Associative Growth of Lactic Acid Bacteria in Cabbage Juice

Combinations of Leuconostoc mesenteroides, Lactobacillus brevis, Pediococcus cerevisiae, and Lactobacillus plantarum were grown in sterile cabbage juice broth. The effects of culture interactions were determined by lag times, generation times, pH change, and total acidity measurements. Fresh filter-sterilized cabbage juice was a better medium than autoclaved cabbage juice, or refrigerated filter-sterilized cabbage juice. The addition of NaCl (2.25%) had a minimal effect on the cultures, except for L. mesenteroides, which was inhibited. In paired association studies, L. mesenteroides was inhibited by all the other cultures, conversely, L. plantarum and L. brevis benefited from most of the culture interactions.     

Characterization of sourdough bread ferments made in the laboratory by traditional methods

Sourdough ferments were reconstitued in the laboratory according to three traditional procedures used in rural areas for building sourdough ferments. The ferments were subcultured on wheat flour to make four generations, which were then used to study the micro-organisms involved in the fermentation of sourdough bread and the characteristic flora that may remain in the ferment for a long time. The analyses carried out on the ferments of the four generations included determinations of lactic acid bacteria (LAB) and yeasts and physico-chemical characteristics (pH, titratable acidity and dough-rising capacity). The results showed thatLactobacillus plantarum, L. delbrückii, Leuconostoc mesenteroides andPediococcus pentosaceus were the most frequent species in all of the trials. Some other species includingLactobacillus buchneri, L. casei andL. sanfrancisco were also isolated in high proportions and in many samples. In some trials the microflora was dominated by LAB and the yeast counts decreased significantly in the fourth generation despite the leavening action of the ferments.

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Charakterisierung von Sauerteigen, die im Labor nach traditionellen Verfahren hergestellt wurden

Zusammenfassung Sauerteig-Kulturen wurden im Labor nach traditionellen, ländlichen Verfahren gewonnen. Sie wurden über vier Generationen auf Weizenmehl kultiviert, dann erfolgte eine Floraanalyse. Bestimmt wurden die Milchsäurebakterien und Hefen sowie deren Charakteristika.Lactobacillus plantarum, L. delbrückii, Leuconostoc mesenteroidis undPediococcus pentosaceus waren die am regelmäßigsten vorkommenden Species.L. buchneri, L. casei undL. sanfrancisco wurden ebenfalls oft isoliert. Mit zunehmender Generationenzahl dominierten die Lactobacillen über die Hefen.

     

Characterization of Proteolytic Effect of Lactic Acid Bacteria Starter Cultures on Thai Fermented Sausages

The objective of this study was to investigate the effect of starter culture addition on proteolysis of Thai fermented sausages. Sausages inoculated with six different external starter cultures—Pediococcus pentosaceous, Pediococcus acidilactici, Weissella cibaria, Lactobacillus plantarum, Lactobacillus pentosus, and Lactobacillus sakei—were compared with naturally fermented sausages. The results of microbiological analysis indicated that the dominance of lactic acid bacteria (LAB) could inhibit the growth of pathogens and spoilage. Proteolysis was observed during fermentation by the reduction of myofibrillar and sarcoplasmic proteins and the increase in nonprotein nitrogen (NPN) and total free amino acids. The highest increase in concentration of NPN and free amino acids was obtained from sausages inoculated with LAB. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) showed a similar pattern of proteolysis of sarcoplasmic proteins in all sausages, while that of the inoculated sausages with L. plantarum, L. pentsus, and L. sakei exhibited increased degradation of myofibrillar protein bands at 200 and 45 kDa.     

Characterization and Distribution of Lactobacilli during Lactic Fermentation of Okra (Hibiscus esculentus)

The distribution and identification of lactobacilli during fermentation of okra were studied. Fermentation characteristics of lactobacilli isolated on MRS agar at 30°C under anaerobic conditions were presented using the API 50 CHL system. The phenogram constructed by an unweighted, pair group, arithmetic average, linkage method and by use of the Jacquard similarity coefficient (1-Sj) was used to identify nine phena. The studies showed five homolactic species initially (Lactobacillus plantarum, Lactobacillus casei subsp. pseudoplantarum, Lactobacillus acidophilus, Lactobacillus leichmannii, Lac-tobacillus salivarius subsp. salicinius) and two heterolactic species (Lactobacillus cellobiosus and Lactobacillus brevis). After 24 hr fermentation, the majority of the isolated strains were L. cellobiosus. During the final stage of fermentation L. plantarum strains dominated.     

