Showing papers on "Bacteria published in 1975"

Microbiological basis of phosphate removal in the activated sludge process for the treatment of wastewater.

Abstract: Several strains resembling members of theAcinetobacter-Moraxella-Mima group of bacteria were isolated from activated sludge-type sewage treatment plants designed for phosphate removal. The bacteria are obligate aerobes but utilize as carbon and energy sources low-molecular intermediates generated anaerobically, particularly acetate and ethanol. These bacteria can be shown to be responsible for the phosphate luxury uptake occurring in these treatment plants. The bacteria are physiologically unusual in that they perform luxury uptake of phosphates in a complete growth medium. Phosphate release occurs on addition of a carbon source to the carbon-starved bacteria, lowering pH or both. The bacteria persist in the system by virtue of their ability to form floc.

Inhibitory Effects of Lipophilic Acids and Related Compounds on Bacteria and Mammalian Cells

Abstract: The inhibitory effect of lipophilic acids, antimicrobial food additives, and analgesics-antipyretics was examined at concentrations from 0.1 to 100 mM in bacteria ( Bacillus subtilis and Escherichia coli ) and mammalian cells (HeLa, human fibroblasts, and mouse neuroblastoma cells). Most compounds inhibit the growth of HeLa cells about as efficiently as that of B. subtilis . However, butyrate and propionate, as well as acetaminophen, antipyrene, phenacetin, and salicylamide, inhibit HeLa at millimolar concentrations whereas, at least 10 times higher concentrations are needed to inhibit B. subtilis . The concentrations needed to inhibit growth by 50% decrease with increasing octanol-water partition coefficients of the compound. Growth of E. coli is inhibited similar to that of B. subtilis by all compounds except butylbenzoate, decanoate, and linoleate which cannot penetrate the lipopolysaccharide layer. All growth inhibitors inhibit amino acid uptake into bacteria and their vesicles, and oxygen consumption in bacteria. In HeLa cells or human fibroblasts, neither amino acid uptake nor adenine 5′-triphosphate synthesis are inhibited by fatty acids at concentrations that completely inhibit growth. Short chain fatty acids (propionate, butyrate, and pentanoate) induce in HeLa the formation of cell processes. In neuroblastoma cells, grown in the presence of 10% fetal calf serum, butyrate also induces such processes which slowly continue to grow in length for at least 7 days; these processes differ in speed of formation, width, and cycloheximide susceptibility from the thin processes produced by serum deprivation alone. Images

Development of dental plaque on epoxy resin crowns in man. A light and electron microscopic study.

Abstract: A method was presented to fabricate epoxy resin crowns to be worn by human subjects requiring full crown restorations. These crowns were utilized in six young adults to study the internal structure of plaque after plaque formation periods of 1 and 3 days, 1 and 3 weeks and 2 months. This study confirmed previous findings that early plaque contains primarily coccal forms, with a shift to predominantly filamentous forms by 3 weeks. Early plaque growth seems to occur by the formation of columnar microcolonies which coalesce and grow by cell division within the colony in a direction perpendicular to the crown surface. Filamentous microorganisms appear in large numbers by 1 week. They appear to colonize the surface of the predominantly coccal plaque, eventually growing into it and replacing the coccal forms. The subgingival, mature plaque contains many motile forms including bacteria with unusual cell wall ultrastructures. Certain bacteria combine into distinctive bacterial aggregations resembling "corn cobs" and "test tube brushes," the latter occurring exclusively in subgingival plaque. Spirochetes appear to grow preferentially on the external surface of subgingival plaque in close contact to the gingival tissue of the deepened sulcus. Their high concentration in the external layer of subgingival plaque suggests that because of their strategic location they may play an important role in the etiology of periodontal disease. Studies of well preserved plaque, possibly combined with the use of serological markers, can serve a useful role in identifying certain microorganisms in dental plaque. Because of their numbers and/or location in relation to periodontal tissues, some of these bacteria may warrant further studies as potential etiologic agents of certain forms of periodontal disease.

