File Name: lactic acid bacteria and bifidobacteria current progress in advanced research .zip
Lactic Acid Bacteria pp Cite as. Lactic acid bacteria LAB is a general term for a class of bacteria that use the metabolism of carbohydrates in the external environment to produce lactic acid.
The purpose of this study was to establish the probiotic potential of lactic acid bacteria LAB starter cultures, Lb. The cultures were examined for tolerance to acid and bile salts, bile salt hydrolase BSH activity, antibiotic susceptibility, biogenic amine production, mucin degradation, hydrophobicity, auto-aggregation, adherence to the ileum, coaggregation, and antimicrobial properties against selected pathogenic species.
All isolates lacked mucolytic activity. The candidate and reference microorganisms were resistant to 10 of 21 and 5 of 21 antibiotics, respectively. The isolates exhibited hydrophobic, auto-aggregation and coaggregation properties. These three properties were exhibited more by the reference than the potential probiotics. The ability of the potential probiotics to attach onto the goat ileum 7. The four LAB inhibited E. The findings indicated potential probiotic activity of the starter cultures.
However, further in vivo examination of these isolates is required to confirm their probiotic capabilities. There is a general global interest in the use of probiotics in food, in feeds, and as supplements to enhance human and animal health. Probiotics are live microorganisms which when administered in adequate amounts confer health benefits to the host [ 1 ]. Some of the health benefits include the following: prevention of antibiotic related diarrhea, treatment of irritable bowel syndrome, production of B vitamins, prolongation of life, production of antioxidants and other geroprotectors, serum cholesterol reduction, prevention of cancers, treatment of Helicobacter pylori , relief from lactose intolerance, and improved immune response, among others [ 2 — 10 ].
The major bacterial probiotics used in functional foods are lactic acid bacteria LAB and Bifidobacteria [ 11 ]. In fact, majority of probiotic research is based on these two groups, given their association with human health, and generally regarded as safe GRAS status [ 12 ]. Traditional fermented foods exhibit a rich biodiversity of microorganisms from which probiotic microorganisms can be selected [ 12 , 13 ].
Indeed, many studies have reported a number of probiotic and potentially probiotic microorganisms from various fermented foods including kule naoto , bryndza cheese, hukati , hidal, dadhi , and dangke [ 14 — 20 ].
Obushera is a traditional fermented sorghum-millet beverage originally from south western Uganda. The beverage is used as a weaning food, thirst quencher, and social drink at gatherings [ 21 ].
Traditionally, it is fermented using wild microorganisms, with LAB being among the dominant species involved [ 22 , 23 ]. LAB are known to contribute to the flavor profile and safety of fermented foods as well as promote health by acting as probiotics [ 24 , 25 ]. These cultures have been piloted for the commercial production of Obushera and have promise for use in related fermented food products. However, hitherto this study, no work had been done to establish whether they possess potential probiotic properties.
Having been isolated from a traditional fermented food, the starter cultures could be weak or may lack functionality in the human gastrointestinal tract GIT. Byakika et al. In summary, candidate microorganisms should be screened for the following 1 tolerance to gastrointestinal conditions, 2 safety, and 3 probiotic benefit s. It was upon these guidelines that the probiotic potentials of Lb.
The reference strain was Lb. The probiotic activity of these starter cultures could translate into technological applications that improve the safety and functionality of fermented foods as well as overall consumer health. The LAB were independently propagated according to the procedure described by Mukisa [ 21 ]. From the stock cultures of Lb. For the E. Bile salt hydrolase BSH activity was also determined according to the method described by Borah et al. Hydrolysis of the bile esculine produced a dark brown coloration on the agar.
Susceptibility of the isolates to different antibiotics Bioanalyse, Ankara, Turkey was determined using the Kirby—Bauer disk diffusion method as previously described [ 32 ].
A total of 21 antibiotics Table 1 were selected from the different classes of antibiotics presented by Charteris et al.
Using sterile cotton swabs, MRS agar plates were swabbed with culture suspensions grown overnight and standardised to 0. The inhibition zone diameter was measured in mm. The isolates were categorized as resistant, moderately susceptible, or susceptible to the respective antibiotics based on the study by Charteris et al.
