Removal of lead and cadmium by halophilic bacteria isolated from the Dead Sea shore, Jordan

Ten Gram-positive and Gram-negative bacterial cultures were recovered from nine water, mud, and soil samples from the Dead Sea shore at Suwaymah. They were able to grow at 10% NaCl and at 45 degrees C. Bacterial cultures 6 and 8 were able to grow in nutrient media supplemented with 2250 ppm of Pb. Bacterial cultures 1, 3-6, 9, and 10 were able to grow in nutrient medium supplemented with 1000 ppm of Cd. Atomic absorption spectrometry was used to estimate the absorbed Pb and Cd by bacterial cultures from 5-, 25-, 100-, and 500-ppm stock solutions of both elements. After 2 wk, the results showed that the maximum absorption for Pb was achieved by culture 6 in the following percentages: 79.8%, 70.48%, 89.48%, and 83.39%, respectively. The maximum absorption of the same concentration of Cd was achieved by culture 9 with the following percentages: 69.2%, 32.24%, 44.98%, and 60.0%, respectively. After 3 wk of incubation, the estimated absorption of both heavy metals was achieved by the same cultures (6 and 9), respectively, in the following percentages: 86.8%, 76.72%, 96.25%, and 96.0% for Pb and 82.60%, 93.2%, 92.74%, and 89.79% for Cd. The accumulation of the absorbed metals was found to be maximum in the protoplast of all the cultures. The accumulation at the cell wall was maximum in culture 2, and between the cell wall and the plasma membrane, it was maximum in cultures 2 and 8 for Pb and Cd, respectively.     

Growth of Nitrosomonas europaea in batch and continuous culture

Summary A clear medium has been used to grow pur cultures of Nitrosomonas europaea in flasks and in a continuous culture apparatus.Of several metallic ions examined in flask cultures of Nitrosomonas, Fe at 2 ppm and Co, Mn and Zn at 1 ppm were not toxic, Ni and Cr at concentrations greater than 0.25 ppm inhibited growth and Cu stopped growth completely at 0.5 ppm and inhibited at 0.1 ppm. Stainless steel of the specification EN58 B did not affect growth.In the continuous culture vessel, Nitrosomonas showed a growth response to Fe only when the population exceeded about 500×10⁶ organisms/ml. The minimum doubling time was about 8 hours in flasks and 11 hours in the culture vessel. With effective aeration and automatic P_H control, cultures of Nitrosomonas were grown successfully in continuous culture and gave a yield of 2.14 g dry weight of bacteria from 30 litres of culture in 5 days.     

Effect of the dietary oregano (Origanum vulgare) on Cu and Zn balance in weaned piglets

A 4-week study conducted on 20 weaned piglets (average initial weight 15 kg) evaluated the effects of dietary oregano (Origanum vulgare) used in the presence/absence of phytase on the Cu and Zn balance, while reducing/eliminating their inclusion in the diet as inorganic salts. Oregano was harvested from the wild flora. The Cu and Zn concentrations that were taken into consideration (9.85 ppm and 53.31 pmm, respectively) were the consensus values obtained in an interlaboratory study. The piglets were assigned to 4 groups (C, E1, E2, E3), housed in individual metabolic cages and fed on corn–soybean meal-based diets. The diet of the control group (C) with addition of 1% inorganic mineral premix (MP), contained: 40.92 ppm Cu, 144.96 ppm Zn. The experimental diets differed from the C diet as follows: E1 – 3% oregano, 0% phytase (5000 PU/g), 0% MP; E2 – 3% oregano, 0.01% phytase, 0% MP; E3 – 3% oregano, 0% phytase, 0.5% MP, E4 – 3% oregano, 0.01% phytase, 0,5% premix. For groups E1, E2, E3 and E4, 0.5% Zn of the MP were included in the diet, because the dietary oregano amount did not meet the requirements (NRC) for piglets. The mineral balance was determined during 3 periods of 5 days each. The levels of Cu and Zn were measured by FAAS in the samples (weekly samples/piglet) of ingesta, faeces and urine. It was noticed that although the dietary Cu ingested by the groups without MP was 75% (10.08 ppm) lower than C, the absorption coefficients were only 47% (28.83) lower than for group C (54.22%), while in the groups with 0.5% MP, the absorption was just 10% (48.86%) lower than for group C. For Zn, where the amount ingested by the experimental groups was 33% (97.62 ppm) lower than for group C, the absorption coefficients were just 20% (46.3%) lower than for group C (57.64%). No significant differences were noticed for Cu and Zn in terms of apparent absorption, between the groups with/without phytase. The deposits of Cu and Zn in the main organs and serum (from slaughtered piglets) were also evaluated.     

