Removal of pesticides in water by microbial cells adsorbed to magnetite

The removal of lindane (γ-isomer of 1,2,3,4,5,6-hexachlorocyclohexane), 2.4-D (2,4-dichlorophenoxyacetic acid) and 2,4,5-T (2,4,5-trichlorophenoxyacetic acid) from water by microbial cells immobilized on magnetite was studied. The removal of lindane by cells of a yeast, two bacteria and an alga ranged from 29 to 57%. A bacterium, Rhodopseudomonas sphaeroides had the highest sorption factor. No effect of pH in the range pH 4.0-8.0 on sorption of lindane by this bacterium was found. Sorption of lindane by R. sphaeroides reached equilibrium after 1 min. Sorption of lindane by live cells was not significantly different from sorption by heat killed cells. Four sorption stages employing fresh cells of R. sphaeroides on magnetite removed 90% of the lindane from a water sample. Magnetite alone removed 70% of the lindane in the four stage process. During a mixing period of 1 h, cells of Alcaligenes eutrophus removed 81%, 2,4-D; 21.4% lindane and 12.6% of the 2,4,5-T added to water samples. A mixture of A. eutroplus and R. sphaeroides cells immobilized on magnetite removed 76.4%, 2,4-D and 33% lindane from water samples containing the two pesticides

Removal of chlorinated hydrocarbons from water and wastewater by bacterial cells adsorbed to magnetite

The simultaneous removal of six chlorinated hydrocarbons, α- and γ-hexachlorocyclohexane (α- and γ-HCH), dieldrin, heptachlor, aldrin and p,p′-DDT from spiked samples of water and a wastewater by cells of the bacterium Rhodopseudomonas sphaeroides immobilized on magnetite was studied. In a contact time of 20 min, levels of heptachlor, aldrin and p,p′-DDT in water were reduced below the level of detection of the electron capture detector and concentrations of α-HCH, γ-HCH and dieldrin were reduced by 29.5, 32.0 and 88.9% respectively. Removal of p,p′-DDT from a spiked wastewater was complete whereas the removals of aldrin, heptachlor, dieldrin, γ-HCH and α-HCH were 92.9, 90.8, 89.9, 30.0 and 32.1% respectively. Sorption of all chlorinated hydrocarbons by the bacterial cells reached equilibrium within 20 min

Formation and degradation of soil-bound [14C] fenitrothion residues in two agricultural soils

The formation of non-extractable residues of [14C]fenitrothion and their degradation in a black earth and a red yellow podzolic soil was studied. After a 65-day incubation, non-extractable radioactivity represented 73.7 and 59.35% of the applied radioactivity in the black earth and podzolic soil respectively, while evolved 14CO2 accounted for only 9.4 and 12.7%. The effects of various amendments and treatments on the degradation of the non-extractable residues to 14CO2 was studied. All of the amendments produced a priming effect and significantly increased the formation of 14CO2 in both soils. The addition of unlabelled fenitrothion and 3-methyl-4-nitrophenol to the black earth and 3-methyl-4-nitrophenol to the podzolic soil produced the greatest increases in 14CO2 evolution. The evidence presented suggests that a part of the unextractable residue is either fenitrothion or 3-methyl-4-nitrophenol

A numerical taxonomic study of proteolytic and lipolytic psychrotrophs isolated from caprine milk

Lipolytic and proteolytic psychrotrophs were isolated from raw and pasteurized goats’milk, which had been stored at 5°C for 7d. The 241 strains isolated and 20 reference strains were examined by 149 biochemical, physiological, and morphological tests. The results yielded 195 characters suitable for taxonomic analysis. Computer‐assisted complete linkage analysis, using the Jaccard coefficient, produced 22 phenons at 75% S. The results showed that Pseudomonas fluorescens was the predominant psychrotrophic bacterium, but that Pseudomonas fragi was dominant in some milk samples. Strains of Serratia liquefaciens and Flavobacterium balustinum were also identified

Identification of psychrotrophic pseudomonads from goats' milk by computer-assisted analysis of carbon source assimilation data

The results of carbon source assimilation tests on a group of psychrotrophic pseudomonas were compared with published data for established Pseudomonas taxa, using computer-assisted numerical taxonomic analysis and a modified diagnostic computer program. Several phenons were not grouped at the biovar level by numerical taxonomic analysis. Identification of strains by the diagnostic program revealed heterogeneity among those in the unassigned phenons, and supported a continuum concept among the fluorescent pseudomonads

The effects of organo-phosphorus pesticides on the respiration of Azotobacter vinelandii

The effects often organo-phosphorus pesticides at 2 and 100 parts/106 upon O2-uptake of Azotobacter vinelandii with glucose as substrate was studied by means of polarography. When washed suspensions of the bacterium were exposed to the pesticides for 2 h before measurement of oxygen uptake. respiration rate was greatly reduced in the case of Naled, Terracur-P, Coumaphos. DDVP, Malathion. Nemacur-P, Chlorpyrifos, DOWCO 217 and DOWCO 214 at 100 parts/106 concn. At 2 parts/106, respiration was inhibited with Naled, Coumaphos, DDVP, Chlorpyrifos and to a lesser extent with DOWCO 217 and Nemacur-P. No inhibition was found with Terracur-P, or DOWCO 214 at 2 parts/106 concn. Malathion stimulated respiration at 2 parts/106 concn whereas Diazinon stimulated respiration at both concentrations. Endogenous respiration was stimulated by Naled at 2 parts/106 and by Nemacur-P and DDVP at both the concentrations. The effect on respiration was less when the bacterium was grown in the presence of 100 parts/106 DDVP or Naled, but in the case of Terracur-P there was still a marked inhibition

Incidence of Aeromonas and Listeria spp. in red meat and milk samples in Brisbane, Australia

A total of 150 samples, 50 each of beef, lamb and pork from 10 local retail stores in Brisbane metropolitan area as well as 150 raw bovine bulk milk tank samples obtained from Queensland United Foods (QUF), were examined for the presence of Aeromonas and Listeria spp. over a period of 1 year. Different sets of enrichment and plating media were used to recover the organisms with subsequent identification using conventional biochemical and serotyping techniques. A total of 509 isolates consisting of Aeromonas spp. (350) and Listeria spp. (159) were obtained from 60%, 58%, 74%, 26.6%, 34%, 40%, 30%, 2.6% of samples of beef, lamb, pork and milk respectively. Motile aeromonads (A. hydrophila, A. sobria, A. caviae) and Listeria innocua were isolated from all kinds of samples whereas L. monocytogenes was only isolated from flesh food. A. hydrophila contributed the largest percentage of the motile aeromonads (60%). The majority of L. monocytogenes cultures were serotype 4

Enterotoxigenic aeromonads on retail lamb meat and offal

Enrichment in alkaline peptone water was compared with the direct plating method for the isolation of Aeromonas spp. from lamb meat and offal samples. The enrichment method significantly increased the isolation rate of aeromonads. Motile Aeromonas species (A. hydrophila, A. sobria and A. caviae) were present in all kinds of samples investigated. Seventy-three Aeromonas strains isolated in this survey were characterized to species level and examined for their ability to produce virulence factors. Strains identified as A. sobria were the strongest producers of haemolysin and enterotoxin, whereas A. caviae strains were consistently non-haemolytic and non-enterotoxigenic. Thus it is likely that lamb meat and offal are potentially significant sources of virulent Aeromonas species and may play an important role in the aetiology of Aeromonas-associated gastro-enteritis