Nonpigmented Pseudomonas Research Articles

The Virulence of Pigmented and Non-Pigmented Pseudomonas Aeruginosa in Mice with Antibiotics Susceptibility

The Virulence of Pigmented and Non-Pigmented Pseudomonas Aeruginosa in Mice with Antibiotics Susceptibility

Types of Bacteria and Shelf-Life of Evacuated Carbon Dioxide-Injected and Ice-Packed Broilers

Broiler carcasses were packed in low-permeability film bags that were evacuated, injected with CO2, then held at 2 C. Broilers were examined microbiologically and for off-odor to determine the shelf-life and types of bacteria. Vacuum level did not significantly affect bacterial counts. Broilers stored in 65% CO2 had a 1-day longer shelf-life than those held in 20% CO2 and about a 5-day longer shelf-life than ice-packed broilers. Spoiled carcasses from either 20 or 65% CO2 packages had an acid-sour off-odor, and more than 90% of the bacteria present were Lactobacillus. Ice-packed broilers had the typical putrid off-odor at spoilage, and more than 95% of the bacteria were non-pigmented Pseudomonas.

Microbial degradation of phyllosilicates during simulated podzolization

Perfusion experiments were conducted to study mechanisms in the transformation of phyllosilicates by oxalic acid and other complexing agents synthesized by microorganisms that survived partial sterilization. Those resistant to thymol were mostly non-pigmented Pseudomonas sp. and Bacillus but included a few yeasts. The organic acids formed by the microorganisms dissolved large amounts of mineral elements from samples of granites and granitic sand. Organo-metal complexes were formed with Fe and Al. 70–100% of the dissolved Fe were in complexes stable over a wide range in pH. 10–30% of the dissolved Fe and Al were in very stable anionic complexes that were not exchangeable with strong cationic resins. The acidic compounds that were formed solubilized appreciable amounts of ferromagnesian minerals, mainly biotite, and destroyed primary chlorite and some vermiculite. Under some experimental conditions, illite-vermiculite was transformed into vermiculite and biotite into vermiculite or into a white and brittle residue of Si and Al. Because similar mineral transformations have been shown to occur during podzolization in the field, our experiments are thought to provide a satisfactory model of weathering in that soil-forming process.

Storage Stability and Bacteriological Profile of Refrigerated Ground Beef from Electrically-Stimulated Hot-Boned Carcasses

An incubation temperature of 22 C was found adequate for estimating the psychrotrophic bacterial population of ground beef from electrically-stimulated carcasses. The aerobic plate count of the product was as low as 8.0 – 9.0 × 103/g. Electrical stimulation of beef carcasses prolonged the lag phase of the psychrotrophic bacterial population by 2 days but enhanced the growth rate during the logarithmic phase of growth (12.2 and 9.9 generations formed in the electrically-stimulated and control samples respectively). The shelf life of the ground beef from electrically-stimulated carcasses was prolonged by 3 days as compared to the control (4–5 vs. 7–8 days respectively). Nonpigmented Pseudomonas predominated in the flora at spoilage of ground beef from electrically-stimulated carcasses and the control. Clostridium perfringens, Salmonella and coliform organisms were not detected, but Staphylococcus aureus was found at a level as low as 10 cells/g.

EFFECT OF GLUCOSE ON THE BACTERIAL SPOILAGE OF BEEF

ABSTRACTGround beef with less than 2% added glucose showed typical spoilage characteristics by gram‐negative psychrophiles during refrigerated storage. In samples containing 2–10% glucose, acids produced at the expense of the carbohydrate lowered the meat pH from 5.8 to 5.0–5.2. This low pH persisted in the meat until all glucose was depleted. During this period growth of the predominant nonpigmented Pseudomonas organisms was hindered, and no spoilage characteristics such as slime and off‐odors were observed. When the glucose disappeared the meat pH started to rise. Incipient spoilage (off‐odors and tackiness) became apparent when a pH value of 6.0 was exceeded. Lactobacilli counts were slightly higher in glucose‐treated meat than in the control, but no bacterial shift was observed. Instead, the added glucose caused a shift in nutrient utilization by the spoilage microflora. Normally these bacteria attack the nitrogenous compounds in meat, resulting in production of alkaline by‐products and elevated meat pH. In the presence of glucose, the same microorganisms utilized the carbohydrate preferential to other compounds in the meat. The oxidatively formed acids lowered the meat pH, affected the growth rate of the spoilage bacteria and hence retarded spoilage. The addition of 2% glucose to ground beef prolonged its average shelf life at refrigerated temperatures from 5 days to 8–10 days.

The distribution of the isocitrate lyase serine pathway amongst one-carbon utilizing organisms.

