Screening of Microorganisms Isolated from Different Environmental Samples for Extracellular Lipase Production

Lipases are hydrolytic enzymes that hydrolyse triglycerides to free fatty acids and glycerol and those from microbes have occupied a prominent position as industrial biocatalysts. Microorganisms isolated from oil polluted environmental samples were screened for their lipase producing ability. A total of thirty seven bacteria and seventeen fungal strains belonging to the genera Trichoderma (16 spp.) and Aspergillus (1 sp.) were obtained from the samples. Acinetobacter sp. had the highest frequency of occurrence (37.8%). The lipolytic activity of the bacteria when screened on solid agar ranged within 3.0m - 15.5amm, 3.0n - 15.5amm and 3.0 - 16a mm at 24, 48 and 72 hours of incubation, respectively. Acinetobacter sp. (OG3) had the highest activity at different hours of incubation. Eight isolates did not show any activity throughout the incubation period. On submerged fermentation, the growth of the lipolytic bacteria ranged within 0.093 - 1.003 in which Acinetobacter sp. had the highest growth while Bifidobacterium sp. had the lowest. Lipase production ranged within 1.25 U/ml - 8.65 U/ml in which Acinetobacter sp. had the highest production. During submerged fermentation, the growth of the selected fungal isolate ranged within 0.00 - 0.200a , 0.00 - 0.25a and 0.00 - 0.3190a in which T. FISO1 had the highest at 3 and 7 days of incubation while T. virens FSU/AW3 had the highest at 14 days of incubation. There was a significant difference in lipase production by the fungi, it ranged within 0.70n - 12.35a U/ml, 1.8k - 19.15a U/ml and 2.50n - 19.8a U/ml in which Hypocrea patella FAD1, T. stromaticum FSUAW1 and T. virens FSU/AW3 had the highest at day 3, 7 and 14, respectively. The study has shown that the bacteria and Trichoderma strains isolated are potential lipase producers

Screening of Some Basidiomycetes for Bio-polymers and Biomass Production in Submerged Cultivation

Twenty-one species of edible and non-edible basidiomycetes were screened for bio-polymers and biomass production in submerged cultivation. All the basidiomycetes produced bio-polymers and there was variation in quantities of bio-polymers produced by the strains at different incubation times. The bio-polymers production ranged within 44 - 9,177 mg/l, 63 - 14,525 mg/l and 69 - 6,367 mg/l at days 2, 7 and 14, respectively. Coriolus versicolor produced the highest yield at day 7. The biomass production at days 2, 7 and 14 ranged within 0.12 - 0.23g dry w/l, 0.13 - 0.25g dry w/l and 0.13 - 0.30g dry w/l in which C. versicolor also had the highest yield. The highest biomass production was recorded on day 14

Screening of Lactic Acid Bacteria Isolated from Fermented Food for Bio-molecules Production

Production of bio-molecules is an important factor in assuring the proper consistency and texture of fermented foods. Lactic acid bacteria (LAB) isolated from fermented food were screened for lactic acid, diacetyl, hydrogen peroxide, pH development and Exopolysaccharide (EPS) production. Thirty-five strains of LAB were isolated and characterized from fermented dairy and non-dairy foods. The LAB species identified include: Lactobacillus fermentum, Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus cellobiosus, Lactobacillus delbruekii, Lactobacillus coryniformis, Lactobacillus casei, and Leuconostoc messenteroides. The most predominant species was Lactobacillus plantarum (34.29%). All the isolates were screened for lactic acid, hydrogen peroxide, diacetyl and pH and EPS production. Lactic acid production ranges within 0.11-1.96 mg/l in which the highest was produced by L. plantarum LPF2. L. plantarum LPF2 also produced the largest amount of diacetyl (1.92 mg/l). Hydrogen peroxide produce by the isolates ranges within 0.0002-.35 mg/l and L. fermentum LFBO1 produced the highest. The pH ranged within 3.2-6.5 in which L. plantarum LPF2 had the least. L. plantarum LPW7 and LPBO9, Leu. messenteroides LMWO2 and LMW4 bring the reduction of the pH of the fermentation medium to 3.8 at 36 hours. All the isolates were screened for EPS production on solid medium. The isolates were all creamy; four were highly mucoid, eight were mucoid while twenty-three were slightly mucoid. All the isolates are EPS producers, EPS production ranged within 120-1,390 mg/l in which the highest was produced by L. fermentum LF6

Influence of Different Nutrient Sources on Exopolysaccharide Production and Biomass Yield by Submerged Culture of Trametes versicolor and Coprinus sp.

