Comparative evaluation of spoilage-related bacterial diversity and metabolite profiles in chilled beef stored under air and vacuum packaging.

Microbial spoilage is a complex event to which different bacterial populations and metabolites can contribute depending on the storage conditions. This study explored the evolution of spoilage and related volatile organic compounds (VOCs) in chilled beef under air and vacuum packaging (VP). The results suggested that different storage conditions affected changes in bacterial communities and metabolites in beef and consequently affected the odor properties of the stored beef, thereby leading to spoilage. Bacterial species belonging to Pseudomonadaceae (Pseudomonas spp.) and lactic acid bacteria (Lactobacillus sp.) dominated the bacterial communities in beef stored under air and VP, respectively, with several VOCs associated with off-odors of the stored beef and most likely produced by both bacteria. Our results suggested several microbial VOCs that could be used as potential spoilage indicators, including acetic acid, butanoic acid, and 2-butanone in VP-stored beef and 3-methylbutan-1-ol, ethyl acetate, acetoin, 2-butanone, and diacetyl in air-stored beef. These findings might provide valuable information regarding the quality monitoring of beef during storage.

Viable bacterial population and persistence of foodborne pathogens on the pear carpoplane.

BACKGROUND: Knowledge on the culturable bacteria and foodborne pathogen presence on pears is important for understanding the impact of postharvest practices on food safety assurance. Pear fruit bacteria were investigated from the point of harvest, following chlorine drenching and after controlled atmosphere (CA) storage to assess the impact on natural bacterial populations and potential foodborne pathogens. RESULTS: Salmonella spp. and Listeria monocytogenes were detected on freshly harvested fruit in season one. During season one, chemical drenching and CA storage did not have a significant effect on the bacterial load of orchard pears, except for two farms where the populations were lower 'after CA storage'. During season two, bacterial populations of orchard pears from three of the four farms increased significantly following drenching; however, the bacterial load decreased 'after CA storage'. Bacteria isolated following enumeration included Enterobacteriaceae, Microbacteriaceae, Pseudomonadaceae and Bacillaceae, with richness decreasing 'after drench' and 'after CA storage'. CONCLUSION: Salmonella spp. and L. monocytogenes were not detected after postharvest practices. Postharvest practices resulted in decreased bacterial species richness. Understanding how postharvest practices have an impact on the viable bacterial populations of pear fruit will contribute to the development of crop-specific management systems for food safety assurance. © 2016 Society of Chemical Industry.

Study of psychrophilic and psychrotolerant micro-organisms isolated in cold rooms used for pharmaceutical processing.

AIMS: To examine for psychrophilic or psychrotolerant micro-organisms in pharmaceutical cold rooms (in relation to numbers, incidents and species) and to determine, where such micro-organisms are present, whether standard microbiological environmental monitoring regimes require modification. This is presented as a case study. METHODS AND RESULTS: Comparative environmental monitoring within different pharmaceutical facility cold rooms (using standard mesophilic and low temperature incubation). Data were collected over two periods, 5 years apart. The results indicated that psychrophilic micro-organisms were not present and that those micro-organisms deemed psychrotolerant, primarily pseudomonads, could be grown on standard media under mesophilic conditions. CONCLUSIONS: Psychrophilic micro-organisms were not detected and those considered to be psychrotolerant were only found in low numbers. Pyschrotolerant organisms were recovered under both low temperature incubation conditions and under standard conditions (between 20 and 35°C). Further evaluation may be required, using alternative agar, and microbiologists should regularly review the species recovered to note differences between different environments. SIGNIFICANCE AND IMPACT OF THE STUDY: The study came about from requests made by US and UK regulators concerning the risk of any extremophiles present in pharmaceutical manufacturing facilities upon product safety. Regulators expressed concerns about whether standard, and accepted, environmental monitoring regimes were capable of detecting such micro-organisms. The data provide a benchmark to support pharmaceutical manufacturers in relation to their existing monitoring programmes or as a case study with which to undertake a similar study.

Changes in psychrotrophic microbial populations during milk creaming to produce Grana Trentino cheese.

