Lactic Acid Bacteria Cultures Research Articles

Lantibiotics biosynthesis genes and bacteriocinogenic activity of Lactobacillus spp. isolated from raw milk and cheese

Lactobacillus species are usually used as starters for the production of fermented products, and some strains are capable of producing antimicrobial substances, such as bacteriocins. Because these characteristics are highly desirable, research are continually being performed for novel Lactobacillus strains with bacteriocinogenic potential for use by food industries. The aim of this study was to characterise the bacteriocinogenic potential and activity of Lactobacillus isolates. From a lactic acid bacteria culture collection obtained from raw milk and cheese, 27 isolates were identified by 16S rDNA as Lactobacillus spp. and selected for the detection of lantibiotics biosynthesis genes, bacteriocin production, antimicrobial spectra, and ideal incubation conditions for bacteriocin production. Based on the obtained results, 21 isolates presented at least one of the three lantibiotics biosynthesis genes (lanB, lanC or lamM), and 23 isolates also produced antimicrobial substances with sensitivity to at least one proteinase, indicating their bacteriocinogenic activity. In general, the isolates had broad inhibitory activity, mainly against Listeria spp. and Staphylococcus spp. strains, and the best antimicrobial performance of the isolates occurred when they were cultivated at 25 °C for 24 or 48 h or at 35 °C for 12 h. The present study identified the bacteriocinogenic potential of Lactobacillus isolates obtained from raw milk and cheese, suggesting their potential use as biopreservatives in foods.

Identification of bacteriocinogenic Lactococcus isolates from raw milk and cheese capable of producing nisin A and nisin Z

From a lactic acid bacteria culture collection obtained from raw milk and cheese, 27 isolates identified as Lactococcus spp. were studied to characterise their bacteriocinogenic activities. Twenty one isolates were PCR-positive for lantibiotic biosynthesis genes, and 18 of these were for the nisin gene. Twenty isolates were phenotypically identified as bacteriocinogenic, from which 18 also encoded lantibiotic biosynthesis genes and 13 for the nisin gene. The isolates presented wide inhibitory spectra, mainly against Listeria spp., and had their best antimicrobial performance when cultured in de Man, Rogosa and Sharpe (MRS) and modified MRS (0.5% dextrose) broths, incubated at either 25°C for 24h or 35°C for 12h. PCR products for the nisin gene from 8 isolates were sequenced, translated and compared with the nisin A sequence. Differences were observed in three isolates, indicating their capability of producing nisin Z variant. The findings suggest the potential use of these isolates as biopreservatives.

Response of lactic acid bacteria to milk fortification with dietary zinc salts

Zinc is essential for many basic physiological functions in humans. The human body has a limited zinc storage capacity; zinc deficiency can develop rapidly when intakes are low. Food fortification is a successful strategy to control zinc deficiency. Very little information is available about the response of lactic acid bacteria (LAB) to milk fortified with different zinc salts. In this study, the acidifying activity of 98 LAB cultures in reconstituted skim milk fortified with zinc aspartate, zinc sulphate or zinc gluconate was assessed. Based on the overall results, a strain-dependent response was seen irrespective of the zinc source. The cultures with the best performance in terms of acidification rate and acidification extent were used for the formulation of multi-strain starters destined for the manufacture of two zinc-reinforced Italian cheeses (Squacquerone and Caciotta). The cheese-making trials showed that zinc fortification had no impact on the main properties of the cheeses.

