De Man Rogosa Sharpe Agar Research Articles

In vitro prebiotic activity of millets with selected probiotic microorganisms

Abstract BACKGROUND: Millets are an inexpensive grain that contains many major and minor nutrients, such as carbohydrates, protein, fats, and dietary fibers. As millets are rich in carbohydrates, and carbohydrates tend to be a great prebiotic source for the proliferation of gut microbes (probiotics), this study was designed to evaluate the prebiotic potential of millets. Millets used in this study include pearl millet (Pennisetum glaucum L.), finger millet (Eleusine coracana L.), sorghum (Sorghum bicolor L.), and foxtail millet (Setaria italica L.). METHODS: The prebiotic activity was performed by using them as a sole carbon source in De Man–Rogosa–Sharpe agar media with probiotic strains Lactobacillus plantarum [Microbial Type Culture Collection (MTCC) 1407], Lactobacillus paracasei (Microbial Culture Collection 4490), Lactobacillus rhamnosus (MTCC 1408), and Saccharomyces boulardii. Millets were ground into a fine powder with the grinder, and the powder was used as a carbon source in media for cultivating microorganisms under anaerobic conditions maintained in an anaerobic jar at 37°C. RESULTS: The results revealed that the growth of all microorganisms was confluent on their respective Petri plates under anaerobic conditions as observed on positive control plates. When these selected millets powder were mixed in the same ratio and used as a carbon source to check prebiotic activity, the results showed similar trends as observed with individual millets. CONCLUSION: The study concludes that whole grain millets showed prebiotic activity and thus can be recognized as an essential prebiotic nutritious food. These millets may support the growth of the population of healthy gut microbes, thus playing an important role in promoting digestion. Further, in-vivo and clinical validation is necessary to establish the prebiotic potential of these millets leading to the development of millets based ayurvedic prebiotic formulations.

Determination of antibacterial Activity of Bacteriocin of Lactic Acid Bacteria Isolated from Meat Samples

The present study is aimed at determination of antimicrobial activity of lactic acid bacteria isolated from meat samples against common food borne pathogens. The meat samples were collected from local meat shops and were inoculated in sterile saline to make suspension. The isolates were enriched in tomato juice at acidic pH and then the bacteriocin producing lactic acid bacteria were isolated by using de-Man Rogosa Sharpe (MRS) agar supplemented with 0.01% sodium azide and 2%  Glycerophosphate. The plates were overlaid with the same media and incubated at 35 oC for 48- h. The production of crude bacteriocin was carried out by growing isolated strain in MRS broth, which was then centrifuged at 10000 rpm for 15 min at 4 oC to get the bacteriocin fraction in the cell free supernatant. The crude bacteriocin preparation was subjected to characterization with respect to heat stability, pH, susceptibility to denaturation by enzymes and detergents. Antagonistic activity of bacteriocin was studied by agar well diffusion method against different microorganisms such as B. subtilis, B. cereus, S. typhi, M. luteus, S. aureus, E.coli and P vulgaris. The result showed that bacteriocin producing lactobacilli obtained from meat samples have potential to inhibit bacteria such as B.cereus, S. typhi, S. aureus, E.coli, P. vulgaris.

Latilactobacillus fragifolii sp. nov., isolated from leaves of a strawberry plant (Fragaria x ananassa).

Thirteen Gram-positive, catalase-positive, rod-shaped single colonies were obtained after culturing a strawberry leaf on de Man–Rogosa–Sharpe agar. Based on 16S rRNA gene and rpoA gene sequence similarities, ranging between 99.0–100% and 96.5–100%, respectively, the 13 isolates were found to be closely related to each other. Two of the independent isolates, AMBP162T and AMBP252, were whole-genome sequenced, and showed to be undistinguishable with an average nucleotide identity (ANI) value of 100 %. Compared to the reference genomes for all species in the family Lactobacillaceae , the AMBP162T genome was most similar to the reference strain of Latilactobacillus curvatus with ANI of only 89.5 %, indicating they were a different species. Based on genotypic and phenotypic data, a novel Latilactobacillus species, Latilactobacillus fragifolii sp. nov., with the type strain AMBP162T (=LMG 32285T=CECT 30357T) is proposed.

