Antibiotic resistance, putative virulence factors and curli fimbrination among Cronobacter species.

This study aimed to investigate antibiotic resistance and putative virulence factors among Cronobacter sakazakii isolated from powdered infant formula and other sources. The following 9 cultures (CR1-9) were collected from our culture collection: C. sakazakii and 3 Cronobacter species: C. sakazakii ATCC® 29544™, C. muytjensii ATCC® 51329™, C. turicensis E866 were used in this study. Isolates were subjected to antibiotic susceptibility and the following virulence factors (protease, DNase, haemolysin, gelatinase, motility and biofilm formation) using phenotypic methods. All the bacteria were able to form biofilm on agar at 37 °C and were resistant to ampicillin, erythromycin, fosfomycin and sulphamethoxazole. It was observed from this study that tested strains formed weak and strong biofilm with violet dry and rough (rdar), brown dry and rough (bdar), red mucoid and smooth (rmas) colony morphotypes on Congo red agar. Rdar expresses curli and fimbriae, while bdar expresses curli. Both biofilm colony morphotypes are commonly found in Enterobacteriaceae including Salmonella species. This study also reveals a new colony morphotypes in Cronobacter species. Conclusively, there was correlation between putative virulence factors and antibiotic resistance among the tested bacteria. Further study on virulence and antibiotic resistance genes is hereby encouraged.

Tolerance of Tithonia diversifolia and Chromolaena odorata in heavy metal simulated-polluted soils and three selected dumpsites.

Soil heavy metals pollution is of global concern in view of their flow through the food chain. The convectional, physical, and chemical approaches to remediate polluted soils are usually expensive and not eco-friendly. Phytoextraction is a promising alternative because of the cost effectiveness and eco-friendliness. Therefore, this study was designed to determine the abilities of Chromolaena odorata (Co) and Tithonia diversifolia (Td) to extract heavy metals from polluted soil. Soil analysis was done in part per million (ppm) before Td and Co were grown separately on sixty soil samples of 6.5 kg each collected from 3 selected dumpsites in Irese, New Stadium, and a control site (Ijare), Akure in Ondo State. Three replicates of the soil samples collected from Ijare were simulated with 10 g/kg each of cadmium (Cd), zinc (Zn), iron (Fe), copper (Cu) and lead (Pb) and used in assessing the phytoextraction capabilities of Co and Td. Two grams per kilogram of each of the heavy metals were mixed together and used in simulating three soil samples collected from Ijare and phytoextraction capabilities of Co and Td assessed. A control experiment using soil sample from Ijare was also set up in three replicates for Co and Td. Soil analyses were also carried out after the experiment in ppm. Plant biomass was assessed. Heavy metal contents in roots, shoots and soil samples were analyzed after harvest to determine the bioaccumulation (BF). Data obtained were subjected to one way Analysis of Variance at α0.05. The most contaminated soil sample before and after the experiment was obtained in soil sample (mg/kg) from OD with Cd = 0.08 and 0.071, Zn = 1.92 and 1.85, Fe = 8.44 and 6.94, Cu = 3.04 and 2.54 and Pb = 1.4 and 0.93 respectively. The highest fresh and dry weights (g) for Td and Co were recorded in the plants grown in the control soil. The fresh weight (g) for Td and Co shoots and roots were 110.58 and 52.90; and 48.41 and 7.18 respectively. The dry weights (mg) for Td and Co shoots and roots were 20.56 and 4.68; and 16.66 and 0.36 respectively. Uptake of heavy metals in T. diversifolia and C. odorata tissues (ppm) were Cd (0.43 and 0.06), Zn (6.57 and 3.8), Cu (3.93 and 2.21), Pb (2.37 and 1.94) and Fe (55.15 and 32.82) respectively. This study showed Tithonia diversifolia and C. odorata were capable of reducing heavy metals in polluted soils. Thus the plants are good candidates for the phytoextraction of heavy metals from polluted soils.

Toxicological evaluation of the essential oil from Mentha longifolia L. subsp. capensis leaves in rats.