Bioconversion of ovine scotta into lactic acid with pure and mixed cultures of lactic acid bacteria

Scotta is the main by-product in the making of ricotta cheese. It is widely produced in southern Europe and particularly in Italy where it represents a serious environmental pollutant due to its high lactose content. With the aim of evaluating whether scotta bioconversion into lactic acid can be considered as an alternative to its disposal, besides providing it with an added value, here the growth, fermentative performances, and lactic acid productions of pure and mixed cultures of Lactobacillus casei, Lactobacillus helveticus, and Streptococcus thermophilus were evaluated on ovine scotta-based media, without and with the addition of nutritional supplements. The outcomes indicate that ovine scotta can be utilized for the biotechnological production of lactic acid with yields up to 92%, comparable to those obtained on cheese-whey. Indeed, the addition of nutritional supplements generally improves the fermentative performances of lactic acid bacteria leading to about 2 g l(-1) h(-1) of lactic acid. Moreover, the use of mixed cultures for scotta bioconversion reduces the need for nutritional supplements, with no detrimental effects on the productive parameters compared to pure cultures. Finally, by using L. casei and S. thermophilus in pure and mixed cultures, up to 99% optically pure L: -lactic acid can be obtained.

Effect of By-product Incorporation on Physicochemical and Microbiological Quality and Shelf Life of Buffalo Meat Fermented Sausage

Studies were conducted on production quality (physicochemical and microbiological) evaluation and shelf life of buffalo meat semi dry fermented sausage. Physicochemical characteristics were based on pH, moisture content, and TBA number, while the microbiological characteristics were dependent on total plate count and yeast and mold count. pH of six samples of fermented sausages incorporated with different levels of by- product (heart, kidney and liver) was found in the range of 5.10-5.16in fresh condition. This reduction of pH was due to the fermentation carried out by the culture of lactic acid bacteria. The moisture contents of sausages samples were in the range of 44.1-45.5. This lowering down of moisture content was due to smoking and dying which was done in succession as the part of production. Thiobarbituric acid (TBA) number is physicochemical property which defines the oxidation states of the fat present in the sausage. TBA values were all six samples of found 0.102-0.140. TPC and Yeast and mold count of the sausage sample express in log cfu/g was not detected in fresh condition. Storage study under refrigerated storage condition (4°C) revealed that pH value and moisture content of buffalo meat semidry fermented sausage decreased consistently while TBA number was found to increase during 75 days of storage at the end of storage (for 75 days). The TBA was found in the 0.211-0.230. TBA values were found in the safe limit even after 75 days of storage. TPC and Yeast & mold count was found in the range 4.10-4.38 and 3.59-4.02 respectively. This indicated shelf life of buffalo meat semi dry fermented sausage incorporated by products was at least 75 days at 4°C.

Organic Acids and Volatile Organic Compounds Produced During Traditional and Starter Culture Fermentation of Bushera, a Ugandan Fermented Cereal Beverage

Starter cultures of lactic acid bacteria (Lactobacillus fermentum MINF99, Weissella confusa MINF8, Lactobacillus plantarum MINF277, Lactobacillus brevis MINF226, and Lactobacillus paracasei subsp paracasei MINF98) were used to ferment Bushera during fermentation (96 h). Organic acids and volatile compounds produced during starter and natural fermentation were investigated. Microbial counts, pH, and sugars were also determined. LAB counts increased from 5.87 ± 0.00 to 8.32 ± 0.02 log cfu mL−1 while yeasts increased from 4.39 ± 0.02 to 7.10 ± 0.04 log cfu mL−1 during natural fermentation. The pH decreased from 6.5 to 3.55–4.0. W. confusa MINF8 attained similar final pH (3.55) as naturally fermented Bushera. Lactate was the dominant acid and varied between 0.34% and 0.66%. W. confusa MINF8 produced the highest amounts of lactate (0.66%). Lactate content in naturally fermented Bushera was 0.89%, 96 h. Glucose and maltose decreased from 8.64–9.27 g kg−1 to 0.13–2.11 gkg−1 and 7.95–8.42 g kg−1 to 0.06–2.66 g kg−1, respectively, in all starter fermented Bushera within 24 h. Glucose and maltose increased during the first 24 h of natural fermentation and then decreased. No citrate was detectable after 24 h. Succinate, pyruvate, and pyro-glutamate were detected and varied between 1.44 and 1495.93 mg kg−1. Methyl alcohols increased with fermentation time and ranged between 0.02 and 0.53 mg kg−1. Methyl alcohols concentration of naturally fermented Bushera were significantly higher (P < 0.05) than those of starters after 24 h. Acetaldehyde levels detected in starter fermented bushera was below 5 mg kg−1 compared to 17.6 mg kg−1 of naturally fermented Bushera. All starters except L. paracasei subsp. paracasei MINF98 reduced the methyl aldehydes within 12 h to levels ranging between 0.01 and 0.06 mg kg−1. Ethyl alcohol was the predominant volatile compound and ranged from 2.16 to 1406 mg kg−1. W. confusa MINF8 produced the highest amounts of ethyl alcohol (1406 g kg−1). Maximum ethyl alcohol amount detected in naturally fermented Bushera was 10.4 g kg−1. Other volatiles detected were butanone, 2, 3-pentanone, diacetyl and ethyl acetate. The study has shown that all starters have ability to singly ferment Bushera. The varying amounts of the volatile compounds observed may influence the sensory properties of Bushera and may be the basis for selecting suitable starters for commercial production.

