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Biomedical subjects

M Alexander

Publications and source records attributed to M Alexander.

At least 289 records · Page 16Linked to original sources
PubMed1979

Phosphate and soil binding: factors limiting bacterial degradation of ionic phosphorus-containing pesticide metabolites.

Soils that had a high binding capacity for inorganic orthophosphate (Pi) had reduced capacities to bind ionic alkyl phosphorus compounds. Only ionic methylphosphonate (MPn) and ionic phenylphosphonate exhibited moderate binding. Pseudomonas testosteroni used either MPn or Pi as a sole phosphorus source and exhibited diauxic utilization of MPn and Pi. The utilization of MPn was suppressed in the presence of Pi. This suppression was abolished by a Pi-binding soil. The soil did not have a significant effect on the maximum rate of degradation of either MPn or the poorly bound ionic O-isopropyl methylphosphonate, whereas the amount of MPn (but not the amount of O-isopropyl methylphosphonate) metabolized was reduced in the presence of soil

Biodegradation, Environmental↗
PubMed1979

Utilization of chlorobenzoates by microbial populations in sewage.

Microorganisms in sewage decomposed 3.4-dichlorobenzoate and m-, p-, and o-chlorobenzoates. As the substrate disappeared, populations capable of growing on these compounds proliferated. Neither 2,4-dichlorobenzoate nor 2,3,6-trichlorobenzoate was destroyed by the sewage microflora. The addition of glucose or benzoate and m-chlorobenzoate to the sewage did not promote degradation of 2,4-di- or 2,3,6-trichlorobenzoates. The populations responsible for the biodegradation of the chlorinated compounds were initially less than 100 cells/ml. During the metabolism of m-chlorobenzoate, 5-chlorosalicylate and 4-chlorocatechol were formed.

Bacteria↗
PubMed1979

Microbial cleavage of various organophosphorus insecticides.

Bacteria able to utilize Aspon, Azodrin, Dasanit, diazinon, malathion, Orthene, parathion, Trithion, dimethoate, Dylox, methyl parathion, and Vapona as sole phosphorus sources were isolated from soil and sewage. Individual isolates used from 3 to 10 of these insecticides as sole phosphorus sources. The extent of growth of two Pseudomonas strains in media containing diazinon and malathion was in the range expected from the amount of insecticide supplied, and their proliferation resulted in disappearance of the chemical. Resting cells of the pseudomonads derived from cultures grown on diazinon or malathion but not orthophosphate caused extensive destruction of these two organophosphates in the presence or absence of chloramphenicol. Extracts of the two bacteria derived from organophosphate-grown cultures catalyzed the disappearance of Aspon, Azodrin, Dasanit, diazinon, malathion, Orthene, parathion, and Trithion but not dimethoate, Dylox, methyl parathion, and Vapona. Results from gas chromatographic analysis suggested that the extracts formed dimethyl phosphate from azodrin, dimethyl phosphorodithioate from malathion, diethyl phosphorodithioate from Trithion, and diethyl phosphorothioate from Dasanit, diazinon, and parathion. Dimethyl phosphate, dimethyl phosphorothioate , dimethyl phosphorodithioate, diethyl phosphate, and diethyl phosphorothioate were not used by the pseudomonads as sole phosphorus sources.

Biodegradation, Environmental↗
PubMed1979

Microbial metabolism of carbon monoxide in culture and in soil.

Nocardia salmonicolor readily oxidized CO to CO2. Slight activity was found among species of Actinoplanes, Agromyces, Microbispora, Mycobacterium, and other nocardias, and no oxidation was detected in the algae, fungi, and other bacteria tested. Carbon monoxide was oxidized rapidly to CO2 in the dark in two soils incubated in air or under flooded conditions, but little of the 14C from 14CO was incorporated into the organic fraction of these soils. The reaction was microbial because appreciable CO was not converted to CO2 in autoclaved or gamma-irradiated soil. Heating the soil for 25 min at 70 degrees C destroyed its CO-oxidizing activity. The incorporation of 14CO2 into the cells of microorganisms in soil and soil suspension was not enhanced by incubating the samples in the presence of CO, suggesting that CO oxidation was not the result of autotrophic metabolism. The oxidation of 17 mu 1 of CO per liter in the head space was nearly complete in 6 h in soil incubated in air or anaerobically.

Air Pollution↗
PubMed1979

Effect of concentration of organic chemicals on their biodegradation by natural microbial communities.

The effect of concentration on the biodegradation of synthetic organic chemicals by natural microbial communities was investigated by adding individual C-labeled organic compounds to stream water at various initial concentrations and measuring the formation of CO(2). The rate of degradation of p-chlorobenzoate and chloroacetate at initial concentrations of 47 pg/ml to 47 mug/ml fell markedly with lower initial concentrations, although half or more of the compound was converted to CO(2) in 8 days or less. On the other hand, little mineralization of 2,4-dichlorophenoxyacetate and 1-naphthyl-N-methylcarbamate, or the naphthol formed from the latter, occurred when these compounds were present at initial concentrations of 2 to 3 ng/ml or less, although 60% or more of the chemical initially present at higher concentrations was converted to CO(2) in 6 days. It is concluded that laboratory tests of biodegradation involving chemical concentrations greater than those in nature may not correctly assess the rate of biodegradation in natural ecosystems and that low substrate concentration may be important in limiting biodegradation in natural waters.