Xylanolytic Activity of Clostridium acetobutylicum

Of 20 strains of Clostridium spp. screened, 17 hydrolyzed larch wood xylan. Two strains of Clostridium acetobutylicum, NRRL B527 and ATCC 824, hydrolyzed xylan but failed to grow on solid media with larch xylan as the sole carbon source; however, strain ATCC 824 was subsequently found to grow on xylan under specified conditions in a chemostat. These two strains possessed cellulolytic activity and were therefore selected for further studies. In cellobiose-limited continuous cultures, strain NRRL B527 produced maximum xylanase activity at pH 5.2. Strain ATCC 824 produced higher xylanase, xylopyranosidase, and arabinofuranosidase activities in chemostat culture with xylose than with any other soluble carbon source as the limiting nutrient. The activities of these enzymes were markedly reduced when the cells were grown in the presence of excess glucose. The xylanase showed maximum activity at pH 5.8 to 6.0 and 65°C. The enzyme was stable on the alkaline side of pH 5.2 but was unstable below this pH value. The extracellular xylanolytic activity from strain ATCC 824 hydrolyzed 12% of the larch wood xylan during a 24-h incubation period, yielding xylose, xylobiose, and xylotriose as the major hydrolysis products. Strain ATCC 824, after being induced to grow in batch culture in xylan medium supplemented with a low concentration of xylose, failed to grow reproducibly in unsupplemented xylan medium. A mutant obtained by mutagenesis with ethyl methanesulfonate was able to grow reproducibly in batch culture on xylan. Both the parent strain and the mutant were able to grow with xylan as the sole source of carbohydrate in continuous culture with the pH maintained at either 5.2 or 6.0. Under these conditions, the cells utilized approximately 50% of the xylan.     

Monoterpenoid oxindole alkaloid production by Uncaria tomentosa (Willd) D.C. cell suspension cultures in a stirred tank bioreactor

Cell growth, monoterpenoid oxindole alkaloid (MOA) production, and morphological properties of Uncaria tomentosa cell suspension cultures in a 2-L stirred tank bioreactor were investigated. U. tomentosa (cell line green Uth-3) was able to grow in a stirred tank at an impeller tip speed of 95 cm/s (agitation speed of 400 rpm), showing a maximum biomass yield of 11.9 +/- 0.6 g DW/L and a specific growth rate of 0.102 d(-1). U. tomentosa cells growing in a stirred tank achieved maximum volumetric and specific MOA concentration (467.7 +/- 40.0 microg/L, 44.6 +/- 5.2 microg/g DW) at 16 days of culture. MOA chemical profile of cell suspension cultures growing in a stirred tank resembled that of the plant. Depending on culture time, from the total MOA produced, 37-100% was found in the medium in the bioreactor culture. MOA concentration achieved in a stirred tank was up to 10-fold higher than that obtained in Erlenmeyer flasks (agitated at 110 rpm). In a stirred tank, average area of the single cells of U. tomentosa increased up to 4-fold, and elliptical form factor increased from 1.40 to 2.55, indicating enlargement of U. tomentosa single cells. This work presents the first report of U. tomentosa green cell suspension cultures that grow and produce MOA in a stirred tank bioreactor.     

