Identification and technological properties of lactic acid bacteria isolated from raw goat milk of four Algerian races

Biochemical and Microbiological Changes Associated with Fermentation of Durum Wheat for Lemzeïet Processing, a Traditional Algerian Fermented Food

In Algeria, “Lemzeïet” is prepared by the natural fermentation of wheat. This study aimed to follow the evolution of microbiological and biochemical properties of Lemzeïet with and without vinegar addition for 3, 6, 9 and 12 months. Lactic acid bacteria (LAB) were identified and the microbial count, as well as pH, acidity, protein, fat, ash and starch contents were determined. Results showed that Lemzeïet samples represented a safe product after the gradual absence of fungi. It also contained a significant load of LAB that were cocci or rods, white or yellow, grouped in chain, pair and tetrad. LAB isolates were mannitol positive, grew between 10 and 45 °C, showed resistance at 63.5 °C and the majority were homo-fermentative. Results showed a significant decrease in pH during fermentation regardless of the vinegar addition. Protein content increased up to 14.90% and 15.50% at the end of fermentation. The fat and starch contents decreased after 12 months of fermentation, regardless of the vinegar addition. Ash content remained high (1.41% and 1.45%) after six months of fermentation with and without vinegar, respectively. The microbiological and the biochemical characteristics of Lemzeïet make it a very interesting raw material in the manufacturing of healthy foods.

Harnessing diversity of Lactococcus lactis from raw goat milk: Design of an indigenous starter for the production of Rocamadour, a French PDO cheese

Twenty-four strains of Lactococcus lactis isolated from raw goat milk collected in the Rocamadour PDO area were analysed by MLST typing and phenotypic characterisation. The strains were combined to design an indigenous starter for the production of Rocamadour PDO cheese. The strains were divided into three classes based on their technological properties: acidifying and proteolytic strains in class I (12/24 strains), slightly acidifying and non-proteolytic strains in class II (2/24 strains), and non-acidifying and non-proteolytic strains in class III (10/24 strains). Interestingly, all but three strains (21/24) produced diacetyl/acetoin despite not having citrate metabolism genes, as would classically be expected for the production of these aroma compounds. Three strains (EIP07A, EIP13D, and EIP20B) were selected for the indigenous starter based on the following inclusion/exclusion criteria: (i) no negative interactions between included strains, (ii) ability to metabolize lactose and at least one strain with the prtP gene and/or capable of producing diacetyl/acetoin, and (iii) selected strains derived from different farms to maximise genetic and phenotypic diversity. Despite consisting exclusively of L. lactis strains, the designed indigenous starter allowed reproducible cheese production with performances similar to those obtained with an industrial starter and with the sensory qualities expected of Rocamadour PDO cheese.

Probiotic bacteria from 10 different traditional Iranian cheeses: Isolation, characterization, and investigation of probiotic potential

In this study, 10 different traditional Iranian cheeses, which are still consumed by people in rural areas of Iran, were examined to isolate new strains of probiotic bacteria. Isolated bacteria were identified by 16s rRNA gene amplification and subjected to series of in vitro tests to find out their probiotic potential. A total of 2345 colonies were collected and 465 of them were confirmed as lactic acid bacteria (LAB), of which Lactiplantibacillus plantarum, Lactobacillus bulgaricus, and Lacticaseibacillus casei were the top three isolated bacteria. Among the different species of LAB isolated in this study, Lactip. plantarum was the most isolated species, and seven isolates had the significant criteria for being a probiotic strain than other isolates indicating the most adaptable properties of this species. Lactiplantibacillus plantarum was the most resistant bacteria in the bile resistance test and was also the most durable bacteria in gastrointestinal conditions, for example, acidic environment (pH = 2.5) and trypsin. In contrast, Lacticaseibacillus casei was the most susceptible bacterial strain. Lactobacillus rhamnosus showed the most antibacterial effect against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. This study showed that probiotic strains isolated from local cheeses could be considered as suitable biopreservatives and used as specific starter cultures for the production of functional cheeses.