Potent γ-amino butyric acid producing psychobioticLactococcus lactis LP-68 from non-rhizospheric soil of Syzygium cumini (Black plum).

Gamma amino butyric acid (GABA) is a chemical messenger that plays a significant role in muscle relaxation and brain health. Certain lactic acid bacteria (LAB) produce significant levels of GABA and thus act as potential psychobiotic cultures. In the present study, LAB were isolated from non-rhizospheric soil sample of Syzygium cumini (Black plum). A total of 57 LAB were isolated on the basis of their morphological and acid producing characteristic on de Man Rogosa Sharpe (MRS) agar. Only seven isolates were found to produce GABA (0.09-1.13gL-1) in MRS broth and were identified as Lactococcus. However, L. lactis LP-68 produced highest amount of GABA and was selected for further optimization of culture conditions (pH, temperature and MSG) by response surface methodology (RSM). The optimization resulted in approximately four-fold increase in GABA production (4.11gL-1). The results indicate that the L. lactis LP-68 can be used as starter culture for production of GABA-enriched functional foods.

Assessment of Antimicrobial and Proteolytic Activity of Lactic Acid Bacteria Isolated from Dadih: Naturally Fermented Buffalo Milk From West Sumatra, Indonesia

Dadih is a traditional fermented food from West Sumatra Indonesia and had become an integral diet and culture for Minangkabau tribes. The aims of this study were evaluated antimicrobial and proteolytic activity of lactic acid bacteria (LAB) isolated from dadih. Four different dadih samples was taken from 2 origins based on fermentation methods. Samples were isolated and screening for morphological, genotype and phenotype characteristic. Isolation was conducted in de Man Rogosa Sharpe (MRS) agar containing 0.5% CaCO3 followed by morphological identification. All isolates were selected based on antimicrobial and proteolytic activity with agar well diffusion method. Finally, the selected isolate were identified based on 16S rRNA partial gene sequence analysis and fermentation profile using API 50 CHL kit test. Seventeen isolates not only exhibited wide spectrum of antimicrobial activity against gram positive and negative bacteria, but also high proteolytic activity. Partial gene sequence analysis and API 50 CHL kit showed 12 isolates were identified as Lactococcus lactis, 3 isolates were identified as Lactobacillus plantarum, and 1 isolate each was identified as Lactobacillus pentosus and Pediococcus pentosaceus respectivelly. The result shows that dadih was a potential source of LAB with high antimicrobial (range between 1.0 to 6.1 mm) and proteolytic traits (range between 15 to 2.1 mm). This makes it possible to develop the functional properties of these isolates as a starter culture in milk fermentation.

Microbial changes during the fermentation of baobab (Adansoniadigitata) fruit pulp yoghurt

This study was conducted to assess the microbial changes during the fermentation of Baobab (Adansoniadigitata)fruit pulp yoghurt. The Baobab fruit pulp yoghurt was prepared in the Laboratory using the conventional method. Lactobacillus bulgaricus and Streptococcus thermophilus were used as starter cultures while a control was produced without the starter cultures. de Man Rogosa Sharpe (MRS) agar was used to culture lactic acid bacteria. The microbialload, succession and percentage occurrences were determined using standard methods. The total aerobic bacterial count wasfound to be within the range of 1.9x103 - 1.4x105 cfu/ml. The Lactic acid bacteria and fungal count ranges were 4.5 x 103 - 7.5 x 103 cfu/ml and 8.0 x 101 – 2.8 x 104 cfu/ml respectively. At the end of fermentation time, there was significant difference between the test and control Baobab yoghurt at P<0.05. Lactic acid bacteria recorded the highest count of 6.2 x 104 and 7.5 x 103 cfu/ml in the test and control respectively. Bacillus species , Staphylococcus aureus, Lactobacillus bulgaricus,Streptococcus thermophilus and Micrococcus species were the bacteria isolated while the fungal isolates were Saccharomyces cerevisiae and Hansenula species. Lacbacillusbulgaricus, Streptococcus thermophilus, Bacillus species and Saccharomyces cerevisiae were the only microorganisms found at the end of fermentation time. The study obtained low microbial count and isolated less number and type of microorganisms from Baobab fruit pulp yoghurt because of the antimicrobial effect of baobab pulp and pasteurization treatment.Based on the results of this study, Baobab fruit pulp yoghurt can be said to be of good microbiologicalquality for human consumption. The industrial use of Baobab fruit pulp in the production of yoghurt is recommended.