Bovine colostrum supports the serum-free proliferation of epithelial cells but not of fibroblasts in long-term culture

Medium lacking serum but supplemented with milk will support the growth of sparse cells in culture. Milk obtained within 8 h after the birth of a calf (day 1 colostrum) is the most effective in supporting proliferation. In mixed cultures of early-passage bovine embryonic kidney (BEK) or early-passage calf kidney (CK) cells, both epithelial cells and fibroblasts grow in Dulbecco’s modified eagle’s medium (DMEM) supplemented with serum. However, only cells that appear to be epithelial-like grow in DMEM supplemented with colostrum. Sparse cultures of early-passage human and rat fibroblasts that grow readily in DMEM supplemented with serum do not grow in DMEM supplemented with colostrum. Canine kidney epithelial cells (MDCK), when plated sparsely, grow exponentially in DMEM supplemented with day 1 bovine colostrum. The generation time is 26 h, the same growth rate as in DMEM supplemented with calf serum. The MDCK cells can be subcultured and regrown to confluence repeatedly in colostrum-supplemented DMEM. Growth in DMEM supplemented with colostrum does not alter the morphological characteristics of the MDCK cells, which are polygonal, contain microvilli at the apical surface, and are connected by tight junctions and desmosomes. MDCK cells do not proliferate in DMEM supplemented with milk obtained 1 wk after the birth of a calf.     

The effect of humic acid and Na2EDDHA on the uptake of Cu,Fe, and Zn by barley in sand culture

Summary Humic acid affected nutrient uptake differently in sand culture. It generally increased Cu uptake, slightly, though insignificantly, increased Fe uptake and practically had no effect on Zn uptake. Such results agree fairly well with the relative stability of humic acid with these metals.When humic acid was added to sand culture at increasing concentration of the metal, it considerably increased dry weight, Cu uptake and Cu concentration through decreasing its toxicity to plant. With Fe, however, humic acid and Na₂EDDHA slightly increased Fe uptake at lower Fe concentration (30 ppm) but significantly reduced both Fe uptake and Fe concentration in plant at higher concentration of Fe compared to the control treatment. Humic acid reduced Zn uptake and Zn concentration in plant at concentrations of 0.5–1.5 ppm Zn, and guarded against Zn toxicity which developed at higher concentration of Zn when no humic acid was added.     

Effect of different heavy-metal concentrations on Drosophila melanogaster larval growth and development

The survival percentage of Drosophila melanogaster larvae on synthetic media containing different concentrations of heavy metals, including Cd, Cu, Pb, and Zn, in the first generation indicated no significant reduction in their growth and development up to 500 ppm for all tested heavy-metal concentrations. At 500 ppm, results showed that there was a significant reduction in pupa and adult stages: 65% and 25% for Cd, 50% and 25% for Cu, 100% and 95% for Pb, and 85% and 75% for Zn, respectively. The survival percentages at 1000 ppm were further significantly reduced: 15% and 0% for Cd, 35% and 15% for Cu, 45% and 90% for Pb, and 65% and 35% for Zn, respectively for pupa and adult stages. For the second generation, there was no significant reduction in survival growth and development up to 100 ppm, but above 500 ppm, there was a significant reduction. For most of these heavy-metal concentrations, the survival percentages of the second generation at the pupa stage was higher than the first generation, whereas for the adult, there was a lower survival percentage, indicating some effect on metamorphosis of these heavy-metal concentrations on Drosophila melanogaster Comparing the survival percentage between first and second generations at 500 ppm for pupa indicate a significant increase on Cu only, and for the adult, there was a significant reduction for Cd.     

Isolation and monolayer culture of human fallopian tube epithelial cells

Summary In the present study we have established a pure monolayer culture system of human fallopian tube epithelial cells. The cells were isolated using collagenase digestion, and were cultured in Medium 199 supplemented with 15% fetal bovine serum. The epithelial cells derived from primary and secondary culture were characterized using immunocytochemical staining and electron microscopy. The cells continued to grow for 2 to 3 wk once the monolayer culture of the cells was established. It is currently possible to maintain the cultures until the third generation. Proliferation of these cells was enhanced by epidermal growth factor but not by basic-fibroblast growth factor, insulin, transferrin, estradiol-17β, or progesterone. This culture system offers a good model for determining characteristics of the tubal epithelium and would permit effective study of co-culture with embryos.     