乳酸菌カルチャーを接種した発酵乾燥食肉製品の特徴

乳酸菌カルチャーを接種した発酵乾燥食肉製品の特徴

Basic Physical-Chemical and Sensorial Evaluation of Some Fermented Mashes Produced from Wheat, Husked Millet, Barley Malt and Oat

Fermented mashes based on different cereal grist are a healthy and nutritious beverage, a source for new functional products with beneficial effects on human health. These mashes are a thick consistency and sour-sweet taste, different colors depending on the ingredients and method of preparation. In this study were determined the main physical and chemical characteristics (pH, volatile and total acidity, total and soluble dry substances, alcohol concentration, dynamic viscosity) and was made sensorial analysis of some boiled aqueous mashes obtained from wheat, husked millet, barley malt and oat. Mashes were fermented at 30°C with a mixed culture of mesophilic cheese lactic acid bacteria and wheat beer yeast for 23h, followed by a cold maturation at 4°C for 42h. This study allows exploring the potential of different cereals to produce cereal-based beverages. The best results were obtained for mashes containing a larger amount of barley malt, followed by mashes with oat. Highest dynamic viscosities were recorded for mashes obtained only from wheat and millet. All determinations were made in triplicate and data were shown as mean ± SD.

Isolation and identification of cultivable lactic acid bacteria in traditional yak milk products of Gansu Province in China

Various traditional fermented yak milk and raw milk foods could be considered as an abundant resource for obtaining novel lactic acid bacteria (LAB) with unique properties. Eighty-eight samples of yak milk products were collected from Gansu Province in China. Three hundred and nineteen strains of LAB isolated from these samples were identified by phenotypic methods, 16S rRNA gene sequence analysis and PCR-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) technology. Among the isolates, one hundred and sixty-four isolates (51.41% of the total) were classified under Lactobacilli, and one hundred and fifty-five (48.59%) belonged to cocci. All the isolates were classified to six genera (Lactobacillus, Lactococcus, Leuconostoc, Streptococcus, Enterococcus and Weissella) and twenty-one species. Lactobacillus helveticus (87 strains), Leuconostoc mesenteroides subsp. mesenteroides (49 strains), Streptococcus thermophilus (39 strains), Lactobacillus casei (31 strains) and Lactococcus lactis subsp. lactis (19 strains) were considered as the predominant populations in the yak milk products. The results showed that there were abundant genus and species LAB existing in yak milk products in Gansu Province in China. The obtained LAB pure cultures may be a valuable source for further starter selection.