The effects of the essential oil from the leaves of Mentha longifolia L. subsp. capensis on some biochemical parameters of Wistar rats were studied. The oil at 125, 250, 375, and 500 microL/kg of body weight reduced (P < .05) the red blood cells and lymphocytes with no definite pattern on the white blood cells and mean cell volume. The doses significantly increased the neutrophils, monocytes, large unstained cells, liver-body weight ratio, and serum concentrations of cholesterol, triglyceride, high-density lipoprotein-cholesterol, and inorganic phosphate but had no effect on the heart body weight ratio and serum low-density lipoprotein-cholesterol, Na(+), Ca(2+), Cl(-), K(+), creatinine, and uric acid. The oil at 500 microL/kg of body weight also increased the kidney-body weight ratio. In contrast, the oil reduced the serum urea and atherogenic index. The total and conjugated bilirubin, together with the total protein and albumin, in the serum increased only with oil at 125 microL/kg of body weight. The serum alkaline phosphatase activity also increased with no significant change in those of gamma-glutamyl transferase and alanine and aspartate aminotransferase. The results indicate dose- and parameter-specific effect of the essential oil. Although the essential oil from M. longifolia leaves may not predispose to atherosclerosis, it may increase the functional activity of the rat liver at the lowest dose investigated. Therefore, the essential oil from M. longifolia may not be completely "safe" at the doses investigated.

Effect of rearing temperature on the fecundity and development of Euzopherodes vapidella Mann (Lepidoptera: Pyralidae), a pest of stored yam.

The fecundity and development of the yam moth, Euzopherodes vapidella Mann on Dioscorea alata L. was investigated in the laboratory at four different temperatures, 20, 24, 29 and 33 degrees C. The mean fecundity per female at 20, 24, 29 and 33 degrees C was 51.8+/-3.5, 102.4+/-3.8, 123.3+/-4.4 and 124.4 +/-4.4 eggs, respectively. Hatchability of eggs was highest at 29 degrees C and lowest at 20 degrees C. The mean developmental time at 20, 24, 29 and 33 degrees C was 12.1+/-0.6, 6.2+/-0.3, 3.0+/-0.0 and 2.7+/-0.1 days for the egg, 23.6+/-1.1, 20.0+/-0.9, 15.4+/-0.7 and 12.9+/-0.4 days for the larval stages, 13.0+/-0.03, 8.9+/-0.02, 7.9+/-0.02, and 6.4+/-0.03 days for the pupa and 48.7+/-3.5, 35.1+/-2.3, 26.3+/-1.2 and 22.0+/-1.0 days for the period from egg to adult emergence, respectively. The developmental threshold for the egg stage was estimated as 16.8 degrees C with thresholds of 8.0, 6.2 and 11.4 degrees C for larvae, pupae, and egg to adult emergence, respectively. Storage of yam tubers at low temperatures (but higher than 12 degrees C to avoid damage to tubers) will significantly retard the development of E. vapidella and therefore help in their control. Adult males ranged from 0.50 to 0.65cm in length and females from 0.70 to 0.90cm.

Three edible wild mushrooms from Nigeria: their proximate and mineral composition.

The pilei (caps) and the stipes (stalks) of the button and early open-cap (cup) stages of Lentinus subnudus, Psathyrella atroumbonata and Termitomyces striatus were assayed separately for their proximate and mineral composition. The differences observed in the contents of some of the proximate components seem to be related to species and mushroom parts. P. atroumbonata was richest in crude and true protein, L. subnudus was richer in crude fiber, ash and carbohydrates. Mineral contents appeared to be dependent on type and parts of the mushrooms analysed. The three mushrooms were good sources of magnesium, zinc and iron. L. subnudus contained between 14.83 and 20.00 ppm of iron, P. atroumbonata contained between 20.01 and 22.09 ppm and T. striatus contained between 17.13 and 22.93 ppm of iron. The pilei of P. atroumbonata and T. striatus are very good sources of zinc. Zinc contents for the pilei of P. atroumbonata were 63.81 and 64.94 ppm respectively. Zinc contents for T. striatus were 90.45 and 92.49 ppm respectively.