A study of several one-carbon-utilizing organisms was conducted to determine the distribution of the recently found isocitrate-lyase-positive serine pathway of C1 assimilation. The results showed that this pathway is restricted to soil-isolated, non-pigmented Pseudomonas, initially isolated in methylamine enrichments, and to certain species of Hyphomicrobium. It was not detected in any organisms possessing a pink pigment.

Spoilage Odors in Poultry Meat Produced by Pigmented and Nonpigmented Pseudomonas

Twenty isolates identified as Pseudomonas were obtained from spoiled poultry carcasses. Eleven isolates were pigmented strains (P. boreopulis, P. convexa, P. fairmontensis, P. syncyanea) and the other nine were nonpigmented (P. fragi).To determine whether there was a difference in the spoilage capabilities of pigmented and nonpigmented strains of Pseudomonas, each of the 20 organisms was inoculated into four different sterilized media: (1) blended chicken breast meat and water, (2) blended chicken skin and water, (3) chicken bouillon (commercial), and (4) nutrient broth in which poultry breast meat was substituted for beef extract. Incubation was at 20°C. for 7 days or 4°C. for 14 days. Experienced judges individually evaluated coded samples for intensity and character of odor at the end of each incubation period.Statistical analysis showed that there were no differences in mean odor scores among media, between incubation temperatures or in the opinions of judges. However, difference between pigmented and nonpigmented strains was significant (p = .001); the nonpigmented strains produced more intensive “off” odors.

Extracellular enzymic activity of poultry spoilage bacteria.

The extracellular enzymic activity has been studied of 224 strains of bacteria isolated mainly at 1° from spoiling chickens and turkeys and from poultry processing plants. The isolates comprised 44 strains of pigmented Pseudomonas, 57 strains of nonpigmented Pseudomonas, 29 strains of Ps. putrefaciens, 50 strains of oxidase positive Acinetobacter and 44 strains of oxidase negative Acinetobacter. None of the strains showed any significant activity against dextrin, starch, glycogen, inulin, dextran, xylan or pectin. Proteolytic activity was found mainly amongst 2 groups of pigmented pseudo‐monads, and Ps. putrefaciens. Nuclease activity was found particularly amongst strains of Ps. putrefaciens and the oxidase negative Acinetobacter strains isolated from spoiling poultry. Almost all of the strains showed lipolytic activity when tested with tributyrin and a proportion of strains could also attack chicken fat. This latter property was particularly evident amongst the nonpigmented Pseudomonas strains.

Microbial growth on oxalate by a route not involving glyoxylate carboligase.

1. The metabolism of oxalate by the pink-pigmented organisms, Pseudomonas AM1, Pseudomonas AM2, Protaminobacter ruber and Pseudomonas extorquens has been compared with that of the non-pigmented Pseudomonas oxalaticus. 2. During growth on oxalate, all the organisms contain oxalyl-CoA decarboxylase, formate dehydrogenase and oxalyl-CoA reductase. This is consistent with oxidation of oxalate to carbon dioxide taking place via oxalyl-CoA, formyl-CoA and formate as intermediates, and also reduction of oxalate to glyoxylate taking place via oxalyl-CoA. 3. The pink-pigmented organisms, when grown on oxalate, contain l-serine-glyoxylate aminotransferase and hydroxypyruvate reductase but do not contain glyoxylate carboligase. The converse of this obtains in oxalate-grown Ps. oxalaticus. This indicates that, in contrast with Ps. oxalaticus, synthesis of C(3) compounds from oxalate by the pink-pigmented organisms occurs by a variant of the ;serine pathway' used by Pseudomonas AM1 during growth on C(1) compounds. 4. Evidence in favour of this scheme is provided by the finding that a mutant of Pseudomonas AM1 that lacks hydroxypyruvate reductase is not able to grow on oxalate.

EFFECT OF PSYCHROTOLERANT BACTERIA ON THE AMINO ACID CONTENT OF CHICKEN SKIN

SUMMARYChanges induced by type‐cultures of Achromobacter, nonpigmented Pseudomonas, pigmented Pseudomonas and a mixture of all three types in the amino acid content of fresh chicken skin were studied during storage at PC for up to 21 days. The Achromobacter and nonpigmented Pseudomonas cultures reduced the amount of all amino acids to below detectable levels during the early log phase of growth and produced no detectable change subsequently. The pigmented Pseudomonas caused no appreciable change initially but produced a marked increase in the amount of most amino acids during the late log phase, after off‐odor had developed; an increase in free and total extractable proline and hydroxyproline indicated that collagenous proteins were attacked. The mixed inoculum gave intermediate results, producing comparatively little change in the total free amino acid content throughout the incubation period. Results indicate that the pigmented pseudomonads are the most proteolytic of the common types of psychrotolerant spoilage bacteria and that they possess collagenase.

