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Biomedical subjects

G Molin

Publications and source records attributed to G Molin.

At least 73 records · Page 4Linked to original sources
PubMed1984

Effect of temperature on the microbial flora of herring fillets stored in air or carbon dioxide.

The microbial development on fillets of herring from the Baltic Sea was studied at temperatures from 0-15 C in air or 100% carbon dioxide (96-100% CO2). The shelf-life of the fillets , defined as the time for the 'total aerobic count' to reach 1 X 10(7) c.f.u./g increased with decreased temperature from 1 d at 15 degrees C to 7 d at 0 degrees C (air). The corresponding values in CO2 were 3 d and 33 d, respectively. The initial flora of the herring fillets was dominated by Alteromonas putrefaciens and Pseudomonas spp. and so was the spoilage flora after storage in air (together 62-95% of the flora: all temperatures). Alteromonas putrefaciens predominated slightly at 2 degrees C to 15 degrees C, while Pseudomonas spp. dominated at 0 degrees C. The Pseudomonas flora was mainly split between Ps. fragi , Ps. fluorescens and a heterogenous group of unidentified Pseudomonas spp. The proportions were not influenced by temperature. In 100% CO2 at the time of spoilage the flora consisted of a significant number of Lactobacillus spp. Below 4 C the domination was almost complete while at 10 degrees C and 15 degrees C. Enterobacteriaceae, Vibrionaceae and Alt. putrefaciens was also found. It was concluded that the microbiological shelf-life of herring fillets is improved by refrigeration storage in 100% CO2 but for good results the temperature should not exceed 2 degrees C.

Animals↗
PubMed1984

Growth and end-product formation in fermenter cultures of Brochothrix thermosphacta ATCC 11509T and two psychrotrophic Lactobacillus spp. in different gaseous atmospheres.

The effects of different gaseous atmospheres were determined on the maximum specific growth rate (mumax) and end-product formation by Brochothrix thermosphacta ATCC 11509T, Lactobacillus viridescens SMRICC 174 and Lactobacillus sp. SMRICC 173 (homofermentative). The highest mumax-values for Lact. viridescens (0.47/h) and Broc. thermosphacta (0.49/h) were obtained in air. Under anaerobic conditions mumax was reduced, an atmosphere containing CO2 alone giving the greatest reduction. Lactobacillus sp. 173 did not grow in air or N2. Aerobic growth was obtained by adding peroxidase while anaerobic growth occurred in the presence of 5-20% CO2. Carbon dioxide alone reduced the growth rate. All test organisms produced mainly lactic acid anaerobically. Lactobacillus viridescens also produced ethanol while Broc. thermosphacta produced small amounts of ethanol and formic acid. With O2 present, the number of end-products increased for all organisms. Lactobacillus sp. 173 produced small amounts of acetic acid and acetoin together with lactic acid. Oxygen induced acetic acid production in Lact. viridescens and Broc. thermosphacta. Aerobically, Broc. thermosphacta also produced a large amount of acetoin and smaller amounts of 2,3-butanediol, iso-valeric acid and iso-butyric acid. The production of lactic acid by Broc. thermosphacta was completely prevented under strictly aerobic conditions. All test organisms consumed O2 during aerobic growth. Hydrogen peroxide was produced by Lact. viridescens and Lactobacillus sp. 173.

Aerobiosis↗
PubMed1983

The microbial flora of smoked pork loin and frankfurter sausage stored in different gas atmospheres at 4 degrees C.

The development of the microflora of smoked pork loin and frankfurter sausage was followed during storage in vacuum, N2 and CO2 atmospheres at 4 degrees C. The total aerobic count on the smoked pork loin reached 10(7) organisms/g after 37 d in vacuum, 43 d in N2 and 49 d in CO2. The corresponding value for the sausage was 77 d in vacuum, while the growth stopped at 6 x 10(40 organisms/g after 98 d in N2, and at 4 x 10(2) organisms/g after 48 d in CO2. The predominant organisms on the fresh products were Bacillus spp., coryneform bacteria, Flavobacterium spp. and Pseudomonas spp. At the end of the storage time the microflora on both products in the three gas atmospheres, consisted mainly of Lactobacillus spp. and two large groups of organisms that could not be identified as any described genus. Some of the unidentified strains could be classified as a Lactobacillus sp. after subsequent subculturing on laboratory media. The numbers of Lactobacillus spp. at the end of storage decreased in the order, CO2 greater than N2 greater than vacuum. Lactobacillus viridescens generally constituted a substantial part of the Lactobacillus flora (5-72%). On the sausages two large uniform groups of unidentifiable homofermentative Lactobacillus spp. were also found.

Actinomycetales↗
PubMed1983

The microbial flora of herring fillets after storage in carbon dioxide, nitrogen or air at 2 degrees C.

