scholarly journals Antimicrobial Characteristics of Lactic Acid Bacteria Isolated from Homemade Fermented Foods

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Dayong Ren ◽  
Jianwei Zhu ◽  
Shengjie Gong ◽  
Hongyan Liu ◽  
Hansong Yu

Objective. Lactic acid bacteria (LAB) were isolated from fermented foods, such as glutinous rice dough, corn noodle, chili sauce, potherb mustard pickles, and stinky tofu, in northeast China. LAB strains with antimicrobial activities were screened, and seven of these Lactobacillus strains were identified as L. plantarum, L. pentosus, and L. paracasei through 16S rRNA gene analysis. After the supernatant of LAB was treated with proteinase K, pepsin, and papain, their antibacterial effect almost disappeared. Most strains with antibacterial activities were highly resistant to heat (65°C–121°C), acidity (pH 2–6), and alcohol. The antimicrobial effect of most strains treated with the Tween-80 surfactant was significantly reduced, and the antibacterial property of T4 was even lost. Ammonium sulfate precipitation, PCR, and nanoLC-ESI-MS/MS results confirmed that T8 produced antibacterial substances belonging to a protein family, and its zone of inhibition against pathogens significantly increased (>13 mm). In bacterial growth inhibition experiments, the colony count of Staphylococcus aureus was up to 1015 CFU/mL in the 3⁎de Man, Rogosa, and Sharpe (MRS) group, and this value was more than that in the 3⁎S6 supernatant group (1012 CFU/mL) and the control group (1010 CFU/mL) at 12 h. This study provided a basis for the selection of antimicrobial peptides and the development and utilization of LAB.

2021 ◽  
Vol 13 (1) ◽  
pp. 122-127
Author(s):  
Ayomide F. Sowemimo ◽  
Abiola O. Obisesan ◽  
Funmilola A. Ayeni

Kunu is a non-alcoholic fermented cereal beverage consumed primarily as a refreshing drink. This study investigated the effects of storage conditions on viability of Lactic Acid Bacteria (LAB) in kunu and the antibacterial effects of Kunu against diarrhoea caused by Escherichia coli strains. Kunu was prepared according to local traditional method. Viability counts of LAB in kunu stored at two different conditions, cold (4 ℃ average) and room temperature (26 ℃ average), were evaluated. Isolated LAB from kunu were identified by partial sequencing of 16S rRNA gene. Five pathotypes of diarrhoea caused by E. coli strains were co-cultured with kunu to evaluate its antimicrobial activities. Viable LAB count in kunu ranged from 5.0 x 109 to 1.0 x 1011 cfu/mL. Pediococcus pentosaceus, Lactobacillus plantarum and Leuconostoc pseudomesenteroides were identified from kunu. There is a drastic decrease (2-5 log reduction) in E. coli strains co-cultured with kunu. The observed high viable counts of beneficial LAB in kunu with its antimicrobial activities against diarrhoeaogenic E. coli strains indicates that kunu is not just a refreshing drink, but it also has antimicrobial potential against diarrhoea caused by E. coli.


2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Stellah Byakika ◽  
Ivan Muzira Mukisa ◽  
Robert Mugabi ◽  
Charles Muyanja

Bacterial contamination of fermented foods is a serious global food safety challenge that requires effective control strategies. This study characterized presumptive E. coli isolated from Obushera, a traditional fermented cereal beverage from Uganda. Thereafter, the antimicrobial effect of lactic acid bacteria (LAB) previously isolated from Obushera, against the E. coli, was examined. The presumptive E. coli was incubated in brain heart infusion broth (pH = 3.6) at 25°C for 48 h. The most acid-stable strains were clustered using (GTG)5 rep-PCR fingerprinting and identified using 16S rRNA sequencing. E. coli was screened for Shiga toxins (Stx 1 and Stx 2) and Intimin (eae) virulence genes as well as antibiotic resistance. The spot-on-the-lawn method was used to evaluate antimicrobial activity. Eighteen isolates were acid stable and are identified as E. coli, Shigella, and Lysinibacillus. The Stx 2 gene and antibiotic resistance were detected in some E. coli isolates. The LAB were antagonistic against the E. coli. Lactic acid bacteria from traditional fermented foods can be applied in food processing to inhibit pathogens. Obushera lactic acid bacteria could be used to improve the safety of fermented foods.