Decarboxylation medium was formulated according to Bridson [ 34 ]. The pH of the media was adjusted to 6. Ten milliliters of the sterile medium was separately inoculated with 0. Decarboxylation medium without added amino acids was used as a control. Decarboxylase activity was indicated by a deep purple coloration. To examine mucolytic ability of the isolates, the procedure described by Abe et al. Mucin obtained from a fresh goat ileum was used.
To obtain the mucin, the ileum of a 6-month-old healthy goat was obtained immediately after slaughter from a local abattoir. The ileum was cut open, and the mucin was scrapped off using a microscope glass slide. Mucin sterilized this way does not affect the biological activity of its constituents [ 37 ]. Intestinal microorganisms from a stool sample obtained from a healthy adult volunteer were used as a positive control.
Auto-aggregation was determined according to the procedure described by Kos et al. To examine adhesion, the method described by Abbasiliasi et al. After it was washed to remove ingesta and delivered to the laboratory, the ileum was cut into several 2. To determine the residual microbial counts C 1 on the ileum pieces after the third stage of vortexing, selected serial dilutions of the washed ileum were pour plated in sterile PCA. A negative control consisting of the ileum pieces in sterile diluent were also incubated at the same conditions.
Thereafter, the pieces were rinsed with sterile diluent to remove the unattached LAB. The experiment was done in duplicates. Coaggregation was determined following the method described by Kos et al. Antimicrobial activity was determined using the agar well diffusion assay as described by Vinderola et al. The CFCS was filtered through a 0. To examine if the antimicrobial activity was mediated by organic acids, the pH of the CFCS used was adjusted to 6. All experiments were performed in duplicate.
There was a one log decline in cell counts in both treatments throughout the incubation period. Gastric juice and bile salts are biological barriers in the stomach and duodenum, respectively, that can be inhibitory to many microorganisms [ 43 ].
Similarly, they must survive passage in the duodenum where bile salt levels can be high as 0. Surviving in these harsh gastric conditions enables probiotics to reach the ileum alive, colonize it, and impart their benefits [ 48 ].
The survival of microorganisms in gastric juice is attributed to generation of a proton motive force, which expels protons from the cells, thus maintaining a normal intracellular pH [ 48 ]. Tolerance to bile is a prerequisite for colonization and metabolic activity of probiotics in the ileum [ 43 , 50 ]. Bile salts are known to have antimicrobial effects against some microorganisms [ 51 ] and may slow down growth [ 52 ].
They can disrupt the microbial cellular homeostasis as well as dissociate the lipid bilayer and integrity of the cell membrane resulting in cell death [ 12 ]. However, some LAB produce bile salts hydrolase BSH which hydrolyzes conjugated bile salts, thus lowering their toxicity [ 45 ].
The average bile concentration in the duodenum is about 0. Goldin and Gorbach [ 55 ] recommend 0. These findings are in agreement with those of several authors [ 54 , 56 , 57 ]. The intensity of hydrolysis was in the order as follows: W. BSH is an enzyme produced by intestinal microflora that catalyzes the deconjugation of glycine- or taurine-linked bile salts [ 58 ]. These findings are in agreement with those of other authors who also reported BSH activity in LAB [ 14 , 16 , 20 , 59 ].
Deconjugation of bile salts reduces their toxicity, thus enabling probiotic LAB to survive in the duodenum [ 45 , 60 ]. Deconjugated bile salts are lethal to some pathogens [ 61 ], and therefore, BSH activity by the LAB starters could contribute towards their antimicrobial properties.
The mechanism by which probiotics protect themselves against these deconjugated salts is yet to be understood. Deconjugated bile salts not only inhibit pathogens but also are associated with reduction of serum cholesterol [ 4 , 61 ]. This is because deconjugated bile salts are poorly reabsorbed in the liver, which results in their excretion in stool. This increases the demand for serum cholesterol for the de novo synthesis of bile salts in the liver [ 4 , 62 ].
The LAB starters in this study may therefore possess cholesterol-lowering effects. This property is particularly useful for individuals with hypercholesterolemia. Table 1 shows the susceptibility of the LAB to different antibiotics. However, susceptibility to amoxicillin, cephalexin, streptomycin, levofloxacin, and novobiocin against LAB is currently not documented. Therefore, susceptibility to these was based on antibiotics within their classes.
Results showed that the Obushera LAB starter cultures and reference probiotic were resistant to 10 and 5 of 21 antibiotics, respectively. The Obushera starters were generally resistant to penicillin G, ampicillin, vancomycin, gentamycin, kanamycin, tetracycline, ciprofloxacin, metronidazole, sulphamethoxazole-trimethoprin, and colistin.
