapid onset of the death phase of the staphylococci was observed in all increased sugar concentrations and seemed to be a pH effect rather than a result of competition. Sucrose exerted an inhibitory effect on the growth of saprophytes at and above room temperature. In the presence of 2.5% corn starch, staphylococcal growth in mixed cultures was slightly inhibited, while the death phase was sharply accelerated. Thus, carbohydrates exert their influence on staphylococcal growth in mixed cultures through their effect on the saprophytes by decreasing or increasing competition.     

Staphylococci in Competition: V. Effect of Eggs, Eggs Plus Carbohydrates, and Lipids on Staphylococcal Growth

As is generally known, custards have been frequently involved in staphylococcal food poisonings and are regarded by some as an ideal culture medium. Previous studies showed that high carbohydrate concentrations repressed the growth of competing saprophytic species, allowing the growth of staphylococci in a mixture rather than stimulating the growth of the staphylococci. In an extension of those studies, the influence of the egg constituent of custard was investigated to determine its role in affecting the growth of pathogenic staphylococci in a competing mixture of psychrotrophic saprophytes. The normal competitive effect of the saprophytes on the growth of staphylococci was very slightly affected by the addition of 25% whole egg to the growth media. Approximately 9% egg yolk alone added to the medium resulted in a slight increase in the length of the lag period of the psychrotrophs and a slight increase in the number of staphylococci which grew. Addition of 25% whole egg plus 14.5% sucrose resulted in repression of saprophyte growth similar to that seen in high sucrose concentrations. Staphylococcal growth was more extensive in the presence of both whole egg and sucrose than in the presence of either ingredient alone. Incorporation of 4% corn oil in media was effective in repressing growth of the saprophytes at 37 C only. This allowed the staphylococci to dominate the population. At lower temperatures, staphylococci were unable to compete effectively. Buffering media of high carbohydrate content resulted in lengthened lag periods for the psychrotrophs and the appearance of very large staphylococcal populations.     

Staphylococci in Competition: II. Effect of Total Numbers and Proportion of Staphylococci in Mixed Cultures on Growth in Artificial Culture Medium

In studies carried on in bacteriological media with selected cultures, definite repressive effects were noted on the growth of the Staphylococcus population by a mixture of saprophytic, psychrophilic bacterial species. This repressive effect became more pronounced as the relative proportion of the bacterial population which was staphylococcal became smaller. A varied saprophytic bacterial flora of some numbers apparently would offer definite protection to foods through repression of staphylococcal growth and by rendering the food inedible before the rise of appreciable numbers of staphylococci. It would appear that at the optimal temperature for staphylococcal growth, staphylococci could multiply rapidly in the mixed population due to the comparative shortness of the generation time of this species and because of the lengthened lag phase of the saprophytic bacterial species at this elevated temperature, especially when only cultures having psychrophilic characteristics were present. This temperature is substantially above that encountered in practical experience. With the passage of time, the staphylococcal population was completely overgrown by the saprohytes present. This effect might be eliminated in the presence of psychrophilic and mesophilic, saprophytic species. The repressive effect of competition by saprophytic, psychrophilic organisms is extremely effective up to room temperature on the staphylococcal population. Even when significant staphylococcal populations were achieved in the artificial media, such tremendous numbers of saprophytes were obtained either earlier or at the same time so that a frozen food containing this population would be organoleptically unacceptable due to the degradative action of enzymes from the saprophytic psychrophile population.     

Physical factors influencing microbial interactions and biochemical changes during the Baceman stage of Indonesian Kecap (soy sauce) production

The composition of samples taken from the baceman stage of traditional Indonesian kecap (soy sauce) production can vary greatly from batch to batch and from manufacturer to manufacturer. This variability could be caused by physical factors such as salt concentration, temperature, dissolved oxygen tension and pH. The effect of these factors on the changes in microflora and biochemical composition during the baceman stage are described in this report. Salt concentration was found to have a large influence on the spoilage of the baceman. At low salt concentrations pellicle-forming yeasts were able to grow. The pellicle on the liquid surface formed by these yeasts provided an acrobic environment in which coryneform bacteria could grow. These bacteria consumed amino acids and fermentation products like acetate and lactate, which resulted in a rise in pH and subsequent spoilage of the baceman. An aerobic baceman showed the same development as those with a low salt concentration. Salt concentration as well as temperature had a large influence on the rate of growth of bacteria. Growth of bacteria and associated lactate and acetate production were also stimulated by a high pH, while growth of yeasts and ethanol and glycerol formation was better at low pH. Also, the production of formol nitrogen by enzymes resulting from the previous bungkil stage was greatly influenced by temperature and pH, with higher temperature and pH giving rise to higher formol nitrogen contents. The consequences of these physical factors on the production of traditional Indonesian kecap are discussed.     

