Isolation and partial characterization of a new moderate thermophilic Albidovulum sp. SLM16 with transaminase activity from Deception Island, Antarctica

BACKGROUND: A moderately thermophilic, slightly halophilic, aerobic, Gram-stain negative, bacterial strain, SLM16, was isolated from a mixed of seawater-sand-sediment sample collected from a coastal fumarole located in Whalers Bay, Deception Island, Antarctica. The aim was to screen for thermophilic microorganisms able to degrade primary amines and search for amine transaminase activity for potential industrial application. RESULTS: Identification and partial characterization of the microorganism SLM16 were carried out by means of morphological, physiological and biochemical tests along with molecular methods. Cells of strain SLM16 were non-motile irregular rods of 1.5-2.5 µm long and 0.3-0.45 µm wide. Growth occurred in the presence of 0.5-5.5% NaCl within temperature range of 35-55 °C and pH range of 5.5-9.5, respectively. The DNA G+C composition, estimated from ftsY gene, was 66% mol. Phylogenetic analysis using de 16S rRNA gene sequence showed that strain SLM16 belongs to the marine bacterial genus Albidovulum. CONCLUSION: Strain SLM16 is a moderate thermophilic Gram negative microorganisms which belongs to the marine bacterial genus Albidovulum and is closely related to Albidovulum inexpectatum species based on phylogenetic analysis. Additionally, amine-transaminase activity towards the arylaliphatic amine α-methylbenzylamine was detected.

Variation and Characterization of Bacterial Communities Contaminating Two Saunas Operated at 64degrees C and 76degrees C

This study was performed to analyze 6 day-term variations in bacterial communities contaminating the floor of two dry saunas that were operated at 64degrees C (low temp) and 76degrees C (high temp). Bacteria were sampled daily from the saunas for 6 days from Monday to Saturday. Genomic DNA was isolated directly from bacteria-collected cotton swabs. The diversity of the bacterial communities collected from the saunas was analyzed using thermal gradient gel electrophoresis (TGGE). The total numbers of DNA bands separated by TGGE for bacteria collected from the low temp and high temp sauna were 20 and 18, respectively, during the 6 days. Seven of 20 bacteria in the low temp sauna and eight of 18 bacteria in the high temp sauna were detected more than three times over the 6 experimental days. Twelve of the 26 bacterial genera contaminating the saunas were cross detected. Bacteria belonging to the genera Moraxella and Acinetobacter were selectively detected in the low temp sauna, whereas those belonging to Aquaspirillum, Chromobacterium, Aquabacterium, Gulbenkiania, Pelomonas, and Aquitalea were selectively detected in the high temp sauna. Three species of bacteria contaminating both the low and high temp saunas were thermophile or thermoduric. The results indicate that the sauna-contaminating bacteria may have been transferred from outside the saunas by user traffic but did not inhabit the saunas.

Evaluation of biomass production, carotenoid level and antioxidant capacity produced by Thermus filiformis using fractional factorial design

A fractional factorial design 2(5-1) was used to evaluate the effect of temperature, pH, and concentrations of yeast extract, tryptone and Nitsch's trace elements on the biomass, total carotenoids and protection against singlet oxygen by carotenoid extracts of the bacterium Thermus filiformis. In addition, the carotenoid composition was determined by high-performance liquid chromatography connected to a diode array and mass spectrometer detectors (HPLC-DAD-MS/MS). The production of biomass ranged from 0.113 to 0.658 g/L, the total carotenoid from 137.6 to 1,517.4 mg/g and the protection against singlet oxygen from 4.3 to 85.1 %. Results of the fractional factorial design showed that temperature had a negative effect on biomass production and a positive effect on carotenoid content and protection against singlet oxygen, besides, high levels of pH value, concentrations of yeast extract and tryptone had a positive effect on biomass production only at lower temperatures. The main carotenoids of T. filiformis were thermozeaxanthins. In the tested conditions, changes in the levels of the variables influenced the biomass, carotenoid production, and protection against singlet oxygen, although they did not influence the carotenoid profile. The results of this study provide a better understanding on the interactions among certain nutritional and cultivation conditions of a thermophile bacterium, Thermus filiformis, on biomass and carotenoid amounts, as well as on the antioxidant capacity.

Characterization of Bacterial Community Contaminating Floor of A Hot and Dry Sauna

The purpose of this study was to examine profile of bacteria contaminated in a dry sauna. Bacteria sampled from the floor of the dry sauna (75~80degrees C) were separated and identified by using a thermal gradient gel electrophoresis (TGGE) technique, and were cultivated using a defined medium at 50degrees C. Bacteria grown in the defined medium were identified based on 16S-rDNA sequence homology. The band number of DNA separated by TGGE was 15, indicating the species diversity of bacteria contaminating the dry sauna. Seven species of bacteria were successfully cultured on agar plate medium at 50degrees C, which represented a combination of thermophilic and thermoduric bacteria contaminating the dry sauna. The highest limit temperature for growth of the bacterial isolates was generally 50degrees C when cultivated in a defined medium, but was raised to 60degrees C when cultivated in a complex medium. Consequently, the bacteria grown at 50~60degrees C are thermoduric or thermophilic, but others may not be.

Comparative study of two purified inulinases from thermophile Thielavia Terrestris NRRL 8126 and mesophile Aspergillus Foetidus NRRL 337 grown on Cichorium Intybus l

Thirty fungal species grown on Cichorium intybus L. root extract as a sole carbon source, were screened for the production of exo-inulinase activities. The thermophile Thielavia terrestris NRRL 8126 and mesophile Aspergillus foetidus NRRL 337 gave the highest production levels of inulinases I & II at 50 and 24 ºC respectively. Yeast extract and peptone were the best nitrogen sources for highest production of inulinases I & II at five and seven days of incubation respectively. The two inulinases I & II were purified to homogeneity by gel-filtration and ion-exchange chromatography with 66.0 and 42.0 fold of purification respectively. The optimum temperatures of purified inulinases I & II were 75 and 50 ºC respectively. Inulinase I was more thermostable than the other one. The optimum pH for activity was found to be 4.5 and 5.5 for inulinases I & II respectively. A comparatively lower Michaelis-Menten constant (2.15 mg/ml) and higher maximum initial velocity (115 µmol/min/mg of protein) for inulinase I on inulin demonstrated the exoinulinase's greater affinity for inulin substrate. These findings are significant for its potential industrial application. The molecular mass of the inulinases I & II were estimated to be 72 & 78 kDa respectively by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.