Identification and probiotic potential of lactic acid bacteria from camel milk

In the present study, a total of 80 presumed lactic acid bacteria (LAB) were isolated from camel milk. Selected LAB were identified as Lactococcus lactis (cam 12), Enterococcus lactis (cam 14) and Lactobacillus plantarum (cam 15) and their potential were tested by tolerance & de-conjugation of bile salts, antimicrobial activity, surface hydrophobicity and adhesion potential) along with this of probiotics were evaluated for curd formation and assessed for sensory properties and syneresis. Selected LABs showed antimicrobial activity against wide range of pathogenic bacteria (Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus cereus and Escherchiaia. coli). LAB (cam 12, cam 14 and cam15) were highly sceptible to chloramphenicol, vancomycin, and tetracyclin. In vitro adhesion studies with Caco-2 cells demonstrated strong adhesion activity with hydrophobicity (99%) was observed. Acute oral toxicity of E. lactis and L. plantarum showed non-toxic, non-virulent and safe for industrial application. The study provides potential LAB which may act as a substitute of functional food, synthetic feed and industrial curd formulation with in the shortest span (240 min at 28–32 °C).

Diversity of non-starter lactic acid bacteria in autochthonous dairy products from Western Balkan Countries - Technological and probiotic properties

The aim of this review was to summarize the data regarding diversity of non-starter lactic acid bacteria (NSLAB) isolated from various artisanal dairy products manufactured in Western Balkan Countries. The dairy products examined were manufactured from raw cow's, sheep's or goat's milk or mixed milk, in the traditional way without the addition of commercial starter cultures. Dairy products such as white brined cheese, fresh cheese, hard cheese, yogurt, sour cream and kajmak were sampled in the households of Serbia, Croatia, Slovenia, Bosnia and Herzegovina, Montenegro, and North Macedonia. It has been established that the diversity of lactic acid bacteria (LAB) from raw milk artisanal dairy products is extensive. In the reviewed literature, 28 LAB species and a large number of strains belonging to the Lactobacillus, Lactococcus, Enterococcus, Streptococcus, Pediococcus, Leuconostoc and Weissella genera were isolated from various dairy products. Over 3000 LAB strains were obtained and characterized for their technological and probiotic properties including: acidification and coagulation of milk, production of aromatic compounds, proteolytic activity, bacteriocins production and competitive exclusion of pathogens, production of exopolysaccharides, aggregation ability and immunomodulatory effect. Results show that many of the isolated NSLAB strains had one, two or more of the properties mentioned. The data presented emphasize the importance of artisanal products as a valuable source of NSLAB with unique technological and probiotic features important both as a base for scientific research as well as for designing novel starter cultures for functional dairy food.

Probiotic and technological features of Enterococcus and Weissella isolates from camel milk characterised by an Argane feeding regimen

The objectives of this study were to isolate lactic acid bacteria (LAB) from a raw Moroccan camel milk collected after the incorporation of a specific Argane by-products diet, and to investigate their technological properties as well as their probiotic features. The molecular identification of the isolates indicated that they belong to Weissella confusa, Weissella cibaria or Enterococcus durans species. Our results revealed that the tested isolates have a fast acidifying ability (values ranging between 0.045 ± 0.01 to 0.93 ± 0.01 after only 4 h incubation), important proteolysis, autolysis, lipolytic activities and an important diacetyl and exopolysaccharides production. All these isolates demonstrated a high tolerance to gastrointestinal conditions, namely to gastric simulated juice (survival rate ranged between 75.05 ± 7.88 and 85.55 ± 1.77%) and to bile salts (survival rate between 42.79 ± 1.11 and 82.75 ± 1.01%). The autoaggregation, hydrophobicity and antioxidant activity mean values of the isolates were 13.26-41.16%, 13.23-54.47% and 47.57-63.31%, respectively. Importantly, LAB cultures exhibited antibacterial activity against Gram-negative and Gram-positive pathogenic bacteria and none of the tested isolates presented antibiotic resistance, haemolytic or DNase activities. This study revealed interesting properties for LAB isolated and supported their utilization as autochthone starters for camel milk fermentation that represent a challenge process. These results presented as well the probiotic potential for a possible human consumption.

