Combination of culture-dependent and culture-independent molecular methods for the determination of lactic microbiota in sucuk

In this study, the culture-dependent and culture-independent molecular methods were used for the identification of lactic acid bacteria (LAB) in sucuk a Turkish fermented dry sausage. On the one hand, the PCR-DGGE method targetting the V1 and V3 regions of 16S DNA was applied to DNA that was directly extracted from sucuk samples. On the other hand, rep-PCR fingerprinting was performed for the primary differentiation and grouping of the isolates, and the results were confirmed by sequencing of the 16S rDNA and 16S-23S rDNA intergenic spacer region. As a result of the PCR-DGGE analysis of all the samples, total 8 different lactic acid bacteria were identified, and Lactobacillus sakei, Lactobacillus curvatus and Weissella viridescens were the dominant microbiota among these bacteria. The culture-dependent approach indicated that the majority of the strains belonged to the Lactobacillus genera including Lb. sakei, Lactobacillus plantarum, Lb. curvatus, Lactobacillus brevis, Lactobacillus farciminis and Lactobacillus alimentarius. However, Leuconostoc and Weisella were also detected as minor genera. Again, Lactococcus piscium, Weissella halotolerans, Staphylococcus succinus and the comigrated Staphylococcus piscifermentans/Staphylococcus condimenti/Staphylococcus carnosus group were detected only with the culture-independent method while Lb. plantarum, Leuconostoc mesenteroides and Leuconostoc citreum were identified only by using the culture-dependent method. In the results, it was concluded that the combination of culture-dependent and culture-independent methods was necessary for reliable and detailed investigation of LAB communities in fermented food products.     

A culture-dependent and -independent approach for the identification of lactic acid bacteria associated with the production of nem chua,a Vietnamese fermented meat product

In this study, the diversity of the native lactic acid bacteria (LAB) population in nem chua, a popular traditional Vietnamese uncooked fermented meat, was described using a combination of culture-dependent and culture-independent methods. A total of two hundred seventy-three LAB isolates were subjected to a polyphasic identification approach combining (GTG)₅-PCR fingerprinting and phenylalanyl-tRNA synthase α subunit (pheS) and RNA polymerase α subunit (rpoA) gene sequence analysis. LAB associated with nem chua were identified as Lactobacillus pentosus (21%), Lactobacillus plantarum (29.7%), Lactobacillus brevis (5%), Lactobacillus paracasei (0.4%), Lactobacillus fermentum (0.7%), Lactobacillus acidipiscis (0.4%), Lactobacillus farciminis (23%), Lactobacillus rossiae (0.4%), Lactobacillus fuchuensis (0.7%), Lactobacillus namurensis (0.4%), Lactococcus lactis (0.4%), Leuconostoc citreum (9.5%), Leuconostoc fallax (1%), Pediococcus acidilactici (1%), Pediococcus pentosaceus (4%), Pediococcus stilesii (1%), Weissella cibaria (0.7%) and Weissella paramesenteroides (0.7%). Furthermore, PCR-DGGE was also applied as a culture-independent method in this study. Results indicated the presence of species of which no isolates were recovered, i.e. Lactobacillus helveticus/crispatus, Lactococcus garvieae and Vagococcus sp. Conversely, not all isolated bacteria were detected by PCR-DGGE. Principal component and discriminant analysis disclosed correlations between the different production locations and certain isolated LAB species and strains and/or DGGE bands suggesting possible influences of locally prevailing production practices on the nem chua LAB microbiota.     

A polyphasic approach in order to identify dominant lactic acid bacteria during pasta manufacturing

Using a polyphasic approach, we have isolated and identified, lactic acid bacteria (LAB) in samples directly collected from an artisanal pasta-making manufactory located in Puglia (South Italy). Samples were collected during several steps of pasta processing and LAB were isolated on MRS and M17 plates. Furthermore, strains were grouped in a total of eight species by means of randomly amplified polymorphic DNA (RAPD)-polymerase chain reaction (PCR) typing and 16S rDNA sequencing. The majority of strains were identified as belonging to Pediococcus pentosaceus and Enterococcus faecium species. The remaining strains were characterized and assigned to Weissella confusa, Pediococcus acidilactici, Leuconostoc mesenteroides, Leuconostoc citreum, Lactobacillus fermentum and Lactobacillus plantarum species. Strains were identified from all the analysed samples, and growth of LAB was monitored from extrusion to pre-heating steps.     