Application of quantitative approach focused on the competition of lactic acid bacteria culture with coagulase-positive staphylococci under the conditions related to artisanal cheese fermentation

A quantitative analysis of Staphylococcus aureus growth was carried out in milk fermented with the mesophilic mixed-strain culture of lactic acid bacteria (LAB), in relation to the conditions prevailing during artisanal ewes&amp;rsquo; lump cheese production. Both the temperature and initial volume of the culture had a dramatic effect on the behaviour of the S. aureus strain under study. Depending on the conditions, the growth, reaching maximal population density (N&lt;sub&gt;max&lt;/sub&gt;) and a strong inhibition of S. aureus were observed. Regression analysis of the results enabled us to explain the relationships between the parameters such as the growth or inhibition rate, lag phase and N&lt;sub&gt;max&lt;/sub&gt;&amp;ndash;N&lt;sub&gt;0&lt;/sub&gt; and the temperature and initial culture density on the other hand. The surface methodology enabled to show that the rate of S. aureus inhibition (r&lt;sub&gt;inh&lt;/sub&gt;) was affected by the temperature and volume of LAB inoculum following the equation: r&lt;sub&gt;inh &lt;/sub&gt;=&amp;ndash;0.1302 + 0.02325 &amp;times; T &amp;ndash; 0.000975 &amp;times; T &lt;sup&gt;2 &lt;/sup&gt;&amp;ndash; 0.00001 &amp;times; T &lt;sup&gt;2 &lt;/sup&gt;&amp;times; V &lt;sub&gt;0&lt;/sub&gt;&lt;sup&gt;2&lt;/sup&gt; (R = 0.965). The fact that S. aureus increased in number mostly only by about 1 log and did not reach 10&lt;sup&gt;6&lt;/sup&gt; CFU/ml during our model experiments was the most useful for good manufacturing practice. The knowledge obtained in this study concerned with the quantitative behaviour of S. aureus including the information on the inhibition at the selected environmental factors (temperature, inoculum size, and pH) is essential for the improvement of the fermentation process, quality and safety of artisanal ewes&amp;rsquo; cheese production used as a raw material for industrial Bryndza cheese production.

Isolation and identification of cultivable lactic acid bacteria from traditional goat milk cake in Yunnan province of China

Thirteen goat milk cake samples which were collected from different households in Yunnan province in China were used for isolation and identification of lactic acid bacteria (LAB). The results showed that LAB and yeasts were the dominant microflora in the samples with the LAB counts in all samples ranged from 8.32 log 10 CFU/g to 10.16 log 10 CFU/g. The number of yeasts in most samples ranged from 1.60 log 10 CFU/g to 6.15 log 10 CFU/g respectively. Seventy-six strains of LAB were isolated from these samples and identified by conventional and 16S rRNA gene sequence analysis methods. The LAB strains were found to belong to five general and nine different species, among which the ratio of cocci bacteria (96.1%) was higher than that of rod (3.9%), and was considered to be the major population. The results also showed that Lactococcus lactis, subsp. lactis (72.4%) and Lactococcus garvieae (10.5%) could be considered as the dominant groups population in these samples. The obtained LAB pure cultures may serve as valuable sources for further selection of starter cultures in dairy industry.

Stability of Viable Counts of Lactic Acid Bacteria during Storage of Goat Milk Soft Cheese

The use of goat milk is limited in Indonesia due to lack of good milking practices resulted in disliked goaty smell. One of the method to eliminate this off flavor is by processing the goat milk into soft cheese. The aim of this research was to study the stability of viable starter lactic acid bacteria cultures (Lactobacillus acidophilus FNCC-0051 and L. casei FNCC-0090) during storage of goat milk soft cheese. Three batches of goat milk soft cheeses were produced with different starter cultures L. acidophilus FNCC-0051 (5.0 x 106 cfu mL-1); L. casei FNCC-0090 (5.0 x 106 cfu mL-1); and the mixture of L. acidophilus FNCC-0051 (2.5 x 106 cfu mL-1) and L. casei FNCC-0090 (2.5 x 106 cfu mL-1). The goat milk cheeses had white color and soft. The viable lactic acid bacteria in the goat milk soft cheese reached 109 cfu g-1, which was stable for 8 weeks at 5 °C. Panelists liked goat milk soft cheeses, especially in term of its aroma. The specific aroma produced could mask the disliked goaty smell.