Studies on some edible wild mushrooms from Nigeria: 1. Nutritional, teratogenic and toxic considerations.

The biological value of 5 mushrooms Chlorophyllum molybditis, Psathyrella atroumbonata, Termitomyces robustus, Termitomyces striatus and Volvariella esculenta from our collection of wild edible mushrooms were determined using weanling rats. C. molybditis supported rapid growth with PER (2.63) higher than the casein control (2.50). P. atroumbonata was average in biological performance (PER 1.50) while T. robustus and V. esculenta did not support growth at all. Rats on T. striatus dried at 60 degrees C for 48 h lost weight rapidly and showed pathological signs of toxicity by the second day. All rats on this diet died by the fourth day of the experiment. When the diet of T. striatus dried at 90 degrees C for about 8 h was fed, the rats gained weight marginally but all survived. Prolonged storage of T. striatus at 60 degrees C for 5-8 weeks also seemed to detoxify the poisonous component such that PER and NPR values were 0.8 and 2.0 respectively. 2 pairs each of adult rats fed C. molybditis and Tricholoma lobayensis diets for 10 days were mated. Rats of C. molybditis diet gave 5 and 6 litters each and only one of these litters seemed to have retarded growth. Rats on T. lobayensis diet did not produce any litters for 14 weeks but the female produced off-spring when mated with control male rats.

Effect of storage temperature, time and wrapping materials on the microbiology and biochemistry of ogiri-a fermented-castorseed soup condiment.

Wrapping ogini in perforated cellophane bags at 28°C increased its pH value during 7 days' storage. Storage at 10°C decreased microbial numbers in ogiri wrapped with both plantain leaves and cellophane. The temperature rose from 28 to 42°C during natural ogiri fermentation. Samples of ogiri inoculated with Bacillus sp. and a combination of Bacillus and Micrococcus spp. produced the typical ogiri odour.

The effect of heme-linked ionizable groups on cyanide binding to methemoglobin.

The pH dependence of the kinetics of the binding of cyanide ion to methemoglobins A and S and to guinea pig and pigeon methemoglobins appears to be not directly correlated with the net charges on the proteins. The kinetics can, however, be adequately explained in terms of three sets of heme-linked ionizable groups with pK1 ranging between 4.9 and 5.3, pK2 between 6.2 and 7.9, and pK3 between 8.0 and 8.5 at 20 degrees C. pK1 is assigned to carboxylic acid groups, pK2 to histidines and terminal amino groups, and pK3 to the acid-alkaline methemoglobin transition. Kinetic second order rate constants have also been determined for the binding of cyanide ion by the four sets of methemoglobin species present in solution. The pKi values and the rate constants of methemoglobin S are strikingly different from those of methemoglobin A. This result is explained in terms of different electrostatic contributions to the free energy of heme linkage arising from differences in the environments of ionizable groups at the surfaces of the two molecules.

Resistance of Rhizobium strains to phygon, spergon, and thiram.

Strains of Rhizobium meliloti, Rhizobium sp. nodulating cowpeas, and R. phaseoli derived from cultures susceptible to tetramethylthiuram disulfide (thiram), 2,3-dichloro-1,4-naphthoquinone (phygon), and 2,3,5,6-tetrachloro-p-benzoquinone (spergon), respectively, grew in the presence of high concentrations of the fungicides and converted them to products not toxic to the sensitive rhizobia. The results of chemical assays demonstrated that the pesticides were destroyed by the resistant bacteria but not by the susceptible parent rhizobia. Resting cells of thiram-metabolizing R. meliloti formed large quantities of dimethyldithiocarbamate, dimethylamine, and CS2 from the pesticide. The products were characterized by gas and thin-layer chromatography, colorimetric reactions, and ultraviolet spectrometry. Dimethylamine and CS2 were formed spontaneously from dimethyldithiocarbamate, but the yield was higher in the presence of R. meliloti. The phygon-resistant bacterium converted the fungicide to five metabolites and thereby rendered the chemical nontoxic to a test fungus. The resistant strain of R. phaseoli generated at least one organic product and released about one-third of the chlorine during its detoxication of spergon.