Molecular identification of the microbiota of French sourdough using temporal temperature gradient gel electrophoresis

The microbiota of four industrial French sourdoughs (BF, GO, VB and RF) was characterized by PCR temporal temperature gel electrophoresis (TTGE). The TTGE technique reveals differences in the 16S rDNA V6–V8 regions of these bacteria. DNA was extracted directly from sourdough samples. A specific TTGE fingerprint was determined for 30 bacterial species, including members of the genera Lactobacillus, Leuconostoc and Weissella, all known to be present in sourdough.These sourdoughs contain different species of lactic acid bacteria (LAB) depending on ecological conditions prevailing in the different sourdough fermentations. Only a few LAB species were found to be competitive and became dominant. Lactobacillus sanfranciscensis was observed as the most frequently found species. In sourdough GO, L. sanfranciscensis, Lactobacillus panis and two new species, Lactobacillus nantensis and Lactobacillus hammesii, were detected. Sourdough BF contain L. sanfranciscensis, Lactobacillus spicheri and Lactobacillus pontis. In sourdough VB, which differed in the process temperature, we identified exclusively L. sanfranciscensis and Leuconostoc mesenteroïdes subsp. mesenteroïdes. Lactobacillus frumenti, L. hammesii and Lacobacillus paralimentarius became the predominant species in sourdough RF. Compared with conventional bacteriological methods, the use of this new molecular approach to analyze the sourdough ecosystem should therefore allow a more complete and rapid assessment of its specific microbiota.     

Biodiversity of lactic acid bacteria and yeasts in spontaneously-fermented buckwheat and teff sourdoughs

In this study, four different laboratory scale gluten-free (GF) sourdoughs were developed from buckwheat or teff flours. The fermentations were initiated by the spontaneous biota of the flours and developed under two technological conditions (A and B). Sourdoughs were propagated by continuous back-slopping until the stability was reached. The composition of the stable biota occurring in each sourdough was assessed using both culture-dependent and -independent techniques. Overall, a broad spectrum of lactic acid bacteria (LAB) and yeasts species, belonging mainly to the genera Lactobacillus, Pediococcus, Leuconostoc, Kazachstania and Candida, were identified in the stable sourdoughs. Buckwheat and teff sourdoughs were dominated mainly by obligate or facultative heterofermentative LAB, which are commonly associated with traditional wheat or rye sourdoughs. However, the spontaneous fermentation of the GF flours resulted also in the selection of species which are not consider endemic to traditional sourdoughs, i.e. Pediococcus pentosaceus, Leuconostoc holzapfelii, Lactobacillus gallinarum, Lactobacillus vaginalis, Lactobacillus sakei, Lactobacillus graminis and Weissella cibaria. In general, the composition of the stable biota was strongly affected by the fermentation conditions, whilst Lactobacillus plantarum dominated in all buckwheat sourdoughs. Lactobacillus pontis is described for the first time as dominant species in teff sourdough. Among yeasts, Saccharomyces cerevisiae and Candida glabrata dominated teff sourdoughs, whereas the solely Kazachstania barnetti was isolated in buckwheat sourdough developed under condition A. This study allowed the identification and isolation of LAB and yeasts species which are highly competitive during fermentation of buckwheat or teff flours. Representatives of these species can be selected as starters for the production of sourdough destined to GF bread production.     

Free D- and L-Amino Acid Evolution During Sourdough Fermentation and Baking

The evolution of free D- and L-amino acids in sourdoughs started with various lactic acid bacteria (LAB) and yeasts was studied. Lactobacillus brevis subsp. lindneri CB1 and Lactobacillus plantrum DC400 had high proteolytic activity. During sourdough fermentation, Saccharomyces cerevisiae 141 and Saccharomyces exiguus M14 sequentially utilized free amino acids produced by bacterial activity. Due to increased cell yeast autolysis, more S. exiguus M14 inocula caused more free amino acids which were partially utilized by LAB without causing hydrolysis of wheat flour protein. D-alanine, D-glutamic acid and traces of other D-isomers were observed in sourdoughs fermented with L. brevis subsp. lindneri CB1 and S. cerevisiae 141. Free total D- and L-amino acid content decreased by more than 44% after baking the sourdoughs. No abiotic generation of new D-amino acid isomers was detected in the baked sourdoughs.     