Isolation and characterisation of lactic acid bacteria from jiang-gua (fermented cucumbers), a traditional fermented food in Taiwan

BACKGROUND: Jiang‐gua (fermented cucumbers) is a popular traditional fermented food in Taiwan. The microflora of lactic acid bacteria (LAB) in jiang‐gua have not been investigated in detail. In this study, LAB from jiang‐gua were isolated, characterised and identified. RESULTS: A total of 103 LAB were isolated; 70 cultures were isolated from jiang‐gua samples and 33 cultures were isolated from its raw substrate, cucumber. These isolates were mainly characterised phenotypically and then divided into seven groups (A‐G) by restriction fragment length polymorphism analysis and sequencing of 16S ribosomal DNA. The isolates were identified as Enterococcus casseliflavus, Leuconostoc lactis, Leuconostoc mesenteroides, Lactobacillus pentosus, Lactobacillus plantarum, Lactobacillus paraplantarum, Lactococcus lactis subsp. lactis, Weissella cibaria and Weissella hellenica. The antibacterial activities of the isolates were determined and 11 Lc. lactis subsp. lactis strains showed inhibitory activity against the indicator strain Lactobacillus sakei JCM 1157^T. CONCLUSION: Heterofermentative W. cibaria and Leu. lactis were the major LAB found in jiang‐gua samples without soy sauce. In soy sauce‐added samples, homofermentative L. pentosus and L. plantarum were the most abundant LAB. In addition, the results also suggested that HhaI and RsaI restriction enzymes could be applied to distinguish W. hellenica and Weissella paramesenteroides. Copyright © 2012 Society of Chemical Industry     

Enzymatic activity of lactic acid bacteria (with antimicrobial properties) isolated from a traditional Spanish cheese

Twenty-four strains of lactic acid bacteria (LAB) isolated from a traditional Spanish cheese (Genestoso cheese) were evaluated for their enzymatic activities (acidifying and proteolytic abilities and carboxypeptidase, aminopeptidase, dipeptidase, caseinolytic and esterase activities), in order to select indigenous strains of technical interest for the manufacture of cheese. These strains were selected on the basis of their antimicrobial activity relative to five reference strains and were identified as Lactococcus lactis subsp. lactis (thirteen strains), Leuconostoc mesenteroides (two strains), Leuconostoc pseudomesenteroides (one strain), Lactobacillus paracasei (two strains), Lactobacillus plantarum (one strain) and Enterococcus faecalis (five strains).     

Diversity of lactic acid bacteria associated with traditional fermented dairy products in Mongolia

Spontaneous milk fermentation has a long history in Mongolia, and beneficial microorganisms have been handed down from one generation to the next for use in fermented dairy products. The objective of this study was to investigate the diversity of lactic acid bacteria (LAB) communities in fermented yak, mare, goat, and cow milk products by analyzing 189 samples collected from 13 different regions in Mongolia. The LAB counts in these samples varied from 3.41 to 9.03 log cfu/mL. Fermented yak and mare milks had almost identical mean numbers of LAB, which were significantly higher than those in fermented goat milk but slightly lower than those in fermented cow milk. In total, 668 isolates were obtained from these samples using de Man, Rogosa, and Sharpe agar and M17 agar. Each isolate was considered to be presumptive LAB based on gram-positive and catalase-negative properties, and was identified at the species level by 16S rRNA gene sequencing, multiplex PCR assay, and restriction fragment length polymorphism analysis. All isolates from Mongolian dairy products were accurately identified as Enterococcus faecalis (1 strain), Enterococcus durans (3 strains), Lactobacillus brevis (3 strains), Lactobacillus buchneri (2 strains), Lactobacillus casei (16 strains), Lactobacillus delbrueckii ssp. bulgaricus (142 strains), Lactobacillus diolivorans (17 strains), Lactobacillus fermentum (42 strains), Lactobacillus helveticus (183 strains), Lactobacillus kefiri (6 strains), Lactobacillus plantarum ssp. plantarum (7 strains), Lactococcus lactis ssp. lactis (7 strains), Leuconostoc lactis (22 strains), Leuconostoc mesenteroides (21 strains), Streptococcus thermophilus (195 strains), and Weissella cibaria (1 strain). The predominant LAB were Strep. thermophilus and Lb. helveticus, which were isolated from all sampling sites. The results demonstrate that traditional fermented dairy products from different regions of Mongolia have complex compositions of LAB species. Such diversity of LAB provides useful information for further studies of probiotic strain selection and starter culture design, with regard to the industrial production of traditional fermented milk.     