Antibacterial Activity of the Lactoperoxidase System in Milk Against Pseudomonads and Other Gram-Negative Bacteria

Abstract: Products of thiocyanate oxidation by lactoperoxidase inhibit gram-positive bacteria that produce peroxide. We found these products to be bactericidal for such gram-negative bacteria as Pseudomonas species and Escherichia coli, provided peroxide is supplied exogenously by glucose oxidase and glucose. By the use of immobilized glucose oxidase the bactericidal agent was shown to be dialyzable, destroyed by heat and counteracted, or destroyed by reducing agents. Because the system is active against a number of gram-negative bacteria isolated from milk, it may possibly be exploited to increase the keeping quality of raw milk.

Action of Polymyxin B on Bacterial Membranes: Morphological Changes in the Cytoplasm and in the Outer Membrane of Salmonella typhimurium and Escherichia coli B

Abstract: Though the primary action of the cationic antibiotic polymyxin B is against the membrane of susceptible bacteria, severe morphological changes are detected in the cytoplasm. Using fluorescence microscopy and a mono-N-dansyl-polymyxin B derivative, we could demonstrate aggregations of the antibiotic with cellular material, possibly nucleic acids and/or ribosomes. These aggregations were only produced by minimum inhibitory or higher concentrations of the antibiotic as shown with Salmonella and Escherichia strains differing in their polymyxin susceptibility. The outer membrane of Salmonella typhimurium revealed characteristic blebs when treated with polymyxin B. This was investigated by the gentle methods of spray-freezing and freeze-etching. The obtained electron micrographs suggest that the polymyxin-induced blebs are projections of the outer monolayer of the outer membrane. A possible mechanism of penetration of polymyxin B through the cell envelope of gram-negative bacteria is presented.

Colorless sulfur bacteria and their role in sulfur cycle

Abstract: The bacteria belonging to the families of the Thiobacteriaceae, Beggiatoaceae and Achromatiaceae are commonly called the colourless sulfur bacteria. While their ability to oxidize reduced inorganic sulfur compounds has clearly been established, it is still not known whether all these organisms can derive metabolically useful energy from these oxidations. During the last decades research has mainly focussed on the genus Thiobacillus. Bacteria belonging to this genus can oxidize a variety of reduced inorganic sulfur compounds and detailed information is available on the biochemistry and physiology of these energy-yielding reactions. The thiobacilli, most of which can synthesize all cell material from CO2, possess a well-regulated metabolic machinery with high biosynthetic capacities, which is essentially similar to that of other procaryotic organisms. Although the qualitative role of colourless sulfur bacteria in the sulfur cycle is well documented, quantitative data are virtually absent. Activities of colourless sulfur bacteria in nature must be related to direct and indirect parameters, such as: the rate of oxidation of (S35) sulfur compounds, the rate of C14O2-fixation, the rate of acid production and numbers and growth rates of the bacteria. However, chemical reactions and similar activities of heterotrophic organisms mask the activities of the colourless sulfur bacteria to various extents, depending on the condition of the natural environment. This interference is minimal in regions where high temperature and/or low pH allow the development of a dominant population of colourless sulfur bacteria, such as hot acid sulfur springs, sulfide ores, sulfur deposits and some acid soils. The oxidation of inorganic sulfur compounds is carried out by a spectrum of sulfur-oxidizing organisms which includes: 1) obligately chemolithotrophic organisms 2) mixotrophs 3) chemolithotrophic heterotrophs 4) heterotrophs which do not gain energy from the oxidation of sulfur compounds but benefit in other ways from this reaction, and 5) heterotrophs which do not benefit from the oxidation of sulfur compounds. The spectrum is completed by a hypothetical group of heterotrophic organisms, which may have a symbiotic relationship with thiobacilli and related bacteria. Such heterotrophs may stimulate the growth of colourless sulfur bacteria and thereby contribute to the oxidation of sulfur compounds. Future research should focus in the first place on obtaining and studying pure cultures of many of the colourless sulfur bacteria. In the second place, studies on the physiological and ecological aspects of mixed cultures of colourless sulfur bacteria and heterotrophs may add to a better understanding of the role of the colourless sulfur bacteria in the sulfur cycle.