Effects of Temperature, pH, and NaCl on Growth and Pectinolytic Activity of Pseudomonas marginalis

The interaction of temperature (4, 10, 18, and 30°C), pH (6, 7, and 8), and NaCl (0, 2.5, and 5%) and their effects on specific growth rate, lag phase, and pectinolytic enzymes of Pseudomonas marginalis were evaluated. Response surface methodology was adapted to describe the response of growth parameters to environmental changes. To obtain good conditions of storage, the combined action of salt and temperature is necessary. At 4°C with an NaCl concentration of 5% and a pH of 7, the lag time was 8 days and no growth was observed at 4°C with 5% NaCl and a pH of 6. In the absence of salt, P. marginalis could grow regardless of temperature and pH. Pectate lyase and pectin lyase were produced by P. marginalis, while pectin methyl esterase activity was not observed in our culture conditions. The enzyme production depended on temperature, pH, and salt concentration but also on the age of the culture. Pectinolytic enzymes were abundantly excreted during the stationary phase, and even at 4°C, after 2 weeks of storage, enzyme activities in supernatant culture were sufficient to damage vegetables. Both bacterial growth and enzymatic production have to be taken into account in order to estimate correctly the shelf life of vegetables.     

Influence of Food Microorganisms on Staphylococcal Growth and Enterotoxin Production in Meat

Forty-four microorganisms were studied for their influence on staphylococcal growth and enterotoxin production. Inhibition was found to be more common than stimulation. Two types of inhibition were observed: inhibition of staphylococcal growth, and inhibition of enterotoxin formation with no apparent effect on growth. By use of a plate test, 12 of the 44 food microorganisms were found to inhibit staphylococcal growth at 35 C. Of the 12, 3 also inhibited growth at 25 C. No significant differences in inhibition were observed with the 15 strains of enterotoxigenic staphylococci. In meat slurries, inhibition of staphylococcal growth was found to be greater at 25 C than at 35 C. Results on inhibition obtained from the plate test could not be correlated with the effect of the organisms in slurries. Environmental conditions were found to affect markedly the influence of food microorganisms on staphylococci. Of the 44 food microorganisms studied, only Bacillus cereus was observed to stimulate significantly staphylococcal growth and enterotoxin formation. Stimulation was more pronounced with Staphylococcus aureus 196E than with other strains of enterotoxigenic staphylococci. Bacillus megaterium and Brevibacterium linens were inhibited by staphylococci. These organisms were completely inhibited when inoculated in mixed cultures with staphylococci. In pure cultures, good staphylococcal growth was found to be accompanied by enterotoxin production; however, in the presence of food microorganisms, good staphylococcal growth occurred without the formation of detectable levels of enterotoxin A.     

Staphylococcus aureus and Staphylococcal Enterotoxin A in Breaded Chicken Products: Detection and Behavior during the Cooking Process

In this study we examined the presence of Staphylococcus aureus and staphylococcal enterotoxin A (SEA) in 20 industrial breaded chicken products obtained from different retail butchers and supermarket stores in Italy. The levels of contamination in the products analyzed were quite low, although the pH values and water activities (a_w) in the samples considered were in ranges favorable for S. aureus growth. As demonstrated by phenotypic and molecular characterization, in spite of the high percentage of coagulase-positive Staphylococcus strains, only three strains could be referred to the species S. aureus. Moreover, all the strains were negative in PCR assays targeting staphylococcal enterotoxin genes (seA to seE, seG to seJ, and seM to seO), as well as the toxic shock syndrome toxin 1 gene, and no SEA was detected in the retail breaded chicken samples analyzed by a reversed passive latex agglutination assay or by Western blotting. Hence, we evaluated the thermal resistance of two strains of SEA-producing S. aureus in a laboratory-scale preparation of precooked breaded chicken cutlets. The heat treatment employed in the manufacture determined the inactivation of S. aureus cells, but the preformed SEA remained active during product storage at 4°C. The presence of the staphylococci and, in particular, of S. aureus in the retail breaded chicken products analyzed is a potential health risk for consumers since the pH and a_w values of these kinds of products are favorable for S. aureus growth. The thermal process used during their manufacture can limit staphylococcal contamination but cannot eliminate preformed toxins.     