The aim of this study was to study the psychrotrophic microbiota developing during milk creaming of Grana Trentino cheese-making. 138 isolates from raw whole milk, cream and skim milk samples were screened by Randomly amplified polymorphic DNA PCR biotyping and representative strains of each biotype were characterised by partial 16S rRNA gene sequencing and enzymatic activity. Pseudomonadaceae were commonly isolated in cream samples while Streptococcaceae and Enterobacteriaceae in milk samples. Moraxellaceae and Flavobacteriaceae were found in both cream and milk samples. More than 80% of psychrotrophic isolates could grow at 37°C. All Flavobacteriaceae and half of Pseudomonadaceae biotypes displayed proteolytic activity on milk agar even at low temperatures such as 10°C. All Streptococcaceae and some of Enterobacteriaceae displayed acidifying activity and almost all Acinetobacter spp. (Moraxellaceae) displayed lipolytic activity towards tributyrin. Even if psychrotrophic bacteria is not the dominant microbial group in raw milk, their total number increases during creaming and becomes one of the most present group together with Lactic Acid Bacteria. Their enzymatic activities may be key players in determining milk quality for cheese making.

Combined effect of MAP and thyme essential oil on the microbiological, chemical and sensory attributes of organically aquacultured sea bass (Dicentrarchus labrax) fillets.

The present study evaluated the combined effect of Modified Atmosphere Packaging (MAP) using two different gas mixtures (40% CO2/50% N2/10% O2; treatment M1, 60% CO2/30% N2/10% O2, treatment M2), and thyme oil (0.2% v/w, T) used as a natural preservative, on the quality and shelf life extension of fresh filleted sea bass, product of organic aquaculture, during refrigerated storage (4 +/- 0.5 degrees C), for a period of 21 days. Aerobically packaged sea bass fillets (A) were used as control samples. The dominant bacteria in the microflora of sea bass fillets, irrespective of treatment, were the pseudomonads and the H2S-producing bacteria while lactic acid bacteria were also part of the dominant microflora. Total viable counts for fresh sea bass fillets stored aerobically exceeded 7 log CFU/g after 7 days, while treatments A+T, M1, M2 and M2+T reached the same value on days 9, 10, 12 and 19, respectively. Among the chemical indices determined, TBA values were within the good quality limits (2-4 mg MDA/kg), during the sensory shelf lives of sea bass samples, irrespective of treatment. TVB-N proved to be a suitable index for the spoilage of sea bass fillets stored at 4 degrees C. Samples A and A+T, M1, M2, M2+T exceeded the proposed upper TVB-N acceptability limit (10 mg N/100 g) on days 6, 8, 9, 13 and 17 of storage respectively. TMA-N values of the samples A, A+T and M1, M2, M2+T exceeded the proposed limit (4 mg N/100 g) on days 6, 9, 9-10, 13 and 19 of storage, respectively, and correlated well with the microbiological data, indicating that along with TVB-N, TMA-N may serve as a useful index for sea bass fillets spoilage. As regards sensory evaluation, the presence of thyme oil proved to improve the sensory quality of sea bass fillets when used in combination with MAP2, providing a shelf life of 17 days as compared to 6 days of the control samples.

Control of spoilage microorganisms in minced pork by a self-developed modified atmosphere induced by the respiratory activity of meat microflora.

The changes in microbial flora of minced pork during aerobic storage at 0, 5, 10 and 15 degrees C were studied. Minced pork samples (100g) were packed using two types of packaging films: (a) a common food film with high permeability (HPF) and (b) a film with low permeability (LPF). The respiratory activity of meat microflora and the use of a LPF resulted in a modified atmosphere in the package headspace developed during storage. Oxygen concentration decreased from 18.7% (after packaging) to 7% (after 15 days of storage) in packages with LPF, stored at 0 degrees C, while CO(2) increased from 3% to 10.5%, respectively. On the contrary, no significant atmosphere changes were observed during storage of HPF packages. The self-developed modified atmosphere in LPF packages resulted in a significant inhibition of pseudomonad growth which was more pronounced at low storage temperatures. For example, during storage at 0 degrees C, the growth rate of pseudomonads in meat packed with LPF was reduced by 48.7% compared to HPF. At 10 degrees C the latter reduction decreased to 13.7%. LPF packaging was also found to inhibit the growth of Brochothrix thermosphacta but this inhibition was weaker compared to pseudomonads. The effect of storage temperature on the growth rate of pseudomonads and B. thermosphacta in minced pork packed with the different films was modeled using an Arrhenius equation. For both bacteria, the activation energy was higher for LPF packaging. This can be attributed to the increased inhibitory effect of the modified atmosphere at lower storage temperature. The Arrhenius model was further used to evaluate the effect of temperature on the time required by the two bacteria to reach a spoilage level of 10(7)CFU/g. The results showed that when LPF packaging is combined with effective temperature control the time-to-spoilage can be significantly extended compared to HPF packaging.

