http://hdl.handle.net/123456789/91 Sun, 19 Apr 2026 10:19:54 GMT 2026-04-19T10:19:54Z http://hdl.handle.net/123456789/1263 CHARACTERISATION OF LACTIC ACID BACTERIA ISOLATED FROM HUMAN BREAST MILK AND INFANT FAECES AS POTENTIAL PROBIOTICS OBISESAN, ABIOLA OLUWATOSIN Infant mortality, particularly in developing countries; remains a concern and one of its major causes is diarrhoea. Human breast milk and faeces contain lactic acid bacteria (LAB), which could have probiotic potential. However, there is a paucity of information on the effect of LAB from faeces of healthy infants and mothers’ breast milk on disease caused by diarrhoeagenic E. coli. This study was undertaken to evaluate the potential of LAB from human breast milk and infant faeces to contribute to the management of infantile diarrhoea. Lactic acid bacteria were isolated from the breast milk of 16 mothers and faeces of 13 infants (healthy volunteers) from Ado-Ekiti, Ekiti State. The LAB strains were identified by partial sequencing of the 16S rRNA gene. The antimicrobial activities of LAB viable cells and Cell-Free Supernatant (CFS) against enterohaemorrhagic, enterotoxigenic, Shiga-toxin producing, enteroinvasive and enteropathogenic E. coli were tested by agar overlay and diffusion methods, respectively. Production of bacteriocin-like substances was evaluated by ammonium sulphate precipitation of CFS. The kill rate of LAB was determined by co culture with diarrhoeagenic E.coli pathotypes. Organic acid production by selected LAB was quantified by HPLC, while the MICs wer/e determined by VITEK®2. The ability of selected strains to withstand simulated gastric conditions (consecutive pH 3 and 0.3% bile) was determined. Autoaggregation, co-aggregation and hydrophobicity abilities of selected strains in n-hexadecane and xylene were assessed by UV spectrophotometry, while anti biofilm effects of1:1, 1:9 and 1:99 dilutions of selected LAB CFS were evaluated by crystal violet assay. The level of IL-6 and IL-10 cytokines in groups of immunosuppressed mice (n=5, 22±4 g) treated with LAB and levamisole hydrochloride (positive control) groups were evaluated in blood and spleen by ELISA as recommended by FAO guidelines. Data were analysed by one-way ANOVA at α0.05. Ninety-three LAB belonging to five genera and 15 species were identified. Lactobacillus (44) was the predominant genus, while L. plantarum (27) was the most abundant species. Inhibition zones of CFS against the tested pathogens ranged from 8.0 to 25.0±1 mm, while viable cell inhibition zones were 12.0 to 20.0±3 mm. Eight LAB strains produced bacteriocin-like substances. Complete inhibition of E.coli strains were observed between iii 16 and 24h. The highest concentration (76.8 mg/mL) of the most prominent organic acid (lactic) was produced by L. rhamnosus A012 (from faeces). L. rhamnosus A012 was susceptible to all tested antibiotics while L. plantarum A011 (from faeces) was resistant to only one of the antibiotics. L.rhamnosus A012 and L. plantarum A011 had the highest resistance to gastric conditions with one log10 reduction in CFU/mL. L. rhamnosus A012 had hydrophobicity of 25.0% in n-hexadecane, 15.0% in xylene, autoaggregation of 32.0% at 5th h and co-aggregation of 6.8%. All dilutions of L. plantarum A011 CFS showed antibiofilm activity. There was a significant decrease in IL-6 and an increase in IL-10 levels in immunosuppressed mice treated with LAB compared to control groups. L. rhamnosus A012 demonstrated antimicrobial activity against diarrhoeagenic E. coli strains and immunomodulatory properties. It is, therefore, a potential probiotic candidate. Mon, 01 Mar 2021 00:00:00 GMT http://hdl.handle.net/123456789/1263 2021-03-01T00:00:00Z http://hdl.handle.net/123456789/858 ISOLATION AND CHARACTERISATION OF CYTOTOXIC COMPOUNDS FROM Caesalpiniabenthamiana(BAILL.) HEREND. & ZARUCCHI (LEGUMINOSAE) AND CombretumracemosumP. BEAUV. (COMBRETACEAE) FAMOJURO, TAYO IBUKUN The incidence of multi-drug resistant cancer cells and the adverse effects associated with available chemotherapy have necessitated the search for new drug candidates. Several traditional healers in Africa utilise plants to treat cancer, but few anticancer drug leads have been reported from African medicinal plants. This study was designed to isolate and characterise the cytotoxic constituents from selected plants used in Nigerian ethnomedicine. Ethnobotanical survey on plants used for the management of different cancers was conducted in three local government areas of Ekiti State, Nigeria. Nine plants selected from the survey were macerated in methanol. Preliminary cytotoxic activity of the plant extracts was assessed using in vitro 3-(4,5-Dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) viability assay in human breast adenocarcinoma (MDA-MB-453) and normal kidney (HEK-293) cell lines with methotrexate as standard. Extracts of the most active plants, Caesalpiniabenthamiana (CB) leaf (FHI-110847) and Combretum racemosum(CR) root bark (FHI-109781) were successively partitioned into n-hexane and dichloromethane. The two fractions were subjected to MTT viability,cyquant direct cell proliferation and caspase-3/7 green detection assays using human breast (MCF-7), lung (A549) and prostate (PC3) carcinoma cells. Active fractions were subjected to column and preparative thin layer chromatographic separations to isolate bioactive compounds. Cytotoxic activity of isolated compounds was further investigated with MTT viability assay using human MCF-7, A549 and PC3 carcinoma cells. Structures of the isolated compounds were determined by spectroscopic techniques (infrared, mass spectrometry and nuclear magnetic resonance) and compared with literature data. The IC50 were determined by fitting the data to a sigmoid dose-response curve. One way ANOVA and Dunnett’s Multiple Comparison test was conducted at α0.05 Ethnobotanical survey revealed 57 plants utilised by respondents in the study area. Methanol extracts with the highest cytotoxic activity were CB (IC50 = 3.21±0.09 and 0.09±0.08 μg/mL) and CR (IC50 = 0.71±0.11 and 0.26±0.20 μg/mL) on MDA-MB-453 and HEK-293 cells, respectively, compared to methotrexate (0.94±0.30 and 0.02±0.13 μg/mL). The dichloromethane fractions of CB (IC50 = 8.45±0.11 – 27.43±0.17 μg/mL) andCR (IC50= 9.76±0.09 – 30.47±0.03 μg/mL) displayed the highest cytotoxic activity, respectively, compared to methotrexate (IC50 = 9.97±0.08 – 12.98±0.07 μg/mL) on tested cell lines. Cyquant direct cell proliferation assay showed significant reduction in live carcinoma cells, while caspase-3/7 green detection assay showed significant increase in number of dead carcinoma cells. Methyl gallate (simple phenol),benthamianoate and 2-methoxyacrylic acid (phenolic acids), benthamianin (alkaloid),benthamiacone and benthamianol (terpenoids) were isolated from CB, while racemonoate (phenolic acid) was isolated from CR. The CB terpenoid, benthamiacone exhibited the highest cytotoxic activity [(IC50 = 13.23±0.10 (R2=0.70) – 21.97±0.06 μg/mL (R2=0.83)]. Cytotoxic activity of benthamiacone was not significantly different from methotrexate (p>0.05). The cytotoxic activity displayed by benthamiacone isolated from Caesalpiniabenthamiana and racemonoate isolated from Combretumracemosum validated the folkloric use of the plants in cancer treatment. The two plants could serve as potential templates and leads for the development of new chemotherapeutic agents. Wed, 01 Jan 2020 00:00:00 GMT http://hdl.handle.net/123456789/858 2020-01-01T00:00:00Z http://hdl.handle.net/123456789/607 CHANGES IN THE GUT MICROBIOTA OF SOME NIGERIAN INFANTS WITHIN THE FIRST YEAR OF LIFE OYEDEMI, OMOLANKE TEMITOPE The gut microbiota plays an important role in health and its negative alteration can lead to different pathologies. Different factors which include birthing methods, diet and antibiotic treatment contribute to infant gut colonisation. Many studies in Western countries have reported the effect of these factors on the gut microbiota of infants but there is dearth of information in Nigeria. This study was designed to investigate the changes in the gut microbiota of some Nigerian infants within the first year of life. This was a longitudinal study of convenience sampled participants. Faecal samples were obtained monthly from 28 infants (gestational age (37.6±2.8 weeks) and birth weight (2.9±0.6 kg) within the first year (8.8±1.3 months) of life at Federal Teaching Hospital, Ido-Ekiti with ethical approval (ERC/2016/09/29/44B) and approved parental consent. The DNA from all samples was extracted with a commercial kit, followed by PCR amplification of the V1-V2 region of the 16S rRNA gene, library preparation and sequencing on Illumina MiSeq. The raw sequences generated underwent downstream bioinformatics analysis with DADA2 pipeline (quality score ≤ 2) to assign taxonomy and to compare the gut microbiota in different groups at different time points (0-4 n=28, 5-8 n=23 and 9-12 months n=13), caesarean section birth (CSB) (n=13) and vaginal birth (VB) (n=15), exclusively breastfed (n=15) and mixed fed (MF) (n=8) and then preweaning and weaning (n=23) groups. The diversity in all the groups was determined by Quantitative Insight into Microbial Ecology (QIIME). Selected antibiotic resistance genes (aac (6’ ), mef A/E, ermA, ermB, blaZ) and tetracycline’s ribosomal protection protein (tet) gene were detected in samples by PCR. Short chain fatty acids (SCFAs) present in each faecal sample were identified by gas chromatography. Alpha diversity significantly increased with infants’ age. Beta diversity showed tight clusters from birth to 4 months, revealing taxonomic similarities and dispersion at 5-8 and 9-12 months, thereby confirming the increased diversity with age. There was no statistically significant difference in the gut microbiota between the