Selection of Mixed Cultures for Meat Fermentation

Strains of Pediococcus cerevisiae, Pediococcus acidilactici, Lactobacillus plantarum, Lactobacillus casei and Micrococcus varians were studied with the aim of preparing mixed cultures of compatible strains for meat fermentations. Addition of 0.18% nitrite was slightly inhibitory while addition of 7% of a spice mix proved stimulatory. Antibiosis was observed between lactobacilli and pediococci. Micrococcus varians did not produce inhibitory substances toward other cultures and was insensitive to bacteriocins produced by the lactobacilli or the pediococci. Antibioses observed using disk assays were confirmed in mixed acidification trials, and mixes of some fast-acidifying strains were unsuccessful.     

The formation of biogenic amines by fermentation organisms

A total of 523 strains representing 35 species related to food fermentation organisms of practical importance were investigated for their potential for formation of biogenic amines (BA). The investigation was performed with resting cells in phosphate buffer (pH 5.5) and the formation of the following BAs was followed: putrescine, cadaverine, histamine, tyramine and 2-phenylethylamine. No potential was observed in species ofLactococcus, Leuconostoc, Pediococcus, Streptococcus and severalLactobacillus spp., such asL. pentosus andL. sake. A remarkable potential to form BA was observed in strains of carnobacteria,Lactobacillus buchneri, L. curvatus, L. reuteri, Staphylococcus carnosus and, to a lesser extent, inL. alimentarius, L. brevis, L. bavaricus, L. delbrueckii ssp.lactis, Micrococcus spp. andS. piscifermentans. In well known species with a practical function in the fermentation of dairy products, wine or cabbage a potential was observed for few strains only. In view of their role as starters in food fermentation, or their potential use in protective cultures and as probiotics, BA formation by the organisms has to be taken into consideration by selecting appropriate strains.

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Die Bildung von biogenen Aminen durch Fermentationsorganismen

Zusammenfassung Das Potential zur Bildung von biogenen Aminen (BA) wurde bei 523 Stämmen, die 35 Spezies aus dem Verwandtschaftsbereich der Lebensmittelfermentationsorganismen zugehörten, untersucht. Zu diesem Zweck wurden ruhende Zellen in Phosphatpuffer (pH 5,5) verwendet und die Bildung der folgenden BA verfolgt: Putrescin, Cadaverin, Histamin, Tyramin, 2-Phenylethylamin. Bei Spezies der GeneraLactococcus, Leuconostoc, Pediococcus, Streptococcus und einigenLactobacillus spp., darunterL. pentosus undL. sake fehlte dieses Potential. Eine deutliche Bildung von BA wurde bei Stämmen von Carnobakterien,Lactobacillus buchneri, L. curvatus, L. reuten undStaphylococcus carnosus beobachtet. Weniger ausgeprägt war die Aminbildung beiLactobacillus alimentarius, L. brevis, L. bavaricus, L. delbrueckii ssp.lactis, Micrococcus spp. undStaphylococcus piscifermentans. Ein Potential bei Spezies, die bei der Fermentation von Milch, Wein und Sauerkraut bekanntermaßen erwünscht sind, wurde nur bei wenigen Stämmen gefunden. In Anbetracht der Bedeutung bestimmter Spezies als Starterkulturen bei Lebensmittelfermentationen und der möglichen Anwendung als Schutzkulturen oder Probiotika ist die mögliche Bildung von BA durch Auswahl geeigneter Stämme ausreichend zu berücksichtigen.