Enterobacterial chelators of iron: their occurrence, detection, and relation to pathogenicity

Abstract: Summary In or on agar media, low-density seedings of enterobacteria fail to grow in the presence of certain concentrations of ethylene diamine-di-orthohydroxyphenyl acetic acid (EDDA); on the other hand, high-density seedings not only grow but secrete iron chelators which release the iron bound by the EDDA in the medium and stimulate the growth of low-density seedings. Plates of media containing EDDA with low-density seedings of indicator organisms were used to survey iron-chelator production in seven enterobacterial genera, including a number of virulent smooth (S) forms from which rough (R) mutants had been obtained. An examination of over 80 strains of Aeromonas, Escherichia, Klebsiella, Proteus, Pseudomonas, Salmonella and Shigella species indicated that the iron chelators from bacteria in all these genera were functionally interchangeable. Chelator production was equally good with randomly selected avirulent and virulent strains of Klebsiella spp. and E. coli; and with the S forms and their avirulent R mutants in one pair of escherichiae, six pairs of salmonellae (4 species) and six pairs of shigellae (3 species). As determinable in vitro, the capacity to synthesise iron chelators is clearly no index of the capacity of a strain to proliferate in vivo.

Degradation of N-Nitrosamines by Intestinal Bacteria

Abstract: A major proportion of bacterial types, common in the gastrointestinal tract of many animals and man, were active in degrading diphenylnitrosamine and dimethylnitrosamine, the former being degraded more rapidly than the latter. At low nitrosamine concentrations (is less than 0.05 micronmol/ml), approximately 55% of added diphenylnitrosamine, 30% of N-nitrosopyrrolidine, and 4% of dimethylnitrosamine were degraded. The route of nitrosamine metabolism by bacteria appears to be different from that proposed for breakdown by mammalian enzyme systems in that carbon dioxide and formate were not produced. In bacteria, the nitrosamines were converted to the parent amine and nitrite ion and, in addition, certain unidentified volatile metabolites were produced from dimethylnitrosamine by bacteria. The importance of bacteria in reducing the potential hazard to man of nitrosamines is discussed.

Microbiology of Nigerian Palm Wine with Particular Reference to Bacteria

Abstract: The bacteria isolated from samples of wine produced by the fermentation of the saps of Elaeis and Raphia palms were identified as Micrococcus, Leuconostoc, Streptococcus, Lactobacillus, Acetobacter, Serratia, Aerobacter (Klebsiella), Bacillus, Zymomonas and Brevibacterium. The organisms occurring most frequently belonged to the first 5 genera. The change from c. pH 7 to c. pH 4.5 during fermentation appeared to be due to lactic acid bacteria and/or certain Gram negative bacteria, e.g. Serratia and Aerobacter (Klebsiella) spp. From about the 3rd day onwards, Acetobacter spp. were recovered.

The physiological function of nitrate reduction in Clostridium perfringens.

Abstract: SUMMARY: Fermentation-balance studies have been carried out on Clostridium perfringens grown in the presence and absence of nitrate in the medium. Nitrate is able to serve as an electron acceptor for these bacteria, permitting increased growth yields over those obtained in its absence. This increase is due to an increase in the proportion of metabolite molecules which can participate in substrate-level phosphorylation reactions when an inorganic acceptor is available. The nitrate reduction can be regarded as a primitive form of anaerobic respiration in these bacteria, since it is clearly coupled to their energy metabolism and is not assimilative in function. We believe that the existence of this kind of energy metabolism in these bacteria has significant evolutionary implications.

H2 Production by Selenomonas ruminantium in the Absence and Presence of Methanogenic Bacteria

Abstract: Selenomonas ruminantium is a nonsporeforming anaerobe that ferments carbohydrates primarily to lactate, propionate, acetate and CO2. H2 production by this species has not been previously reported. We found, however, that some strains produce trace amounts of H2 which can be detected by sensitive gas chromatographic procedures. H2 production is increased markedly, in some cases almost 100-fold, when the selenomonads are co-cultured with methane-producing bacteria. Growth of the methane-producing bacteria depends on H2 production by the selenomonads and the subsequent use of H2 for the reduction of CO2 to CH4. Although no free H2 accumulates in the mixed cultures, the amount of H2 formed by the selenomonads can be calculated from the amount of methane produced. These studies indicate that the conventional methods for measuring H2 production by pure cultures do not provide an adequate estimate of an organism's potential for forming H2 in an anaerobic ecosystem when H2 is rapidly used, e.g., for formation of CH4.

Evidence for the B12-dependent enzyme ethanolamine deaminase in Salmonella.