Effects of selected lactic acid bacteria on the characteristics of amaranth sourdough

BACKGROUND: As the processing of amaranth in baked goods is challenging, the use of sourdough fermentation is a promising possibility to exploit the advantages of this raw material. In this study the fermentation properties of Lactobacillus plantarum, Lactobacillus paralimentarius and Lactobacillus helveticus in amaranth‐based sourdough were examined in order to validate them as starter cultures. pH, total titratable acidity (TTA) and lactic/acetic acid ratio of the sourdough and sensory properties of the resulting wheat bread were evaluated using fermentation temperatures of 30 and 35 °C. RESULTS: While fermentation pH, TTA and lactic acid concentration showed small variations with the use of L. plantarum and L. paralimentarius, L. helveticus reached the most intensive acidification after initial adaptation to the substrate. Acetic acid production was independent of lactic acid metabolism. Furthermore, the lactic/acetic acid ratio exceeded recommendation by 10–35 times (fermentation quotient 25–82). Sensory evaluation showed no significant differences between the two fermentation temperatures but differences among the three micro‐organisms. CONCLUSION: The results provide relevant information on the fermentation properties required of a customised starter for amaranth flour. Copyright © 2010 Society of Chemical Industry     

Prevalence and impact of single-strain starter cultures of lactic acid bacteria on metabolite formation in sourdough

Flavour of type II sourdoughs is influenced by the ingredients, processing conditions, and starter culture composition. It is, however, not fully clear to what extent different sourdough lactic acid bacteria (LAB) contribute to flavour. Therefore, two types of flour (rye and wheat) and different LAB starter culture strains were used to prepare sourdoughs, thereby leaving the yeast microbiota uncontrolled. All LAB starter culture strains tested were shown to be prevalent and to acidify the flour/water mixture to pH values between 3.1 and 3.9 after 24 h of fermentation. Multiple aldehydes, alcohols, ketones, and carboxylic acids were produced by the sourdough-associated microbiota throughout the fermentation period. Based on the organoleptic evaluation of breads produced with these sourdoughs, five LAB strains were selected to perform prolonged wheat and rye fermentations as to their capacity to result in an acidic (Lactobacillus fermentum IMDO 130101, Lactobacillus plantarum IMDO 130201, and Lactobacillus crustorum LMG 23699), buttermilk-like (Lactobacillus amylovorus DCE 471), or fruity flavour (Lactobacillus sakei CG1). Upon prolonged fermentation, higher metabolite concentrations were produced. For instance, L. sakei CG1 produced the highest amounts of 3-methyl-1-butanol, which was further converted into 3-methylbutyl acetate. The latter compound resulted in a fruity banana flavour after 48 h of fermentation, probably due to yeast interference. Rye fermentations resulted in sourdoughs richer in volatiles than wheat, including 3-methyl-1-butanol, 2-phenylethanol, and ethyl acetate.     

Microbial Diversity of Type I Sourdoughs Prepared and Back‐Slopped with Wholemeal and Refined Soft (Triticum aestivum) Wheat Flours

The fermentation of type I sourdough was studied for 20 d with daily back‐slopping under laboratory and artisan bakery conditions using 1 wholemeal and 2 refined soft wheat (Triticum aestivum) flours. The sourdough bacterial and yeast diversity and dynamics were investigated by plate counting and a combination of culture‐dependent and culture‐independent PCR‐DGGE approach. The pH, total titrable acidity, and concentration of key organic acids (phytic, lactic, and acetic) were measured. Three flours differed for both chemical and rheological properties. A microbial succession was observed, with the atypical sourdough species detected at day 0 (i.e. Lactococcus lactis and Leuconostoc holzapfelii/citreum group for bacteria and Candida silvae and Wickerhamomyces anomalus for yeasts) being progressively replaced by taxa more adapted to the sourdough ecosystem (Lactobacillus brevis, Lactobacillus alimentarius/paralimentarius, Saccharomyces cerevisiae). In mature sourdoughs, a notably different species composition was observed. As sourdoughs propagated with the same flour at laboratory and artisan bakery level were compared, the influence of both the substrate and the propagation environment on microbial diversity was assumed.     