2020 ◽  
Vol 21 (7) ◽  
Author(s):  
Achmad Dinoto ◽  
A’liyatur Rosyidah ◽  
Anggi Ria Puspitasari Susilo ◽  
Heddy Julistiono

Abstract. Dinoto A, Rosyidah A, Susilo ARPS, Julistiono H. 2020. Isolation, identification and antimicrobial activities of Lactic Acid Bacteria from fruits of wild plants in Tambrauw Forest, West Papua, Indonesia. Biodiversitas 21: 3391-3397. Presence of culturable lactic acid bacteria (LAB) in fruits of wild plants and their antimicrobial activities has not been widely reported. The purposes of this study were to isolate LAB from the fruits of wild plants found in the Tambrauw forest area, West Papua Indonesia, and to evaluate their antimicrobial activities. Isolation of LAB from fruit was conducted using MRS medium supplemented with 1% CaCO3. Isolates of LAB were identified based on 16S rRNA gene using BLAST analysis. Antimicrobial assays were carried out by determining the minimum inhibitory concentration (MIC) based on thiazolyl blue tetrazolium blue (MTT) using indicator microorganisms Escherichia coli, Staphylococcus aureus, and Mycobacterium smegmatis. The results showed that total of fourteen isolates of LAB with different characteristics was successfully isolated from 8 of 14 collected wild plants. Based on 16S rRNA sequences, isolates had closest relationships with Lactococcus lactis, Lactococcus garvieae, Weissella confusa, Weissella oryzae, and Enterococcus faecalis with the similarity of 99%. All 16S rRNA nucleotides of these strains have been deposited in the GenBank. Assays for antimicrobial activities were demonstrated by the highest inhibition of supernatant of Lac. lactis HM 1.1 from fruit plant Donax canniformis and W. confusa H14.2 from fruit plant Capparis sp. against E. coli, S. aureus, and M. smegmatis even though the MIC values of those strains were lower than that of bacterial strain from the commercial probiotic product. This study showed that wild fruit from Tambrauw forest harbor beneficial lactic acid bacteria that could be important for health of animals and humans as well. In addition, this study provided basic information on indigenous LAB for promoting further development of medicinal antibacterial compounds.


2019 ◽  
Vol 68 (2) ◽  
pp. 203-209 ◽  
Author(s):  
FOLASHADE GRACE ADEOSHUN ◽  
WERNER RUPPITSCH ◽  
FRANZ ALLERBERGER ◽  
FUNMILOLA ABIDEMI AYENI

The composition of vagina lactic acid bacteria (LAB) differs within the different ethnic group. This study is aimed at determining the prevalence of LAB with their antimicrobial properties in Nigerian women’s vagina during different stages of the menstrual cycle. Microorganisms were isolated from vaginal swabs of ten Nigerian women during different stages of the menstrual cycle and identified by partial sequencing of the 16S rRNA gene. The antimicrobial properties of the LAB were tested against the multidrug-resistant uropathogens. The prevalence of LAB was higher during ovulation period while during menstruation period, it declined. Twenty-five LAB isolates were identified as three species, namely: Lactobacillus plantarum (15), Lactobacillus fermentum (9), Lactobacillus brevis (1) and one acetic acid bacteria – Acetobacter pasteurianus. The LAB had antimicrobial activities against the three uropathogens with zones of inhibition from 8 to 22 mm. The presence of LAB inhibits the growth of Staphylococcus sp. GF01 also in the co-culture. High LAB counts were found during ovulation period with L.plantarum as a dominant species while during menstruation, there was a decrease in the LAB counts. The isolated LAB has antimicrobial properties against the urogenital pathogens tested thus exhibiting their potential protective role against uropathogens.