Abstract: THE enteric bacteria Escherichia coli and Salmonella typhimurium, like man, do not synthesise significant amounts of cobalamin (B12) compounds and thus depend on exogenous vitamin B12 for their B12-dependent enzymes1. In E. coli and S. typhimurium the only reported B12-dependent enzyme catalyses the final step in methionine biosynthesis—the methylation of homocysteine to give methionine. These bacteria do not depend on exogenous B12 for growth, however, for they have an alternative B12-independent homocysteine transmethylase (non-B12 enzyme) which can catalyse the same reaction. The non-B12 transmethylase is much less efficient than the corresponding B12-dependent enzyme: in bacteria grown in the absence of vitamin B12, the non-B12-dependent enzyme comprises 3–5 % of the total soluble protein2. If this enzyme is blocked by mutation, the mutant bacteria require either methionine itself or exogenous B12, which allows them to utilise the B12-dependent enzyme for methionine biosynthesis3. We have sought other B12-dependent enzymes in S. typhimurium and found evidence for an ethanolamine deaminase. We did not find other examples of parallel non-B12-dependent and B12-dependent enzymes in S. typhimurium. E. coli also seems to have an ethanolamine deaminase.

New Method for the Isolation and Identification of Methanogenic Bacteria

Abstract: A new technique is reported for the rapid growth and detection of methanogenic bacteria by using petri plates The method employs an anaerobic glove box containing an inner chamber with separate gas-flushing facilities The numbers of methanogenic bacteria recovered from domestic sewage sludge are comparable to those recovered by other methods The methanogenic organisms isolated from sludge include Methanosarcina, Methanospirillum, Methanobacterium strain MoH, and Methanobacterium formicicum Identification of colonies containing methanogenic bacteria is facilitated by taking advantage of the unique fluorescence properties of these organisms Colonies as small as 05 mm can be detected by exposing them to long-wave ultraviolet light

New medium for isolating iron-oxidizing and heterotrophic acidophilic bacteria from acid mine drainage.

Abstract: A new solid medium is described for growing iron and heterotrophic bacteria from acid mine drainage (AMD) Examination of AMD from five states revealed several kinds of colonies of iron-oxidizing bacteria: (i) smooth, (ii) smooth with secondary growth sectors or branching, (iii) star-shaped, (iv) radiating lobe, and (v) flat-rough All AMD samples yielded whitish colonies that could not use ferrous iron, sulfur, or hydrogen, nor could they grow on nutrient agar, brain heart infusion agar, or Trypticase soy agar Glucose and sucrose supported growth if the sugar-salts medium was at pH 30 The new iron medium has several advantages over others: (i) easy preparation, (ii) rapid growth, (iii) larger colonies, (iv) differentiation of colony morphology, and (v) detection of a new group of heterotrophic acidophilic bacteria

Mutagenicity of organophosphorus compounds in bacteria and drosophila

Abstract: 140 Organophosphorus compounds (OP's) have been tested for mutagenic activity in bacteria, principally by using two specially constructed sets of tester strains of the bacteria Salmonella typhimurium and Escherichia coli . It was found that 20% gave positive mutagenic responses and that this group of chemicals produce base substitutions rather than frame-shift mutations. In most cases the DNA repair genes exrA + and recA + were for mutagenic activity. Seven compounds were further tested in Drosophila melanogaster for the ability to induce recessive lethal mutations. In some of these cases the doses administered to the flies had to be very low due to the highly toxic nature of the compounds. To overcome this problem, the accumulation of recessive lethal mutations was measured in populations which were continually exposed to the compounds over a period of some 18 months. During this time the populations developed increased resistance to the compound and so the dose administered could gradually be increased. Six of the compounds were mutagenic. Of the compounds tested in both systems, those showing mutagenic activity in bacteria were also mutaganic in Drosophila, those mutagenic in bacteria were not mutagenic in Drosophila.

The phototrophic bacteria and their role in the sulfur cycle

Abstract: The unique characteristic of the phototrophic purple and green sulfur bacteria as well as of members of the purple nonsulfur bacteria is their ability to oxidize H2S to sulfate under anaerobic conditions in the course of their anoxigenic photosynthesis. Carbon dioxide — assimilated into cell material — is the electron acceptor of this oxidation process. Thus, a reoxidation of the H2S formed under anaerobic conditions by sulfate reducing bacteria is achieved without the consumption of molecular oxygen.

Nanaomycins, new antibiotics produced by a strain of Streptomyces. I. Taxonomy, isolation, characterization and biological properties.