Bacteriostatic activity of serum against staphylococci

Cybulska, Janina (State Institute of Hygiene, Warsaw, Poland), and J. Jeljaszewicz. Bacteriostatic activity of serum against staphylococci. J. Bacteriol. 91:953-962. 1966.-Antistaphylococcal activity of normal serum against strains exhibiting various patterns of coagulase, clumping-factor, and staphylokinase production is not connected with the presence of these factors. Purified coagulase does not influence this property of serum. Coagulase-negative strains with clumping-factor activity grow in normal serum as typical pathogenic staphylococci. Serum bacteriostatic activity against staphylococci may be reversed by several nonspecific factors, such as sterile broth, supernatant fluids of coagulase-negative strains, and ammonium sulfate precipitates of culture supernatant fluids of various staphylococci. Immune sera with a high agglutinating titer for staphylococcal cells do not prevent growth of serum-resistant strains; serum-susceptible strains are inhibited as in normal serum control. Activation or blocking of the serum fibrinolytic system does not influence serum bacteriostatic activity. The growth rate of serum-resistant strains is identical in serum and in Todd-Hewitt broth; serum-susceptible strains are inhibited to the inoculum level, but decreases and increases in viable count are noted during a 24-hr observation period. Observations made with sera of 10 animal species clearly demonstrated differences in serum bacteriostatic activity, mouse serum being completely noninhibitory and cat serum only weakly inhibitory. The technique of quantitative determination of serum susceptibility of staphylococci is described, and the importance of serum antistaphylococcal activity in vitro is discussed. Experimental staphylococcal infection produced in rabbits by intravenous injection of different Staphylococcus aureus strains did not result in significant changes in serum antistaphylococcal activity. The technique of experimental infection used caused chronic infection, with a peak on the 14th day; this was proved by means of a newly developed 5'-nucleotidase test. At the same time, sera of infected animals exhibited slight inhibitory properties, which returned to initial values 1 week later. Infection was produced by strains recognized as nonpathogenic and was inhibited in vitro by sera from both normal and infected rabbits. It is concluded that antistaphylococcal activity of serum should be considered as an "in vitro" phenomenon, which seems to have no importance in defense mechanisms of rabbits infected intravenously with staphylococci.     

Cohabitation—relationships of corynebacteria and staphylococci on human skin

Skin microbiome main cultivable aerobes in human are coagulase-negative staphylococci and lipophilic corynebacteria. Staphylococcus strains (155) belonging to 10 species and 105 strains of Corynebacterium belonging to nine species from the skin swabs of healthy male volunteers were investigated to determine their enzymatic activity to main metabolic substrates: carbohydrates, proteins, lipids, and response to factors present on the skin such as osmotic pressure, pH, and organic acids. The results showed that lipophilic corynebacteria have different capacity for adaptation on the skin than staphylococci. Most of Corynebacterium spp. expressed lack of proteinase, phospholipase, and saccharolytic enzymes activity. Corynebacteria were also more sensitive than Staphylococcus spp. to antimicrobial agents existing on human skin, especially to low pH. These characters can explain domination of Staphylococcus genera on healthy human skin. It can be suggested that within these two bacterial genus, there exists conceivable cooperation and reciprocal protection which results in their quantitative ratio. Such behavior must be considered as crucial for the stability of the population on healthy skin.     