2021 ◽  
Author(s):  
Iulia-Roxana Angelescu ◽  
Silvia-Simona Grosu-Tudor ◽  
Lucia-Roxana Cojoc ◽  
Gabriel-Mihai Maria ◽  
Medana Zamfir

Abstract Traditionally fermented foods and beverages are still produced and consumed at a large scale in Romania. They are rich sources for novel lactic acid bacteria with functional properties and with potential application in food industry or health. Lactobacillus helveticus 34.9, isolated from a home-made fermented milk is able to inhibit the growth of other bacteria, such as other lactic acid bacteria, but also strains of Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, and Halobacillus hunanensis, a halobacterium isolated from the degraded wall of a Romanian monastery. L. helveticus 34.9 produces a large bacteriocin (35 KDa), active in a wide pH range, but inactivated by heat and proteinase K treatment. Bacteriocin production was enhanced under stress conditions, especially when combined stresses were applied. Its mode of action and degree of inhibition depended on the indicator strain and on the concentration of bacteriocin that was used. L. delbrueckii subsp. bulgaricus LMG 6901T cells from a suspension were killed within 8 h, but the viability of H. hunanensis 5Hum cells was only reduced to 60%. However, the bacteriocin was able to prevent the bacterial growth of both indicator strains when added to the medium prior inoculation. Scanning electron microscopy images revealed morphological changes induced by the bacteriocin treatment in both sensitive strains, but more severe in the case of L. delbrueckii subsp. bulgaricus. This class III bacteriocin, with inhibitory activity against various bacterial species, may find application in food and non-food related fields, including in the restoration of historical buildings.


Foods ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 271
Author(s):  
Jelena Stupar ◽  
Ingunn Grimsbo Holøymoen ◽  
Sunniva Hoel ◽  
Jørgen Lerfall ◽  
Turid Rustad ◽  
...  

Biopreservation is a food preservation technology using microorganisms and/or their inherent antimicrobial metabolites to inhibit undesirable microorganisms. The aim of the present study was to explore the diversity and antimicrobial activity of lactic acid bacteria (LAB) strains (n = 99) isolated from ready-to-eat (RTE) seafood (cold-smoked salmon (CSS), gravlax, and sushi) towards two strains of Listeria monocytogenes (CCUG 15527, F11), Listeria innocua (CCUG 15531) and Escherichia coli (CCUG 38079). The LAB strains were assigned to five different genera (Carnobacterium spp., Lactobacillus spp., Leuconostoc spp., Weissella spp., and Enterococcus sp.) by sequencing a 1150 bp stretch of the 16S rRNA gene. A significant association between the seafood source and the distribution of LAB genera was found (p < 0.001), of which Leuconostoc spp. were most prevalent in sushi and Carnobacterium sp. and Lactobacillus sp. were most frequently isolated from CSS and gravlax. Antimicrobial activity among the LAB was significantly affected by LAB genera (F= 117.91, p < 0.001, one-way ANOVA), product of origin (F = 3.47, p < 0.05), and target (F = 4.64, p = 0.003). LAB isolated from sushi demonstrated a significantly higher antimicrobial effect than LAB from CSS and gravlax (p < 0.05). In general, a significantly higher antimicrobial activity was found towards Listeria spp. than E. coli (p < 0.05). However, Leuconostoc spp. demonstrated similar antimicrobial effects towards E. coli and Listeria spp., except for L. monocytogenes F11 being more sensitive (p < 0.05). This study suggested that seafood-derived LAB strains could be selected for technological application in RTE seafood systems.


2020 ◽  
Vol 6 (2) ◽  
pp. 49-55
Author(s):  
Jieun Yim ◽  
Eun-Young Chang ◽  
Min Young Kim ◽  
Dahyun Song ◽  
Seok-Seong Kang