Microbial Succession and Metabolite Changes during Long‐Term Storage of Kimchi

Kimchi is often stored for a long period of time for a diet during the winter season because it is an essential side dish for Korean meals. In this study pH, abundance of bacteria and yeasts, bacterial communities, and metabolites were monitored periodically to investigate the fermentation process of kimchi for 120 d. Bacterial abundance increased quickly with a pH decrease after an initial pH increase during the early fermentation period. After 20 d, pH values became relatively stable and free sugars were maintained at relatively constant levels, indicating that kimchi fermentation by lactic acid bacteria (LAB) was almost completed. After that time, a decrease in bacterial abundance and a growth in Saccharomyces occurred concurrently with increased free sugar consumption and production of glycerol and ethanol. Finally, after 100 d, the growth of Candida was observed. Community analysis using pyrosequencing revealed that diverse LAB including Leuconostoc citreum, Leuconostoc holzapfelii, Lactococcus lactis, and Weissella soli were present during the early fermentation period, but the LAB community was quickly replaced with Lactobacillus sakei, Leuconostoc gasicomitatum, and Weissella koreensis as the fermentation progressed. Metabolite analysis using ¹H‐NMR showed that organic acids (lactate, acetate, and succinate) as well as bioactive substances (mannitol and gamma‐aminobutyric acid (GABA)) were produced during the kimchi fermentation, and Leuconostoc strains and Lactobacillus sakei were identified as the producers of mannitol and GABA, respectively. Practical Application In this study, we have shown that the growth inhibition of yeasts including Saccharomyces and Candida is necessary to extend the shelf life of kimchi in long‐term storage. Additionally, we have shown that a mixed culture of Leuconostoc strains and Lactobacillus sakei is necessary to produce kimchi that contains both mannitol and gamma‐aminobutyric acid.     

Technological characterization of lactic acid bacteria isolated from Armada cheese (a Spanish goats’ milk cheese)

Thirty-one strains of lactic acid bacteria (LAB) isolated from Armada cheese, Sobado variety, (eight strains of Lactococcus lactis subsp. lactis, four strains of Lactococcus lactis subsp. cremoris, two strains of L. lactis subsp. lactis biovar. diacetylactis, two strains of Leuconostoc mesenteroides subsp. mesenteroides, two strains of Leuconostoc mesenteroides subsp. dextranicum, five strains of Lactobacillus plantarum, six strains of Lactobacillus casei subsp. casei and two strains of Lactobacillus brevis) were screened for their acidifying capacity and enzymatic activity, that included the rapid API-ZYM system, the proteolytic activity, the amino-, di-, and carboxypeptidase activity and the caseinolytic activity. The strains of L. lactis subsp. lactis exhibited the highest acidifying and proteolytic activity. Lipase and esterase activity was practically non-existent for lactococci and lactobacilli; a certain esterase activity was observed among leuconostoc. The highest aminopeptidase activity was demonstrated by the cell-free extract (CFE) of some strains of L. plantarum, L. casei subsp. casei and L. mesenteroides subsp. dextranicum. The CFEs of L. lactis subsp. cremoris and L. lactis subsp. lactis possessed carboxypeptidase and dipeptidase activities, at levels depending on the strain. Appreciable caseinolytic activity was detected for the CFE of L. plantarum and those some lactococci.     