Effect of Select Parameters of the Sourdough Rye Fermentation on the Activity of Some Mixed Starter Cultures

The effect of select parameters (i.e., rye flour ash content, temperature, and dough yield) of the sourdough fermentation on the fermentation activity of different starter cultures (lactic acid bacteria Lactococcus lactis ssp. Lactis, Weissella confusa, Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus helveticus, and yeast Kluyveromyces marxianus subsp. Marxianus) was determined. The major metabolic end products of fermentation (D, L-lactic acid, acetic acid, ethanol and glycerol) and the evolution of total phenolic content and folic acid during bread making were measured. Lactobacillus helveticus and Kluyveromyces marxianus allowed obtaining sourdoughs with the highest lactic acid/acetic acid ratios. The mixed starter culture with Lactococcus lactis and Saccharomyces cerevisiae generated the most important quantities of D/L lactic acid. The maximum values of ethanol concentration were obtained in case of the sourdoughs from whole rye flour fermented at lower temperature (30°C) with mixed starter cultures containing Sacchomyces cerevisiae. The fermentation process and type of starter culture are also tools to increase the bioactive compounds, enabling the increase of the phenolic content of the sourdough.     

Sourdough-isolated<Emphasis Type="Italic"> Lactobacillus fermentum</Emphasis> as a potent anti-mould preservative of a traditional Iranian bread

Sourdough bread is an ancient method for making long microbial shelf life and strongly flavoured breads. Traditional sourdough bread-making has been practised for centuries in Iran. Although rural bread-making is still highly reliant on sourdough, urban bakeries usually use bakers yeast and also sodium bicarbonate instead. In this study the anti-mould preservative effects of three lactic acid bacteria isolates were investigated on one of the popular traditional Iranian bread (Lavash). Starter cultures were prepared using 20 h cultures of three sourdough-isolated strains, Lactobacillus casei, Lactobacillus plantarum and Lactobacillus fermentum. Different concentrations (0.5%, 1%, 2%, 4% and 8%) of lactobacillus starter cultures were used to prepare a variety of sourdoughs. Lavash doughs were inoculated with 20% of each lactobacilli-fermented sourdough. After a 20 h incubation at 30 °C, a decrease in pH was observed in the different lactobacilli sourdoughs. However an 8% inoculum of L. fermentum resulted in a significant decrease in pH (3.87 to 2.70). Concentrations of 2% and higher of the three lactobacilli used in Lavash sourdough delayed mould growth during storage. However this preservative effect was more significant when an 8% inoculum of L. fermentum was used. These results tend to suggest that selected strains of lactobacilli have a beneficial role in prevention of bread waste by mould spoilage, and hence could extend bread shelf life.     

Prevalence,Genetic Diversity,and Technological Functions of the Lactobacillus sanfranciscensis in Sourdough: A Review

The use of sourdough as a leavening agent in bread making is a very old method that can be traced back to ancient times. Sourdoughs harbor a complex microbiota that is affected by multiple factors including factors related to cereal plants, grains, and sourdough processing techniques. Lactobacillus sanfranciscensis is the key autochthonous bacterium of the traditional sourdough microbiota and it is said to be “sourdough adapted” species. Despite the great dominance of this bacterium in sourdoughs, the origin of this species still remains unclear. Lactobacillus sanfranciscensis positively influences all aspects of sourdough and fermented foods. However, the positive influence of this species on sourdough is a strain‐dependent characteristic. The first purpose of this review was to discuss factors affecting the microbiota of sourdoughs with particular emphasis on reasons behind the remarkable prevalence of L. sanfranciscensis in this ecological niche. The second objective was to discuss the genotypic and phenotypic classification of L. sanfranciscensis strains and the influence of this species on technological and functional characteristics of sourdough including its influence on rheological properties of dough and bread characteristics, texture, aroma, and shelf‐life through the inhibition of fungal growth.     

Fundamental study on the effect of hydrostatic pressure treatment on the bread-making performance of oat flour

The use of sourdough in wheat and rye breads has been extensively studied; however, little is known about its potential effect when baking oat bread. Consequently, the impact of sourdough on oat bread quality was investigated. Two different sourdoughs were prepared from wholegrain oat flour without the addition of starter cultures, by continuous propagation at 28 (SD 28) or 37 °C (SD 37) until the composition of the lactic acid bacteria remained stable. The dominant LAB were identified by sequence analysis of the 16S rDNA isolated from pure cultures. LAB from SD 28 belonged to the species Leuconostoc argentinum, Pedicoccus pentosaceus and Weissella cibaria, while Lactobacillus coryniformis dominated SD 37. The isolated LAB were further used as starter cultures for the production of oat sourdoughs. Fundamental rheology revealed softening of the sourdoughs compared to non-acidified and chemically acidified controls, which could not be attributed to proteolytic activity. Incorporation of oat sourdough into an oat bread recipe resulted in significantly increased loaf-specific volume as well as improved texture, independent of addition level or sourdough type. Overall, the results of this study show that sourdoughs containing lactic acid bacteria isolated from oats have the potential to enhance oat bread quality.     