Abstract: Nanomycins are new antibiotics produced by the strain OS-3966 which was designated Streptomyces rosa var. notoensis. Nanomycins A and B were isolated from the culture filtrate by extraction with organic solvent and silica gel chromatography. The physical and chemical properties suggest that nanaomycins A and B are quinone-related compounds having the molecular formulae, C16H14O6 and C16H16O7, respectively. Nanaomycins A and B inhibit mainly mycoplasmas, fungi and Gram-positive bacteria. The acute toxicities (LD50, ip) of nanaomycins A and B in mice are 28.2 and 169 mg/kg, respectively.

Fragmentation of benzylpenicillin after interaction with the exocellular DD-carboxypeptidase-transpeptidases of Streptomyces R61 and R39.

Abstract: THE killing target of penicillin in bacteria is a membrane-bound transpeptidase which catalyses peptide cross linking during wall peptidoglycan synthesis1,2. Streptomyces R61 and R39 excrete during growth DD-carboxypeptidase-transpeptidase enzymes3,4 which seem to be soluble forms of the corresponding membrane-bound transpeptidases5. The exocellular enzymes (E) convert penicillin (I) in to a chemically altered and biologically inactive compound (X)6,7. Kinetically, the simplest mechanism5 for the conversion of I into X is The first step, a rapid equilibrium process, leads to the formation of an equimolar and inactive enzyme–antibiotic complex EI. This complex isomerises into a modified complex EI* which, in turn, undergoes irreversible breakdown. If the experiment is carried out in conditions in which the enzyme is stable, the enzyme is reactivated and recovers its initial penicillin sensitivity. The breakdown of complex EI* is a slow process. At 37 °C and in 10 mM Na phosphate buffer, pH 7.0 (in which conditions the R61 enzyme is stable) the half life of the R61 enzyme–benzylpenicillin EI* complex is 80 min (ref. 7). At 37 °C and in 0.1 M Tris-HCl buffer, pH 7.7, containing 0.1 M NaCl and 0.05 M MgCl2 (in which conditions the R39 enzyme is stable), the half life of the R39 enzyme–benzylpenicillin is 4,250 min (ref. 6). As the enzyme is reactivated during the process, no enzyme is irretrievably lost on reaction with penicillin and after several cycles of inactivation and reactivation, both the enzyme and the accumulated X compound can be reisolated. This technique was applied to 14C-benzylpenicillin (benzyl labelled) and the 14C-X compound produced was isolated.

Ingestion and survival of Y. pseudotuberculosis in HeLa cells.

Abstract: HeLa cells were infected with Yersinia pseudotuberculosis for 0.5–3 h. Intracellular bacteria could then be demonstrated by three different techniques: viable count, fluorescent-antibody staining, and electron microscopy. Most of the bacteria seemed to be viable, since there was a good positive correlation (0.94) between viable and fluorescent bacteria. The bacterial uptake seemed to be mediated by a phagocytic-like procedure. The intracellular bacteria seemed to reside in vacuoles some of which increased in size as a function of time. The kinetics of infection was studied after addition of 107 or 109 bacteria per cell culture (2 × 106 cells). After a lag period of about 30 min there was a linear increase of intracellular bacteria, and this uptake proceeded for 1–2 h until most of the bacteria were ingested or an upper limit of ingested bacteria was reached. The upper limit was calculated to be a mean of 60 per infected cell in the cell culture. More than 90% of the cells could be infected and a reasonabl...

Characterization of Radiation-Resistant Vegetative Bacteria in Beef

Abstract: Ground beef contains numerous microorganisms of various types. The commonly recognized bacteria are associated with current problems of spoilage. Irradiation, however, contributes a new factor through selective destruction of the microflora. The residual microorganisms surviving a nonsterilizing dose are predominantly gram-negative coccobacilli. Various classifications have been given, e.g., Moraxella, Acinetobacter, Achromobacter, etc. For a more detailed study of these radiation-resistant bacteria occurring in ground beef, an enrichment procedure was used for isolation. By means of morphological and biochemical tests, most of the isolates were found to be Moraxella, based on current classifications. The range of growth temperatures was from 2 to 50 C. These bacteria were relatively heat sensitive, e.g., D10 of 5.4 min at 70 C or less. The radiation resistance ranged from D10 values of 273 to 2,039 krad. Thus, some were more resistant than any presently recognized spores. A reference culture of Moraxella osloensis was irradiated under conditions comparable to the enrichment procedure used with the ground beef. The only apparent changes were in morphology and penicillin sensitivity. However, after a few subcultures these bacteria reverted to the characteristics of the parent strain. Thus, it is apparent that these isolates are a part of the normal flora of ground beef and not aberrant forms arising from the irradiation procedure. The significance, if any, of these bacteria is not presently recognized.