Functional and health promoting inherent attributes of Enterococcus hirae F2 as a novel probiotic isolated from the digestive tract of the freshwater fish Catla catla

Background

Probiotic microorganisms are gaining global importance because of their use in the preparation of a nutraceutical or in the treatment of infections. As per the health industry demand, there is an urgent need for exploring new indigenous probiotic strains with its specific origin due to variation in gut microflora, different food habits and specific host-microbial interactions. The main objective of the present study was to isolate and identify a novel probiotic Enterococcus strain from the gut of Catla catla fish and evaluate its potentiality as a potent probiotic.

Methods

The whole study was designed with the isolation of novel lactic acid bacterial strain from the gut of Catla catla fish with their biochemical and molecular identifications. The potentiality of the isolated strain as a potent probiotic was carried out according to the parameters described in FAD/WHO guidelines for the evaluation of probiotics in food.

Results

The isolated strain was confirmed as Enterococcus hirae F2 on the basis of various biochemical and 16s rRNA gene sequencing methods. Enterococcus hirae F2 was able to survive under highly acidic and bile salt concentration with the ability for the production of lipase and Bsh enzyme. It was also able to survive under simulated gastrointestinal conditions with the inhibition ability of various pathogens. The antioxidant potentiality with the cell surface hydrophobicity and cell aggregation ability confirms its potentiality as a potent probiotic. All the results detail the potency of Enterococcus hirae F2 as a novel probiotic for a safer use.

Discussion

The isolation of Enterococcus hirae with probiotic potential from the gut of fish is a new approach and done for the first time. However, the whole study concluded that the isolated strain might be used as a novel probiotic in the food industry for the production of new probiotic products which imparts health benefits to the host.

Technological Properties and Biogenic Amines Production by Bacteriocinogenic Lactococci and Enterococci Strains Isolated from Raw Goat's Milk

Technological properties and biogenic amine production were analyzed in 56 bacteriocinogenic lactococci and enterococci strains isolated from raw goat's milk. Fifteen lactococci strains were able to reduce milk pH to 5.3 or lower after 6 h, while enterococci strains were initially slow in producing acids. Lactococcus lactis subsp. lactis GLc06 and three strains of Enterococcus faecalis (GEn20, GEn22, and GEn23) presented high proteolytic activity. L. lactis subsp. lactis GLc06 and E. faecalis GEn22 also showed a high percentage of autolysis after only 4 h, reaching 71.11 and 97.67%, respectively, after 24 h. No strain was able to secrete exopolysaccharides, and L. lactis subsp. lactis GLc22 and 25 of the Enterococcus strains were able to produce diacetyl. L. lactis subsp. lactis GLc05 and 23 of the Enterococcus strains presented a high tolerance to NaCl at 10% (wt/vol). Regarding biogenic amine production, 12 strains (5 lactococci and 7 enterococci) were capable of forming tyramine and 4 strains (1 lactococcus and 3 enterococci) were capable of forming 2-phenylethylamine, but in very low amounts. GLc06 presented great acidifying, proteolytic, and autolytic activities, and GLc05 was capable of growing at high NaCl concentrations (10%, wt/vol), possessing medium autolytic and proteolytic activities. Some enterococci strains produced diacetyl and high autolytic and extracellular proteolytic activities and also presented resistance to high NaCl concentrations. The interesting technological properties presented by some bacteriocinogenic strains can justify their use by the dairy industry, with the aim of ensuring both safety due to bacteriocin production and technological transformations in fermented products.

Functional Properties of Microorganisms in Fermented Foods

Fermented foods have unique functional properties imparting some health benefits to consumers due to presence of functional microorganisms, which possess probiotics properties, antimicrobial, antioxidant, peptide production, etc. Health benefits of some global fermented foods are synthesis of nutrients, prevention of cardiovascular disease, prevention of cancer, gastrointestinal disorders, allergic reactions, diabetes, among others. The present paper is aimed to review the information on some functional properties of the microorganisms associated with fermented foods and beverages, and their health-promoting benefits to consumers.