Influence of different nutrient sources on Exopolysaccharide (EPS) production and Biomass yield by submerged culture of Trametes versicolor and Coprinus sp. was investigated. The best EPS production by Trametes versicolor and Coprinus sp. was stimulated by sucrose. EPS production ranged within 1,011-17945 mg/l and 200-18,765 mg/l, respectively. The least EPS production was recorded in xylose and glucose, respectively. Xylose and sorbitol supported the highest biomass yield (1.9 gdryw/l and 2.0 gdryw/l) by Trametes versicolor and Coprinus sp., respectively. Yeast extract induced the highest EPS production (7,835 mg/l) by T. versicolor. The EPS ranged within 701-7,835 mg/l. Casein stimulated the highest production of EPS by Coprinus sp. and it ranged within 563-7,474 mg/l. Yeast extract and NaNO3 induced the highest biomass yield by Trametes versicolor and Coprinus sp., respectively. Biomass yield ranged within 1.0-1.6 gdryw/l and 2.0-1.9 gdryw/l. The highest EPS production by the strains was stimulated by glutamic acid and it ranged within 272-3,684 mg/l and 209- 8,899 mg/l, respectively. The least stimulatory amino acids were alanine and glutamate, respectively. The best amino acids for biomass production by the isolates were aspartic acid and asparagines, respectively, and it ranged within 1.0-15.0 gdryw/l and 1.0-16.0 gdryw/l

Moulds, Proximate Mineral Composition and Mycotoxin Contamination of Banda (“kundi”/ “tinko”) Sold in Ibadan, Oyo State, Nigeria

Mycotoxin is an important toxin whose consumption could cause foodborne diseases. The moulds, proximate mineral composition and mycotoxin contamination of Banda samples purchased from different markets in Ibadan, Oyo state, were investigated. A total of 90 samples were collected during July - September and a total of 69 fungi isolates were obtained. The fungal isolates found in samples were Aspergillus niger, A. flavus, A. fumigatus, A. candidus and A. piperis among which A. niger had the highest frequency of occurrence (36.23%) followed in order by A. flavus (30.23%), A. fumigatus (13.04%), A. candidus and A. piperis (10.14%). The samples were found to contain adequate amount of proximate mineral contents. Proximate and mineral analysis carried out showed that the percentage crude protein in Banda samples collected in July is higher than that of August and September. The percentages of most of the mineral elements are higher in samples collected in August. It was observed from the analysis that the proximate and mineral composition in the dried meat was higher than that of the control (Raw meat sample). Mycotoxin analysis revealed that the samples were heavily contaminated with aflatoxins B1, B2, fumonisin (FB1 and FB2) and ochratoxin (OTA). There was a significant difference (P ≤ 0.05) in mycotoxin concentration among the samples. The AFB1 and AFB2 were found in 10% and 90% of the dried meat samples, while 10% were contaminated with FB1 and FB2, respectively. 13.3% were contaminated with OTA. AFB1 was not detected in all of the samples except samples J1, A1 and S4, respectively. For the samples collected in the month of July, the AFB2 concentration ranged within 0.00 - 201.50, FB1, FB2 and OTA concentrations ranged within 0.00i - 1.909a, 0.00i - 1.037a, and 0.00i - 2.00a, respectively. For the samples collected in August, the AFB2, FB1, FB2 and OTA concentrations ranged within 0.00i - 234.20a, 0.00i - 2.327a, 0.00i - 1.003a, and 0.00 - 1.600a in which sample A7 had the highest concentration. The AFB2 concentration ranged within 0.00 - 167.20a in which sample S1 had the highest concentration. The FB1, FB2 and OTA concentrations ranged within 0.373h - 2.199a, 0.167h - 1.965a, and 0.00f - 2.133a for the samples collected in September. The levels of mycotoxin contamination in all the samples exceeded the maximum limit permitted in most countries. The detection of AFB1 and AFB2 in the dried meat samples could be of public health significance and hence there is an urgent need for concerned regulatory bodies to impose necessary measures to safeguard health of consumers. Conclusively, the presence of mycotoxin producing fungi and the level of AFB1 and AFB2 in the dried meat samples call for serious attention in the country and there is a need for some form of quality control and proper preservation before usage

In–Vitro Antibacterial and Antifungal Efficacy of Greenly Fabricated Senna alata Leaf Extract Silver Nanoparticles and Silver Nanoparticle-Cream Blend

Nanoparticles biosynthesis has been extensively studied for its biomedical applications. In this study, the in-vitro antibacterial and antifungal activity of greenly fabricated silver nanoparticles (NPs) from Senna alata leaf extract (SaAgNPs) and silver nanoparticle cream blend (SaAgNPs-cream blend) were investigated. The SaAgNPs were characterized using UV-visible spectrophotometry, FTIR, SEM, TGA, DLS, EDX, and XRD. The presence of surface plasmon band around 500 nm indicates AgNPs formation and functional groups such as alkenes, carboxylic acids, and alkyl aryl ether responsible for capping and stabilization of the nanoparticles. The SaAgNPs were spherical and 1.00 µm in size; TGA shows the formation of stable SaAgNPs, DLS shows 1.8 % intensity with 1905 nm average diameter and a polydispersity index of 0.595. EDX analysis confirmed the formation of pure silver nanoparticles. SaAgNPs supported the production of cosmetically acceptable SaAgNPs-cream blend with appropriate pH and viscosity. SaAgNPs and the SaAgNPs cream-blends had antibacterial activity against all and some of the test bacterial and fungal isolates. SaAgNPs had the highest activity against Pseudomonas aeruginosa 27853, Rhizopus sp. and Candida tropicalis with a zone of 16 mm and 30 mm. The cream-blends had activity against 68.75 % and 75 % of the test bacteria and fungi with the highest activity against Streptococcus epidermidis B (7.0 mm) and Candida albicans B (8.0 mm). In conclusion, the crude Senna alata leaf extracts, the bio-fabrication SaAgNPs and SaAgNPs-cream blend have antibacterial antifungal potentials which can be effectively utilized for the control of pathogenic bacteria and fungi