BACTERIA‐INDUCED BIOCHEMICAL CHANGES IN CHICKEN SKIN STORED AT 5°C

SUMMARY: The effect of psychrotolerant bacteria on the water‐holding capacity as measured by the extract release volume (ERV), pH and protein degradation in chicken skin stored at 5°C was determined using strains of Achromobacter and pigmented and nonpigmented Pseudomonas. All organisms caused a rapid decrease in ERV to about 50% of the original value during the early log phase of growth before development of off‐odor. Changes in pH and content of extractable nitrogenous materials occurred during bacterial growth but were not pronounced until after the count was greater than 108 cells/g of skin and a faint off‐odor was detectable. The content of extractable materials decreased during the early log phase, corresponding to the period of rapid increase in pH; later, during the late log or stationary phases of growth, it rapidly or gradually increased, depending on the organism.

Microbial Flora of Raw and Pasteurized Egg Albumen

SummaryGram negative bacteria were the main spoilage organisms of raw albumen stored at 5, 10, 15 or 20° and were identified as strains of pigmented and nonpigmented Pseudomonas, Acinetobacter and Enterobacter liquefaciens. Only one unidentified Gram negative motile rod which failed to attack glucose was found to survive pasteurization in egg albumen (pH 9‐1) at 57.2° for 3 min. Other Gram negative bacteria isolated from one batch of stored albumen were shown to be heat sensitive, so that recontamination had probably occurred after pasteurization. Most of the organisms which survived pasteurization were found to be faecal streptococci, strains resembling Aerococcus viridans, Microbacterium lacticum and two groups (B and C) of unidentified catalase negative rods, or coccobacilli which in many respects resembled the atypical lactobacilli of Thornley & Sharpe (1959). Of these strains only the faecal streptococci and groups B and C were isolated from stored albumen. The effect of the spoilage flora on the ‘catalase’ activity of albumen before and after pasteurization has been studied in relation to the possibility of a ‘catalase’ test being used to monitor the pasteurization process.

Acute Radiation Mortality in Mice Inoculated with Pigmented or Non-Pigmented Pseudomonas

SUMMARY Different groups of lethally-irradiated and normal control mice were inoculated with a pigmented Pseudomonas (P. aeruginosa), or a non-pigmented Pseudomonas (P. stutzeri), by intraperitoneal and oral routes. Thirty-two of 50 mice receiving P. aeruginosa died within 8 days after irradiation, and 29 of the 32 showed pigmented P. aeruginosa on heart blood culture. Fewer early deaths were seen with oral administration of the organisms than with intraperitoneal administration. Two out of 50 mice given P. stutzeri died within 8 days of exposure to X-rays. Neither showed the organism on heart blood culture. No pigment reversion for cither organism was demonstrated in vivo. These results indicate that P. stutzeri is not involved in the early-death syndrome in X-irradiated mice.

Epidemic meningitis of the newborn caused by Flavobacteria. I. Epidemiology and bacteriology

Neonatal meningitis does not occur commonly and when it does, is more often than not caused by coliform organisms, rather than by nonfermenting gram-negative bacilli. It is also a fact that in many laboratories, when a blood culture or spinal fluid yields biochemically inert organisms resembling Alcaligenes or nonpigmented Pseudomonas, these cultures are unceremoniously discarded. This is especially true if the culture has come from an infant where the difficulty in obtaining these specimens increases the opportunities for contamination. In 1958 Brody et al. 1 reported 2 outbreaks of meningitis in premature nurseries caused by a nonfermenting gram-negative bacillus for which the name Flavobacterium meningosepticum was suggested by King. 2 As a result of the well-publicized nursery outbreaks of Staphylococcus aureus 3-5 our hospital has for the last 2 years cultured the nose and throat of each baby on the day of discharge and of the nursery personnel twice monthly.

Epidemic meningitis of the newborn caused by flavobacteria. I. Epidemiology and bacteriology.

Neonatal meningitis does not occur commonly and when it does, is more often than not caused by coliform organisms, rather than by nonfermenting gram-negative bacilli. It is also a fact that in many laboratories, when a blood culture or spinal fluid yields biochemically inert organisms resembling Alcaligenes or nonpigmented Pseudomonas, these cultures are unceremoniously discarded. This is especially true if the culture has come from an infant where the difficulty in obtaining these specimens increases the opportunities for contamination. In 1958 Brody et al. 1 reported 2 outbreaks of meningitis in premature nurseries caused by a nonfermenting gram-negative bacillus for which the name Flavobacterium meningosepticum was suggested by King. 2 As a result of the well-publicized nursery outbreaks of Staphylococcus aureus 3-5 our hospital has for the last 2 years cultured the nose and throat of each baby on the day of discharge and of the nursery personnel twice monthly.