Identification of Coccoidal Bacteria in Traditional Fermented Milk Products from Mongolia, and the Fermentation Properties of the Predominant Species, Streptococcus thermophilus

The objective of this study was to identify the coccoidal bacteria present in 188 samples of fermented yaks', mares' and cows' milk products collected from 12 different regions in Mongolia. Furthermore, we evaluated the fermentation properties of ten selected isolates of the predominant species, Streptococcus (S.) thermophiles, during the process of milk fermentation and subsequent storage of the resulting yoghurt at 4℃. Overall, 159 isolates were obtained from 188 samples using M17 agar. These isolates were presumed to be lactic acid bacteria based on their gram-positive and catalase-negative properties, and were identified to species level using 16S rRNA gene sequence analysis. These coccoid isolates were distributed in four genera and six species: Enterococcus (E.) durans, Enterococcus (E.) faecalis, Lactococcus (Lac.) subsp. lactis, Leuconostoc (Leuc.) lactis, Leuconostoc (Leuc.) mesenteroides. subsp. mesenteroides and S. thermophilus. Among these S. thermophilus was the most common species in most samples. From evaluation of the fermentation characteristics (viable counts, pH, titratable acidity [TA]) of ten selected S. thermophilus isolates we could identify four isolates (IMAU 20246, IMAU20764, IMAU20729 and IMAU20738) that were fast acid producers. IMAU20246 produced the highest concentrations of lactic acid and formic acid. These isolates have potential as starter cultures for yoghurt production.

Antibiotic susceptibility and heterogeneity in technological traits of lactobacilli isolated from Algerian goat's milk

The objective of this study was to identify and study the heterogeneity of technological traits of lactobacilli from goat's milk of Algeria and to evaluate in vitro their safety aspect. Using API50 CHL system and 16S rDNA sequencing, 51 % of strains were assigned as Lactobacillus plantarum, 34 % as L. pentosus, 7 % as L. rhamnosus and 8 % as L. fermentum. A large variability was noted for the acidifying capacity in skim milk after 6, 12 and 24 h of incubation. All strains expressed aminopeptidase activity against alanine-ρ-NA and leucine-ρ-NA at different levels. All strains were resistant to vancomycin and most of strains showed more susceptibility to β-lactam antibiotic. High susceptibility toward the inhibitors of protein synthesis was also observed. Minimum inhibitory concentrations data obtained revealed that isolates were susceptible to penicillin and chloramphenicol, and resistant to gentamicin and vancomycin. Minimum inhibitory concentrations distribution of other antibiotics showed variability. The analysis of graphical representation of principal component analysis of technological properties of L. plantarum and L. pentosus strains showed diversity among the isolates. Finally, eight L. plantarum (LAM1, LAM3, LAM21, LAM25, LAM35, LF15, LAM34, and LAM35), four L. pentosus (LAM38, LAM39, LF9 and LF16) and two L. rhamnosus (LF3 and LF10) strains, could be good candidates as adjunct culture in dairy product in Algeria.

Phenotypic and genotypic characterization of lactic acid bacteria isolated from raw goat milk and effect of farming practices on the dominant species of lactic acid bacteria

Lactic acid bacteria, in particular Lactococcus lactis, play a decisive role in the cheese making process and more particularly in lactic cheeses which are primarily produced on goat dairy farms. The objective of this study was therefore to identify the main lactic acid bacteria found in raw goats' milk from three different regions in France and evaluate if certain farming practices have an effect on the distribution of species of lactic acid bacteria in the various milk samples. Identification at genus or species level was carried out using phenotypic tests and genotypic methods including repetitive element REP-PCR, species-specific PCR and 16S rRNA gene sequencing. The distribution of the main bacterial species in the milk samples varied depending on farms and their characteristics. Out of the 146 strains identified, L. lactis was the dominant species (60% of strains), followed by Enterococcus (38%) of which Enterococcus faecalis and Enterococcus faecium. Within the species L. lactis, L. lactis subsp lactis was detected more frequently than L. lactis subsp cremoris (74% vs. 26%). The predominance of L. lactis subsp cremoris was linked to geographical area studied. It appears that the animals' environment plays a role in the balance between the dominance of L. lactis and enterococci in raw goats' milk. The separation between the milking parlor and the goat shed (vs no separation) and only straw in the bedding (vs straw and hay) seems to promote L. lactis in the milk (vs enterococci).