Herring fillets from the Baltic Sea were stored in glass vessels in air, nitrogen or carbon dioxide (CO2) at 2 degrees C and the microbial development was studied. The microbiological shelf-life of the herring (the time to reach 10(7) organisms/g) was prolonged by a factor of 3.5 in CO2 as compared to air. The corresponding factor in nitrogen was 1.5. The microflora of fresh and spoiled herring was classified. The initial microflora was dominated by coryneforms, Flavobacterium spp., Moraxella-like organisms and Pseudomonas spp. The spoilage-flora in air (after 9 d) was dominated by Pseudomonas spp. and Moraxella-like organisms, and in nitrogen (14 d) Enterobacteriaceae, Vibrionaceae and Lactobacillus spp. were dominant. Homofermentative Lactobacillus spp. were the only organisms isolated from fillets stored in CO2 (28 d). It was concluded that storing fresh fish in pure CO2 at low refrigeration temperatures is a method with industrial potential. The method (1) improves the microbiological stability and (2) reduces the microbiological health hazards of the fish.

Air↗
PubMed1982

Numerical taxonomy of psychrotrophic pseudomonads.

The taxonomy of 218 psychrotrophic pseudomonad strains (200 field strains from meat and 18 type and reference strains) was numerically studied by 174 biochemical and physiological tests. All strains were Gram-negative rods, oxidative positive and motile by means of one or more polar flagella. The strains clustered into 15 groups, of which 9 were regarded as major clusters. The major clusters were designated as Pseudomonas fragi (112 strains), P. fluorescens biotype III (7 strains), P. fluorescens biotype I (16 strains). P. aureofaciens/chlororaphis (3 strains), P. fluorescens biotype II (3 strains), P. putida biotype I (4 strains), Alteromonas putrefaciens (10 strains) and Aeromonas hydrophila biotype I (5 strains). One major cluster, containing 21 strains (cluster 2), was left unassigned. The phenotypic data indicate that this cluster might represent a new species. The P. fluorescens/P. putida complex matched closely the descriptions of Stanier et al. (1966), but the two largest clusters (1 and 2) were not in agreement with any species described in the eighth edition of Bergey's Manual of Determinative Bacteriology. Cluster 1 included the type strain (ATCC 4973) of the hitherto incompletely described P. fragi. A simplified scheme for the separation between P. fragi, P. fluorescens, P. putida and cluster 2 is presented.

Food Microbiology↗
PubMed1981

The influence of temperature on the growth inhibitory effect of carbon dioxide on Pseudomonas fragi and Bacillus cereus.

The growth inhibitory effect of 50 kPa (0.5 atm) CO2 was tested for Pseudomonas fragi in the temperature range 5-35 degrees C and of 101 kPa (1 atm) CO2 on Bacillus cereus in the range 18-46 degrees C. The maximum specific growth rate (mumax) of P. fragi in air (pH 6.7) was 0.44 h-1 at 35C, 0.66 h-1 at 30 degrees C, and 0.078 h-1 at 5 degrees C. In 50 kPa of CO2 in air the relative inhibition of the growth rate was about 30% at 35 degrees C, 50% at 30 degrees C, and 90% at 5 degrees C. Thus, the inhibitory effect of CO2 successively increased with decreasing temperature, an effect which was explained by the increasing solubility of CO2 with decreasing temperature. The anaerobic growth of B. cereus (101 kPa N2) was optimal at 40 degrees C and stopped at temperatures below 18 degrees C and above 46 degrees C. The relative inhibitory effect of 101 kPa CO2 at the optimum growth temperature was about 40%; this increased to 100% near the maximum and minimum growth temperatures. The growth inhibitory effect of reduced temperature (below optimum) and CO2 and B. cereus was larger than that expected from the increased solubility of CO2 at lower temperatures.

Bacillus cereus↗
PubMed1977

Inactivation of bacillus spores in dry systems at low and high temperatures.

A plot of the thermal resistance of Bacillus subtilis var. niger spores (log D value) against temperature was linear between 37 and 190 degrees C (z = 23 degrees C), provided that the relative humidity of the spore environment was kept below a certain critical level. The corresponding plot for Bacillus stearothermophilus spores was linear in the range 150 to 180 degrees C (z = 29 degrees C) but departed from linearity at lower temperatures (decreasing z value). However, the z value of 29 degrees C was decreased to 23 degrees C if spores were dried before heat treatment. The straight line corresponding to this new z value was consistent with the inactivation rate at a lower temperature (60 degrees C). The data indicate that bacterial spores which are treated in dry heat at an environmental relative humidity near zero are inactivated mainly by a drying process. By extrapolation of the thermal resistance plot obtained under these conditions for B. subtilis var. niger spores, the D value at 0 degrees C would be about 4 years.