Identification of phenotypically and genotypically related Lactobacillus strains based on nucleotide sequence analysis of the groEL, rpoB, rplB, and 16S rRNA genes

Sixty-eight cultures of lactic acid bacteria were isolated and identified from national fermented milk drinks (airan, koumiss, kurunga, shubat) home-made in different regions of the Republic of Kazakhstan and the Buryat Republic of Russia. The cultures of lactic acid bacteria of the genus Lactobacillus were identified as L. paracasei and L. rhamnosus related to the L. casei group and as L. brevis, L. buchneri, L. diolivorans, and L. parabuchneri (the L. buchneri group) using the classical microbiological methods and on the basis of the 16S rRNA gene sequence analysis. The polymorphism of the nucleotide sequences of the genes groEL, rpoB, and rplB encoding specific proteins was studied for intraspecific differentiation of the lactobacilli. The analysis of these genes allowed a more accurate identification of the lactobacilli that are genetically and phenotypically related to the L. casei group as L. paracasei subsp. paracasei and L. paracasei subsp. tolerans. The gene nucleotide sequences of all the genotyped strains were deposited in the GenBank database.

Production of potentially probiotic beverages using single and mixed cereal substrates fermented with lactic acid bacteria cultures

In the present work, single and mixed cereal substrates were fermented with lactic acid bacteria to study and compare the effect of the media formulation on fermentation parameters. Three cereal flours namely malt, barley and barley mixed with malt (barley–malt) were selected and fermented with two probiotic strains: Lactobacillus plantarum (NCIMB 8826) and Lactobacillus acidophilus (NCIMB 8821). The effect of the single and mixed cereal flour suspensions on the fermentation of these two strains of lactic acid bacteria (LAB) was studied at an incubation temperature of 30°C for 28h. It was found that the LAB growth was enhanced in media containing malt and significant amounts of lactic acid were produced (0.5–3.5g/L). A cell concentration between 7.9 and 8.5 Log10 CFU/mL and a pH below 4.0 was achieved within 6h of fermentation. Though the cell populations in the mixed culture fermentations of mixed substrates were similar to the ones obtained with single cereal flours, significant differences in the production of lactic acid were observed. These results suggest that the functional and organoleptic properties of these cereal-based probiotic drinks could be considerably modified through changes in the substrate or inocula composition.

Predominant effect of host genetics on levels of Lactobacillus johnsonii bacteria in the mouse gut.

The gut microbiota is strongly associated with the well-being of the host. Its composition is affected by environmental factors, such as food and maternal inoculation, while the relative impact of the host's genetics have been recently uncovered. Here, we studied the effect of the host genetic background on the composition of intestinal bacteria in a murine model, focusing on lactic acid bacteria (LAB) as an important group that includes many probiotic strains. Based on 16S rRNA gene genotyping, variation was observed in fecal LAB populations of BALB/c and C57BL/6J mouse lines. Lactobacillus johnsonii, a potentially probiotic bacterium, appeared at significantly higher levels in C57BL/6J versus BALB/c mouse feces. In the BALB/c gut, the L. johnsonii level decreased rapidly after oral administration, suggesting that some selective force does not allow its persistence at higher levels. The genetic inheritance of L. johnsonii levels was further tested in reciprocal crosses between the two mouse lines. The resultant F1 offspring presented similar L. johnsonii levels, confirming that mouse genetics plays a major role in determining these levels compared to the smaller maternal effect. Our findings suggest that mouse genetics has a major effect on the composition of the LAB population in general and on the persistence of L. johnsonii in the gut in particular. Concentrating on a narrow spectrum of culturable LAB enables the isolation and characterization of such potentially probiotic bacterial strains, which might be specifically oriented to the genetic background of the host as part of a personalized-medicine approach.