Selection of autochthonous strains as promising starter cultures for Fior di Latte, a traditional cheese of southern Italy

BACKGROUND

This paper describes the selection of promising strains intended as starter cultures from the autochthonous lactic acid bacteria of Fior di Latte cheese (Apulia region, southern Italy).

RESULTS

Ninety-five isolates were randomly selected from whey and Fior di Latte. After preliminary characterization based upon Gram staining, deamination of arginine, hydrolysis of esculine and production of CO2 from glucose and citrate, the isolates were studied for their growth at different temperatures (10, 15 and 45 °C), with salt addition (20, 40 and 65 g L(-1) ) and at pH 4.4 and their acidification score in MRS broth after 6 and 24 h. Data were modeled through the growth index and used as input to run a preliminary cluster analysis and a principal component analysis. In this way, nine promising strains were selected and used for validation at laboratory level, to study the acidification score in milk and propose some possible microbial mixtures.

CONCLUSION

This paper reports the first research focusing on the design of a lactic starter for the production of Fior di Latte cheese, using a quantitative approach based on the evaluation of growth index and acidification score as well as on the use of a multivariate approach to select the most promising nine strains.

Virulence, antibiotic resistance and biogenic amines of bacteriocinogenic lactococci and enterococci isolated from goat milk

The present study aimed to investigate the virulence, antibiotic resistance and biogenic amine production in bacteriocinogenic lactococci and enterococci isolated from goat milk in order to evaluate their safety. Twenty-nine bacteriocinogenic lactic acid bacteria (LAB: 11 Lactococcus spp., and 18 Enterococcus spp.) isolated from raw goat milk were selected and subjected to PCR to identify gelE, cylA, hyl, asa1, esp, efaA, ace, vanA, vanB, hdc1, hdc2, tdc and odc genes. The expression of virulence factors (gelatinase, hemolysis, lipase, DNAse, tyramine, histamine, putrescine) in different incubation temperatures was assessed by phenotypic methods, as well as the resistance to vancomycin, gentamicin, chloramphenicol, ampicillin and rifampicin (using Etest®). The tested isolates presented distinct combinations of virulence related genes, but not necessarily the expression of such factors. The relevance of identifying virulence-related genes in bacteriocinogenic LAB was highlighted, demanding for care in their usage as starter cultures or biopreservatives due to the possibility of horizontal gene transfer to other bacteria in food systems.

Technological aptitude and applications of Leuconostoc mesenteroides bioactive strains isolated from Algerian raw camel milk

Two strains (B7 and Z8) of the Leuconostoc mesenteroides subspecies mesenteroides that were isolated from Algerian camel milk from an initial pool of 13 strains and demonstrated a high ability to inhibit the growth of Listeria spp. were selected and characterised at the phenotypic and genotypic levels. Probiotic profiling and inhibition spectra against food borne pathogens in mixed cultures were also investigated. The bacteriocin produced by L. mesenteroides strain B7 was identified as leucocin B by specific PCR. In vitro studies demonstrated that both Leuconostoc mesenteroides strains exhibited a marked probiotic profile, showing high survival at low pH (2-3 and 4) in the presence of 0.5%, 1%, and 2% of bile salts and at pH 3 in the presence of 3 mg/mL pepsin. Susceptibility testing against antimicrobial agents was also performed for both strains. When tested in a mixed culture with Listeria innocua, Listeria ivanovii, or Staphylococcus aureus, strain B7 reduced the numbers of these species by 1.87, 1.78, and 1.38 log units, respectively. Consequently, these two strains were found to possess good probiotic properties in vitro and a high capacity for Listeria spp. inhibition in mixed cultures. Therefore, these strains have a favourable technological aptitude and a potential application as novel probiotic starters.