Correlation of Aflatoxin Contamination With Zinc Content of Chicken Feed

Feed samples from chicken houses in five commercial chicken operations were analyzed for Zn, Mn, Fe, Cu, Cd, and aflatoxin content. Mean aflatoxin content of these samples was 14 ppb (14 ng/g) as opposed to 1.2 ppb in samples taken when the feed was made. Aflatoxin content of the feed samples correlated (r = 0.325) significantly (P < 0.05) with Zn content but not with Mn, Fe, or Cu, all of which correlated significantly with Zn. Zn content of unamended feed (<20 ppm [20 μg/g]) is normally supplemented with a mineral premix containing Zn, Mn, Fe, and Cu to meet the nutrient requirements of chickens (40 ppm of Zn). The mean zinc concentration of the feed samples (117 ppm) was about threefold greater than the nutrient requirement and ranged from 58 to 162 ppm in individual samples. These field survey results parallel earlier reports of augmented production of aflatoxin in monocultures of aflatoxigenic fungi in corn and other ingredients supplemented with Zn. These results suggest that stricter control of Zn levels during manufacture could reduce aflatoxin contamination of feed consumed by chickens.     

Effects of polyphenol-rich plant products from grape or hop as feed supplements on iron,zinc and copper status in piglets

Polyphenol-rich plant products as feed supplements have been shown to exert beneficial effects on feed efficiency in piglets. However, tannins as components of polyphenol-rich plant products are able to reduce the absorption of various trace elements. The present study investigated the effect of two polyphenol-rich dietary supplements, grape seed and grape marc meal extract (GME) and spent hops (SH), on iron (Fe), zinc (Zn) and copper (Cu) status in piglets supplied adequately with those trace elements. A trial with three groups of piglets which received a Control diet or the same diet supplemented with either 1% GME or 1% SH over a period of 4 weeks was performed. Concentrations of Fe, Zn and Cu in plasma, total iron binding capacity and saturation of transferrin in plasma did not differ between the three groups. Piglets fed the diet supplemented with SH showed no differences in the concentrations of Fe, Zn and Cu in the liver in comparison to the Control group. Piglets fed the diets supplemented with GME showed slightly lower concentrations of Zn and Cu in the liver than Control piglets (p < 0.05); however, concentrations of both elements remained in the physiological range. Overall, this study shows that the polyphenol-rich plant products GME and SH had marginal effect on the status of Fe, Zn and Cu in piglets.     

A comparative study in rats of measures of the availability of dietary zinc and iron

The purpose of this study was to compare three measures of the availability of dietary Zn and Fe in order to test their validity. Thirty-six 5-wk-old rats were fed deionized water and wheat crispbread made from endosperm flour, whole-grain flour, or endosperm flour supplemented with Zn and Fe to the whole-grain levels ad libitum for 14 d. The retention of 65Zn and 59Fe from test meals of the same breads after 1 wk and the sum of the excretion of endogenous Zn and Fe (injected 65Zn and 59Fe) with the Zn and Fe balances, respectively, were used as independent measures of Zn and Fe absorption. Measurements of Zn absorption, Zn balance, and serum Zn concentration gave quite different results with regard to the availability of Zn in the three breads, presumably because of the homeostatic regulation of the absorption and excretion of Zn when the Zn in the diet is in excess of the body's needs. Measurements of Fe absorption, Fe balance, and Fe concentrations in liver and serum were consistent in demonstrating overloading of Fe in the group given wheat-endosperm crispbread supplemented with Zn and Fe, but there was evidence that the isotope retention method overestimated iron absorption.     