Efficacy of extraoral suction devices in aerosol and splatter reduction during ultrasonic scaling: A laboratory investigation.

Background. Ultrasonic scaling generates aerosols and splatters contaminated with microorganisms, increasing the risk of disease transmission in the dental office. The present study aimed to evaluate the effectiveness of extraoral suction (EOS) units in aerosol and splatter reduction during ultrasonic scaling. Methods. Ultrasonic scaling was conducted on a dental manikin headset to simulate a scaling procedure. Water containing Lactobacillus acidophilus at a concentration of 107 colony-forming units per milliliter and 1% fluorescein solution was used as the water supply of the scaler. The scaling procedure was conducted with a high-volume evacuator (HVE) or the combination of HVE and an EOS unit. de Man–Rogosa–Sharpe agar plates were placed at different distances surrounding the dental chair. Filter papers were placed at various positions surrounding the oral cavity and on areas of the body. Results. Bioaerosols were detected at every sampling site and could travel as far as 150 cm from the oral cavity. The combination of HVE and EOS significantly reduced the total number of bacterial colonies in the air (P < 0.001). Dissemination of the stain was in the range of 20 cm from the oral cavity. The maximum contaminated surface area was at the 4 o’clock position from the oral cavity. The combination of EOS and HVE significantly reduced the contaminated area (P < 0.05). The stain was also found on the wrists, chest, abdomen, and lap of the operator and assistant. The lap was the most contaminated area of the body. Conclusion. EOS was effective in reducing the bioaerosols and splatters generated during ultrasonic scaling.

A study on the effect of bacteriocin production from lactic acid bacteria in poultry nutrition

Objective: This research was carried out to isolate lactic acid bacteria from dairy products, to examine the isolated lactic acid bacteria for the production of bacteriocin, its purification as well as its use as supplement in poultry nutrition to improve the growth performance of the birds. Methodology and results: Five (5) samples of cow milk and five (5) samples of fresh yoghurt were procured from the market; each sample was serially diluted to the third fold and plated on De Man Rogosa Sharpe agar (MRS) agar. Pure discrete colonies of Lactobacillus spp were isolated and sub-cultured on MRS broth. Lactobacillus spp isolated from Cow Milk and Fresh Yoghurt was screened using agar well diffusion. Lactobacillus isolates which showed high zone of inhibition against the test organisms (Staphylococcus aureus and Escherichia coli) were designated positive. These isolates were centrifuged at 20,000 rpm (≤40C) for 30 min and their supernatant was adjusted to pH of 7.1 with Na2CO3 to remove lactic acid effect, before filter sterilization using membrane filter (0.2μm). Five (5) mg/ml catalase was added to eliminate peroxides effect. The solution was tagged as bacteriocin crude extract (BCE) which was infused into the poultry feed. Ten (10) three weeks old chicks were separated into two groups (5 each). “Group A” as the control and “Group B” as test. The test chicks had 5ml of bacteriocin infused into their daily feed while the control chicks were fed without any infusion of bacteriocin in their feed. The chicks were weighed every seven (7) days to compare the weight gain between the control and test chicks. At the end of the study, it was found that the test chicks weighed 900g when compared to the control chicks, which weighed 830g. Conclusion and application of results: This therefore means that bacteriocin produced by lactic acid bacteria aids in the weight gain of poultry. This suggests that bacteriocin could be considered a major growth booster in poultry feed and should be applied in its feed formulation. Keywords: Bacteriocin, Cow milk, Fresh yoghurt, Lactic Acid Bacteria, Lactobacillus