Growth of Listeria monocytogenes and Yersinia enterocolitica on Cooked Modified-Atmosphere-Packaged Poultry in the Presence and Absence of a Naturally Occurring Microbiota

Cooked poultry cuts were inoculated with five-strain composite mixtures of either Listeria monocytogenes or Yersinia enterocolitica (1,000 CFU/150-g piece), packaged in 44:56 CO₂-N₂, and stored at 3.5, 6.5, or 10°C for up to 5 weeks. Both L. monocytogenes and Y. enterocolitica grew under all test conditions. The presence of a naturally occurring microbiota did not influence the growth of either pathogen. Addition of lactate with the shelf life extender ALTA 2341 lengthened the lag phases of L. monocytogenes and Y. enterocolitica but did not prevent their growth.     

Nisin inactivation in a culture of the producer Streptococcus lactis strain MGU

The intensive biosynthesis of nizin on the glucose-yeast medium is observed during the logarithmic and early lag phases of the staphylococcal growth. The ratio of nizin in the fermentation broth (free nazin) and that bound with the cells depended on pH of the medium. When pH was maintained at 6.6-6.8, the amount of nazin in the cells during and growth logarithmic phase was equal to its amount in the fermentation broth filtrate. During the lag phase marked inactivation of nizin was noted. periodical feeding of casein prevented the nizin inactivation. The preliminary data are indicative of the enzymatic nature of the antibiotic.     

Isolation,identification and characterization of Staphylococcus sp. from Indian ethnic fermented fish product

Staphylococci from Sheedal of Northeast India was isolated, identified and characterized. All the isolated staphylococci were found to be coagulase negative. Based on the rpoB gene sequences followed by analysis using NCBI-BLAST software, seven species of Staphylococcus namely, S. piscifermentans, S. condimenti, S. arlettae, S. sciuri, S. warneri, S. nepalensis and S. hominis were recognized. Phylogenetic analyses revealed three major cluster groups. All the seven Staphylococcus showed their NaCl tolerance from 2 to 8%. No species was able to grow at 55°C. Except S. arlettae and S. sciuri, all the isolated staphylococcal species exhibited growth at pH 4–8. No isolated species was able to ferment mannitol, sucrose and arabinose. All the species exhibited moderate to maximum proteolytic and lipolytic activities. All the seven species were found to be sensitive to the antibiotics, namely, erythromycin, norfloxacin, ampicillin, streptomycin and vancomycin, whereas all were resistant to co-trimoxazole. Only S. piscifermentans was found antagonist to Salmonella enterica, Escherichia coli and Bacillus subtilis, although the clear zone was minimal. All the staphylococcal species except S. arlettae and S. sciuri exhibited hydrophobicity ranging from 25 to 66%. The observed characteristics of isolated Staphylococci from Sheedal revealed their role in fish fermentation.     

Novel methicillin-resistant coagulase-negative Staphylococcus clone isolated from patients with haematological diseases at the Blood Bank Centre of Amazon,Brazil

Methicillin-resistant Staphylococcus remains a severe public health problem worldwide. This research was intended to identify the presence of methicillin-resistant coagulase-negative staphylococci clones and their staphylococcal cassette chromosome mec (SCCmec)-type isolate from patients with haematologic diseases presenting bacterial infections who were treated at the Blood Bank of the state of Amazonas in Brazil. Phenotypic and genotypic tests, such as SCCmec types and multilocus sequence typing (MLST), were developed to detect and characterise methicillin-resistant isolates. A total of 26 Gram-positive bacteria were isolated, such as: Staphylococcus epidermidis (8/27), Staphylococcus intermedius (4/27) and Staphylococcus aureus (4/27). Ten methicillin-resistant staphylococcal isolates were identified. MLST revealed three different sequence types: S. aureus ST243, S. epidermidis ST2 and a new clone of S. epidermidis, ST365. These findings reinforce the potential of dissemination presented by multi-resistant Staphylococcus and they suggest the introduction of monitoring actions to reduce the spread of pathogenic clonal lineages of S. aureus and S. epidermidis to avoid hospital infections and mortality risks.     