Effect of Supplemental Inorganic Zn and Mn and their Interactions on the Performance of Broiler Chicken,Mineral Bioavailability,and Immune Response

The purpose of this study was to investigate the interaction and main effects of supplemental Zn and Mn levels on growth, tissue mineral uptake, and immune response in broiler chicken. A basal diet of corn–soybean meal was supplemented with Zn at 40, 80, or 160 ppm and Mn at 60, 120, or 240 ppm in a factorial pattern to constitute nine experimental diets. Each diet was offered to nine replicates of six chicks in stainless steel battery brooders. At 35 days of age, body weight gain, feed conversion efficiency, hock joint scores, tibia weight, tibia strength, and percent ash were not influenced by Zn and Mn levels and their interactions. The concentration of Zn (207–238 ppm) and Mn (11.8–16.3 ppm) in tibia increased linearly with progressive raise of mineral inclusion in diets. Mn at 240 ppm level caused higher retention of Zn in tibia, but not vice versa. Manganese either alone or in combination with Zn (Zn160/Mn120 ppm) significantly reduced Cu retention (10.1–7.2 ppm) in tibia. Even in the hepatic tissue, Zn (93.6–98.4 ppm) and Mn (9.3–10.2 ppm) concentration increased linearly with their levels of inclusion in diets. When Zn and Mn levels were maintained at 4:3 ratio (80:60 or 160:120 ppm), the concentration of Zn (100–106 ppm) in liver was higher, while that of Mn was significantly more with low level of Zn (40 ppm) in diet. However, Mn supplementation at 120 ppm level and above significantly decreased Cu accumulation (19.5–17.1 ppm) in liver, but Mn × Zn interaction had no effect on Cu retention. The immune response measured as antibody titers to sheep RBC increased (5.9–7.9 log₂) significantly with higher Zn (80 ppm) supplementation and cell-mediated immune response to phytohemagglutinin (0.57–0.78) with Mn level at 120 ppm. In summary, Zn (40 ppm) and Mn (60 ppm) as recommended by NRC was sufficient for broiler performance and bone parameters. Mn complimented Zn retention in tibia and antagonized Cu in tibia and liver tissues. Higher levels of Zn (80 ppm) and Mn (120 ppm) than those recommended by NRC were needed for improved immune response in broilers at 35 days of age.     

Consecutive zinc balance trials in growing rats

Rats were fed a purified egg white-based diet containing 5 ppm Cu and 2, 14, or 57 ppm Zn. Zinc and copper balances were determined for eight consecutive weekly trial periods. The zinc-deficient group almost ceased to gain weight and was in slightly negative zinc balance. Groups of rats fed 14 and 57 ppm Zn gained weight at equal rates. These groups were in strongly positive zinc balance for four weeks; thereafter, they fed 57 ppm Zn retained about two times as much zinc as did the group fed the diet containing 14 ppm Zn. All groups were in null or slightly negative copper balance throughout the trial. These results suggest that zinc accumulation may be homeostatically controlled to a level in excess of that needed for maximum growth.     

Characteristics of Phytogeochemistry in Naomuhong Copper Mine Area at the Alasan of Nei Monggol

Characteristics of element contents(in ash) for 13 plant species in Naomuhong Cu mine area are disscussed. Results show that the level of element contents in sequence is: Mn>Cu> Zn > Cr > Ni>Pb>Co > Cd > Ag. Cu contents exhibit the greatest difference between species, with a 20 fold difference or more oetween maximum and minimum contents. Cu content is maximal in Potaninia mongolica, being from 209 ppm to 1543 ppm at various sites, with a mean of 735.2 ppm; whereas Cu content is minimal in Salsola passerina, being from 18 ppm to 54 ppm at various sites, with a mean of 31.01 ppm. Cu, Zn contents in skarn are more than in granite and those in limestone are mole than in sandstone. Correlation coefficients of linear regression between elements in the plants are of positive values. However, they are not significant between Cd, Ag and other eight elements, and between Cu, Cr et al. six elements are significant respectively. The correlative coefficients between elements in plants and soils are positive, Zn and Pb contents between P. mongolica and soils, and Pb content between Zygophyllum xanthoxylum and soils, and Cu content between Reaumuria soongorica and soils and significant, It is found that Cu phytogeochemical anomalies in P. mongolica and Reaumuria soongorica correlate closely with Cu ore deposit, and the anomalies were found not only in the outcropping ore, but also in the blind ore deposits.     