Diversity of lactic acid bacteria in sian‐sianzih (fermented clams), a traditional fermented food in Taiwan

Sian-sianzih (fermented clams) is a popular traditional fermented food in Taiwan. The lactic acid bacteria (LAB) microflora in sian-sianzih have not been studied in detail. In this study, LAB from sian-sianzih were isolated, characterized and identified. A total of 186 cultures of LAB were isolated from seven sian-sianzih samples and 29 cultures were isolated from its main raw substrate: clams. The identification results revealed up to 11 distinct bacterial species belonging to five genera in sian-sianzih, and three species belonging to two genera in clams. The most common bacterial genera in sian-sianzih were Lactobacillus and Weissella, followed by Leuconostoc, Pediococcus and Lactococcus. A regional similarity in LAB, with differences in diversity, was observed in the current study. On the other hand, Lactococcus lactis subsp. lactis was the most common species found in raw clam samples. The results also suggested that greater LAB diversity could be observed in wild clams than in cultured ones. Furthermore, antibacterial activities of the isolates were determined, and one Weisella hellenica strain showed inhibitory activity against the indicator strain Lactobacilluas sakei JCM 1157(T) . A sensory assessment of seven sian-sianzih samples was also performed and the results indicated that diversity of LAB has a great effect on its aroma and taste formation. The results demonstrate that various LAB species are distributed in sian-sianzih and have a great effect on the flavor of sian-sianzih.

Simultaneous saccharification and fermentation of furfural residues by mixed cultures of lactic acid bacteria and yeast to produce lactic acid and ethanol

In a cellulosic ethanol production system, yeasts cannot be reused, and it is difficult to avoid the formation of lactic acid. A novel mixed fermentation system based on water-rinsed furfural residue was designed to produce lactic acid and ethanol simultaneously by yeast and lactic acid bacteria. The fermentation broth can be used for the production of lactic acid, ethanol, or ethyl lactate, which is a very suitable alternative green solvent. Simultaneous saccharification and fermentation by mixed cultures of lactic acid bacteria and yeast (MSSF) in different conditions were carried out. Acid/alcohol molar ratios (molar ratio of lactic acid to ethanol) were investigated to determine the effects of temperature, substrate concentration, and mass rate of yeast to lactic acid bacterial cells on MSSF. Cellulose conversion rate was also calculated to evaluate the effectiveness of MSSF. The cellulose conversion rate of MSSF was higher than those of ethanol simultaneous saccharification and fermentation and lactic acid simultaneous saccharification and fermentation. The cellulose conversion rate increased with increasing substrate concentration, while the acid/alcohol molar ratio decreased with increasing substrate concentration. These results indicate that yeast cells could provide nutrients for lactic acid bacteria. MSSF at 38 °C is also apt to obtain a low acid/alcohol molar ratio. A 1:1 lactic acid/alcohol molar ratio will be obtained at a fluctuating temperature (38 °C between 0 and 54 h, 42 °C after 54 h) and a substrate concentration of 9%, while keeping a high cellulose conversion rate and final lactic acid concentration. A probable bottleneck for MSSF and its potential solution are also proposed in this paper.

Lactic acid bacteria in the inhibition of Fusarium graminearum and deoxynivalenol detoxification

Considering the agronomic and industrial damage that is caused by the fungus Fusarium graminearum, as well as the serious health risks it poses to humans and animals exposed to F. graminearum-produced mycotoxin deoxynivalenol (DON), this study evaluated the ability of different lactic acid bacteria (LAB) strains to inhibit fungal development and remove DON in vitro. The antagonistic effects of strains and commercial cultures of LAB were evaluated against F. graminearum IAPAR 2218 by the agar diffusion method. Additionally, the influence of the culture media, pH and the presence of lactic and acetic acid on these effects was tested. The capacity to remove DON by viable cells and heat-inactivated cells was analysed in liquid media and quantified by high performance liquid chromatography (HPLC). All isolated strains and commercial cultures inhibited the fungus and removed DON. The pH and culture media concentration did not influence these abilities, but heat inactivation had a strong effect on the ability of bacteria to remove mycotoxin. The isolated bacteria are able to inhibit F. graminearum growth and remove DON in vitro. This study suggests potential application of the isolated LAB strains in the inhibition of F. graminearum IAPAR 2218 and DON removal in vitro.