Studies on Microbiological, Proximate Mineral and Heavy Metal Composition of Freshwater Snails from Niger Delta Creek in Nigeria

Microbial quality of freshwater snail samples from Itu creek, Niger Delta Nigeria was studied. The bacteria isolates were Proteus sp., Sreptococcus pyrogens, Shigella flexneri, Staphylococcus aureus, E. coli, Klebsiella aerogenes, Citrobacter, Bacillus subtilis, Bacillus cereus, Aeromonas sp., Micrococcus liteus, Streptococcus salivanus, Salmonella typhi, Vibrio parahaemolyticus, Vibrio sp. and Vibrio cholera. Proteus sp, Aeromonas sp. and Micrococcus liteus had the highest frequency of occurrence (10.25%). The fungi isolates were Aspergillus terreus, Cladosporium sp, Fusarium oxysporum, Cryptococcus sp, Aspergillus flavus, Aspergillus glaucus and Aspergillus niger in which A. niger, A. terreus and F. oxysporum had the highest occurrence (16.67%). The total heterotrophic count of the samples ranged from 4.0 x107 -1.42 x 108 cfu/g. The coliform levels were generally high and it ranged from 2.2-6.4 x 107 cfu/g in which the highest was recorded from P. canaliculata (A1). The Salmonella/Shigella counts ranged from 1.1-5.2 x 107 cfu/g in which the highest count was recorded from L. libycus (C1). The total Staphylococci count ranged from 1.7-3.5 x107 cfu/g in which A. fulica (D2) had the highest. The total vibrio counts ranged from 1.6-3.2 x 107 cfu/g. The fungi count ranged from 1.7-3.5 x 107 cfu/g. The total microbial counts obtained from this work were found to be higher than the specified standard limits (1x105 cfu/g) for bacteria and fungi and 1.x102 cfu/g for coliforms) by ICMSF (1982) and USFDA (1991). The crude protein content of the samples ranged from 28.87 d – 33.41a% in which the highest was obtained from A. fulica (D3). The Crude Fat, crude fiber and carbohydrate content ranged from 1.8-4.25% and 00.10-0.18%, respectively. The mineral elements such Na, Ca, K and P were detected in all the freshwater snail samples. The concentration of metal ranges of Zn, Fe, Mn, Mg, Pb, As and Cu in the samples were 78.6j -96.3a mg/kg, 15.7j -28.6a mg/kg, 58.6j -77.5a mg/kg, 0.258 j -0.297a mg/kg, 0.03 i -0.25a mg/kg, 0.04i -0.37a mg/kg and 12.6 j -16.3a mg/kg, respectively. It was observed that different metals were present in the samples at different levels but majority were found to be within the standard limits prescribed by EU and FAO. Freshwater snails from the creek in Niger Delta was found to be nutritionally richer but harbor pathogenic microorganism and heavy metals which can pose serious health hazard to consumers and they are not totally safe for human consumption

A Comparative Study Of Probioticated Kunun-Zaki By Probiotic Strains Of Pediococci spp. And Lactobacillus rhamnosus GG

Non-dairy probiotic functional foods are receiving considerable interest recently owing to the inability to cause allergy in certain segments of the population. Studies on probiotication were carried out to determine the suitability of kunun-zaki as food matrix for production of probiotic beverage using single and mixed culture of Pediococcus acidilactici KU7, Pediococcus pentosaceus CREC5 and Lactobacillus rhamnosus GG. Probioticated and un-probioticated kunun-zaki samples were designated PKZ and UPKZ, respectively. There was a significant difference in the viable count during storage. Viable counts of the LAB strains decreased with increasing storage time with P. acidilactici KU7 having the highest viability at the beginning and end of storage (3.43 ± 0.06 and 0.93± 0.12 x108 cfu/ml). There was a decrease in pH of the PKZ samples within the 1st and 3rd week with corresponding increase in lactic acid production (71.16 ± 0.01 – 441.39 ± 0.01). Marked increase in pH and a decline in lactic acid were observed at the 4th week of storage in all samples. Total soluble solids content of the beverage was observed to decrease with increasing storage time ranging from 8.25 ± 0.01-4.97± 0.01. There was no significant difference in pH and total soluble solids of UPKZ and colour of the PKZ and UPKZ samples during storage. All the PKZ samples were able to inhibit the growth of selected pathogens with marked variability amongst the samples. The UPKZ sample also showed slight inhibitory activity. The samples showed a decline in proximate and mineral composition at the end of storage. Sensory evaluation showed the PKZ samples were preferred over the UPKZ samples. This study shows that probioticated kunun-zaki can serve as a suitable non-dairy alternative to dairy probiotic formulations and would be of health benefits to potential consumers