Antibiotic Resistant Profile of Lactic Acid Bacteria Isolated from Swine and Poultry Faeces in Umuahia Metropolis

Aim: This study’s aim was to determine the antibiotics resistant profile of lactic acid bacteria isolated from poultry and swine faeces.&#x0D; Study design: Faecal samples from swine and birds were randomly collected from livestock and poultry farms located in Umuahia metropolis, Abia State.&#x0D; Place and duration of study: Department of microbiology, Michael Okpara University of Agriculture Umudike, between January 2019 to August 2019.&#x0D; Methodology: A total of 12 faecal samples, 6 each from swines and birds were examined for the presence of lactic acid bacteria using Deman Rogosa Sharpe agar supplemented with 0.3% CaCO3 (w/v). Isolates were identified based on their physiological and biochemical characteristics. Antibiotic susceptibility was carried out using disk diffusion method.&#x0D; Results: Of the 12 faecal samples examined, all were positive for lactic acid bacteria, with counts ranging from 1.74 – 2.36 x 106 in swine and 1.52 – 2.08 x 106 in birds. Total of 14 strains that belong to three genera; Lactobacillus, Lactococcus and Streptococcus were isolated, genus Lactobacillus occurred highest 8(57.1%). The isolates showed multidrug resistance and exhibited high rate of resistance to Augmentin (100%), Ceftazidime (100%), Cefotaxime (92.9%), Erythromycin (85.7%), Ceftriaxone (71.4%) and Azithromycin (71.4%).&#x0D; Conclusion: The antibiotic resistance pattern of the isolated lactic acid bacteria is a clear indication that most animal farmers are misusing antibiotics. Therefore, animal farmers should be advised on antibiotic application safety measures.

Antimicrobial Activity of Lactococcus lactis subsp. lactis Isolated from a Stranded Cuvier's Beaked Whale (Ziphius cavirostris) against Gram-Positive and -Negative Bacteria.

In the present study, we isolated and characterized Lactococcus lactis (L. lactis) subsp. lactis from a female Cuvier’s beaked whale (Ziphius cavirostris) stranded in Shizuoka, Japan. Only five isolates (CBW1-5), grown on Lactobacilli de Man Rogosa Sharpe (MRS) agar plates prepared using 50% artificial seawater, were positive in L. lactis species-specific primer PCR. Their 16S rRNA sequences were highly similar to those of L. lactis subsp. lactis JCM 5805T. The Gram reaction, motility, gas production from glucose, catalase production, and growth conditions were consistent with those of the type strain. Additionally, carbohydrate utilization of the strains was consistent with previously reported marine organism-derived strains. The pH-neutralized cell-free culture supernatant of strain CBW2 inhibited the growth of Bacillus subtilis subsp. subtilis ATCC 6051 and Vibrio alginolyticus ATCC 17749, whereas protease treatment eliminated or diminished its inhibitory activity. The strain possesses a precursor of the nisin structural gene (nisA), which showed 100% homology with nisin Z, and nisin biosynthesis-related genes (nisB, nisC, nisT, nisP, nisF, nisI, and nisRK), suggesting that the strain produces a nisin-like substance. This study provides fundamental information on whale-derived L. lactis subsp. lactis which may be useful for reducing the carriage of B. subtilis subsp. subtilis and V. alginolyticus.