Diversity and technological potential of lactic acid bacteria of wheat flours

Lactic acid bacteria (LAB) were analysed from wheat flours used in traditional bread making throughout Sicily (southern Italy). Plate counts, carried out in three different media commonly used to detect food and sourdough LAB, revealed a maximal LAB concentration of approximately 4.75 Log CFU g⁻¹. Colonies representing various morphological appearances were isolated and differentiated based on phenotypic characteristics and genetic analysis by randomly amplified polymorphic DNA (RAPD)-PCR. Fifty unique strains were identified. Analysis by 16S rRNA gene sequencing grouped the strains into 11 LAB species, which belonged to six genera: Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Pediococcus and Weissella. Weissella cibaria, Lactobacillus plantarum, Leuconostoc pseudomesenteroides and Leuconostoc citreum were the most prevalent species. The strains were not geographically related. Denaturing gradient gel electrophoresis (DGGE) analysis of total DNA of flour was used to provide a more complete understanding of the LAB population; it confirmed the presence of species identified with the culture-dependent approach, but did not reveal the presence of any additional LAB species. Finally, the technological characteristics (acidifying capacity, antimicrobial production, proteolytic activity, organic acid, and volatile organic compound generation) of the 50 LAB strains were investigated. Eleven strains were selected for future in situ applications.     

Selection and evaluation of seafood-borne psychrotrophic lactic acid bacteria as inhibitors of pathogenic and spoilage bacteria

In this study, inhibitory psychrotrophic lactic acid bacteria were isolated and investigated for future use in biopreservation of seafood products. Screening of 5575 colonies isolated from various seafood products resulted in the selection of 132 colonies presenting inhibitory properties. Among them, 52 isolates had characteristics of LAB and showed growth at 15 °C but not at 30 °C. The inhibition spectrum of these 52 isolates against 14 target strains (Gram-positive and -negative) showed inhibition of typical seafood spoiling and pathogenic bacteria and enabled the formation of seven interesting clusters. Sequencing of the 16S rRNA gene of a representative isolate from each cluster identified three Leuconostoc gelidum, two Lactococcus piscium, one Lactobacillus fuchuensis and one Carnobacterium alterfunditum. Theses strains did not produce histamine nor tyramine, and showed no particular antibiotic resistance profile. Growth rate as a function of temperature was tested for one L. piscium and one L. gelidum isolate and confirmed their psychrotrophic behavior. One out of seven isolates showed bacteriocin-like activity. The inhibition mechanisms of the other isolates are still unknown but may be due to competition for substrate. Absence of a bacteriocin-like component could be a positive point to gain rapid authorization for food application in France. This collection of LAB is now ready for testing on products.     

Evaluation of lactic acid bacteria and yeast diversity in traditional white pickled and fresh soft cheeses from the mountain regions of Serbia and lowland regions of Croatia

The goal of this study was the characterisation of indigenous lactic acid bacteria (LAB) and yeasts isolated from nine white pickled (BG) and nine fresh soft (ZG) artisanal cheeses collected in Serbia and Croatia. While LAB were present in all of the cheeses collected, yeasts were found in all BG cheeses but only in three ZG cheese samples. High LAB and yeast species diversity was determined (average H′_L = 0.4 and H′_Y = 0.8, respectively). The predominant LAB species in white pickled (BG) cheeses were Lactococcus lactis, Lactobacillus plantarum, and Leuconostoc mesenteroides, while in fresh soft (ZG) cheeses the most dominant LAB species were L. lactis, Enterococcus faecalis, and Leuconostoc pseudomesenteroides. Among the 20 yeast species found, Debaryomyces hansenii, Candida zeylanoides, and Torulaspora delbrueckii were found to be predominant in BG cheeses, while Yarrowia lipolytica was predominant in ZG cheeses. The characterisation of metabolic and technological potentials revealed that 53.4% of LAB isolates produced antimicrobial compounds, 44.3% of LAB strains showed proteolytic activity, while most of the yeast species possessed either lipolytic or proteolytic activity. In conclusion, the results obtained in this study showed that the composition of LAB and yeast populations in white pickled and fresh soft cheeses is region specific. The knowledge gained in this study could eventually be used to select region specific LAB and yeast strains for the production of white pickled and fresh soft artisanal cheeses with geographically specific origins under controlled conditions.     