Forest leaf litter decomposition in the vicinity of a zinc smelter

Summary Concentrations of about 26,000 ppm Zn, 10,000 ppm Fe, 2,300 ppm Pb, 900 ppm Cd, 340 ppm Cu, and 0.40% S were measured in the O₂ litter horizon about 1 km from a zinc smelter at Palmerton, Pennsylvania. Samples taken about 6 km east of the smelter had concentrations of about 15,000 ppm Zn, 6,500 ppm Fe, 970 ppm Pb, 250 ppm Cd, 170 ppm Cu, and 0.26% S. Samples from a control area about 40 km east of the smelter had concentrations of 2,800 ppm Fe, 650 ppm Zn, 260 ppm Pb, 50 ppm Cu, 9 ppm Cd, and 0.13% S.Litter bags were used to estimate first-year weight loss in sassafras leaves and a mixture of chestnut oak/red oak leaves in the three sites. At the end of one year, average weight loss for sassafras was 39.3% in the control site, 21.8% at 6 km, and 17.5% at the 1 km site. For the chestnut oak/red oak mixture, average weight loss was 36.8% (40 km), 25.7% (6 km), and 19.1% (1 km). Numbers and diversity of soil microarthropods inhabiting the litter bags showed a corresponding decline at sites near the smelter. Concentrations of Ca, Cd, Cr, Cu, Fe, Mg, Mn, N, Na, Ni, P, Pb, S and Zn in the decomposing litter were also measured.The average amount of organic matter on the forest floor was estimated to be 3.8 kg/m² in the control site, about 3.8 kg/m² at 6 km, and about 8.1 kg/m² 1 km from the smelter. Average thickness of the litter horizons in these three sites was 6.0 cm (40 km), 7.0 cm (6 km), and 12.4 cm (1 km), suggesting a long-term depression of decomposition and mineral cycling near the smelter.     

Copper deficient rat heart can compensate for doxorubicin-induced oxidant stress

The hypothesis that copper (Cu) alters drug metabolizing enzymes and functions as an antioxidant nutrient in doxorubicin cardiotoxicity was tested. Male Sprague-Dawley rats were fed Cu adequate (⁺Cu; 5 mg Cu/kg of diet), marginally Cu deficient (MCu; 1.2 mg Cu/kg of diet), or severely Cu deficient (⁻Cu; 0.5 mg Cu/kg of diet) diets for 6 wk. Doxorubicin (1, 2, or 4 mg/kg body wt) or saline were administered intraperitoneally 1 time/wk for 4 wk. Compared to control hearts, Cu, Zn superoxide dismutase activity was decreased by 9% in MCu rats and by 21–40% in⁻Cu rats. Glutathione peroxidase activity was elevated 5–15% in⁻Cu rats. Doxorubicin administration increased heart Cu, Zn superoxide dismutase activity in⁺Cu and⁻Cu rats 18 h after the last of 4 injections, but not 18 h after 1 injection. There was no synergism between doxorubicin and Cu deficiency on lipid peroxidation, plasma creatine phosphokinase, cardiac hypertrophy, electrocardiographic abnormalities, or morphological changes. Heart glutathione S-transferase activity was decreased by Cu deficiency, and like Cu, Zn superoxide dismutase activity, returned to normal in⁻Cu rats given doxorubicin. Thus, the Cu deficient rat heart may be able to compensate for doxorubicin-induced oxidant stress by increasing the activity of Cu,Zn superoxide dismutase and glutathione S-transferase.     