Fermentation of amylolytic yeast and lactic acid bacteria to improve the quality of modified cassava

The amylolytic activity has been studied in yeast and lactic acid bacteria (LAB) which are isolated from various types of traditional fermented cassava. The study aimed to obtain yeast and LAB isolates which high amylolytic activity for inoculum in cassava fermentation. A total of 23 yeasts and 22 LAB isolates were isolated from Gatot, Tiwul, Tapai, and Cassava fermented using chloramphenicol yeast glucose (CYG) media for yeast and de Man Rogosa Sharpe agar (MRSA) + CaCO3 for LAB. Yeast amylolytic activity was tested using yeast extract peptone starch agar medium, while the amylolytic LAB used MRS + starch media with Lugol’s iodine indicator. Colonies showing clear zone areas were measured as amylase activity on the iodine complex method. Isolates that have the highest amylolytic activity were used as inoculum in cassava fermentation. Yeast Tr7 and LAB G6 isolates showed the highest amylolytic activity (0.0624 U/mL and 0.0627 U/mL). Cassava fermentation products using yeast Tr7 and BAL G6 resulted 52.06% of hydrogen cyanide (HCN) reduction higher than without inoculum (32.32%). According to biochemical identification using API 50 CHL kit, LAB G6 isolate was 99.6% identical with Pediococcys pentosaceus whereas biochemical identification using API 20 C AUX showed that yeast Tr7 was 95.8% identical with Candida tropicalis. The biochemical identification result was similar to the molecular identification result. In molecular identification using 28S rRNA sequence analysis revealed that yeast Tr7 was 99% similar with Candida tropicalis NITCSK13 strain. LAB G6 was 100% similar with Pediococcus pentosaceus BSS1375 strain using 16S rRNA sequence analysis. C. tropicalis Tr7 and P. pentosaceus G6 potentially used for inoculum in cassava fermentation process to improve cassava quality as a functional food.

3M Petrifilm Lactic Acid Bacteria Count Plate Is a Reliable Tool for Enumerating Lactic Acid Bacteria in Bacon

This study aimed to evaluate the behavior of Petrifilm Lactic Acid Bacteria Count Plates (PLAB) as an alternative methodology to enumerate lactic acid bacteria (LAB) in bacon. Bacon samples (n = 40) were obtained from retail sale, 10-fold diluted with buffered peptone water (BPW, 0.2% [w/v]) and Letheen broth, and subjected to LAB enumeration according to four protocols: (i) de Man Rogosa Sharpe (MRS) agar, pH 5.7, 30°C; (ii) MRS, pH 5.7, 30°C, anaerobiosis; (iii) all-purpose Tween agar (APT), 25°C; and (iv) PLAB, 30°C. Colonies were enumerated at 24, 48, and 72 h, and the results expressed as log CFU per gram for comparison by analysis of variance and regression (P < 0.05). Furthermore, colonies were randomly selected and characterized as LAB (Gram staining and catalase). Mean LAB counts from MRS and PLAB did not present significant differences independently of incubation time or diluent (P > 0.05), whereas counts in APT with BPW after 24 h were significantly lower (P < 0.05). PLAB counts with BPW (24, 48, and 72 h) presented significant correlation with MRS (r ranging from 0.87 to 0.89; in anaerobiosis, r ranging from 0.94 to 0.95) and APT (r ranging from 0.84 to 0.86). With Letheen broth, PLAB (24, 48, and 72 h) presented significant correlation with MRS (r ranging from 0.92 to 0.94; in anaerobiosis, r ranging from 0.93 to 0.96) and APT (r ranging from 0.77 to 0.79). In total, 1,032 colonies (97%) from 1,063 colonies were characterized as LAB. Thus, PLAB can be considered as an alternative tool for enumerating LAB in bacon, with reliable results even after 24 h of incubation.