Volatile Compound Fingerprinting of Mixed-Culture Fermentations

With the advent of the -omics era, classical technology platforms, such as hyphenated mass spectrometry, are currently undergoing a transformation toward high-throughput application. These novel platforms yield highly detailed metabolite profiles in large numbers of samples. Such profiles can be used as fingerprints for the accurate identification and classification of samples as well as for the study of effects of experimental conditions on the concentrations of specific metabolites. Challenges for the application of these methods lie in the acquisition of high-quality data, data normalization, and data mining. Here, a high-throughput fingerprinting approach based on analysis of headspace volatiles using ultrafast gas chromatography coupled to time of flight mass spectrometry (ultrafast GC/TOF-MS) was developed and evaluated for classification and screening purposes in food fermentation. GC-MS mass spectra of headspace samples of milk fermented by different mixed cultures of lactic acid bacteria (LAB) were collected and preprocessed in MetAlign, a dedicated software package for the preprocessing and comparison of liquid chromatography (LC)-MS and GC-MS data. The Random Forest algorithm was used to detect mass peaks that discriminated combinations of species or strains used in fermentations. Many of these mass peaks originated from key flavor compounds, indicating that the presence or absence of individual strains or combinations of strains significantly influenced the concentrations of these components. We demonstrate that the approach can be used for purposes like the selection of strains from collections based on flavor characteristics and the screening of (mixed) cultures for the presence or absence of strains. In addition, we show that strain-specific flavor characteristics can be traced back to genetic markers when comparative genome hybridization (CGH) data are available.

Fourier Transform Infrared and Raman Spectroscopies for the Rapid Detection, Enumeration, and Growth Interaction of the Bacteria Staphylococcus aureus and Lactococcus lactis ssp. cremoris in Milk

Staphylococcus aureus is one of the main pathogenic microorganisms found in milk and dairy products and has been involved in bacterial foodborne outbreaks in the past. Current enumeration techniques for bacteria are very time-consuming, typically taking 24 h or longer, and bacterial antagonism in the form of lactic acid bacteria (LAB) may inhibit the growth of S. aureus . Therefore, the aim of this investigation was to establish the accuracy and sensitivity of rapid nondestructive metabolic fingerprinting techniques, such as Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy (RS), in combination with multivariate analysis techniques, for the detection and enumeration of S. aureus in milk, as well as to study the growth interaction between S. aureus and Lactococcus lactis ssp. cremoris , a common LAB. The two bacterial species were investigated both in a pure monoculture and in a combined inoculated coculture after inoculation into ultraheated milk during the first 24 h of growth at 37 °C. Plating techniques were used to obtain primary reference data for viable bacteria counts. Principal component discriminant function analysis, canonical correlation analysis, partial least-squares (PLS), and kernel PLS (KPLS) multivariate statistical techniques were employed to analyze the data. FT-IR provided very reasonable quantification results both with PLS and KPLS, the latter providing marginally better predictions, with correlation coefficients in the test set (Q(2)) and training set (R(2)) varying from 0.64 to 0.76 and from 0.78 to 0.88 for different bacterial sample combinations. RS results were less encouraging with high degrees of error and poor correlation to viable bacterial counts. S. aureus growth was not inhibited by the presence of the LAB, but metabolic fingerprinting of the coculture indicated that the phenotype of this dual bacterial culture was closer to that of pure LAB cultures. In conclusion, FT-IR spectroscopy in combination with the above multivariate techniques appears to be a promising discrimination and enumeration analytical technique for the two bacterial species. In addition, it has been demonstrated that the L. cremoris metabolic effect in milk dominates that of S. aureus even though there was no growth antagonism observed.