Studies on the effect of divalent metal ions on exfoliative toxins from Staphylococcus hyicus: indications of ExhA and ExhB being metalloproteins

The exfoliative toxins ExhA and ExhB produced by Staphylococcus hyicus strains NCTC10350 and 1289D-88, respectively, were investigated with regard to the effect of divalent metal ions on toxin production as measured in indirect enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies. Data were obtained as endpoint titer values and used as semiquantitative measures for the amount of exfoliative toxin detected in culture supernatants. It was shown that the endpoint titers of ExhA in supernatants from cultures of strain NCTC10350 grown in the presence of 0.5 mM CaCl2, Cu(NO3)2 or ZnSO4 were higher compared to titers obtained by growth in medium supplemented with a number of other divalent metal salts. The titer of ExhB as determined in the indirect ELISA was increased by addition of 0.5 mM CoCl2, Cu(NO3)2 or CuSO4 to the growth medium. When ExhA or ExhB, prepared without addition of metal salt to the liquid growth medium, was subsequently incubated with 25 mM of Co2+, Cu2+ or Zn2+, the endpoint titers of the toxins were increased. Dialysis of ExhA and ExhB prepared with Zn2+ and Co2+, respectively, against certain metal chelators, resulted in a reduction of the titer determined in ELISA. Other metal chelators had varied effect in the detection of the toxins in ELISA. It was, however, not possible to restore the recognition of toxins by the monoclonal antibodies by incubation of EDDHA-dialyzed toxin preparations with Co2+, Cu2+ or Zn2+. The results of this study suggest that ExhA and ExhB are metalloproteins.     

10 Chlamydomonas acidophila from the berkeley pit lake – a strain adapted to an extreme environment

This research was directed to gather a better understanding about the unicellular alga Chlamydomonas acidophila, one of the 6 algal species found in the Berkeley Pit Lake. Berkeley Pit Lake is a flodded, abandoned pit mine with a pH of 2.7 and high metal concentrations. It has been found that the effective concentrations of metals that limit the growth of C. acidophila by 50% were 9.024 mg/L for Cu2+ and 75.4 mg/L for Zn 2+. We have been able to grow C. acidophila from Berkeley Pit samples at high densities in medium containing 15.36 mg/L Cu2+ and 83.65 mg/L Zn2+. Moreover, this species is able to grow in nutrified Berkeley Pit water, which contains approximately 110 mg/L Cu2+ and 323 mg/L of Zn2+. The hypothesis is that the species found in Berkeley Pit Lake represents a genetic strain adapted to high metal concentrations environments. A comparison between the American Type Culture Collection strain of C. acidophila and the strain collected from Berkeley Pit was made. Growth rate of the two strains in Bold Basil Medium, Modified Acid Medium and Berkeley Pit nutrified water were calculated and compared. Moreover, preliminary investigations of the genome of C.acidophila from the Berkeley Pit Lake were initiated.     

Cholesterol assimilation by lactic acid bacteria and bifidobacteria isolated from the human gut

The objective of this study was to evaluate the effect of human gut-derived lactic acid bacteria and bifidobacteria on cholesterol levels in vitro. Continuous cultures inoculated with fecal material from healthy human volunteers with media supplemented with cholesterol and bile acids were used to enrich for potential cholesterol assimilators among the indigenous bacterial populations. Seven potential probiotics were found: Lactobacillus fermentum strains F53 and KC5b, Bifidobacterium infantis ATCC 15697, Streptococcus bovis ATCC 43143, Enterococcus durans DSM 20633, Enterococcus gallinarum, and Enterococcus faecalis. A comparative evaluation regarding the in vitro cholesterol reduction abilities of these strains along with commercial probiotics was undertaken. The degree of acid and bile tolerance of strains was also evaluated. The human isolate L. fermentum KC5b was able to maintain viability for 2 h at pH 2 and to grow in a medium with 4,000 mg of bile acids per liter. This strain was also able to remove a maximum of 14.8 mg of cholesterol per g (dry weight) of cells from the culture medium and therefore was regarded as a candidate probiotic.