Nucleic acid studies on some heterofermentative lactobacilli: Description of Lactobacillus malefermentans sp.nov. and Lactobacillus parabuchneri sp.nov.

Chemotaxonomic studies were performed on some heterofermentative lactobacilli of uncertain taxonomic position. Two strains from beer and six strains from a variety of habitats were found to be distinct from each other and all other Lactobacillus species examined on the basis of DNA-DNA hybridizations and warrant new species for which the names L. malefermentans and L. parabuchneri , respectively, are proposed.     

Metabolism and some characteristics of lactobacilli isolated from the rumen of young calves

Fourteen strains of lactobacilli isolated from the rumen of young calves were studied to determine their biochemical characteristics, growth parameters, metabolism on lactose and sensitivity to 28 antimicrobial agents. Thirteen homofermentative strains belonged to Lactobacillus acidophilus and one heterofermentative strain resembled Lact. fermentum. The relevance of rumen lactobacilli to the nutrition of calves is discussed.     

Metabolism and some characteristics of lactobacilli isolated from the rumen of young calves

Fourteen strains of lactobacilli isolated from the rumen of young calves were studied to determine their biochemical characteristics, growth parameters, metabolism on lactose and sensitivity to 28 antimicrobial agents. Thirteen homofermentative strains belonged to Lactobacillus acidophilus and one heterofermentative strain resembled Lact. fermentum. The relevance of rumen lactobacilli to the nutrition of calves is discussed.     

Surface characteristics of lactobacilli isolated from human vagina

In the present paper, the taxonomic classification of 134 lactobacilli isolates from vaginal samples of 200 women of Tucumán, Argentina, is reported. They were clustered in three metabolic groups of the genus Lactobacillus, most belonging to the obligately homofermentative group (56%), mainly represented by Lactobacillus delbrueckii subsp. delbrueckii and L. acidophilus. In the facultatively heterofermentative group (24%), the dominant species were L. paracasei subsp. paracasei and L. agilis, and in the obligately heterofermentative group (20%), L. brevis was the dominant species. All strains were studied for surface characteristics and adhesion-predicting properties. A correlation between the methods employed for hydrophobicity testing of the different isolates (Microbial Adhesion to Hydrocarbons and Salt Aggregation Test) is reported. Most strains were highly hydrophobic. Their hemagglutination capability with human erythrocytes was also tested, which was positive only for a few strains. Some isolates were self-aggregating. From our results, strains that shared the properties assayed were selected for further testing of some other desirable characteristics, such as antagonistic substance production, adhesion to biological substrates, and appropriate technological properties, to suggest the elaboration of a probiotic for the vaginal tract.     

A Genomic View of Lactobacilli and Pediococci Demonstrates that Phylogeny Matches Ecology and Physiology

Lactobacilli are used widely in food, feed, and health applications. The taxonomy of the genus Lactobacillus, however, is confounded by the apparent lack of physiological markers for phylogenetic groups of lactobacilli and the unclear relationships between the diverse phylogenetic groups. This study used the core and pan-genomes of 174 type strains of Lactobacillus and Pediococcus to establish phylogenetic relationships and to identify metabolic properties differentiating phylogenetic groups. The core genome phylogenetic tree separated homofermentative lactobacilli and pediococci from heterofermentative lactobacilli. Aldolase and phosphofructokinase were generally present in homofermentative but not in heterofermentative lactobacilli; a two-domain alcohol dehydrogenase and mannitol dehydrogenase were present in most heterofermentative lactobacilli but absent in most homofermentative organisms. Other genes were predominantly present in homofermentative lactobacilli (pyruvate formate lyase) or heterofermentative lactobacilli (lactaldehyde dehydrogenase and glycerol dehydratase). Cluster analysis of the phylogenomic tree and the average nucleotide identity grouped the genus Lactobacillus sensu lato into 24 phylogenetic groups, including pediococci, with stable intra- and intergroup relationships. Individual groups may be differentiated by characteristic metabolic properties. The link between phylogeny and physiology that is proposed in this study facilitates future studies on the ecology, physiology, and industrial applications of lactobacilli.     

