Characterization of lactic acid bacteria isolated from Algerian arid zone raw goats\' milk

Diversity and density of lactic acid bacteria isolated from Algerian raw goats\' milk in arid zones were studied by determination of morphological, cultural, physiological and biochemical characteristics. 206 lactic acid bacterial strains were isolated, with 115 of them belonging to lactic acid cocci and others to the genus, Lactobacillus. The representative species of the total cocci were Lactococcus sp. (76.16%), Streptococcus thermophilus (14.78%) and Leuconostoc sp. (8.6%). The dominating species is Lactococcus lactis subsp. Lactis. Lactobacilli species found in local raw goats\' milk and their proportion were: Lb. curvatus (25.25%), Lb. helviticus (10.98%), Lb. plantarum (9.89%), Lb. reuteri (9.89%), Lb. casei (7.69%), Lb. brevis (5.49%), Lb. bulgaricus (5.49%) Lb. paracasei (4.39%) and Lb. acidophilus (2.19%). Key Words: Lactic acid bacteria, raw milk, goat, arid zones, identification. African Journal of Biotechnology Vol.3(6) 2004: 339-34

The reproducibility of random amplified polymorphic DNA (RAPD) profiles of Streptococcus thermophilus strains with XD9, M13 and OPI-02 MOD primers

We optimized the conditions for generating random amplified polymorphic DNA (RAPD) profiles of Streptococcus thermophilus strains by using the polymerase chain reaction (PCR). Several factors can cause the amplification of false and non reproducible bands in the RAPD profiles. We tested three primers, OPI-02 MOD, M13 and XD9 throughout this study. In addition, we tested different concentrations of primer, DNA template and Taq DNA polymerase. We adjusted the ratio of the primer to DNA template. All the three primers yielded reproducible profiles on several days, under optimized concentrations of components and cycling parameters used. The bands of such profiles probably corresponded to perfect annealing sites amplified with good efficacy or present in multiple copies in the genome. Five months later, repeated experiment generated identical bands. However, extra faint bands were detected with M13 and XD9 primers, possibly, corresponding to nonspecific binding resulting from slight variation in temperature or calibration of the thermocycler. Therefore, OPI-02 MOD was determined as the most reliable primer for reproducible profiles of S. thermophilus strains.Key words: Streptococcus thermophilus, random amplified polymorphic DNA (RAPD), DNA template, Taq DNA polymerase, OPI-02MOD, XD9, M13, optimization, reproducibility

Study of the Antimicrobial and Probiotic Effect of Lactobacillus Plantarum Isolated from Raw Goat's Milk from the Region of Western Algeria

The evolution from a spontaneous fermentation to a directed one is realised with selected lactic starters which give many dairy products processing various organoleptic characters. The integration of new lactic acid bacteria strains isolated from diverse ecosystems is now used to increase the duration of bio-preservation of dairy products. Moreover, some lactic acid bacteria probiotic activity is exploited to produce functional food. The aim of this study is the research of the possible probiotic and technological potential with some preventive and therapeutic characteristics of some Lactobacillus species isolated from Algeria

A new manometric method for measuring carbon dioxide production by dairy starter culture: a case of Leuconostoc mesenteroides

This paper describe a technique for carbon dioxide (CO2) measurement based on the displacement of acidifying liquid in burette at constant pressure. It was adapted to allow the growth of Leuconostoc sp. on semi-synthetic media and milk. A highly precise measurement was obtained using the chemical reaction of sodium carbonate with hydrochloric acid. This method has been proven to present an excellent linear response from 0 to 0.895 mM of CO2 with a high sensitivity. With cultures in milk medium, kinetics of CO2 evolved by Leuconostoc mesenteroides subsp. dextranicum L4 were higher than L. mesenteroides subsp. mesenteroides 19D and L. mesenteroides subsp. cremoris Ec195 grown on milk.. The use of L. mesenteroides subsp. dextranicum L4 and their variants Lac(-)Cit(+), Lac(+)Cit(-) and Lac(-)Cit(-) showed that the CO2 production correlated to the substrate utilization. The curve of CO2 measured was close to the amount of CO2 calculated from lactose and citrate used. The CO2 production rate was higher with the parental strain (6.5 mM/ h) than with the variants. The amount of CO2 produced was always close to the theoritical value, and was also correlated to the growth rate and substrates utilization by L. mesenteroides. The volume of CO2 produced by Leuconostoc in milk was highly correlated with the D-lactate production (r = 0.995). This method could be used routinely for the evaluation and the selection of bacteria having potential ability for CO2 production.Keywords: Leuconostoc sp., CO2 production, lactic acid, mil