Effect of fluorescent pseudomonades and Trichoderma sp. and their combination with two chemicals on Penicillium digitatum caused agent of citrus green mold.

Citrus green mold (Penicillium digitatum) causes economic losses. Chemical fungicides such as imazalil provide the primary means for controlling green mold decay of citrus fruits. Continuous use of fungicides has faced two major obstacles- increasing public concern regarding contamination of perishables with fungicidal residues, and proliferation of resistance in the pathogen populations. The aim of this research was to determine if the attacks of green mold on orange could be reduced by usage of biocontrol agent alone or in combination with low dosage of imazalil or sodium bicarbonate. Pseudomonas fluorescens isolate PN, P. fluorescens isolate PS and Trichoderma virens isolate TE were evaluated as potential biological agents for control of green mold of oranges caused by P. digitatum. Increasing concentration of SB decreased spore germination of P. digitatum. In laboratory tests, a cell suspension (10(8) cells per ml.) of bacterial strains reduced the incidence of green mold. On fruits surface biocontrol activity of antagonistic isolates was significantly increased when combined with low dosage of imazalil (500ppm) or sodium carbonate (5%). Effect of Trichoderma virens on controlling P. digitatum was better than others with or without these chemicals.

Differential expression and positioning of chemotaxis methylation proteins in Caulobacter.

Proteins involved in chemotaxis methylation reactions have been identified in Caulobacter crescentus and their activities, times of synthesis and cellular positions have been determined. The methyl-accepting chemotaxis proteins, the methyl-transferase and the methylesterase were all shown to be active in the flagella-bearing swarmer cell, but all three activities were lost after the swarmer cells shed their flagellum and differentiated into a stalked cell. The membrane methyl-accepting chemotaxis proteins were shown to be synthesized before cell division, coincident with the synthesis of the components of the flagellum, and to be specifically localized in the membrane of the incipient swarmer cell portion of the predivisional cell. The cytoplasmic methylesterase was also found to be differentially synthesized coincident with the period of flagellar biogenesis. Furthermore, methyltransferase activity, present in the predivisional cell, was detected only in the swarmer cell upon cell division. These results demonstrate that the chemotaxis methylation machinery is positionally biased toward one portion of the predivisional cell, and that the time of expression of a set of fla and che genes is correlated with the positioning of their gene products within the cell.

Pseudomonads associated with midrib rot and soft rot of butterhead lettuce and endive.

During the past ten years, bacterial soft rot and midrib rot of glasshouse-grown butterhead lettuce (Lactuca sativa L. var. capitata) and field-grown endive (Cichorium endivia L.) has become increasingly common in the region of Flanders, Belgium. Severe losses and reduced market quality caused by bacterial rot represent an important economical threat for the production sector. Symptoms of midrib rot are a brownish rot along the midrib of one or more inner leaves, often accompanied by soft rot of the leaf blade. Twenty-five symptomatic lettuce and endive samples were collected from commercial growers at different locations in Flanders. Isolations of dominant bacterial colony types on dilution plates from macerated diseased tissue extracts yielded 282 isolates. All isolates were characterized by colony morphology and fluorescence on pseudomonas agar F medium, oxidase reaction, and soft rot ability on detached chicory leaves. Whole-cell fatty acid methyl esters profile analyses identified the majority of isolates (85%) as belonging to the Gammaproteobacteria, which included members of the family Enterobacteriaceae (14%) and of the genera Pseudomonas (73%), Stenotrophomonas (9%), and Acinetobacter (3%). Predominant bacteria were a diverse group of fluorescent Pseudomonas species. They were further differentiated based on the non-host hypersensitive reaction on tobacco and the ability to rot potato slices into 4 phenotypic groups: HR-/P- (57 isolates), HR-/P+ (54 isolates), HR+/P (16 isolates) and HR+/P+ (35 isolates). Artificial inoculation of suspensions of HR-, pectolytic fluorescent pseudomonads in the leaf midrib of lettuce plants produced various symptoms of soft rot, but they did not readily cause symptoms upon spray inoculation. Fluorescent pseudomonads with phenotype HR+ were consistently isolated from typical dark midrib rot symptoms, and selected isolates reproduced the typical midrib rot symptoms when spray-inoculated onto healthy lettuce plants.

A lithotrophic microbial fuel cell operated with pseudomonads-dominated iron-oxidizing bacteria enriched at the anode.