     

Interaction and inactivation of Listeria and Lactobacillus cells in single and mixed species biofilms exposed to different disinfectants

Listeria spp. are ubiquitously found in both the natural and the food processing environment, of which Listeria monocytogenes is of an important health risk. Here, we report on the formation of single and mixed species biofilms of L. monocytogenes/Listeria innocua and Lactobacillus plantarum strains in 24‐well polystyrene microtiter plates and on the inactivation of 24‐hr and 72‐hr biofilms using quaternary ammonium compound‐, tertiary alkyl amine‐, and chlorine‐based disinfectants. Fluorescent in situ hybridization (FISH) and LIVE/DEAD BacLight staining were applied for 72‐hr L. innocua–L. plantarum mixed biofilms in the LabTek system for the species identification and the reaction of biofilm cells to disinfectants, respectively. L. monocytogenes/L. innocua were more resistant to disinfectants in 72‐hr than in 24‐hr biofilms, whereas L. plantarum strains did not show any significant differences between 72‐hr and 24‐hr biofilms. Furthermore, L. innocua when grown with L. plantarum was more resistant to all disinfection treatments, indicating a protective effect from lactobacilli in the mixed species biofilm. The biofilm formation and reaction to disinfectants, microscopically verified using fluorescence in situ hybridization and LIVE/DEAD staining, showed that L. innocua and L. plantarum form a dense mixed biofilm and also suggested the shielding effect of L. plantarum on L. innocua in the mixed species biofilm.     

Development of novel species‐specific primers for species identification of the Lactobacillus casei group based on RAPD fingerprints

BACKGROUND: It is difficult to clearly distinguish and identify specific species of the Lactobacillus casei group using phenotypic and genotypic (16S ribosomal DNA sequence analysis) techniques alone. Some species of this group are probiotic and are widely used in the food and feed industries. The objective of this study was to develop species‐specific primers based on randomly amplified polymorphic DNA (RAPD) fingerprinting for species identification within the closely related L. casei group of bacteria. RESULTS: Three random primers termed OPT‐14, OPA‐11 and OPT‐16 were developed for analysis. The primer pairs each produced a species‐specific band found only in the tested Lactobacillus rhamnosus, Lactobacillus paracasei subsp. tolerans and Lactobacillus zeae isolates respectively. These specific fragments were then sequenced for further analysis. The species‐specific primers were designed according to cloned sequencing, which was employed for polymerase chain reaction (PCR) with the template DNA of Lactobacillus strains. Single 102, 179 and 451 bp species‐specific bands were found only in L. rhamnosus, L. paracasei subsp. tolerans and L. zeae respectively. CONCLUSION: Using PCR, the novel species‐specific primers have been shown to rapidly, accurately and effectively identify species of L. rhamnosus, L. paracasei subsp. tolerans and L. zeae from within the L. casei group of probiotic bacteria. Copyright © 2009 Society of Chemical Industry     

OPTIMIZATION OF THE LACTIC ACID FERMENTATION OF HYDROLYZED COD (GADUS MORHUA) GURRY WITH CORN SYRUP AS CARBOHYDRATE SOURCE

ABSTRACT The purpose of this study was to determine the optimum concentrations of corn syrup required with the use of several species of homofermentative lactic acid bacteria and a commercial mixed culture inoculum in the fermentation of hydrolyzed cod gurry. Among the three homofermentative bacteria studied, Lactobacillus plantarum, Streptococcus faecium, and Pediococcus acidilactici, consistent results regarding the most rapid rate of pH reduction and the lowest final pH were obtained with L. plantarum. S. faecium was the least desirable organism on the basis of fermentation rates and the extent of pH reduction after 72 h of incubation. Corn syrup at a concentration of 4.0% (w/w) was found to be optimum for achieving a rapid and successful lactic acid fermentation of hydrolyzed cod gurry with Lactobacillus plantarum. Corn syrup at a concentration of 4.5% was found to be optimum for rapidly achieving a final pH of 4.0 with the commercial mixed inoculum Stabisil. The maltose content of corn syrup was utilized at a notably slower rate than glucose by all three microorganisms during the first 18 h of incubation. Throughout the fermentations, maltotriose was utilized significantly by only L. plantarum.     

