Enrichment and key features of a robust and consistent indigenous marine-cognate microbial consortium growing on oily bilge wastewaters.

Oily bilge wastewater (OBW) is a hazardous hydrocarbon-waste generated by ships worldwide. In this research, we enriched, characterized and study the hydrocarbon biodegradation potential of a microbial consortium from the bilges of maritime ships. The consortium cZ presented a biodegradation efficiency of 66.65% for total petroleum hydrocarbons, 72.33% for aromatics and 97.76% removal of n-alkanes. This consortium showed the ability to grow in OBWs of diverse origin and concentration. A 67-fold increase in biomass was achieved using a Sequential Batch Reactor with OBW as the only carbon and energy source. The bacterial community composition of the enriched OBW bacterial consortium at the final stable stage was characterized by 16S amplicon Illumina sequencing showing that 25 out of 915 of the emerged predominant bacterial types detected summed up for 84% of total composition. Out of the 140 taxa detected, 13 alone accumulated 94.9% of the reads and were classified as Marinobacter, Alcanivorax, Parvibaculum, Flavobacteriaceae, Gammaproteobacteria PYR10d3, Novispirillum and Xanthomonadaceae among the most predominant, followed by Thalassospira, Shewanella, Rhodospirillaceae, Gammaprotobacteria, Rhodobacteriaceae and Achromobacter. The microbial community from OBW bioreactor enrichments is intrinsically diverse with clear selection of predominant types and remarkably exhibiting consistent and efficient biodegradation achieved without any nutrient or surfactant addition. Due to there is very little information available in the OBW biodegradation field, this work contributes to the body of knowledge surrounding the treatment improvement of this toxic waste and its potential application in wastewater management.

New Findings on Aromatic Compounds' Degradation and Their Metabolic Pathways, the Biosurfactant Production and Motility of the Halophilic Bacterium Halomonas sp. KHS3.

The study of the aromatic compounds' degrading ability by halophilic bacteria became an interesting research topic, because of the increasing use of halophiles in bioremediation of saline habitats and effluents. In this work, we focused on the study of aromatic compounds' degradation potential of Halomonas sp. KHS3, a moderately halophilic bacterium isolated from hydrocarbon-contaminated seawater of the Mar del Plata harbour. We demonstrated that H. sp. KHS3 is able to grow using different monoaromatic (salicylic acid, benzoic acid, 4-hydroxybenzoic acid, phthalate) and polyaromatic (naphthalene, fluorene, and phenanthrene) substrates. The ability to degrade benzoic acid and 4-hydroxybenzoic acid was analytically corroborated, and Monod kinetic parameters and yield coefficients for degradation were estimated. Strategies that may enhance substrate bioavailability such as surfactant production and chemotactic responses toward aromatic compounds were confirmed. Genomic sequence analysis of this strain allowed us to identify several genes putatively related to the metabolism of aromatic compounds, being the catechol and protocatechuate branches of ß-ketoadipate pathway completely represented. These features suggest that the broad-spectrum xenobiotic degrader H. sp. KHS3 could be employed as a useful biotechnological tool for the cleanup of aromatic compounds-polluted saline habitats or effluents.

Video processing analysis for the determination and evaluation of the chemotactic response in bacterial populations.

The aim of the present work was to design a methodology based on video processing to obtain indicators of bacterial population motility that allow the quantitative and qualitative analysis and comparison of the chemotactic phenomenon with different attractants in the agarose-in plug bridge method. Video image sequences were processed applying Shannon's entropy to the intensity time series of each pixel, which conducted to a final pseudo colored image resembling a map of the dynamic bacterial clusters. Processed images could discriminate perfectly between positive and negative attractant responses at different periods of time from the beginning of the assay. An index of spatial and temporal motility was proposed to quantify the bacterial response. With this index, this video processing method allowed obtaining quantitative information of the dynamic changes in space and time from a traditional qualitative assay. We conclude that this computational technique, applied to the traditional agarose-in plug assay, has demonstrated good sensitivity for identifying chemotactic regions with a broad range of motility.

Discrimination of motile bacteria from filamentous fungi using dynamic speckle.

We present a dynamic laser speckle method to easily discriminate filamentous fungi from motile bacteria in soft surfaces, such as agar plate. The method allows the detection and discrimination between fungi and bacteria faster than with conventional techniques. The new procedure could be straightforwardly extended to different micro-organisms, as well as applied to biological and biomedical research, infected tissues analysis, and hospital water and wastewaters studies.

Achromobacter marplatensis sp. nov., isolated from a pentachlorophenol-contaminated soil.

A polyphasic taxonomic approach was applied to the study of a Gram-negative bacterium (B2(T)) isolated from soil by selective enrichment with pentachlorophenol. 16S rRNA gene sequence analysis of strain B2(T) showed that the strain belongs to the genus Achromobacter within the Betaproteobacteria. The 16S rRNA gene sequence displayed more than 99 % similarity to the sequences of the type strains of all species of Achromobacter, with the highest sequence similarity to those of Achromobacter spanius CCM 7183(T) and A. piechaudii CCM 2986(T) (99.8 %). On the basis of phylogenetic analysis, genomic DNA-DNA relatedness and phenotypic characteristics, including chemotaxonomic (cellular fatty acid profile) analysis, a novel species is proposed, Achromobacter marplatensis sp. nov., with the type strain B2(T) ( = CCM 7608(T)  = CCUG 56371(T)  = CECT 7342(T)).

Analysis of bacterial chemotactic response using dynamic laser speckle.

Chemotaxis has a meaningful role in several fields, such as microbial physiology, medicine and biotechnology. We present a new application of dynamic laser speckle (or biospeckle) to detect different degrees of bacterial motility during chemotactic response experiments. Encouraging results showed different bacterial dynamic responses due to differences in the hardness of the support in the swarming plates. We compare this method to a conventional technique that uses white light. Both methods showed to be analogous and, in some cases, complementary. The results suggest that biospeckle processed images can be used as an alternative method to evaluate bacterial chemotactic response and can supply additional information about the bacterial motility in different areas of the swarm plate assay that might be useful for biological analysis.