Identification of cultivable bifidobacterium species isolated from breast-fed infants feces in West-Algeria

Gastrointestinal microflora exerts a high impact on its host mainly by performing a great variety of metabolic activities, protecting the host against colonization by pathogen and stimulating the gut immune system. The integration of bifidobacteria in dairy products is of interest for reinstalling the intestinal microflora. The mother\'s milk is a prebiotic factor which stimulate the bifidobacteria growth in vivo. Results obtained in west Algeria area show that the number of bifidobacteria reach 26 109 cfu/g in breast-fed infant feces. The microbiological, fructose–6-phospho-ketolase and the biochemical tests have revealed Bifidobacterium strains. The most prevalent isolates belong to the species Bifidobacterium longum (75%) and Bifidobacterium breve (25%). In order to evaluate the potential use as a starter culture, the occurrence of some selected properties such as growth and survival in fermented milk were investigated. These strains have a fast growth in glucose, galactose and lactose media compared to reference species. All isolates studied are sensitive to the pH 8. the B. breve strain support the conservation conditions in pure culture better than in mixed culture with Streptococcus thermophilus or Lactobacillus acidophilus.African Journal of Biotechnology Vol. 4 (5), pp. 422-430, 200

Activité Anti-Bactérienne de Lactobacillus plantarum isolée du lait cru de chèvre d’Algérie vis à vis de Staphylococcus aureus

The food contamination is a major problem for the consumer especially during the summer period in the hot countries. The bacterial interactions exploitation is a new strategy to fight against these pathogenic microorganisms. The objectif of this study was to characterize Lactobacillus sp isolated from raw goat's milk which can produce an anti-microbial substance toward the growth of Staphylococcus aureus. The microbiological and biochemical methods were used to identify the isolates of lactic acid bacteria which have an antimicrobial activity. Nine isolates of lactic acid bacteria were identified and belonging to Lactobacillus species. The dominant species are: Lb. rhamnosus, Lb. plantarum, Lb. casei, Lb. paracasei subsp. paracasei, Lb. acidophilus, Lb. delbrueckii subsp. lactis, Lb. fermentum, Lb. paraplantarum and Lactobacillus sakei subsp. sakei. The study of the interactions revealed the capacity of three strains Lb. plantarum (58), Lb. paracasei subsp. paracasei (55) and Lb. rhamnosus (68) which can inhibite Staphylococcus aureus. In mixed culture with Lb. plantarum the growth of Staphylococcus aureus was 1.6 log cfu/ml after 12 h and no growth was observed after 72 h of incubation. The chemical characterization of inhibiting substance of Staphylococcus aureus revealed the protein nature.La contamination des aliments est un problème majeur pour le consommateur surtout durant la période estivale dans les pays méditerranéens. L’exploitation des interactions bactériennes est un nouveau moyen pour lutter contre les germes indésirables. L’objectif de ce travail est la recherche des bactéries lactiques productrices de substances antimicrobiennes vis-à-vis des germes nuisibles. Les méthodes microbiologiques et biochimiques ont été utilisées pour identifier les bactéries présentant une activité antimicrobienne. Neuf isolats de bactéries lactiques ont été identifiés à partir du lait cru de chèvre dans les régions de l’Ouest algérien. Les espèces dominantes appartenant au genre Lactobacilles sont : Lb. rhamnosus, Lb. plantarum, Lb. casei, Lb. paracasei subsp. paracasei, Lb. acidophilus, Lb. delbrueckii subsp lactis, Lb. fermentum, Lb. paraplantarum et Lactobacillus sakei subsp. sakei. L’étude des interactions a révélé la capacité de trois espèces Lb. plantarum (58), Lb. Paracasei subsp. paracasei (55) et Lb. rhamnosus (68) à inhiber Staphylococcus aureus. En culture mixte, Lb. plantarum réduit considérablement la croissance de Staphylococcus aureus de 1,6 log après 12 h d’incubation et aucune croissance n’a été observée après 72h. Les différents tests utilisés révèlent la nature protéique de cette substance impliquée dans l’inhibition de Staphylococcus aureus

Polyphasic Characterisation of Non-Starter Lactic Acid Bacteria from Algerian Raw Camel’s Milk and Their Technological Aptitudes