Characteristics of isolates of Lactobacillus fermentum from the rumen of sheep

A detailed characterization of four representative Lactobacillus isolates from the rumen was undertaken after tests with API CH50 kits had indicated that they differed from currently recognized species. These isolates are shown to be related to Lactobacillus fermentum , although they differ from the type and reference strains of this species in sodium dodecyl sulphate polyacrylamide gel electrophoresis patterns and electrophoretic mobility of LDH. It seemed that certain heterofermentative lactobacilli could give negative results for some fermentation tests (particularly fructose and lactose) in API kits, whilst showing good growth on the same substrates in conventional tests.     

Citrate utilization by homo- and heterofermentative lactobacilli

Citrate utilization by several homo- and heterofermentative lactobacilli was determined in Kempler and McKay and in calcium citrate media. The last medium with glucose permitted best to distinguish citrate-fermenting lactobacilli. Lactobacillus rhamnosus ATCC 11443, Lactobacillus zeae ATCC 15820 and Lactobacillus plantarum ATCC 8014 used citrate as sole energy source, whereas in the other strains, glucose and citrate were cometabolized. Some lactobacilli strains produced aroma compounds from citrate. Citrate transport experiments suggested that all strains studied presented a citrate transport system inducible by citrate. The levels of induction were variable between several strains. Dot blot experiment showed that lactobacilli do not present an equivalent plasmid coding for citrate permease.     

A survey of lactic acid bacteria in Italian silage

G razia , L. & S uzzi , G. 1984. A survey of lactic acid bacteria in Italian silage. Journal of Applied Bacteriology 56 , 373–379.
Lactic acid bacteria, isolated from Italian ensiled products, were represented by strains of the genera Lactobacillus and Leuconostoc . The predominant strains were heterofermentative lactobacilli, with Lactobacillus buchneri being the most frequent. Among homofermentative lactic acid bacteria, strains of Lact. plantarum and Lact. casei were recovered. Almost all strains utilized malic acid and showed good acid-tolerance, but only some of them were able to metabolize malic acid at extremely low pH; these were five homofermentative lactobacilli (4 Lact. plantarum and 1 Lacr. casei var. casei ) and two heterofermentative lactobacilli ( Lact. cellobiosus and Lactobacillus sp.).     

THE DIFFERENTIATION OF BACTERIAL SPECIES BY PAPER CHROMATOGRAPHY. VII. THE USE OF ELECTRONIC COMPUTATION FOR THE OBJECTIVE ASSESSMENT OF CHROMATOGRAPHIC RESULTS

SUMMARY: The use of electronic computation in the objective analysis of the chromato-graphic patterns of 90 strains of heterofermentative lactobacilli is described. The results showed that there was such a spread of properties among the different strains that a division into species was not justifiable.     

DNA-DNA homology, physiological characteristics and distribution of lactic acid bacteria isolated from maize silage

Lactic acid bacteria represent a dynamic bacterial group in maize silages. their establishment, variations and characterization have been studied by investigating 22 samples taken at different times during the ensilage process. After a preliminary screening based on physiological characteristics, 100 of 229 strains isolated were chosen for further taxonomic investigation. Twenty-nine strains of homo-fermentative lactobacilli were identified as Lactobacillus plantarum, L. casei and L. coryniformis subsp. coryniformis ; 24 heterofermentative strains were allotted to the species L. buchneri, L. brevis, L. fermentum and Leuconostoc paramesenteroides ; 22 coccal strains were assigned to Pediococcus pentosaceus and P. acidilactici and 25 coccal strains were identified as Enterococcus faecium, Streptococcus lactis and Strep. bovis. A few strains remained unidentified.     