English

In this study lactic acid bacteria were investigated for their presence in fresh palm wine and their effects on humoral immunity examined. The bacteria were isolated from fresh palm wine in a tenfold serial dilution. The isolates were purified by repeated subculture on De Man Rogosa Sharpe (MRS) agar and characterized phenotypically and genotypically. The identified Lactobacillus spp. were investigated for their effects on antibody (humoral immunity) - IgG, IgG1 and IgG2a secretion using sheep red blood cell as antigen (SRBC). Lactobacillus spp. were identified as Lactobacillus brevis, Lactobacillus paracasei subsp. tolerans, Lactobacillus paracasei and Lactobacillus yonginensis. The isolates produced no significant effect on IgG antibody after 4 days’ post-secondary challenge. However, they had significant percentage stimulation at 9 days post-secondary challenge of 100.2, 122.9, 106.4 and 118.3% for L. brevis, L. paracasei sub. tolerans, L. paracasei, and L. yonginensis, respectively. The isolates had marginal and somewhat suppressive effects on IgG1 and IgG2a at both 4 and 9 days’ post-secondary challenge. The results show that fresh palm wine contains Lactobacillus spp. capable of stimulating antibodies production. Key words: Humoral immunity, antibody, palm wine, Lactobacillus spp.

CHARACTERIZATION OF LACTIC ACID BACTERIA AND ANTIMICROBIAL ACTIVITY IN SUI WU’U FROM BAJAWA DISTRICT, NUSA TENGGARA TIMUR, INDONESIA

Objective: This research aimed to isolate, determine the characteristics of lactic acid bacteria (LAB) of Sui Wu’u from Bajawa, Nusa Tenggara Timur and identify LAB using 16S rRNA potential as antimicrobial activity against pathogenic bacteria.&#x0D; Methods: Sui Wu’u which has been stored for 6 months was obtained from Bajawa district, inoculated on de Man Rogosa-Sharpe Agar (Merck) + 0.5% CaCO3, purification of LAB, characterization of selected isolates, biochemical test, tolerance test for pH, viability to test temperature, and content NaCl, determination of antimicrobial action by the agar well disk diffusion method using antibiotic (Amoxicillin) as a control and as indicator bacteria (Staphylococcus aureus and Escherichia coli) and isolation of genomic 16S rRNA; molecular identification.&#x0D; Results: Based on research results obtained five isolates of LAB, Gram staining the LAB isolated from Sui Wu’u showed that the isolated bacteria (bacilli and coccus) are Gram-positive, catalase-negative and the isolates have tolerance of viability at temperatures of 10°C, 45°C, and 50°C and to salinitas of 4% and 6.5%. The inhibitory zone LAB isolates (2PKT) against E. coli bacteria (20 mm) and S. aureus (12 mm), and (2PKB) against E. coli bacteria (17 mm) and S. aureus (10 mm). The two selected isolates were identified as Lactobacillus fermentum strain HB bacteria with 100% identification value and 98.93% query cover and L. fermentum strain HT with 100% identification value and 99.23% query cover.&#x0D; Conclusion: L. fermentum from Sui Wu’u has antibacterial activity against Staphylococcus aureus and Escherichia coli.

Application of culturomics to characterize diverse anaerobic bacteria from the gastrointestinal tract of broiler chickens in relation to environmental reservoirs

Characterization of the microbiota of chickens is of current interest. The goals of the current study were to apply anaerobic isolation methods to comprehensively isolate and identify bacteria from the gastrointestinal tract of chickens and their environment. Bacterial communities within the drinking water were dominated by Escherichia, whereas communities in litter were more representative of the cecum. The crop and small intestine (jejunum and ileum) were dominated by Lactobacillus and Enterococcus spp., and the cecum was dominated by Proteus spp. The collection of bacteria isolated was dominated by Enterococcus spp., Escherichia/Shigella spp., Lactobacillus spp., and Proteus spp.; however, many rare taxa were observed. These included members of the Clostridiales and Clostridium spp., which were commonly isolated from the ileum and cecum. Bacteria isolated by enrichment and direct plating differed. The selective de Man-Rogosa-Sharpe agar was commonly associated with the isolation of Lactobacillus spp. and yielded the lowest diversity of all methods utilized. Increased diversity and frequency of Clostridium spp. was observed in enrichments of blood and mucus or by plating on Columbia agar supplemented with 10% blood and gentamicin. The bacteria isolated from this study provide source material for genomic and functional studies in chicken hosts.