Investigation of Microbial Communities of Chinese Sourdoughs Using Culture‐Dependent and DGGE Approaches

Sourdough is typically characterized by the complex microbial communities mainly comprising of yeasts and lactic acid bacteria (LAB). The objective of this study was to explore the microbiota of Chinese traditional sourdoughs collected from different areas of China using culture‐dependent and denaturing gradient gel electrophoresis (DGGE) methods. A total of 131 yeasts, 2 molds, and 106 LAB strains were isolated and identified. Based on the culture‐dependent analysis, the populations of yeasts and LAB were at the level of 10⁵ to 10⁷ and 10⁶ to 10⁷ cfu/g, respectively. Similarly, the results of RT‐qPCR showed that the values of total yeasts and LAB populations were in the range of 10⁶ to 10⁷ and 10⁷ to 10⁸ copies/g, respectively. Using culture‐dependent method, a total of 7 yeasts, 2 molds and 7 LAB species were identified. Results showed that Saccharomyces cerevisiae and Lactobacillus plantarum were the predominant species among the yeasts and LAB microflora. Similarly, using PCR‐DGGE approach, 7 yeasts, 1 mold and 9 LAB species were detected. The yeast, S. cerevisiae, represented the predominant, while the yeast Candida tropicalis represented the subdominant species of the yeast community. Among the LAB community, Lactobacillus sanfranciscensis was the predominant species, while Lactococcus qarvieae, Enterococcus faecium, Lactobacillus delbrueckii and Enterococcus cecorum were among the less dominant species.     

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.     

Lactic acid bacteria community dynamics and metabolite production of rye sourdough fermentations share characteristics of wheat and spelt sourdough fermentations

Four spontaneous rye sourdough fermentations were performed over a period of ten days with daily back-slopping. Samples taken at all refreshment steps were used for culture-dependent and culture-independent characterization of the microbiota present. Furthermore, an extensive metabolite target analysis was performed through a combination of various chromatographic methods, including liquid chromatography coupled to mass spectrometry (LC/MS) and gas chromatography coupled to mass spectrometry (GC/MS). Spearman’s rank correlation coefficients were calculated and a principal component analysis (PCA) was performed on the data obtained in this study combined with data obtained previously for wheat and spelt sourdoughs. In general, the establishment of a stable microbial ecosystem occurred through a three-phase evolution, with mainly Lactobacillus plantarum and Lactobacillus fermentum dominating the rye sourdough ecosystems. PCA revealed that ornithine and mannitol were positively correlated with rye sourdoughs, contributing to bacterial competitiveness at the onset of sourdough production. Wheat and spelt sourdoughs showed a high degree of similarity, although certain compounds (e.g. indolelactic acid) appeared to be specific for spelt sourdoughs. The production of amino acid metabolites, mainly hydroxy acids (e.g. phenyllactic acid) and alcohols (e.g. 3-methyl-1-butanol), contributed to the equilibration of the redox balance and further enhanced the competitiveness of dominant species in stable sourdoughs.     

Microbiological and technological characterization of sourdoughs destined for bread-making with barley flour

The aim of the present study was the microbiological and technological characterization of laboratory- made sourdoughs for use in barley-flour-based bread-making. A defined multi-strain starter culture consisting of selected lactic acid bacteria (LAB) and yeasts from wheat sourdoughs was inoculated into three flour–water mixtures, composed of: (i) 100% wheat flour (ii) 50% wheat flour and 50% hull-less barley flour (composite flour); (iii) 100% hull-less barley flour. After two months of continuous propagation, the chemical characteristics of the three sourdoughs were investigated by measuring: pH, total titratable acidity and concentrations of various microbial metabolites by HPLC (i.e. lactic, acetic, phenyllactic and butyric acids and diacetyl). The microbial traits were studied through viable counts, isolation and typing of LAB and yeasts and PCR-DGGE analyses. Only Saccharomyces cerevisiae and Lactobacillus plantarum were detectable in the sourdoughs together with other lactobacilli species which were different depending on the type of flour blend used. The molecular typing of the isolates highlighted that only a few strains among those initially inoculated prevailed. The volume increases of the three types of sourdough were also investigated and a correlation was seen between an increase in the barley flour content and a reduction in the dough volume.     