Journal Article↗
PubMed1979

Effect of SO2 and bisulfite on heterotrophic activity in an acid soil.

Glucose oxidation was inhibited in a forest soil (pH 4.01) previously exposed by 1.0 microliter of SO2 per liter, the extent of inhibition and the decline in pH being directly related to the length of exposure. The phase of rapid CO2 evolution in protein hydrolysate-amended soil previously treated with 5.0 microliter of SO2 per liter for 24 h or 1.0 microliter/liter for 48 h was delayed, but the degradation of the amino acid mixture then proceeded rapidly. Bacterial numbers in soil incubated for 48 h with 1.0 microliter of SO2 per liter were reduced, but the bacteria grew rapidly if glucose or an amino acid mixture was added after the exposure period. Low levels of bisulfite inhibited amino acid decomposition in soil at pH 3.89, but the effect was less pronounced in soil at pH 4.01. Comparable levels of sulfate were not toxic to carbon mineralization. Approximately 1.0 microgram of bisulfite S and about 20 microgram of sulfate S per g of soil appeared when the soil was treated with 1.0 microliter of SO2 per liter for 48 h. Bisulfite added to the soil disappeared readily. The possible ecological significance of the findings is discussed.

Air Pollutants↗
PubMed1979

Effect of interactions among algae on nitrogen fixation by blue-green algae (cyanobacteria) in flooded soils.

Nitrogen fixation (C(2)H(2) reduction) by algae in flooded soil was limited by interactions within the algal community. Nitrogen fixation by either indigenous algae or Tolypothrix tenuis was reduced severalfold by a dense suspension of the green alga Nephrocytium sp. Similarly, interactions between the nitrogen-fixing alga (cyanobacterium) Aulosira 68 and natural densities of indigenous algae limited nitrogen-fixing activity in one of two soils examined. This was demonstrated by developing a variant of Aulosira 68 that was resistant to the herbicide simetryne at concentrations that prevented development of indigenous algae. More nitrogen was fixed by the resistant variant in flooded soil containing herbicide than was fixed in herbicide-free soil by either the indigenous algae or indigenous algae plus the parent strain of Aulosira. Interference from indigenous algae may hamper the development of nitrogen-fixing algae introduced into rice fields in attempts to increase biological nitrogen fixation.

Journal Article↗
PubMed1979

Toxicity of NO(2): Effect of Nitrite on Microbial Activity in an Acid Soil.

In an acid forest soil of pH 4.0 to 4.2 amended with glucose, 1.0 mug of nitrite-N per g of soil inhibited the rate of O(2) utilization and CO(2) evolution. The inhibition was evident only for several hours after nitrite addition, and the subsequent rate of glucose mineralization was the same as in soil not receiving nitrite. The decomposition of protein hydrolysate was reduced by 10 mug of nitrite-N per g of soil but not lower concentrations, and the inhibition of this process by 20 mug of nitrite-N per g had dissipated after 24 h. Nitrite disappeared readily from this soil. More than 20 mug of bisulfite-S per g of soil was required to inhibit glucose decomposition. The data suggest that the possible antimicrobial effects of low levels of NO(2), which give rise to nitrite in soil, require further evaluation.

Journal Article↗
PubMed1979

[Clinico-pathological correlations in lupus nephritis with reference to therapeutic and prognostic aspects (author's transl)].

Since 1970 in 27 out of 46 patients with the diagnosis of systemic lupus erythematosus (SLE) a renal biopsy could be taken. The morphological outcome was followed in 14 patients with a total of 18 repeated biopsies. By light- and electron microscopy renal involvement was demonstrable in all patients. Four histologic subgroups could be differentiated: Mesangio-proliferative (MESLN, 14), focal proliferative (FLN, 6), diffus proliferative (DLN, 6), and membranous lupus nephritis (MLN, 1). Some biopsies demonstrated linear deposits with IgG/IgA-specificity. 2/27 patients only showed a clinical deteriorating course with progressive renal insufficiency despite steroid or steroid-azathioprine therapy. One patient with DLN died in terminal renal failure. The morphological follow-up showed an unfavourable course in 3/14 patients only. One MESLN demonstrated a transition to DLN, one DLN an increase of proliferative lesions and a second DLN focal and local sclerosis. In our experience renal involvement in SLE can adequately characterised and controlled by repeated be clinico-pathological correlations an aggressive therapeutic regimen is not indicated and can be avoided.

Azathioprine↗
PubMed1979

[Erythrocyte metabolism in vitamin D deficiency rickets].

In an attempt to explain the hemolysis observed in vitamin D deficiency rickets in the infant, we studied erythrocytic glycolysis, the level of ATP and some of the key enzymes of the glycolytic pathway. This study was performed in one group of vitamin D deficient infants and in one control group. The values obtained in these two groups did not differ significantly. In the absence of a defect in the glycolytic pathway, we suggest that an anomaly exists in the red cell membrane of these patients.