Bio-control of waterborne pathogens using Lactobacillus spp

Bacteria play a significant role in water contamination. Chemicals are mostly used for the treatment of bacteriologically contaminated water. The use of bacterial interactions is a new approach to limit the pathogens' growth. Detection of antimicrobial substances produced by lactic acid bacteria against the waterborne pathogens is the objective of this work. Microbiological and biochemical methods were used to identify lactic acid bacteria having an antimicrobial activity. Evaluation of antimicrobial activity with growth kinetic measurements was performed. Four isolates of lactic acid bacteria obtained from whey and curd were identified. The predominant species belonging to the Lactobacillus genera are: Lactobacillus rhamnosus, Lactobacillus sakei, Lactobacillus paracasei, and Lactobacillus paraplantarum. The present study revealed that the Lactobacillus consortium is able to inhibit Staphylococcus aureus's growth along with Escherichia coli and Vibrio species. In mixed culture, after 24 h, the Lactobacillus consortium reduces the growth of S. aureus by 2.03 log; moreover, the growth of the latter bacteria totally ceased after 72 h of incubation. The protein produced by the Lactobacillus consortium was responsible for arresting the growth of S. aureus.

Dietary supplementation with nonconventional feeds from the Middle East: assessing the effects on physicochemical and organoleptic properties of Awassi sheep milk and yogurt

Increased feed costs affect the livelihoods of dairy sheep farmers in the Middle East. Farmers endure high risks with large fluctuations in the price of grain used as animal feed, which is further affected by drought and declining range productivity. Using agricultural by-products and treated straw or vetch grazing for supplementing sheep diets would provide resource-poor dairy farmers with increased options to reduce feed costs, but the effects of such feeds on the quality of yogurt (the main product) need to be better understood. Two experiments were conducted to evaluate these effects. The first trial evaluated alternative diets using locally available feedstuffs, including agricultural by-products, compared with traditional diets used by dairy sheep farmers, and was conducted on-station at the International Center for Agricultural Research in Dry Areas (ICARDA, Tel Hadya, Aleppo, Syria). Milking Awassi ewes (n=56) were used to test 6 alternative diets against a traditional control diet containing barley, wheat bran, and barley straw. The 6 alternative diets contained 4 or more of the following ingredients: barley, sugar beet pulp, molasses, cotton seed cake, wheat bran, urea-treated wheat straw, and barley straw. Ewes on one of the alternative diets grazed vetch pasture, whereas ewes on the control diet and the 5 alternative diets grazed native range pasture. The milk fat content was higher in diets containing urea-treated straw. Yogurt firmness and adhesiveness were significantly lower in energy-rich diets (e.g., the control diet) and in the diets rich in soluble sugar (molasses). The effects of diet on yogurt color and on citric and succinic acid contents were significant. A yogurt produced from the milk of the group grazing on vetch was the most yellowish in color, which is appealing to Syrian consumers. The content of citric acid tended to be higher in yogurts produced from diets containing molasses. The second trial was conducted on 3 farms in northern Syria to assess an alternative diet (1 of the 6 tested in the first trial) on 15 milking ewes compared with the farmer's traditional diet (control). The alternative diet increased yogurt firmness and adhesiveness by 7 to 9% and 10 to 16%, respectively. The use of nonconventional feeds available in the region enhances yogurt quality, may reduce requirements for expensive grains, and thus, increase farmers' livelihoods by targeting expanding markets with better quality products.

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). Lactococcus strains were those that showed the greatest degree of acidifying and proteolytic activity. The cell-free extracts (CFE) of L. paracasei exhibited the highest level of aminopeptidase activity. The highest level of caseinolytic activity was shown by the CFE of one strain of L. lactis. High values were also obtained with the CFE of Lactobacillus and of several Leuconostoc. The highest level of dipeptidase activity was found amongst the strains of L. lactis. Carboxypeptidase activity was generally very low or undetectable for the majority of strains. The greatest degree of esterolytic activity was detected for Enterococcus.