Structural and rheological characterisation of heteropolysaccharides produced by lactic acid bacteria in wheat and sorghum sourdough

Hydrocolloids improve the volume, texture, and shelf life of bread. Exopolysaccharides (EPS) produced by lactic acid bacteria (LAB) during sourdough fermentation can replace hydrocolloids. It was the aim of this study to determine whether heteropolysaccharides (HePS) synthesized intracellularly from sugar nucleotides by glycosyltransferases are produced in wheat and gluten-free sorghum sourdough at effective levels. The HePS-producing strains Lactobacillus casei FUA3185, L. casei FUA3186, and Lactobacillus buchneri FUA3154 were used; Weissella cibaria 10M producing no EPS in the absence of sucrose served as control strain. Cell suspensions of L. buchneri in MRS showed the highest viscosity at low shear rate. Glycosyltransferase genes responsible of HePS formation in LAB were expressed in sorghum and wheat sourdough. However, only HePS produced by L. buchneri influenced the rheological properties of sorghum sourdoughs but not of wheat sourdoughs. Sorghum sourdough fermented with L. buchneri exhibited a low |G^∗| compared to the control, indicating a decrease in resistance to deformation. An increase in tan δ indicated decreased elasticity.The use of LAB producing HePS expands the diversity of EPS and increases the variety of cultures for use in baking.     

Effect of Fermentation by Pure Cultures of Yeasts and Lactobacilli on Phytic Acid and Polyphenol Content of Pearl Millet

Single and mixed pure culture fermentations of pearl millet flour with yeasts and lactobacilli, namely, Saccharomyces diastaticus, Saccharomyces cerevisiae, Lactobacillus brevis and Lactobacillus fermentum, at 30^oC for 72 hr brought about a significant reduction in phytic acid and polyphenols which were present in considerable amounts in pearl millet flour. Reduction in phytic acid was more pronounced than that in the polyphenols.     

Identification of lactic acid bacteria isolated from oat sourdoughs and investigation into their potential for the improvement of oat bread quality

The use of sourdough in wheat and rye breads has been extensively studied; however, little is known about its potential effect when baking oat bread. Consequently, the impact of sourdough on oat bread quality was investigated. Two different sourdoughs were prepared from wholegrain oat flour without the addition of starter cultures, by continuous propagation at 28 (SD 28) or 37 °C (SD 37) until the composition of the lactic acid bacteria remained stable. The dominant LAB were identified by sequence analysis of the 16S rDNA isolated from pure cultures. LAB from SD 28 belonged to the species Leuconostoc argentinum, Pedicoccus pentosaceus and Weissella cibaria, while Lactobacillus coryniformis dominated SD 37. The isolated LAB were further used as starter cultures for the production of oat sourdoughs. Fundamental rheology revealed softening of the sourdoughs compared to non-acidified and chemically acidified controls, which could not be attributed to proteolytic activity. Incorporation of oat sourdough into an oat bread recipe resulted in significantly increased loaf-specific volume as well as improved texture, independent of addition level or sourdough type. Overall, the results of this study show that sourdoughs containing lactic acid bacteria isolated from oats have the potential to enhance oat bread quality.     

Diversity of Lactic Acid Bacteria Isolated from Brazilian Water Buffalo Mozzarella Cheese

The water buffalo mozzarella cheese is a typical Italian cheese which has been introduced in the thriving Brazilian market in the last 10 y, with good acceptance by its consumers. Lactic acid bacteria (LAB) play an important role in the technological and sensory quality of mozzarella cheese. In this study, the aim was to evaluate the diversity of the autochthones viable LAB isolated from water buffalo mozzarella cheese under storage. Samples were collected in 3 independent trials in a dairy industry located in the southeast region of Brazil, on the 28th day of storage, at 4 ºC. The LAB were characterized by Gram staining, catalase test, capacity to assimilate citrate, and production of CO₂ from glucose. The diversity of LAB was evaluated by RAPD‐PCR (randomly amplified polymorphic DNA‐polymerase chain reaction), 16S rRNA gene sequencing, and by Vitek 2 system. Twenty LAB strains were isolated and clustered into 12 different clusters, and identified as Streptococcus thermophilus, Enterococcus faecium, Enterococcus durans, Leuconostoc mesenteroides subsp. mesenteroides, Lactobacillus fermentum, Lactobacillus casei, Lactobacillus delbrueckii subsp. bulgaricus, and Lactobacillus helveticus. Enterococcus species were dominant and citrate‐positive. Only the strains of L. mesenteroides subsp. mesenteroides and L. fermentum produced CO₂ from glucose and were citrate‐positive, while L. casei was only citrate positive. This is the first report which elucidates the LAB diversity involved in Brazilian water buffalo mozzarella cheese. Furthermore, the results show that despite the absence of natural whey cultures as starters in production, the LAB species identified are the ones typically found in mozzarella cheese.     

