Characterization of a sodium dodecyl sulphate-degrading Pseudomonas sp. strain DRY15 from Antarctic soil.

A bacterium capable of biodegrading surfactant sodium dodecyl sulphate (SDS) was isolated from Antarctic soil. The isolate was tentatively identified as Pseudomonas sp. strain DRY15 based on carbon utilization profiles using Biolog GN plates and partial 16S rDNA molecular phylogeny. Growth characteristic studies showed that the bacterium grew optimally at 10 degrees C, 7.25 pH, 1 g l(-1) SDS as a sole carbon source and 2 g l(-1) ammonium sulphate as nitrogen source. Growth was completely inhibited at 5 g l(-1) SDS. At a tolerable initial concentration of 2 g l(-1), approximately 90% of SDS was degraded after an incubation period of eight days. The best growth kinetic model to fit experimental data was the Haldane model of substrate inhibition with a correlation coefficient value of 0.97. The maximum growth rate was 0.372 hr(-1) while the saturation constant or half velocity constant (Ks) and inhibition constant (Ki), were 0.094% and 11.212 % SDS, respectively. Other detergent tested as carbon sources at 1 g l(-1) was Tergitol NP9, Tergitol 15S9, Witconol 2301 (methyl oleate), sodium dodecylbenzene sulfonate (SDBS), benzethonium chloride, and benzalkonium chloride showed Tergitol NP9, Tergitol 15S9, Witconol 2301 and the anionic SDBS supported growth with the highest growth exhibited by SDBS.

Isolation and characterization of a Pseudomonas diesel-degrading strain from Antarctica.

A diesel-degrading bacterium from Antarctica has been isolated. The isolate was tentatively identified as Pseudomonas sp. strain DRYJ3 based on partial 16S rDNA molecular phylogeny and Biolog GN microplate panels and Microlog database. Growth on diesel was supported optimally by ammonium sulphate, nitrate and nitrite. The bacterium grew optimally in between 10 and 15 degrees C, pH 7.0 and 3.5% (v/v) diesel. The biodegradation of diesel oil by the strain increased in efficiency from the second to the sixth day of incubation from 1.4 to 18.8% before levelling off on the eighth day n-alkane oxidizing and aldehyde reductase activities were detected in the crude enzyme preparation suggesting the existence of terminal n-alkane oxidizing activity in this bacterium.

Isolation and characterization of an acrylamide-degrading Antarctic bacterium.

The presence of acrylamide in the environment poses a threat due to its well known neurotoxic, carcinogenic and teratogenic properties. Human activities in various geographical areas are the main anthropogenic source of acrylamide pollution. In this work, an acrylamide-degrading bacterium was isolated from Antarctic soil. The physiological characteristics and optimum growth conditions of the acrylamide-degrading bacteria were investigated. The isolate was tentatively identified as Pseudomonas sp. strain DRYJ7 based on carbon utilization profiles using Biolog GN plates and partial 16S rDNA molecular phylogeny. The results showed that the best carbon sources for growth was glucose and sucrose with no significant difference in terms of cellular growth between the two carbon sources (p>0.05). This was followed by fructose and maltose with fructose giving significantly higher cellular growth compared to maltose (p<0.05). Lactose and citric acid did not support growth. The optimum acrylamide concentration as a nitrogen source for cellular growth was at 500 mgl(-1). At this concentration, bacterial growth showed a 2-day lag phase before degradation took place concomitant with an increase in cellular growth. The isolate exhibited optimum growth in between pH 7.5 and 8.5. The effect of incubation temperature on the growth of this isolate showed an optimum growth at 15 degrees C. The characteristics of this isolate suggest that it would be useful in the bioremediation of acrylamide.

[Bacterial flora of the digestive tract of specimens of Notothenia neglecta caught in Caleta Potter (South Shetland Archipelago, Antarctica)]. / Flora bacteriana del tracto digestivo de especímenes de Notothenia neglecta pescados en Caleta Potter (Arch. Shetland del Sur, Antártida).

A qualitative and quantitative study of the predominant heterotrophic bacterial flora in the stomach and intestine of the Antarctic fish Notothenia neglecta was carried out: 10 newly caught specimens (Potter cove, King George Island, South Shetland Islands) were analyzed. The cultures were made under aerobic and anaerobic conditions. The stomach flora showed variable results between samples which are probably related to the flora ingested with food. The gut flora was composed almost exclusively of Vibrio spp. These results are in agreement with those attributing to Vibrio the nature of indigenous flora of the intestine of marine teleosts and show that this flora had not changed, not even during the adaptation of these fish to the extreme Antarctic environmental conditions.

Flora bacteriana del tracto digestivo de especímenes de Notothenia neglecta pescados en Caleta Potter (Arch. Shetland del Sur, Antártida). / [Bacterial flora of the digestive tract of specimens of Notothenia neglecta caught in Caleta Potter (South Shetland Archipelago, Antarctica)]

A qualitative and quantitative study of the predominant heterotrophic bacterial flora in the stomach and intestine of the Antarctic fish Notothenia neglecta was carried out: 10 newly caught specimens (Potter cove, King George Island, South Shetland Islands) were analyzed. The cultures were made under aerobic and anaerobic conditions. The stomach flora showed variable results between samples which are probably related to the flora ingested with food. The gut flora was composed almost exclusively of Vibrio spp. These results are in agreement with those attributing to Vibrio the nature of indigenous flora of the intestine of marine teleosts and show that this flora had not changed, not even during the adaptation of these fish to the extreme Antarctic environmental conditions.