Characterization of microbial traits involved with the elaboration of the Cotija cheese

Physicochemical and microbial analyses were conducted for artisanal and semi-industrial manufacturing processes of the Cotija cheese. Differences between manufacturing processes in Cotija cheese affect the microbial composition in the final product. Lactic acid bacteria are important microorganisms in the artisanal Cotija cheese manufacturing. Thirty-one different microorganisms were isolated and identified by ribosomal sequencing analysis during the production of this artisanal cheese. The yeast isolates comprised the following species: Kluyveromyces lactis, Kluyveromyces marxianus, Pichia guillermondii, Rhodotorula mucilaginosa, Galactomyces reessii, and Galactomyces geotrichum. Bacterial isolates were members of the Lactobacillaceae family with the follow species: Pediococcus pentosaceus, Lactobacillus brevis, Lactobacillus plantarum, and Lactobacillus casei. The possible role of these microorganisms in the final flavor and taste, and their utility in the control of undesirable microorganisms in artisanal Cotija cheese is discussed.     

Dialysis Pure-Culture Process for Lactic-Acid Fermentation of Vegetables

Blanched and brined cucumbers and green beans were fermented with pure cultures of lactic acid bacteria by use of a dialyzer with microporous membrane separating the continuously circulated vegetable brines and cultures. Dialysis fermentations were conducted separately with Lactobacillus brevis, L. plantarum and Pediococcus cerevisiae; L. brevis performed the most satisfactorily. Maximal populations of all three species were lo-100 times higher in the dialysis cultures than when cultivated directly in blanched cucumber brines. Five lots of the vegetables were fermented consecutively for 8 wk with the same culture of L. brevis. Addition of calcium acetate as a pH buffer increased cell populations, extended cell viability, and increased fermentation rates.     

Survival of Escherichia coli O157:H7 in dry sausage fermented by probiotic lactic acid bacteria

Probiotic Lactobacillus rhamnosus GG, L rhamnosus E‐97800, L rhamnosus LC‐705 and commercial Pediococcus pentosaceus were studied for their ability to inhibit the growth of Escherichia coli O157:H7 in dry sausage. The strains were able to produce technologically high‐quality dry sausage. The number of E coli O157:H7 decreased from approximately 5 to approximately 2 log cfu g⁻¹ It was concluded that the above‐mentioned strains and the commercial culture were equally effective in inhibiting E coli O157:H7. © 2000 Society of Chemical Industry     

不同乳酸菌强化接种发酵辣椒挥发性风味成分分析

为更好地了解强化接种发酵对辣椒的风味特征影响,采用固相微萃取-气相色谱-质谱技术检测4株乳酸菌强化接种发酵辣椒风味成分。结果共检出挥发性风味物质20类191种。不同菌种发酵样品风味物质的种类及含量有较大差异,发酵乳杆菌共检出挥发性风味物质15类76种,乳链球菌共检出8类20种,植物乳杆菌共检出13类84种,乳酸片球菌共检出11类73种。经主成分分析方法统计显示,发酵乳杆菌的风味物质综合评分为11.28分、乳酸片球菌为3.65分,植物乳杆菌为－0.08分,乳酸链球菌为－11.30分,自然发酵为－3.56分。风味物质综合排名为：发酵乳杆菌＞乳酸片球菌＞植物乳杆菌＞自然发酵＞乳链球菌,发酵乳杆菌、乳酸片球菌以及植物乳杆菌强化发酵较自然发酵辣椒风味品质突出。     

Putrescine production from different amino acid precursors by lactic acid bacteria from wine and cider

The aim of this work was to study the production of biogenic amines and particularly putrescine in lactic acid bacteria (LAB) related to wine and cider. We applied an analytical protocol that involves the use of PCR and TLC techniques to determine the production of putrescine from different precursors. Moreover, we also studied the ability of the Lactobacillus and Pediococcus tested to produce histamine and tyramine. The results showed that the majority of the Lactobacillus brevis analyzed harbour both AgDI and tdc genes and are tyramine and putrescine producers. Conversely, among the other LAB tested, only one Lactobacillus hilgardii and one Pediococcus pentosaceus produced putrescine. The AgDI gene was also detected in two other LAB (Lactobacillus mali and Pediococcus parvulus), but no putrescine production was observed. Finally, hdc gene and histamine production were found in strains (L. hilgardii 5211, isolated from wine, and Lactobacillus casei 18, isolated from cider) that were not putrescine producers.     