birthing methods. However, Klebsiella (33.8%) and Staphylococcus (13.5%) were most abundant in CSB, iii while Streptococcus (29.9%) and Enterococcus (20.2%) were most abundant in VB. Exclusively breastfed infants had Significant Differential Abundance (SDA) ofCollinsella, Bacteroides, Sutterella and Actinomyces while Bifidobacterium was differentially abundant in MF. Firmicutes were predominant in preweaning and weaning period. However, there was a shift from Proteobacteria to Actinobacteria as the next SDA phylum in preweaning and weaning groups respectively. The effect of antibiotics was marked with decrease in number of observed taxa at point of administration or the next time point while tet was the most prevalent (27.0%) resistance gene. Butyrate only appeared, while other SCFAs (acetate, lactate and propionate) increased during weaning indicative of complex carbohydrate metabolic functions. Observed gut microbiota taxonomic differences between preweaning and weaning in some Nigerian infantsas well as butyrate production were influenced by diet. Introduction of solid foods encouraged the colonisation and adaptation of specific marker organisms associated with carbohydrate metabolism helpful for a healthy life. Sun, 01 Dec 2019 00:00:00 GMT http://hdl.handle.net/123456789/607 2019-12-01T00:00:00Z http://hdl.handle.net/123456789/601 ANTI-SALMONELLA ACTIVITY AND PROBIOTIC POTENTIAL OF LACTIC ACID BACTERIA ISOLATED FROM HEALTHY CATTLE FAECES ADETOYE, ADEWALE AYODEJI Salmonella is an important cause of foodborne zoonosis with significant public and animal health burden.Current interventions targeted at mitigatingSalmonella carriage in livestock include antibiotic use, which selects for antibiotic resistance. The use of Lactic Acid Bacteria (LAB) as probiotics is a possible alternative intervention against the carriage of zoonotic enterobacteria.This study was undertaken to characterise the anti-Salmonella and probiotic potential of LAB in cattle against enterobacteria. Salmonella entericaand LAB were cultured from 138 and 40 faecal samples of cattle, respectively, from University of Ibadan Teaching and Research farm. The Salmonella strains were identified with MALDI-TOF-MS and biochemical profiling system, while LAB were identified by partial sequencing of 16S rRNA gene. The antimicrobial activities of LAB Cell-Free Supernatant (CFS) and viable cells against S. entericaserovarTyphimuriumATCC 14028 andselected Salmonella from cattle were evaluated by cup diffusion and agar overlay methods,respectively. The Salmonella kill rate was determined by co-culture with selected LAB and LAB bacteriocin production was tested by ammonium sulphate precipitation. Organic acid production was quantified by HPLC, whilethe MICs of selected antibiotics toS.entericaand LAB were determined by automated antimicrobial susceptibility testing and gradient MIC strips, respectively. The ability of selected LAB strains to withstand simulated gastric conditions (consecutive pH 3 and 7% bile) and haemolysison bovine blood agar was determined. The potential of selected LAB (approximately 8.6 x 1010 cfu/day for 30 days) to inhibit enterobacteria in vivoin calves (weight= 50 ± 10 kg, n= 6) was evaluated using qPCR with three untreated calves as controls. The effect of freeze drying and 3 months room temperature storage of selected LAB was determined by bacterial viable count.Data were analysed bydescriptive statistics andStudent’s t- test at α0.05. Thirty twoS. entericaisolates were identified with a prevalence of 23.2%.A total of 88 LAB belonging to four genera and 15 species were identified; Lactobacillus (11) was the predominant genus, while Streptococcus infantarius (26) was the most abundant species. The inhibition of CFS against the tested pathogens was ≤ 20.0 mm, while viable cells inhibition was ≤ 22.0 mm. Complete inhibition of S.entericawas observed after 16 hours of co-incubation with LAB and no LAB produced bacteriocin. The organic acid with the highest concentrationwas lactic acid (67.9 ± 1.5 mg/mL) produced by Lactobacillus salivariusC86. All the Salmonella and LAB evaluated were susceptible to all the antibiotics tested.Lactobacillus amylovorus C94 and L.salivarius C86demonstrated the highest resistance to gastric conditions with a final 2 log10 reduction and were not haemolytic. The antibacterial activity of L.amylovorus C94 and L.salivarius C86 against enterobacteriainvivo were significant compared with the control (p=0.01). Lactobacillus amylovorus C94 and L. salivarius C86 both survived freeze drying with a reduction of 1 log10 viability per month. Lactobacillus amylovorus C94 and Lactobacillus salivarius C86 demonstrated antimicrobial activity against Salmonella entericastrains and reduced enterobacteria carriage in calves. They are therefore promising probiotic candidates Sat, 01 Jun 2019 00:00:00 GMT http://hdl.handle.net/123456789/601 2019-06-01T00:00:00Z