Antioxidant Activities of Exopolysaccharides Produced by Lactic Acid Bacteria Isolated from Commercial Yoghurt Samples

An antioxidant is a substance that inhibits the oxidation of other molecules caused by free radicals. The inbuilt antioxidant systems possessed by living organisms are generally not enough to prevent them from oxidative damages and the uses of synthetic antioxidants also have some harmful effects. This study was aimed at evaluating the antioxidant activities of exopolysaccharides produced by lactic acid bacteria isolated from yoghurt. Lactic acid bacteria (LAB) were isolated from six different brands of commercially available yoghurt using deMan Rogosa Sharpe (MRS) agar. The LAB isolates were identified based on morphological and biochemical analyses and were screened for exopolysaccharide (EPS) production. The LAB isolates screened positive were used for EPS production in a liquid medium and the EPS produced were purified and quantified using standard methods. Antioxidant activities of the EPS were evaluated by determining the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity, ferric ion reducing power, and total phenolic contents. Data obtained were analysed using Analysis of Variance. Total lactic acid bacterial count obtained from the yoghurt samples ranged from 0 - 3.9 × 104 CFU/mL with sample A (Fan Yoghurt) having the highest LAB count (3.9 × 104 CFU/mL). The isolated LAB and their incidence rate were Lactobacillus plantarum (25.49%), L. delbrueckii (19.61%), L. fermentum (15.69%), L. acidophilus (13.73%), Leuconostoc mesenteroides (11.76%), Lactococcus lactis (7.84%), and Lactobacillus casei (5.88%). Fifty-one out of the 64 LAB isolates were screened positive for EPS production and only six were able to produce substantial quantity of EPS ranging from 127.4 - 208.5 mg/L. The exopolysaccharides produced by L. fermentum had the highest DPPH radical scavenging activity (62.90%) while that of L. plantarum had the lowest (23.10%) at a concentration of 1000 μg/mL. Also, the EPS produced by L. fermentum recorded the highest ferric ion reducing power (12.89 mg AAE/mL) at 1000 μg/mL while that of L. plantarum had the lowest (5.62 mg AAE/mL). At 1000 μg/mL, the total phenolic contents of the EPS samples ranged from 1.41 - 1.58 mg GAE/mL, and the EPS produced by L. fermentum had the highest (1.58 mg GAE/mL) while those produced by L. paracasei had the lowest (1.41 mg GAE/mL). This study revealed that the exopolysaccharides produced by the LAB isolates showed high antioxidant activities with respect to their DPPH free radical scavenging activity, ferric ion reducing power and total phenolic contents.

Isolation And Characterization Of Lactic Acid Bacteria (Lab) From Small Intestine Content Of Duck (Anas Sp.) As A Probiotic Candidate

A group of lactic acid bacteria (LAB) as a probiotic agent have been known to have a beneficial effect on health chicken. The objectives of this study were to isolate, characterize and determine of the LAB which originated from the small intestine content of domestic duck (Anas sp.) for candidate of probiotic. Isolation, selection and identification of bacteria was done using de Man Rogosa Sharpe (MRS) agar + 1% bromocresol purple. Characterization of bacteria based on morphological by Gram staining methods, and identification of biochemical characters using catalase activity, and Triple Sugar Iron Agar (TSIA). The data of isolate confirmed to Bergey’s Manual of Systematic Bacteriology. This research carried out on the Microbiology Laboratory, Microbiology Study Program, Yala Radjabhat University (YRU), Faculty of Science and Agriculture.The results showed that according to physiological and biochemical characteristics in various media, the bacteria had Gram +, catalase -, coccus in shape, and were able to ferment glucose to be lactic acid. Based on the result, it is concluded that the LAB isolate shows a similar characteristic to the member of genus Lactobacillus sp. The isolated bacteria shows characteristic resistance to acidic pH and bile salts so the bacteria were fulfilled as a probiotic candidate.