Antibiotic resistance is inherent in some LAB, and the mechanisms involved include absence of a target, low permeability, antibiotic inactivation, and presence of efflux mechanisms, among others [ 12 ]. There are concerns that some antibiotic resistant LAB may be reservoirs of antibiotic resistance genes that could be transferred to pathogens [ 63 , 64 ]. However, with intrinsic resistance, the risk of resistance gene transfer is not only still speculative but also practically impossible [ 12 , 65 ].
For instance, Lactobacilli are known to have a high natural chromosomally encoded resistance to vancomycin [ 66 ]. This resistance is due to the absence of D -Ala- D -lactate in their cell wall which is the target for vancomycin; therefore, such resistance is nontransferable [ 67 , 68 ]. The natural resistance of Lactobacilli to vancomycin could thus explain the results in Table 1.
In fact, these results are in agreement with those of Zhou et al. In addition, the resistance of Lactobacilli to aminoglycosides such as gentamycin, kanamycin, and streptomycin is also thought to be intrinsic by Hummel et al.
The resistance of LAB to penicillin G, ampicillin, vancomycin, gentamycin, kanamycin, tetracycline, ciprofloxacin, metronidazole, sulphamethoxazole-trimethoprin, and colistin is also reported elsewhere [ 66 ] [ 16 , 57 , 68 , 72 ].
Six lactic acid bacteria LAB , isolated from the intestinal tract of the longevous population, were prominent for their strong bacteriostatic ability. In this study, the adhesion properties of the six strains were determined in vitro to explore their potential to be used as probiotics. The hydrophobicity and aggregation activity were firstly detected and were varied from Moreover, the adhesion activity to the intestinal crypt cells IEC-6 cells was proved to be varied from 5. Meanwhile every sample was inclined to exclude rather than displace or compete to inhibit the indicator microorganisms to adhere to IEC-6 cells. Afterwards, the adhesion activities of the LAB were demonstrated to be highly affected by the surface proteins considering the treatments of heat, pepsin, trypsin and NaIO 4. This study will be beneficial to examine the characteristics of these strains especially L.
Request PDF | On Aug 1, , H. B. Ghoddusi published Lactic Acid Bacteria and Bifidobacteria: Current Progress in Advanced Research.
Lactobacillales are an order of gram-positive , low-GC , acid-tolerant, generally nonsporulating, nonrespiring , either rod-shaped bacilli or spherical cocci bacteria that share common metabolic and physiological characteristics. These bacteria, usually found in decomposing plants and milk products, produce lactic acid as the major metabolic end product of carbohydrate fermentation , giving them the common name lactic acid bacteria LAB. Production of lactic acid has linked LAB with food fermentations , as acidification inhibits the growth of spoilage agents.
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Lactic acid bacteria LAB and bifidobacteria are amongst the most important groups of microorganisms used in the food industry. For example, LAB are used in the production of fermented products, such as yoghurts, cheese and pickled vegetables. Both LAB and bifidobacteria are also thought to have health-promoting abilities and many are used as probiotics for the prevention, alleviation and treatment of intestinal disorders in humans and animals. In this comprehensive book, expert international authors review the most recent cutting-edge research in these areas. Topics include: Lactobacillus genomics; Bifidobacterium gene manipulation technologies; metabolism of human milk oligosaccharides in bifidobacteria; proton-motive metabolic cycles; oxidative stress and oxygen metabolism; Bifidobacterium response to O 2 ; bile acid stress in LAB and bifidobacteria; protein structure quality control; bacteriocin classification and diversity; lactococcal bacteriocins; lactobacilli bacteriocins; other bacteriocins; production of optically pure lactic acid; antihypertensive metabolites from LAB; the anti- H.
They have generated many tables that will be very useful to researchers in the fıeld. Lactic acid bacteria and bifidobacteria: current progress in advanced.
The purpose of this study was to establish the probiotic potential of lactic acid bacteria LAB starter cultures, Lb. The cultures were examined for tolerance to acid and bile salts, bile salt hydrolase BSH activity, antibiotic susceptibility, biogenic amine production, mucin degradation, hydrophobicity, auto-aggregation, adherence to the ileum, coaggregation, and antimicrobial properties against selected pathogenic species. All isolates lacked mucolytic activity.
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