In this study, we attempted to enrich neutrophilic iron bacteria in a microbial fuel cell (MFC)-type reactor in order to develop a lithotrophic MFC system that can utilize ferrous iron as an inorganic electron donor and operate at neutral pHs. Electrical currents were steadily generated at an average level of 0.6 mA (or 0.024 mA cm(-2) of membrane area) in reactors initially inoculated with microbial sources and operated with 20 mM Fe(2+) as the sole electron donor and 10 ohm external resistance; whereas in an uninoculated reactor (the control), the average current level only reached 0.2 mA (or 0.008 mA cm(-2) of membrane area). In an inoculated MFC, the generation of electrical currents was correlated with increases in cell density of bacteria in the anode suspension and coupled with the oxidation of ferrous iron. Cultivation-based and denaturing gradient gel electrophoresis analyses both show the dominance of some Pseudomonas species in the anode communities of the MFCs. Fluorescent in-situ hybridization results revealed significant increases of neutrophilic iron-oxidizing bacteria in the anode community of an inoculated MFC. The results, altogether, prove the successful development of a lithotrophic MFC system with iron bacteria enriched at its anode and suggest a chemolithotrophic anode reaction involving some Pseudomonas species as key players in such a system. The system potentially offers unique applications, such as accelerated bioremediation or on-site biodetection of iron and/or manganese in water samples.

The response of Gluconobacter oxydans to sorbic and benzoic acids.

The minimal inhibitory concentrations (MIC) of sorbic and benzoic acids for Gluconobacter oxydans were 1000 mg/l and 900 mg/l respectively at pH 3.8. A reduction in the pH of the test medium to 3.3 reduced the MIC of both preservatives by about 300 mg/l. When G. oxydans was grown in the presence of sublethal concentrations of sorbic or benzoic acids before the MIC was determined, the MIC of both compounds increased substantially within 1 h. Growth of G. oxydans was modified in several ways by the presence of sorbic acid in the medium. The duration of the lag phase increased and there was a substantial decrease in the viable count during the lag phase in the presence of high concentrations. The generation time increased and the viable count at the end of the logarithmic phase was reduced. At 1 degree C, G. oxydans grew in the absence of sorbic acid but was inactivated by 400 mg sorbic acid/l. At 37 degrees C the viable count of suspensions of G. oxydans decreased in both the absence and presence of sorbic acid. Sorbic acid increased the death rate. Growth of G. oxydans was prevented by eliminating air from culture vessels, combined with the addition of ascorbate to the medium containing 400 mg sorbic acid/l.

Effect of irradiation on microorganisms in strawberries.

Seventeen samples of strawberries from seven different growers were analysed for total counts, Enterobacteriaceae, fluorescent pseudomonads and yeast and mould counts before and after irradiation at 1.2 or 2 kGy. Enterobacteriaceae were absent (less than 5 cfu/g) from all irradiated strawberries but were always detected at counts of greater than 30 cfu/g in untreated samples. This criterion was true for both fresh and stored (5 days at 8 degrees C) strawberries. Assuming no other sanitizing treatment, the Enterobacteriaceae count appears to be suitable for differentiating between irradiated and non-irradiated strawberries. The other counts used in this study were not suitable for this purpose. Isolates from irradiated strawberries could be classified into four types based on colony morphology. Three types consisted of aerobic spore-forming bacteria whilst the fourth group consisted of yeasts.

A novel modelling approach for predicting microbial growth in a raw cured meat product stored at 3 degrees C and at 12 degrees C in air.

To predict microbial growth during chill storage of a traditional Greek raw sausage, a numerical model was developed and validated. In our novel approach, the specific growth rate of each microbial population was calculated on the basis of the main microbial populations grown in the sausage. In addition, the specific destructive effect of the sausage ecosystem was introduced to evaluate microbial growth. The model was integrated by the Runge-Kutta method and the parameter values were optimised by the least squares method. Fitting of the model to the experimental data derived from four sausage batches stored aerobically at 3 and 12 degrees C successfully described the microbial growth kinetics in the sausage niche. Finally, the parameter values estimated by the fitting of the model on the data set from each batch were used to predict microbial growth in the other batches at both storage temperatures.

Influence of soft rot bacteria on growth of Listeria monocytogenes on potato tuber slices.