Bacterial community dynamics,lactic acid bacteria species diversity and metabolite kinetics of traditional Romanian vegetable fermentations

BACKGROUND: Artisanal vegetable fermentations are very popular in Eastern European countries. Fresh vegetables undergo a spontaneous fermentation in the presence of salt, which is mainly carried out by lactic acid bacteria (LAB). RESULTS: Culture‐dependent and culture‐independent analyses of end‐samples of various spontaneous vegetable fermentations carried out in houses of the Chiodju region (central Romania) revealed Lactobacillus plantarum and Lactobacillus brevis as the most frequently isolated LAB species. Leuconostoc mesenteroides and Leuconostoc citreum were also found. Furthermore, the community dynamics of spontaneous cauliflower and mixed‐vegetable (green tomatoes, carrots and cauliflower) fermentations revealed three steps: an initial phase characterised by the presence of Enterobacteriaceae and a wide LAB species diversity, encompassing Weissella species; a second phase from day 3 onwards wherein L. citreum and Lb. brevis occurred; and a final phase characterised by the prevalence of Lb. brevis and Lb. plantarum. Metabolite target analysis revealed that glucose and fructose were mostly depleted at the end of fermentation. The main products of carbohydrate metabolism were lactic acid, acetic acid, ethanol and small amounts of mannitol, indicating heterolactate fermentation. CONCLUSION: Given their prevalence at the end of vegetable fermentations, Lb. brevis and Lb. plantarum appear to be good candidate starter cultures for controlled vegetable fermentation processes. © 2012 Society of Chemical Industry     

Isolation of novel homopolysaccharide-producing lactic acid bacteria from Romanian raw milk and fermented dairy products

Traditionally fermented foods can be a rich source of diverse lactic acid bacteria (LAB) with interesting functional properties, such as exopolysaccharide (EPS) production. The objectives of this study were to map the mucoid and/or ropy LAB isolated from raw milk and traditionally fermented dairy products, collected in different regions of Romania, to study the species diversity within the samples and to further explore the EPS-producing capacity of the isolates. Seventy-three LAB strains were isolated and identified through (GTG)₅-PCR genomic fingerprinting and SDS-PAGE of whole-cell proteins. Lactococcus lactis was the most frequently encountered species, followed by Lactobacillus plantarum, Leuconostoc spp., and Enterococcus spp. Nine strains produced homopolysaccharides (HoPS, glucose monomers), namely L. lactis 1.8; Leuc. citreum 1.10, 1.11, 1.12, 2.8, and 4.11; Leuc. mesenteroides 21.2; Leuc. pseudomesenteroides 20.6; and Weisella confusa/cibaria 38.2, six of them in the concentrations above 10 g/L, both in milk and MRS medium supplemented with sucrose. In all EPS, the glucose constituents were connected by different α-linkages, among which α-1,6-linkages were the most prevalent.     

Functional Properties of Lactic Acid Bacteria Isolated from Romanian Fermented Vegetables

A total of 139 lactic acid bacterium (LAB) strains isolated from Romanian traditionally fermented vegetables were screened for the ability to produce exopolysaccharides and for their antagonistic activity against a set of nine LAB strains, three Bacillus strains, and four Gram-negative bacteria. Eighty-five of the tested strains showed a variable antimicrobial activity against Listeria monocytogenes ATCC 1911, 35 of the strains showed a limited inhibition zone against Escherichia coli ATCC25922, and 26 strains against Salmonella enterica ATCC 14024, while 19 strains showed inhibition against one or all three Bacillus strains used as indicators. None of the tested strains showed an antimicrobial activity against Staphylococcus aureus ATCC 25923. Several strains showed antibacterial activity against more than one indicator strain. For instance, Lactobacillus plantarum 307, Lactobacillus brevis 308, and Lactobacillus plantarum/pentosus 358 were active against five of the indicator strains used, while other 23 LAB were active against three indicator strains. In the case of two strains, namely Leuconostoc citreum 344 and Lactobacillus brevis 183, the activity was maintained after neutralizing the pH of the cell-free supernatant likely due to the production of bacteriocins. The gel permeation chromatography-based screening revealed seven EPS-producing LAB strains. Two of the positive strains, namely Leuconostoc citreum 177 and Leuconostoc citreum 52, have been shown to produce large amounts of EPS, of about 20 g/L. All isolated EPS have a high molecular mass, of above 1400 KDa, and a monomer composition dominated by the presence of glucose.     