Species composition of intestinal lactoflora of healthy rhesus monkeys

The results of the study of the species composition of the fecal microflora of 15 healthy rhesus macaques, from whom 204 strains of lactobacilli have been isolated and identified, are presented. The intestinal microflora has been shown to include different species, subspecies and biovars of homo- and heterofermentative lactobacilli and to possess definite individual properties. L. acidophilus, mannose-negative biovar I, and L. fermentum, mannose-negative biovars I and II, occur most frequently in feces. Certain differences in the species composition of lactoflora in monkeys and humans have been revealed: in the former, L. fermentum, mannitose-positive biovar III, and L. casei occur considerably more seldom. The inclusion of L. acidophilus strain I L. fermentum strains I and II isolated from rhesus macaques into eubiotics for these monkeys has been suggested.     

A note on the heterofermentative Lactobacillus isolated from kefir grains

M arshall , V.M., C ole , W.M. & F arrow , J.A.E. 1984. A note on the heterofermentative Lactobacillus isolated from kefir grains. Journal of Applied Bacteriology 56 , 503–505.
Heterofermentative lactobacilli have been isolated from kefir grains obtained from four different sources. A number of these isolates ferment only L-arabinose and gluconate and are similar to the species 'Lactobacillus desidiosus' . The DNA of these isolates, however, have 85–109% homology with 'L. caucasicus' NCDO 190 which is now regarded as L. kefir . The relationship between these strains is discussed.     

Citric acid metabolism in hetero- and homofermentative lactic acid bacteria.

The effect of citrate on production of diacetyl and acetoin by four strains each of heterofermentative and homofermentative lactic acid bacteria capable of utilizing citrate was studied. Acetoin was quantitatively the more important compound. The heterofermentative bacteria produced no acetoin or diacetyl in the absence of citrate, and two strains produced traces of acetoin in its presence. Citrate stimulated the growth rate of the heterofermentative lactobacilli. Acidification of all heterofermentative cultures with citric acid resulted in acetoin production. Destruction of accumulated acetoin appeared to coincide with the disappearance of citrate. All homofermentative bacteria produced more acetoin and diacetyl in the presence of citrate than in its absence. Citrate utilization was begun immediately by the streptococci but was delayed until at least the middle of the exponential phase in the case of the lactobacilli.     

Citric acid metabolism in hetero- and homofermentative lactic acid bacteria.

The effect of citrate on production of diacetyl and acetoin by four strains each of heterofermentative and homofermentative lactic acid bacteria capable of utilizing citrate was studied. Acetoin was quantitatively the more important compound. The heterofermentative bacteria produced no acetoin or diacetyl in the absence of citrate, and two strains produced traces of acetoin in its presence. Citrate stimulated the growth rate of the heterofermentative lactobacilli. Acidification of all heterofermentative cultures with citric acid resulted in acetoin production. Destruction of accumulated acetoin appeared to coincide with the disappearance of citrate. All homofermentative bacteria produced more acetoin and diacetyl in the presence of citrate than in its absence. Citrate utilization was begun immediately by the streptococci but was delayed until at least the middle of the exponential phase in the case of the lactobacilli.     

Identification of lactobacilli isolated in traditional ripe wheat sourdoughs by using molecular methods

Eleven sourdoughs from Molise region (Southern-Italy) were subjected to microbiological analyses in order to select predominant lactobacilli species to be utilised as starter culture for bread production. A multiple approach was used, consisting of the growth in different culture media, DGGE analysis, 16S rRNA gene sequencing and RAPD-PCR typing. Forty-three lactobacilli were identified and four different species, facultatively or obligately heterofermentative lactobacilli, were found. Lactobacillus plantarum and Lactobacillus brevis represented the prevailing lactobacilli, while Lactobacillus casei and Lactobacillus paracasei ssp. paracasei were detected only in few samples. The use of different media demonstrated that there is no efficient medium for the study of sourdoughs and the cultivation in different substrates remains the best tool to obtain a picture of lactic acid bacteria population. DGGE and 16S rRNA gene sequencing allowed to obtain a reliable identification of strains, while RAPD-PCR resulted a suitable method for typing lactobacilli at strain level.     