Comparative ultrastructure of methanogenic bacteria

Abstract: Electron-microscopic studies using thin sections revealed that methane-producing bacteria were an ultrastructurally diverse group. Fine structure and morphological characteristics separated these bacteria into four discrete cell types. Methanogenic bacteria displayed a gram-positive cell wall that varied considerably among different cell types. Differences in granular inclusions, reserve materials, and intracytoplasmic membranes were observed. Unique ultrastructural features were not shared by all methanogenic species studies.

Abnormal forms of bacteria produced by antibiotics.

Abstract: Subinhibitory concentrations of antibiotics can produce in vitro aberrant forms of bacteria that are similar to those observed in specimens and cultures from patients being treated with antibacterial agents. Eight species of bacteria were grown on membranes placed on agar containing subinhibitory concentrations of nine antibiotics. The resulting organisms were examined by Gram stain and electron microscopy. Gram stains showed filamentous and granular forms of enterobacteria with bipolar staining, giant staphylococci, and rodlike pneumococci. Electron micrographs showed changes in the number and distribution of ribosomes in enterobacteria and septum abnormalities in cocci. Such abnormal forms can occasionally simulate the appearance of quite different species, and they may indicate the presence of a subinhibitory antibiotic concentration at the site of infection as a result of prior antibacterial therapy.

Studies on phagocytosis in fish. I. In vitro uptake and killing of living Staphylococcus aureus by peripheral leucocytes of carp (Cyprinus carpio).

Abstract: The clearance and uptake of Staphylococcus aureus were studied in vitro in whole blood of immunized and non-immunized carp. Bacterial numbers were determined by : (1) counting viable cells in agar plates; (2) counting radioactivity of 14C-labelled bacteria. Similar results were obtained by these two methods. Neither the bacterial growth nor the ingestion of bacteria into the cells seem to be influences by immunization. In both immunized and non-immunized groups the number of intracellular bacteria increased rapidly during the first 120 minutes, then progressed at a slow rate during the next 60 minutes, after which there was a rapid decrease in the number of bacteria only in the immune blood. It is concluded that the phagocytic cells of immune blood are more effective in activating or killing bacteria.

Competition for carbon compounds by a leaf surface bacterium and conidia of Botrytis cinerea

Abstract: There was a large initial loss of 14C from labelled Botrytis cinerea conidia immediately on suspension in water. The presence of cells of a leaf surface bacterium (Pseudomonas sp., isolate 14) did not appreciately increase the rate of loss of substrates from conidia. A proportion of the leaked 14C was taken up by bacteria causing a rapid decline in the amount of 14C in solution. Less than 2% of 14C derived from conidia could be recovered from cells of bacteria. The addition of bacteria to conidia caused a reduction in the total amount of released 14CO2. Results indicated that a substantial proportion of the 14C taken up by bacteria was released as 14CO2 and tha amount of 14CO2 from conidia was reduced in the presence of bacteria. Bacteria removed over 85% of added 14C glutamine when grown in solution whilst under similar conditions conidia removed less than 10%. Most of the glutamine had taken taken up by bacteria in the first 3 h and was accompanied by a high rate of 14CO2 evolution. The results indicate that bacteria on leaf surfaces, by utilizing nutrients derived both from conidia and from exogenous sources, would adversely affect germination of conidia.

Bacterial flora of soil after application of oily waste

Abstract: The influence of mineral oils and oily waste on the bacterial flora of soil was studied both in the field and in model experiments by plate counts followed by examination of the composition of the bacterial flora developing on the plates and by enrichment cultures followed by isolation of pure cultures. A strong increase in bacterial numbers after oil application was observed both in field and model experiments, and this increase occurred within all groups of bacteria, except spore formers and streptomycetes. The most important species of oil decomposing bacteria belonged to the genera Arthrobacter and Pseudomonas.