Isolation and characterisation of lactic acid bacteria strains from raw camel milk for potential use in the production of fermented Tunisian dairy products

The aim of this work was to study the suitability of camel milk for the production of dairy products by lactic acid fermentation. Sixty strains of lactic acid bacteria (LAB) were isolated from camel milk. The strains were tested for their acidification activity, ability to use citrate, exopolysaccharide production, lipolytic, proteolytic activities and resistance to antibiotics. Ten strains were investigated for their ability to metabolize carbohydrates and that resulted in the identification of 5 Lactococcus lactis, 1 Lactobacillus pentosus, 2 Lactobacillus plantarum, 1 Lactobacillus brevis and 1 Pediococcus pentosaceus strains. Two strains of Lactococcus lactis SCC133 and SLch14 were selected to produce traditional Tunisian fermented dairy products (Lben, Raib, Jben cheese and Smen). These strains were chosen based on their acid production capacity and their ability to produce a high yield of biomass.     

Analysis of volatile compounds produced by different species of lactobacilli in rye sourdough using multiple headspace extraction

Profiles of volatile organic compound (VOC) produced by nine individual lactic acid bacteria (LAB) during rye sourdough fermentation were compared by automated SPME and GC/MS‐Tof. The dough samples were inoculated with individual strains, placed inside the headspace vials and incubated during next 24 h. The production or loss of VOC‐s was followed by adsorbing volatiles onto 85‐m Car/PDMS fibre in every 4 h. Volatile profiles differed among LAB species and divided LAB into two main groups – hetero‐ and homofermentative. Hetrofermentative LAB (Lactobacillus brevis; Leuconostoc citreum; Lactobacillus vaginalis, Lactobacillus panis) showed high production of acetic acid, CO₂, ethanol, ethylacetate, producing also hexyl acetate, ethyl hexanoate and isopentyl acetate. Whereas homofermentative LAB species (Lactobacillus helveticus; Lactobacillus casei; Lactobacillus sakei; Lactobacillus curvatus) produced a considerable amount of 2,3‐butanedione. Production of l ‐leucine methyl ester was unique for Lb. sakei, Lb. casei and Lb. curvatus strains. Lb. helveticus was the only LAB that produced benzaldehyde.     

Screening selected strains of probiotic lactic acid bacteria for their ability to produce biogenic amines (histamine and tyramine)

The aim of this study was to investigate the production of biogenic amines (BA), histamine and tyramine by some probiotic lactic acid bacteria (LAB). Fifteen strains representing six LAB species were screened qualitatively by growing them in a decarboxylase medium. Quantitative analysis was carried out by HPLC analysis with direct derivatization of acid extracts. Lactobacillus casei (TISTR 389) and Lactobacillus delbrueckii subsp. bulgaricus (TISTR 895) were found to produce BA. The highest levels of histamine (1820.9 ± 3.5 mg L^?1) and tyramine (5486.99 ± 47.6 mg L^?1) formation were observed for the TISTR 389 strain, while TISTR 895 produced only histamine (459.1 ± 0.63 mg L^?1) in the decarboxylase broth. Biogenic amine potential was not observed for the Lactobacillus acidophilus, Lactobacillus lactis subsp. lactis, Lactococcus lactis subsp. lactis, and Lactobacillus plantarum strains studied. This study confirmed that BA formation is strain dependent and not related to the species. Therefore, careful screening for amino acid decarboxylase activity is recommended before selecting LAB as appropriate starter or probiotic strains in food and dairy industry.     