Isolation and characterization of anti-listerial and amylase sensitive enterocin producing Enterococcus faecium DB1 from Gajami-sikhae, a fermented flat fish in Korea

Bacteriocinogenic Enterococcus faecium DB1 was isolated from Korean gajami-sikhae, a lactic fermented flat fish. The antimicrobial spectrum of E. faecium DB1 was limited to Listeria monocytogenes, Lactobacillus curvatus, and Pediococcus acidilactici in agar well diffusion assay; while it was expanded to other Grampositive and negative bacteria by direct and deferred assays. Induction of enterocin DB1 by co-culturing with sensitive indicators was not detected. Inactivation of bacteriocin activity was observed after treatment of crude enterocin DB1 with proteolytic enzymes and α-amylase, but not with catalase, sodium dodecyl sulfate, Tween 20 and 80. The bacteriocin activity was retained in pH between 2.0 and 10.0, and after treatment at 121°C for15 min. Maximum activity (1,280 AU/mL) against L. monocytogenes KCTC 3569 was observed in MRS broth and remained for at least 16 hr. The molecular weight of partially purified enterocin DB1 was approximately 16.5 kDa, and mode of action is bactericidal. Enterocin DB1 production trait is linked to a chromosomal DNA.     

Assessment of antibiotic susceptibility within lactic acid bacteria strains isolated from wine

Susceptibility to 12 antibiotics was tested in 75 unrelated lactic acid bacteria strains of wine origin of the following species: 38 Lactobacillus plantarum, 3 Lactobacillus hilgardii, 2 Lactobacillus paracasei, 1 Lactobacillus sp, 21 Oenococcus oeni, 4 Pediococcus pentosaceus, 2 Pediococcus parvulus, 1 Pediococcus acidilactici, and 3 Leuconostoc mesenteroides. The Minimal Inhibitory Concentrations of the different antibiotics that inhibited 50% of the strains of the Lactobacillus, Leuconostoc and Pediococcus genera were, respectively, the following ones: penicillin (2, < or =0.5, and < or =0.5 microg/ml), erythromycin (< or =0.5 microg/ml), chloramphenicol (4 microg/ml), ciprofloxacin (64, 8, and 128 microg/ml), vancomycin (> or =128 microg/ml), tetracycline (8, 2, and 8 microg/ml), streptomycin (256, 32, and 512 microg/ml), gentamicin (64, 4, and 128 microg/ml), kanamycin (256, 64, and 512 microg/ml), sulfamethoxazole (> or =1024 microg/ml), and trimethoprim (16 microg/ml). All 21 O. oeni showed susceptibility to erythromycin, tetracycline, rifampicin and chloramphenicol, and exhibited resistance to aminoglycosides, vancomycin, sulfamethoxazole and trimethoprim, that could represent intrinsic resistance. Differences were observed among the O. oeni strains with respect to penicillin or ciprofloxacin susceptibility. Antibiotic resistance genes were studied by PCR and sequencing, and the following genes were detected: erm(B) (one P. acidilactici), tet(M) (one L. plantarum), tet(L) (one P. parvulus), aac(6')-aph(2") (four L. plantarum, one P. parvulus, one P. pentosaceus and two O. oeni), ant(6) (one L. plantarum, and two P. parvulus), and aph(3')-IIIa (one L. plantarum and one O. oeni). This is the first time, to our knowledge, that ant(6), aph(3')-IIIa and tet(L) genes are found in Lactobacillus and Pediococcus strains and antimicrobial resistance genes are reported in O. oeni strains.     

Microbial characterization of Iranian traditional Lighvan cheese over manufacturing and ripening via culturing and PCR-DGGE analysis: identification and typing of dominant lactobacilli

This paper reports on the diversity and dynamics of the dominant microbial populations during manufacturing and ripening of Lighvan, a traditional, starter-free Iranian cheese made from raw ewe and goat’s milk as determined by culturing and PCR-DGGE. Similar dominant populations, composed of Lactococcus lactis and Lactobacillus spp. strains, were found by both techniques. However, discrepancies regarding the identity of the Lactobacillus species were encountered. Lactobacillus curvatus and Lactobacillus sakei proved to be dominant by PCR-DGGE; in contrast, Lactobacillus paraplantarum, Lactobacillus paracasei, Lactobacillus brevis and Lactobacillus plantarum were the majority cultivable organisms. RAPD typing of lactobacilli isolates showed wide genetic diversity among the species. Moreover, strain compositions change over time; L. brevis and L. paraplantarum were dominant in milk and were replaced by L. plantarum and L. paracasei strains as ripening progressed.     