Pozadina istraživanja. Spontano fermentirano devino mlijeko često se konzumira u Alžiru, što ga čini održivim izvorom različitih bakterija mliječno-kiselog vrenja, koje se mogu dodati starter kulturi radi poboljšanja kakvoće i sigurnosti fermentiranih mliječnih proizvoda. Eksperimentalni pristup. Dvanaest uzoraka sirovog devinog mlijeka upotrijebljeno je kao izvor autohtonih bakterija mliječno-kiselog vrenja, koje su zatim okarakterizirane pomoću 39 fenotipskih osobina što imaju tehnološki značaj. Rezultati i zaključci. Trideset i devet nestarterskih bakterija mliječno-kiselog vrenja izolirano je iz 12 uzoraka alžirskog sirovog devinog mlijeka, te je mikrobiološki, biokemijski i genetički okarakterizirano. Neki su izolati imali proteolitičku aktivnost, svojstvo zakiseljavanja, sposobnost korištenja citrata i proizvodnje dekstrana i acetoina. Etanol, acetaldehid, metil-acetat, acetoin i octena kiselina glavni su hlapljivi spojevi pronađeni u uzorcima. Klasterskom analizom pomoću metode UPGMA (engl. unweighted pair group method with arithmetic mean) određena je prosječna udaljenost klastera na osnovu trideset i devet ispitanih fenotipskih značajki, te je potvrđena mikrobiološka raznolikost sirovog devinog mlijeka. Novina i znanstveni doprinos. Sojevi izolirani iz netipičnog izvora imali su zanimljive tehnološke značajke koje ih čine prikladnim za dodavanje starter kulturi. Klasterska analiza na osnovu ispitanih fenotipskih osobina pokazala se kao koristan alat za tipiziranje izolata u slučaju kad ne postoje genetske informacije o sojevima. Ove spoznaje mogu se primijeniti u industrijskoj proizvodnji prerađevina devinog mlijeka.Research background. Consumption of spontaneously fermented camel’s milk is common in Algeria, making it a feasible source of diverse lactic acid bacteria (LAB) with the potential to be used as adjunct cultures to improve quality and safety of fermented dairy products. Experimental approach. Twelve raw camel´s milk samples were used as a source of indigenous LAB, which were further characterised by examining 39 phenotypic traits with technological relevance. Results and conclusions. Thirty-five non-starter LAB (NSLAB) were isolated from 12 Algerian raw camel\u27s milk samples and they were microbiologically, biochemically and genetically characterised. Some isolates showed proteolytic activity, acidifying capacity, the ability to use citrate, and to produce dextran and acetoin. Ethanol, acetaldehyde, methyl acetate, acetoin and acetic acid were the major volatile compounds detected. Cluster analysis performed using the unweighted group with arithmetic average (UPGMA) method, and based on the thirty-nine phenotypic characteristics investigated, reflected the microbial diversity that can be found in raw camel´s milk. Novelty and scientific contribution. The isolated strains, from a non-typical source, showed interesting technological traits to be considered as potential adjunct cultures. Cluster analysis based on the examined phenotypic characteristics proved to be a useful tool for the typification of isolates when no genetic information is available. These findings may be of use towards an industrialised production of camel\u27s milk dairy products

Characterization of lactic acid bacteria isolated from Algerian arid zone raw goats' milk

Diversity and density of lactic acid bacteria isolated from Algerian raw goats' milk in arid zones were studied by determination of morphological, cultural, physiological and biochemical characteristics. 206 lactic acid bacterial strains were isolated, with 115 of them belonging to lactic acid cocci and others to the genus, Lactobacillus . The representative species of the total cocci were Lactococcus sp. (76.16%), Streptococcus thermophilus (14.78%) and Leuconostoc sp. (8.6%). The dominating species is Lactococcus lactis subsp. Lactis . Lactobacilli species found in local raw goats' milk and their proportion were: Lb. curvatus (25.25%), Lb. helviticus (10.98%), Lb. plantarum (9.89%), Lb. reuteri (9.89%), Lb. casei (7.69%), Lb. brevis (5.49%), Lb. bulgaricus (5.49%) Lb. paracasei (4.39%) and Lb. acidophilus (2.19%)

Antimicrobial activity of lactic acid bacteria and the spectrum of their biopeptides against spoiling germs in foods

The objective of this study was to isolate LAB from dairy, meat products and agro-industrial wastes and to investigate their antagonist activity. A total of 141 isolates were screened for the inhibitory effect on ten indicator strains in the agar spot test. Results showed that strain LBbb0141 contained antimicrobial compound with wide spectrum that inhibited the growth of ten indicator Gram-positive and Gram-negative strains. The bacteriocin activity attained its maximum value using the MRS agar at initial pH 7.5 and 30°C incubation temperature