Bacillus subtilis↗
PubMed1976

Formation of dry-heat resistant Bacillus subtilis var. niger spores as influenced by the composition of the sporulation medium.

Bacillus subtilis var. niger spores were produced on 20 different media. The spore yield from each medium and the dry-heat resistance at 160 C of the different spore populations were determined. The yield varied with a factor of 10(6) and the variation in D 160-value was about 10-fold (less than 20 S-190 S). A "synthetic" medium producing a high yield of spores with high dry-heat resistance was formulated. The concentrations of glucose, sucrose and calcium were found to be critical.

Bacillus subtilis↗
PubMed1976

Dry-heat inactivation of Bacillus subtilis var. niger spores with special reference to spore density.

The dry-heat inactivation kinetics of Bacillus subtilis var. niger (ATCC9372) spores has been studied in the temperature range of 120-190 degrees C. The spores were applied to glass plates of a standardized area (3.24 cm2). Spore preparations of five different spore densities were used (8.3 X 10(4), 7.4 X 10(6), 6.3 X 10(7), and 6.6 X 10(8) spores per sample, respectively). The heat resistance of the spore was dependent on the number of spores per surface unit. Maximum resistance was observed when the concentration was 7.4 X 10(5) spores per sample. The D-values obtained at 160 degrees C from these samples were about twice as high as the D-values obtained from samples with a concentration of 6.3 X 10(7) or 6.6 X 10(8) spores per sample. The z-value was found to be independent of spore density. Thus, for the two concentrations 7.4 X 10(5) and 6.3 X 10(7) spores per sample, the z-value was found to be 22 degrees C and constant over the temperature range investigated.

Bacillus subtilis↗
PubMed1975

Dry-heat inactivation of Bacillus subtilis spores by means of infra-red heating.

An experumental equipment for dry-heat inactivation of bacterial spores in an open system using Infrared (IR) radiation for energy transfer was deveoped. The dry-heat-inactivation kinetics for Bacillus subtilis ATCC 6633 spores were studied in the temperature range of 120-180 C. The z value (z = 23C) was constant in the temperature range investigated. The advantages offered by using IR radiation in sterilization systems are pointed out.

Bacillus subtilis↗
PubMedDate not supplied

Oral arginine supplementation in acute liver injury.

Acute liver failure is accompanied by a high rate of bacterial and septic complications. Arginine has a potent effect on the immune system and modulates bacterial clearance in septic models. We studied the effect of oral arginine supplementation on the extent of liver injury and the associated bacterial translocation in an acute liver injury model in rats. Sprague-Dawley rats were divided into normal, liver injury, and arginine supplemented groups. In the arginine group, 2% arginine was supplemented daily through a nasogastric tube for 8 d. Acute liver injury was induced on the eighth day by intraperitoneal injection of D-galactosamine (1.1 g/kg body wt). Samples were collected 24 h after the liver injury. In the arginine-supplemented group, alkaline phosphatase, bilirubin, and aspartate aminotransferase were reduced significantly compared with the acute liver injury control group. The results of bacterial translocation in the arginine-supplemented group showed a significantly reduced number of translocated bacteria to the liver and mesenteric lymph nodes than occurred in the acute liver injury group. The histological study of the liver in arginine-supplemented group showed scattered areas of hepatocellular necrosis and inflammatory cell infiltration, and in the acute liver injury group there were more and widespread hepatocellular necrosis and inflammatory cell infiltration. Oral supplementation of arginine in an acute liver injury model improves significantly the state of the liver injury and reduces bacterial translocation to the liver and mesenteric lymph nodes.

Acute Disease↗
PubMedDate not supplied

Identification of the translocating bacteria in rats with acute liver injury and their relation to the bacterial flora of the intestinal mucosa.

The bacterial flora of the intestine and the bacteria found in liver, mesenteric lymph nodes, portal and arterial blood after D-galactosamine-induced liver injury, with and without pretreatment with Lactobacillus plantarum DSM 9843, were studied in the rat. Dominating representatives were identified to species level by 16S rDNA sequencing and typed by randomly amplified polymorphic DNA (RAPD) and by restriction endonuclease analysis (REA) for strain definition. It was proven that bacterial strains from the intestine occur at extraintestinal sites after liver injury. Lactobacillus spp. dominated the intestinal flora and were also the most frequently found genus in the liver and the mesenteric lymph nodes. Some of the blood isolates, identified as Staphylococcus aureus, Proteus vulgaris and Bacteroides merdae, were not found as a dominating part of the mucosal flora. Treatment with L. plantarum before liver injury decreased translocation and made the intestinal flora increasingly dominated by lactobacilli.

Acute Disease↗