Isolation and description ofHaloanaerobium praevalens gen. nov. and sp. nov., an obligately anaerobic halophile common to Great Salt Lake sediments

A new halophilic species is described that was isolated from the hypersaline (>20%) surface sediments of Great Salt Lake, Utah, via transfer from MPN end-dilution tubes that contained a complex organic medium. The organism was an obligate anaerobe that proliferated optimally at approximately 13% salt, but did not grow significantly at <2% or ≥30% salt. It stained Gram-negative, was nonmotile, nonsporing, and contained an outer-wall membranous layer. The complex lipids of the organism were fatty acid esters that did not change dramatically during growth at 5% or 25% NaCl. The DNA base composition was 27.0±1 mol% guanosine plus cytosine. The temperature range for growth was >5°C and <60°C, the pH range was between 6.0 and 9.0. The doubling time for growth in complex medium with 25% NaCl was 7 h. The organism utilized carbohydrates, peptides, and amino acids. Butyrate, acetate, propionate. H₂, and CO₂ were the major fermentation end products formed. Glucose, mannose, fructose,n-acetyl glucosamine, and pectin were used as energy sources for growth. Methylmercaptan was produced from methionine degradation. The nameHaloanaerobium praevalens gen. nov. sp. nov. is proposed for the type strain GSL which has been deposited as DSM 2228. The taxonomic relationships ofH. praevalens to other obligate halophiles and anaerobes, as well as its biological role in the Great Salt Lake microbial ecosystem, are discussed.     

Reisolation of Staphylococcus salivarius from the human oral cavity

Twenty-four strains of gram-positive facultative cocci, arranged primarily in small clusters, were isolated from the surface of the human tongue. With the exception of 14 catalase-negative isolates, these strains were identical in cultural and biochemical characteristics and in deoxyribonucleic acid base composition. All cultures produced viscous growth in both liquid and agar media. They fermented glucose anaerobically, reduced nitrate beyond nitrite, were benzidine-positive, and failed to grow in the presence of 5% NaCl or at 45 C. In addition, they exhibited guanine plus cytosine (G + C) contents of 55.4 to 58.3%. These isolates differed from strains of pediococci, aerococci, and micrococci which were included for comparison. On the basis of G + C content, these organisms appear to be intermediate between micrococci and staphylococci; however, on the basis of anaerobic glucose fermentation, it is suggested that they be placed in the genus Staphylococcus. It is proposed that they be recognized as S. salivarius.     

Effects of Preculturing Conditions on Lag Time and Specific Growth Rate of Enterobacter sakazakii in Reconstituted Powdered Infant Formula

Enterobacter sakazakii can be present, although in low levels, in dry powdered infant formulae, and it has been linked to cases of meningitis in neonates, especially those born prematurely. In order to prevent illness, product contamination at manufacture and during preparation, as well as growth after reconstitution, must be minimized by appropriate control measures. In this publication, several determinants of the growth of E. sakazakii in reconstituted infant formula are reported. The following key growth parameters were determined: lag time, specific growth rate, and maximum population density. Cells were harvested at different phases of growth and spiked into powdered infant formula. After reconstitution in sterile water, E. sakazakii was able to grow at temperatures between 8 and 47°C. The estimated optimal growth temperature was 39.4°C, whereas the optimal specific growth rate was 2.31 h⁻¹. The effect of temperature on the specific growth rate was described with two secondary growth models. The resulting minimum and maximum temperatures estimated with the secondary Rosso equation were 3.6°C and 47.6°C, respectively. The estimated lag time varied from 83.3 ± 18.7 h at 10°C to 1.73 ± 0.43 h at 37°C and could be described with the hyperbolic model and reciprocal square root relation. Cells harvested at different phases of growth did not exhibit significant differences in either specific growth rate or lag time. Strains did not have different lag times, and lag times were short given that the cells had spent several (3 to 10) days in dry powdered infant formula. The growth rates and lag times at various temperatures obtained in this study may help in calculations of the period for which reconstituted infant formula can be stored at a specific temperature without detrimental impact on health.     

Surface electrokinetic properties of two strains of Staphylococcus aureus during their cell growth cycle

Two strains of Staphylococcus aureus were investigated: S. aureus H, a normal wild-type strain, and 52A5, a mutant strain whose cell wall contains no teichoic acid but is made up entirely of mucopeptide. S. aureus H cells in the lag or stationary phase of growth had an electrophoretic mobility of ?1.10 μm/s/V/cm while those in the logarithmic phase had a mobility of ?0.80 μm/s/V/cm in saline at pH 7.2, 0.6 mM NaHCO₃, 25°C (I = 0.145 g-ions/l). S. aureus 52A5 cells in the same solution had a mobility of ?0.87 μm/s/V/cm in lag and stationary growth phases but a mobility of ?1.30 μm/s/V/cm in the logarithmic growth phase. The S. aureus H cell surfaces at lag phase had pKs of 3.2 and 9.5; at logarithmic phase, 4.2 and 9.0; and at stationary phase, 3.0 and 9.5. The 52A5 cell surfaces at lag phase had pKs of 2.3 and 10.3; at logarithmic phase, 1.7 and 8.5; at stationary phase, 2.6 and 10.2.     