2020 ◽  
Author(s):  
◽  
Mellisa Nokulunga Jula

Cereal fermented products are popular in developing countries, especially in Asia and Africa, because of their unique taste and fulfilment. Throughout the years, they have played a vital part in bringing up infants as part of their weaning foods and contributing to the daily diet of many households. Food fortification and supplementation of cereal grains with inexpensive readily available legumes, which have higher protein content compared to cereals may lead to a potential decrease in protein-energy malnutrition. Underutilised and indigenous crops such as Bambara groundnut can be in incorporated into the fermentation of cereal fermented foods, such as injera. In this study, injera was prepared by substituting only 9% and 12% Bambara groundnut flour and comparing them with the traditionally fermented original control, which is injera made from only tef flour. The first part of the study was to identify and characterise the lactic acid bacteria (LAB) and yeast involved in the spontaneous fermentation of traditional tef-injera and the newly developed injera fortified with Bambara groundnut (which contains 12% Bambara groundnuts) at different fermentation intervals of 0, 24, 48, and 72 hour. A total of 70 LAB isolates and 30 yeast isolates were identified from both fermentations using rep-PCR fingerprinting followed by sequencing the 16S rRNA gene and the D1/D2 region of the 26S rRNA gene. Weissella confusa, Lc. lactis and Lb. curvatus predominated in both fermentations at different intervals of the fermentation. The second part of the study investigated the effectiveness of the isolated LAB starter cultures on the production of injera and injera fortified with Bambara groundnut after which their physicochemical properties were evaluated. There was a significant increase (p<0.05) in titratable acidity and a significant decrease in pH to below four within 24 hours; recorded for samples inoculated with LAB starter cultures when compared to samples fermented without inoculation. The third and fourth parts of the study investigated the proximate composition and storage stability of the injera samples. Injera fortified with 12% Bambara groundnut + LAB culture had a significantly high (p<0.05) protein of 23.21%, the lowest protein content being Tef injera at 7.35%. The protein digestibility of Tef injera increased with the addition of Bambara groundnut and LAB starter culture. The digestibility of protein increased from 40% for Tef injera to 80% for injera fortified with 12% Bambara flour + LAB culture. There was no significant increase (p >0.05) in the amino acid content after the addition of Bambara flour + LAB cultures; the amino acid concentrations were slightly lower than the standard concentration recommended by the Food and Agricultural Organisation/World Health Organisation for adults. Injera samples fortified with Bambara groundnut flour and inoculated with lactic acid starter cultures were stable with microbial counts ranging from 4.42 log cfu/g to 4.68 log cfu/g for TPC at 4 ̊C, yeast and mould, coliforms and aerobic spore formers were not detected in all the samples from day 0 to day three upon storage. Higher counts had been perceived at room temperature ranging from 4.60 log cfu/g to 7.53 log cfu/g for moulds and 4.90 log cfu/g to 9.26 cfu/g for TPC; coliforms were detected in one tef injera only ranging from 4.48 log cfu/g to 6.16 log cfu/g and no detection of aerobic spore formers in all samples. Refrigeration temperatures effectively maintained the microbiological quality of injera for three days. The nutritional quality, distinctively the protein content increased with the addition of Bambara groundnut flour and through the use of lactic acid bacteria as a starter culture This will potentially pave the way for the commercialisation of injera in the industry with the use of LAB starter culture to ensure a fast and continuous supply of fresh injera that is in high demand.


Food Research ◽  
2021 ◽  
Vol 5 (3) ◽  
pp. 163-173
Author(s):  
A. Ismail ◽  
M.N. Lani ◽  
H.A. Zakeri ◽  
N.N. Hasim ◽  
R. Alias ◽  
...  

Fermented tilapia (Tilapia nicoliticus) is one of the famous fermented food in Malaysia. Lactic acid bacteria (LAB) which well known as GRAS (Generally Regarded as Safe) are present in most fermented foods and they are well-known non-pathogenic bacteria that play an important role in everyday life. Apart from LAB, spices have also been used for centuries across different regions of the world to improve aroma, flavour and food preservative. This research was aimed to explore a potential natural food preservative using LAB isolated from fermented Tilapia nicoliticus incorporated with various spices (9% turmeric, 6% chilli and 9% black pepper) against foodborne pathogens. The isolation of LAB in different media (MRS, MRS+CaCO3, M17 and Tomato Juice Agar) showed the highest LAB count on day-9 and day-15 during the fermentation period in fermented Tilapia incorporated with black pepper, turmeric and chilli. The highest antimicrobial activity by LAB against Bacillus cereus was observed in fermented tilapia incorporated with black pepper. On the other hand, fermented fish incorporated with chilli showed the highest antimicrobial activity against Staphylococcus aureus, Escherichia coli and Salmonella enterica serovar Typhimurium. Higher antimicrobial activity was detected in fermented Tilapia in the presence of LAB together with the spices, in comparison to the presence of LAB alone, suggesting synergistic effects between LAB in fermented fish with spices could enhance stronger antimicrobial activities against food pathogens and therefore, served as a natural food preservative.


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