Studies concerning the use of <Emphasis Type="Italic">Lactobacillus helveticus</Emphasis> and <Emphasis Type="Italic">Kluyveromyces marxianus</Emphasis> for rye sourdough fermentation

The aim of this study was to investigate the fermentation behaviour, antioxidant activity and rheological behaviour of the sourdoughs prepared with Lactobacillus helveticus and Kluyveromyces marxianus. The final acidity of the sourdough after 18 h of fermentation was higher at higher temperatures (40 °C) and for the formulations with whole rye flour. The highest lactic/acetic acid ratios were obtained in case of more fluid sourdoughs fermented at 40 °C. The antioxidant properties of the sourdoughs are correlated with metabolic activity of the microorganisms, the DPPH radical scavenging activity being higher for optimum conditions of Lactobacillus helveticus growth. On the other hand, the rheological properties of the sourdoughs are not significantly influenced by the temperature. Sourdoughs formulations with whole flour are more viscous, as well as the controls fermented by the spontaneous microflora. The results of the bread-making process simulation by means of Mixolab indicate differences between dough formulations mainly depending on flour type.     

Die Mikroflora des Sauerteiges XXI. Mitteilung: Die in Sauerteigen schwedischer B?ckereien vorkommenden Lactobacillen

Zusammenfassung Es wurden Untersuchungen angestellt über die Bakterienflora von 9 Sauerteigen, die in schwedischen Bäckereien bei der Bereitung von Roggen/Weizen-Mischbroten und Weizenbroten Anwendung finden. Bei diesen Sauerteigen fanden als Starter Sauerteige Anwendung, die z. T. seit mehr als 10 Jahren fortgeführt werden. Es wurden insgesamt 238 Isolate gewonnen und als Vertreter der GattungLactobacillus identifiziert. Von den Isolaten waren 31 der UntergattungThermobacterium (Lactobacillus delbruekkii,L. delbrueckii ssp.bulgaricus,L. acidophilus) zuzuordnen, 40 Isolate der UntergattungStreptobacterium (Lactobacillus plantarum,L. casei rhamnosus,L. farciminis) und 112 Isolate der UntergattungBetabacterium (Lactobacillus fermentum,L. brevis ssp.lindneri,L. viridescens,L. brevis). Weitere 55 Isolate homo- und heterofermentativer Sauerteigbakterien waren nicht eindeutig einer Art des GenusLactobacillus zuzuordnen. Aufgrund der Verbreitung, der Häufigkeit des Auftretens und des Verhaltens im Säuerungsversuch sind für die untersuchten SauerteigeLactobacillus fermentum sowie die nicht identifizierten Sauerteigbakterien der Gruppierung h als typisch anzusehen.

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The Microflora of Sourdough. XXI. Communication: The lactobacillus species of sourdough from Swedish bakeries

Summary We investigated the bacterial flora of 9 sourdoughs which are used for the preparation of mixed breads (rye/wheat flour) and wheat breads in Swedish bakeries. These sourdoughs were employed as starter and some of them have been propagated for more than ten years. 238 isolates were obtained and speciated asLactobacillus. 31 of the isolates belonged to the subspeciesThermobacterium (Lactobacillus delbrueckii, L. delbrueckii ssp.bulgaricus,L. acidophilus), 40 to the subspeciesStreptobacterium (Lactobacillus plantarum,L. casei rhamnosus,L. farciminis) and 112 isolates to the subspeciesBetabacterium (Lactobacillus fermentum,L. brevis ssp.lindneri,L. viridescens,L. brevis). A further isolates 55 of homo- and heterofermentative sourdough bacteria did not clearly belong to any species of the genusLactobacillus. Because of the frequency of occurence and the behaviour in the acidification testLactobacillus fermentum and the not identified sourdough bacteria of group h are typical for the investigated sourdoughs.

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Nr. 5237 der Veröffentlichungen der Bundesforschungsanstalt für Getreide- und Kartoffelverarbeitung, Detmold