Improved Staphylococcus Medium No. 110

Most media have been unreliable when used to determine the number of coagulase-positive staphylococci in meat pot pies in the presence of overwhelming numbers of Bacillus cells. Various metabolic inhibitors were tested to determine whether they would suppress the growth of Bacillus cells without appreciably affecting the staphylococcal growth. The use of Staphylococcus Medium No. 110 modified by the addition of 0.75 mM sodium azide appears to be practical for the isolation of small numbers of coagulase-positive staphylococci from frozen meat pot pies.     

Occurrence,antibiotic resistance and enteroxigenicity of Staphylococcus spp. in tonsils of slaughtered pigs in Greece

The aims of the present study were to examine the occurrence of Staphylococcus spp. in the tonsils of slaughtered pigs in a regional slaughterhouse in Greece, the antibiotic resistance of the Staphylococcus spp. isolates, and the enteroxigenicity of the S. aureus isolates. Staphylococcus spp. were isolated in 70 (48·61%) out of the total 144 tonsil samples. The predominant species was S. aureus in coagulase-positive staphylococci (CoPS), while the predominant species were Staphylococcus epidermidis and Staphylococcus saprophyticus in the coagulase-negative staphylococci (CoNS). Staphylococcus spp. isolates presented high antibiotic resistance frequencies to tetracycline (97·1%) or clindamycin (80·0%) and low antibiotic resistance frequencies to fusidic acid (14·3%). No methicillin-resistant S. aureus (MRSA) strains were identified, and all Staphylococcus spp. isolates were susceptible to vancomycin. Among the 26 S. aureus isolates, 21 (80·76%) possessed staphylococcal enterotoxin genes with seven different enterotoxin gene profiles. The predominant enterotoxin profile was seg, sei and sej with seven S. aureus isolates. The occurrence of multidrug resistant Staphylococcus spp. in pig tonsils indicate public health risk to pork consumers and handlers in developing antimicrobial resistance.     

Staphylococcus sp. KW-07 contains nahH gene encoding catechol 2,3-dioxygenase for phenanthrene degradation and a test in soil microcosm

We isolated three species of phenanthrene-degrading bacteria from oil-contaminated soils and marine sediment, and assessed the potential use of these bacteria for bioremediation of soils contaminated by polycyclic aromatic hydrocarbons (PAHs). Based on 16S rDNA sequences, these bacteria were Staphylococcus sp. KW-07 and Pseudomonas sp. CH-11 from soil, and Ochrobactrum sp. CH-19 from the marine sediment. By PCR amplification, catechol 2,3-dioxygenase genes (nahH genes) mediating PAH degradation in the chromosome of Staphylococcus sp. KW-07 and Ochrobactrum sp. CH-19, and in plasmid DNA of Pseudomonas sp. CH-11 were detected. All isolates had a similar optimal growth temperature (25 °C) and optimal growth pH (7.0) in a minimal salt medium (MSM) with 0.1% (w/v) phenanthrene as the sole source of carbon and energy. Pseudomonas sp. CH-11 and Staphylococcus sp. KW-07 degraded 90% of added phenanthrene in 3 days and Ochrobactrum sp. CH-19 degraded 90% of the phenanthrene in 7 days under laboratory batch culture conditions. However, Staphylococcus sp. KW-07 was the most effective among the three strains in degradation of phenanthrene in soil. After inoculation of 1 × 10¹¹ cells of Staphylococcus sp. KW-07, over 90% degradation of 0.1% phenanthrene (0.1 g/100 g soil) was achieved after 1 month at 25 °C. The results collectively suggest that the Staphylococcus sp. KW-07 strain isolated may be useful in bioremediation of PAH-contaminated soils.