Growth of Listeria monocytogenes on potato tuber slices and its interaction with four representative species of soft rot bacteria (Pseudomonas fluorescens, P. viridiflava, Erwinia carotovora subsp. carotovora, and Xanthomonas campestris) were investigated. When potato tuber slices were inoculated with one of two L. monocytogenes strains (Scott A and ATCC 15313), an increase in numbers of 3 to 4 logs per gram of tissue was observed with samples that were stored at 20 degrees C for 6 days. However, an increase of about 2 logs was observed with samples that were stored at 8 degrees C for 12 days. When potato slices were simultaneously inoculated with L. monocytogenes and one of the four soft rot bacteria, the growth of L. monocytogenes was inhibited in the presence of P. fluorescens or P. viridiflava but was not significantly affected in the presence of E. carotovora or X. campestris. The antagonism of the two pseudomonads to L. monocytogenes was also observed in potato tuber extract and in culture media. Formation of inhibition zones was observed only in iron-deficient media but not in the medium supplemented with FeCl3. In addition, production of fluorescent siderophore (pyoverdin) by these two pseudomonads was demonstrated. L. monocytogenes was unable to colonize macerated plant tissue induced by soft-rotting bacteria 2 days before inoculation of the pathogen. These results indicate that growth of L. monocytogenes on potato tuber slices is differentially affected by soft rot bacteria and that antagonism of fluorescent pseudomonads to L. monocytogenes is possibly caused by the production of iron-chelating siderophore by these pseudomonads.

Level of methionine synthase activity and interconversion of methylcobalamin and adenosylcobalamin in a facultative methylotroph, Protaminobacter ruber.

Protaminobacter ruber was cultured in a medium containing [57Co]cyanocobalamin with a "two-step cultivation method" and the forms of vitamin B12 compounds in the cells were examined. Methylcobalamin was detected in the early phases of growth and reached a maximum of about 40% of all cobalamins extracted from the cells. In the stationary phase of growth, almost all cobalamins consisted of adenosylcobalamin. Recultivation of the cells of the stationary phase in a fresh medium resulted in the conversion of adenosylcobalamin into methylcobalamin. Interconversion of methylcobalamin and adenosylcobalamin was presumed from these facts. The formation of adenosylcobalamin from methylcobalamin was demonstrated with a cell-free extract system from P. ruber. The rate of conversion of methylcobalamin into adenosylcobalamin was highest among several cobalamin analogs tested. Propylation of 5-methyltetrahydrofolate: homocysteine methyltransferase with 1-iodopropane did not affect this conversion reaction, which was probably catalyzed by methyltransferase and adenosyltransferase.

[Species of the genus Beijerinckia Derx isolated from a soil of Corrientes (Argentina)]. / Especies del género Beijerinckia Derx aisladas en un suelo de Corrientes (República Argentina).

Four species of bacteria were isolated from one soil of Corrientes (Argentina). They were first classified as Beijerinckia genus based on their cultural, morphological and physiological characteristics. The basic criteria were: growth media without combined nitrogen and fixation of high amounts of gaseous nitrogen (as determined by the acetylene-ethylene assay). Further studies permitted the classification of these microorganisms in the following species: Beijerinckia indica, Beijerinckia fluminensis, Beijerinkia mobilis and Beijerinckia derxii.

[Conditions for immobilizing Streptomyces erythreus in a calcium alginate gel and the apparatus setup for the process]. / Izuchenie uslovii immobilizatsii Streptomyces erythreus v kal'tsii-al'ginatnom gele i apparaturnoe oformlenie protsessa.

A laboratory unit for production of calcium alginate gel granules with immobilized microorganisms is described. It provides sterile production of particles from tens micrometers to 2 mm in diameter. Expediency of using biocatalysts in the form of fine granules is exemplified with a number of immobilized microorganisms. Conditions for immobilizing the erythromycin producing organism by its incorporation into the calcium alginate gel were studied. Viability of the actinomycete in the gel was shown by consumption of the nutrients and biosynthesis of the antibiotic.

Presence and survival of Escherichia coli O157:H7 on lettuce leaves and in soil treated with contaminated compost and irrigation water.