Lactobacillus paraplantarum sp. now., a new species related to Lactobacillus plantarum

Four strains of facultatively heterofermentative lactobacilli isolated from beer and human feces have physiological characteristics similar to those of Lactobacillus plantarum. Unlike 66% of the L. plantarum strains tested (F. Bringel, M.-C. Curk, and J.-C. Hubert, Int. J. Syst. Bacteriol. 46:588-594, 1996), these strains do not catabolize alpha-methyl-D-mannoside. However, because they exhibit little DNA relatedness to L. plantarum and Lactobacillus pentosus, these four strains were classified as members of a new species, Lactobacillus paraplantarum; strain CNRZ 1885 (= CIP 104668) is the type strain.     

Fructose 6-phosphate phosphoketolase activity in wild-type strains of Lactobacillus, isolated from the intestinal tract of pigs

Phosphoketolases are key enzymes of the phosphoketolase pathway of heterofermentative lactic acid bacteria, which include lactobacilli. In heterofermentative lactobacilli xylulose 5-phosphate phosphoketolase (X5PPK) is the main enzyme of the phosphoketolase pathway. However, activity of fructose 6-phosphate phosphoketolase (F6PPK) has always been considered absent in lactic acid bacteria. In this study, the F6PPK activity was detected in 24 porcine wild-type strains of Lactobacillus reuteri and Lactobacillus mucosae, but not in the Lactobacillus salivarius or in L. reuteri ATCC strains. The activity of F6PPK increased after treatment of the culture at low-pH and diminished after porcine bile-salts stress conditions in wild-type strains of L. reuteri. Colorimetric quantification at 505 nm allowed to differentiate between microbial strains with low activity and without the activity of F6PPK. Additionally, activity of F6PPK and the X5PPK gene expression levels were evaluated by real time PCR, under stress and nonstress conditions, in 3 L. reuteri strains. Although an exact correlation, between enzyme activity and gene expression was not obtained, it remains possible that the xpk gene codes for a phosphoketolase with dual substrate, at least in the analyzed strains of L. reuteri.     

Molecular characterization of lactic acid bacteria from sourdough breads produced in Sardinia (Italy) and multivariate statistical analyses of results

The objective of this work was to investigate the structure and diversity of lactic acid bacteria (LAB) communities in sourdough used for the production of traditional breads (Carasau, Moddizzosu, Spianata, Zichi) in Sardinia. 16S rDNA sequencing and Randomly Amplified Polymorphic DNA (RAPD-PCR) was applied for the identification and typing of the LAB isolated from 25 samples of sourdoughs. Multivariate statistical techniques were applied to RAPD-PCR pattern to study the biological diversity of sourdough samples. Twelve different species of LAB were identified, and most isolates were classified as facultative heterofermentative lactobacilli. Lactobacillus pentosus dominated the lactic microflora of many samples while Lactobacillus sanfranciscensis was isolated only from a limited number of samples. Although heterofermentative species represented between between 30% and 60% of the isolates in Carasau, Spianata and Zichi sourdoughs, only 2% of the isolates from Moddizzosu sourdoughs were identified as heterofermentative LAB. RAPD-PCR with a single primer followed by cluster analysis did not allow the identification of the isolates at the species level. However, a multidimensional scaling/bootstrapping approach on the RAPD-PCR patterns uncovered the diversity of the LAB communities of LAB showing differences both within and between bread types.     

The Ecology and Classification of Strains of Lactobacillus collinoides nov. spec.: A Bacterium Commonly Found in Fermenting Apple Juice

S ummary : Most heterofermentative lactic rods occurring throughout the cider industry are quite similar and form a fairly coherent group. The constituent bacteria are sufficiently different from other heterofermentative lactobacilli to be considered a new species. They have, therefore, been named Lactobacillus collinoides nov. spec. These occur most frequently in factories where sulphur dioxide, the only permitted preservative, is either used in small quantities or not at all.     

Investigations on the Glycerol Metabolism of Lactobacilli

S ummary . The glycerol metabolism of homofermentative and heterofermentative strains of Lactobacillus obtained either from Culture Collections or isolated from sausages has been investigated.
The results show that the homofermentative lactobacilli ( Thermobacterium and Streptobacterium ) produce mannose phosphate which is then metabolized to lactic acid and other byproducts.