Halotolerance and Survival Kinetics of Lactic Acid Bacteria Isolated from Jalapeño Pepper (Capsicum annuum L.) Fermentation

The microbiota associated with spontaneous fermentation of vegetables in a saline substrate may represent an important group of bacteria in the food industry. In this work, the lactic acid bacteria (LAB) Weissella cibaria, Lactobacillus plantarum, Lactobacillus paraplantarum, and Leuconostoc citreum were identified by partial 16S rRNA gene sequence analysis. In addition, entophytic bacteria such as Pantoea eucalypti, Pantoea anthophila, Enterobacter cowanii, and Enterobacter asburiae were detected, but they were irrelevant for the fermentation process and were inhibited after 12 h of fermentation when the pH decreased from 6.5 to 4.9. Moreover, 2 species of yeast were isolated and identified as Hanseniaspora pseudoguilliermondii and Kodamaea ohmeri by their partial 26S rRNA gene sequence. The growth of LAB was evaluated at different sodium chloride contents. L. citreum was the most halotolerant species followed by L. plantarum and W. cibaria with a concentration index to obtain a 50% population reduction (IC₅₀) of 7.2%, 6.6%, and 5.2%, respectively. Furthermore, the growth of LAB and Escherichia coli O157:H7 was evaluated in the presence of the main phenylpropanoids from chilli peppers such as p‐coumaric and ferulic acid. It was determined that LAB can grow in both acids at 4 mM, unlike E. coli O157:H7, whose growth is inhibited in the presence of these acids.     

Diversity and probiotic potentials of lactic acid bacteria isolated from gilaburu,a traditional Turkish fermented European cranberrybush (Viburnum opulus L.) fruit drink

The aim of the present study was to characterize lactic acid bacteria (LAB) strains isolated from traditional fermented gilaburu fruit juice and their probiotic potential. The LAB counts of the fermented gilaburu fruit juice were in the range of 3.92–8.30 log cfu/g. Total of 332 isolates belonging to Lactobacillus and Leuconostoc species were characterized from traditional fermented gilaburu juice by genotypic methods. It was also determined that the major LAB strains belong to Lactobacillus plantarum (173 isolates), Lactobacillus casei (52 isolates) and Lactobacillus brevis (24 isolates), while Lactobacillus buchneri, Lactobacillus parabuchneri, Lactobacillus pantheris, Leuconostoc pseudomesenteroides and Lactobacillus harbinensis were the least in isolated LAB strains. In terms of the probiotic potentials, Lb. plantarum strains were able to grow at pH 2.5, but 3 of Lb. casei strains, one of each Lb. brevis and Lb. buchneri strains could not grow at the same pH. All selected LAB stains were resistant to bile salt at ≤ 0.3% concentration. While all the LAB species grew at 15 °C, two Lactobacillus hordei strains could also grow at 45 °C. The highest cell hydrophobicity degrees were for Lb. casei (G20a) and Lb. plantarum (G19e) as 87.5 and 86.0%, respectively. Listeria monocytogenes and Bacillus cereus were the most sensitive bacteria against the selected LAB strains, while Escherichia coli and Staphylococcus aureus were the most resistant. Again all the isolated LAB species were resistant to three antibiotics; kanamycin, streptomycin and vancomycin. Characterization and probiotic potentials of the LAB isolated from fermented gilaburu (Viburnum opulus) juice were studied first time, and further research needs to be done on their behaviors in similar food formulations as a probiotic.     

Inactivation of food spoilage bacteria by high pressure processing: Evaluation with conventional media and PCR–DGGE analysis

Microbial diversity and dynamic changes of sliced vacuum-packed cooked ham during refrigerated storage (0–90 days) after high pressure processing (400 MPa at 22 °C for 10 min) was investigated by using culture-dependent and culture-independent approaches. Isolation of genome DNA and total RNA directly from meat samples, followed by PCR–denaturing gradient gel electrophoresis (DGGE) and RT-PCR–DGGE on 16S rDNA V3 region, was performed to describe the structure of the bacterial community and active species in pressurized sliced cooked ham. The DGGE profile showed that most spoilage bacteria including Lactococcus garvieae, Weissella cibaria, Lactobacillus sakei, Lactobacillus curvatus, Weissella paramesenteroides, Leuconostoc carnosum and Lactococcus lactis subsp. lactis were completely inactivated after high pressure processing (HPP), whereas Weissella viridescens and Weissella minor survived HPP and induced the final spoilage. The microbial diversity of HPP samples during the whole refrigerated storage period was extremely simple. Our results clearly indicated that HPP was an efficient method for avoiding the growth of the major spoilage bacteria and could be used to prolong the shelf-life of sliced vacuum-packed cooked ham.