Escherichia coli O157:H7 outbreaks associated with produce consumption have brought attention to contaminated compost manure, and polluted irrigation water as potential sources of pathogens for the contamination of these crops. The aim of this study was to determine the potential transfer of E. coli O157:H7 from soil fertilized with contaminated compost or irrigated with contaminated water to edible parts of lettuce together with its persistence in soil under field conditions in two different seasons (fall and spring). Moreover, its survival on lettuce sprinkled with contaminated irrigation water was evaluated, as well as the prevalence of aerobic mesophilic, Enterobacteriaceae and Pseudomonadaceae in control lettuce samples. Four treatments, contaminated compost, surface and sprinkle irrigation with contaminated water and uninoculated pots, were used in this work. Contaminated compost was applied to soil in the pots before lettuce was transplanted and contaminated irrigation water was applied twice and three times on the plants after the seedlings were transplanted, for sprinkle and surface irrigation, respectively. E. coli O157:H7 survived in soil samples for 9 weeks at levels, 4.50 log cfu gdw(-1) (dw, dry weight) in fall and 1.50 log cfu gdw(-1) in spring. The pathogen survives better in fall, indicating an important influence of environmental factors. E. coli O157:H7 population in lettuce leaves after sprinkle irrigation was very high (between 10(3) and 10(6) cfu g(-1)), but decreased to undetectable levels at field conditions. There was also transfer of E. coli O157:H7 from soil contaminated with compost or irrigated with contaminated water to lettuce leaves, mainly to the outer ones. The mean counts for aerobic mesophilic, Enterobacteriaceae and Pseudomonadaceae populations were also influenced by environmental conditions; higher levels were observed under fall conditions than in spring conditions. Contamination of lettuce plants in the field can occur through both contaminated composted manure and irrigation water and persist for several months.

Shelf-life extension of fresh Tuber aestivum and Tuber melanosporum truffles by modified atmosphere packaging with microperforated films.

The aim of this study was to design a modified atmosphere packaging suitable for Tuber melanosporum and Tuber aestivum truffles that extend their shelf life and their availability as a fresh product. Their respiration rates were determined by O(2) depletion and CO(2) formation in closed systems performed at different temperatures: 4, 10, and 23 degrees C. The results were fitted by exponential equations and derivatives of these equations were used to obtain the experimental respiration rates. Our results revealed high respiration rates in both species of truffles and respiratory quotients (RQ) higher than 1 in all the cases studied. A linear dependence of respiration rate, both R(O2) and R(CO2), on O(2) concentration was revealed. A mathematical model was used to predict the evolution of the gaseous composition at 4 degrees C in the interior of polypropylene trays (250 mL) heat sealed with 4 microperforated films of different transmission rates. A microperforated film with 2 holes (90 x 50 microm) was selected to produce an internal atmosphere of 15%CO(2)/7%O(2) at 4 degrees C. The predicted atmosphere composition was confirmed by the experimental results. The quality and microbiological characteristics of fresh truffles, packaged in these conditions, revealed that the microbial counts of pseudomonads and Enterobacteriaceae were decreased, the weight loss was reduced, the typical hard texture was maintained, and the development of mycelium growth was delayed, enabling good scores for aroma and flavor, and therefore prolonging the shelf life of T. melanosporum and T. aestivum truffles to 28 and 21 d, respectively. Practical Application: This study describes the benefits of using MAP with microperforated films in the postharvest storage of Tuber melanosporum and Tuber aestivum fresh truffles. The shelf life of T. aestivum is prolonged to 21 d and of T. melanosporum to beyond 28 d increasing the possibilities for a foreign market.

Use of Lactobacillus plantarum and glucose to control the fermentation of "Bella di Cerignola" table olives, a traditional variety of Apulian region (Southern Italy).

UNLABELLED: The purpose of this study was to evaluate the use of Lactobacillus plantarum, isolated from table olives "Bella di Cerignola," a traditional variety of Apulian region (Southern Italy), as a starter for this kind of food. We focused on the interaction of the starter with the natural occurring microflora, the quantitative/qualitative composition of yeast population, the decrease of pH, and the content of organic acids. After a preliminary characterization, 3 strains of Lb. plantarum, selected for their probiotic and technological performances, were used as a multiple-strain starter and inoculated (approximately 2%) in olives, processed according to Spanish style, brined at 8% and 10% of NaCl and added with 0.5% of glucose. The combination of the starter and glucose assured a correct fermentation course, decreasing the pH up to a safe value (4.3 to 4.5) and controlled the growth of yeasts. The concentrations of both L- and D-lactic acids increased throughout the fermentation, while citric and malic acids (both the isomers D and L) remained at low levels (0.2 to 0.4 g/L). Concerning yeast species, Candida guilliermondii was mainly isolated at the beginning (7 to 14 d), while C. famata prevailed at the end of fermentation. PRACTICAL APPLICATIONS: To the question "How to standardize and maintain quality of "Bella di Cerignola" olives (Southern Italy)" we can suggest the following answer: use Lb. plantarum and a low amount of glucose (0.5%). The result is a decrease of the pH below the safety break point.