Adenosine Triphosphate↗
PubMed1979

[Germinal change and its significance in the hospital (author's transl)].

To receive objective informations about clinically supposed difference of bacteria spectrum in hospital infections within the last 20 years, we made statistical comparatively investigations between varying periods and in different fields. In the whole material of the Medical Department we found an increase of Proteus, Pseudomonas and Klebsiella (p = 0,01%) and an increase of Candida while Staphylococci, Streptococci, Pneumococci, Clostridium and Meningococci have clearly decreased. In the Department of Nephrology we found a significant increase of Proteus and Pseudomonas (in regard to the manifold findings also of Klebsiella) and a significant decrease of Enterococci (in regard to the manifold findings also of E. coli). In the Reanimation Department there were in opposite to a strong increase of Candida, followed by Pseudomonas, Klebsiella, Enterobacter and Pneumococci, a decrease of Staphylococcus aureus, Enterococci and Streptococci in the sputum findings. In the Urological Clinic while the period of report Pseudomonas and Enterobacter increased significantly, Staphlococcus aureus and Streptococci decreased significantly. In the Neurosurgical Clinic the part of the gramnegative germs of all germinal isolations increased from 8,3% to 51,5% at which especially E. coli, Enterobacter and Pseudomonas were more often found.

Anti-Bacterial Agents↗
PubMed1978

Bacterial and spontaneous dehalogenation of organic compounds.

Only 3 of more than 500 soil enrichments contained organisms able to use 1,9-dichlorononane as a sole carbon source. One isolate, a strain of Pseudomonas, grew on the compound and released much of the halogen as chloride. Resting cells dehalogenated 1,9-dichlorononane aerobically but not anaerobically. Pseudomonas sp. grew on and resting cells dehalogenated 1,6-dichlorohexane, 1,5-dichloroheptane, 2-bromoheptanoate, and 1-chloro-, 1-bromo-, and 1-iodoheptane, but the bacterium cometabolized but did not grow on 3-chloropropionate. p-Methylbenzyl alcohol, chloride, and p-methylbenzoate were formed when resting cells were incubated with alpha-chloro-p-xylene; the first two products were also formed in the absence of the bacteria. Similarly, o- and m-methylbenzyl alcohols were generated from the corresponding chlorinated xylenes in the presence or absence of Pseudomonas sp. The formation of m- and p-chlorobenzoic acid from m- and p-chlorobenzyl chloride proceeded only in the presence of the cells, but p-chlorobenzyl alcohol was generated from p-chlorobenzyl chloride even in the absence of the bacterium. These results are discussed in terms of possible mechanisms of dehalogenation.

Biodegradation, Environmental↗
PubMed1978

Effects of low concentrations of bisulfite-sulfite and nitrite on microorganisms.

A wide range of microorganisms was tested to determine their sensitivity to low concentrations of bisulfite-sulfite and nitrite, solubility products of SO2 and NO2, respectively. Photosynthesis by blue-green algae (cyanobacteria) was more strongly inhibited by 0.1 mM bisulfite-sulfite and 1 mM nitrite at pH 6.0 than photosynthesis by eucaryotic algae and respiration of bacteria, fungi, and protozoa. At pH 7.7, blue-green algae were still more sensitive to bisulfite-sulfite and nitrite than eucaryotic algae, but the toxicity of bisulfite-sulfite and nitrite decreased as the pH increased. Photosynthesis by Anabaena flos-aquae at pH 6.0 was inhibited 25% by a bisulfite-sulfite concentration of 10 micrometer and 15% by a nitrite concentration of 50 micrometer. Photosynthesis by the blue-green alga, Lyngbya sp., was not exceptionally sensitive to chlorate and thiosulfate. Acetylene-reducing activity of Beijerinckia indica was completely inhibited by 0.1 mM bisulfite-sulfite at pH 4.0, the suppression being decreased with increasing pH.

Animals↗
PubMed1978

Bacterial dehalogenation of halogenated alkanes and fatty acids.

Sewage samples dehalogenated 1,9-dichloronane, 1-chloroheptane, and 6-bromohexanoate, but an organism able to use 1,9-dichlorononane as the sole carbon source could not be isolated from these samples. Resting cells of Pseudomonas sp. grown on n-undecane, but not cells grown on glycerol, dehalogenated 1,9-dichlorononane in the presence of chloramphenicol. Resting cells of five other n-undecane-utilizing bacteria cleaved the halogen from dichlorononane and 6-bromohexanoate, and four dehalogenated 1-chloroheptane; however, none of these organisms used 1,9-dichlorononane for growth. By contrast, four benzoate-utilizing bacteria removed bromine from 6-bromohexanoate but had little or no activity on the chlorinated hydrocarbons. Incubation of sewage with 1,9-dichlorononane increased its subsequent capacity to dehalogenate 1,9-dichlorononane and 6-bromohexanoate but not 1-chloroheptane. A soil isolate could dehalogenate several dichloralkanes, three halogenated heptanes, and halogen-containing fatty acids. An enzyme preparation from this bacterium released chloride from 1,9-dichlorononane.

Caproates↗