Inhibitory and Stimulatory Effects of Oregano on Lactobacillus Plantarum and Pediococcus Cerevisiae

Increasing concentrations of oregano from 0.5 to 8 g/L in a liquid medium resulted in stimulation, delay, or inhibition of acid production and viability of Lactobacillus plantarum and Pediococcus cerevisiae. The inhibitory factor could be removed from oregano by solvent extraction or autoclaving; residues from these treatments stimulated acid production by the organisms. Organisms growing in media containing sublethal oregano concentrations that had delayed growth and acid production developed resistance to the deleterious effects of the spice. L. plantarum was more resistant than P. cerevisiae to the inhibitory effects of oregano.     

Identification of lactic acid bacteria isolated during traditional fura processing in Ghana

Fura is a millet-based spontaneously fermented dumpling produced and consumed in parts of West Africa, particularly Nigeria, Burkina Faso and Ghana. From eight traditional fura production sites in northern Ghana, 862 lactic acid bacteria were isolated and identified to species level using a combination of genotypic and phenotypic methods including (GTG)₅-based PCR fingerprinting and 16S rRNA gene sequencing, multiplex PCR by means of recA gene sequence comparison, conventional morphological characteristics and carbohydrate fermentation profiling. During millet dough fermentation, pH decreased from 5.6–6.4 to 4.1–3.7 and total lactic acid bacteria (LAB) counts increased from 4.4–5.3 to 7.9–9.2 log₁₀ (cfu/g). The initial stages of the fermentation were characterized by co-dominance of homo- and heterofermentative species of Pediococcus acidilactici, Weisella confusa, Lactobacillus fermentum, Lactobacillus reuteri, Lactobacillus salivarius, and Lactobacillus paraplantarum whereas L. fermentum was dominating at the end of the fermentation. L. fermentum was predominant in all fermentations (p < 0.05) and a high uniformity was observed among production sites regarding the dominance of L. fermentum. L. fermentum and W. confusa were isolated in all production sites and almost at all fermentation stages indicating that they are indigenous to traditional fura processing. The other LAB bacteria species which comprised a minor proportion of the total LAB occurred occasionally and in an irregular pattern among the production sites.     

Adaptability of lactic acid bacteria and yeasts to sourdoughs prepared from cereals, pseudocereals and cassava and use of competitive strains as starters

The adaptability of lactic acid bacteria (LAB) and yeasts to sourdoughs prepared from cereals, pseudocereals and cassava was investigated using PCR-DGGE and bacteriological culture combined with rRNA gene sequence analysis. Sourdoughs were prepared either from flours of the cereals wheat, rye, oat, barley, rice, maize, and millet, or from the pseudocereals amaranth, quinoa, and buckwheat, or from cassava, using a starter consisting of various species of LAB and yeasts. Doughs were propagated until a stable microbiota was established. The dominant LAB and yeast species were Lactobacillus fermentum, Lactobacillus helveticus, Lactobacillus paralimentarius, Lactobacillus plantarum, Lactobacillus pontis, Lactobacillus spicheri, Issatchenkia orientalis and Saccharomyces cerevisiae. The proportion of the species within the microbiota varied. L. paralimentarius dominated in the pseudocereal sourdoughs, L. fermentum, L. plantarum and L. spicheri in the cassava sourdough, and L. fermentum, L. helveticus and L. pontis in the cereal sourdoughs. S. cerevisiae constituted the dominating yeast, except for quinoa sourdough, where I. orientalis also reached similar counts, and buckwheat and oat sourdoughs, where no yeasts could be detected. To assess the usefulness of competitive LAB and yeasts as starters, the fermentations were repeated using flours from rice, maize, millet and the pseudocereals, and by starting the dough fermentation with selected dominant strains. At the end of fermentation, most of starter strains belonged to the dominating microbiota. For the rice, millet and quinoa sourdoughs the species composition was similar to that of the prior fermentation, whereas in the other sourdoughs, the composition differed.