Distribution and diversity of bacterial endophytes from four Pinus species and their efficacy as biocontrol agents for devastating pine wood nematodes

In this study, we isolated a total of 238 culturable putative bacterial endophytes from four Pinus species (Pinus densiflora, P. koraiensis, P. rigida, and P. thunbergii) across 18 sampling sites in Korea. The samples were cultured in de Man Rogosa Sharpe and humic acid-vitamin agar media. These selective media were used to isolate lactic acid bacteria and Actinobacteria, respectively. Analysis using 16S ribosomal DNA sequencing grouped the isolated putative bacterial endophytes into 107 operational taxonomic units (OTUs) belonging to 48 genera. Gamma-proteobacteria were the most abundant bacteria in each sampling site and three tissues (needle, stem and root). The highest OTU richness and diversity indices were observed in the roots, followed by stem and needle tissues. Total metabolites extracted from three isolates (two isolates of Escherichia coli and Serratia marcescens) showed significant nematicidal activity against the pine wood nematode (Bursaphelenchus xylophilus). Our findings demonstrated the potential use of bacterial endophytes from pine trees as alternative biocontrol agents against pine wood nematodes.

Characteristics and performance of biofilms on the electrode of bioelectrical systems within industrial wastewater in fisheries

Microbial fuel cell (MFC) is a bioreactor which utilizes exoelectrogenic bacteria as electrocatalysis to convert bioenergy from biochemical substances into electrical energy. This research aimed to determine the formation of biofilms attached, the electrical voltage generated from MFC and its effect to reduce biological oxygen demand (BOD), chemical oxygen demand (COD), total ammonia nitrogen (TAN), and to determine the characteristics of the microbes formed. The MFC system has a single chamber using boiled fish processing wastewater as media. Microbial density within the biofilm attached to anode and cathode of the MFC showed different microbial counts. There was quite high density on the cathode but no microbial growth on the anode, either by Nutrient Agar (NA) or deMan-Rogosa Sharpe agar (MRSA) media in plating method. The electricity produced was 0.39 V on average, the highest value was 0.49 V at 42 hours. The MFC system was able to decrease the average value of 83.0% BOD and 83.5% COD. The TAN value increased from 0.063±0.01 to 0.36±0.16 mg/L. There were 12 bacterial isolates, six grown on NA and others on MRSA. Three isolates that grew on NA had different characteristic groups of colony and six on MRSA showed six different characteristics.

Profile of microbial community of naturally fermented Sumbawa mare’s milk using next-generation sequencing

This study aimed to investigate the bacterial and fungal/yeast diversity in naturally fermented Sumbawa mare’s milk through a next-generation sequencing approach, and evaluate the quality of fermented mare’s milk based on the presence of pathogenic or undesirable microorganisms. Microbial density determined using plate count agar (total aerobic bacteria), de Man Rogosa Sharpe agar (Lactobacillus), M17 agar (Lactococcus) and yeast peptone dextrose agar supplemented with streptomycin 50 ppm (yeast). Nutritional content and acidity level of each fermented milk sample were also evaluated. Genomic DNA was extracted using FastDNA Spin (MPBIO). The total gDNA was further analyzed using illumina high-throughput sequencing (paired-end reads), and the sequence results were analysed using QIIME v.1.9.1 to generate diversity profiles. The difference in nutrient content of mare’s milk was thought to affect the density and diversity of microbes that were able to grow. Fermented mare’s milk samples from Sumbawa had the highest bacterial diversity compared to samples from Bima and Dompu. However, fermented mare’s milk from Dompu had the best quality which was indicated by the absence of bacteria that have the potential to be pathogenic or food spoilage, such as members of the Enterobacteriaceae family (Enterobacter, Klebsiella and Escherichia-Shigella) and Pseudomonas. Genus of Kazachstania and Kluyveromyces, as well as family Dipodascaceae were frequently observed fungi/yeast from Sumbawa fermented mare’s milk. The presence of potential pathogenic bacteria warrants special attention in improving the hygiene of manufacturing process.