Extraction of chlorophyll a from Tetradesmus obliquus-a method upgrade.

Nowadays, the use of algae is prevalent for both industrial and agricultural purposes. The determination of chlorophyll (Chl) content is a commonly used method for estimating the phytoplankton abundance in different water bodies or biomass density of algal cultures. The aim of the present work is to optimise the efficiency of the Chl extraction from the green alga Tetradesmus obliquus using methanol as extracting solvent. The extraction efficiency was estimated by measuring the Chl a concentration of the extracts using fluorescence spectroscopy. To increase the extraction yield, glass fibre filters with algal cells on top were treated with 10% (v/v) formalin prior to the extraction. We found that this pretreatment significantly enhanced the extraction yield of Chl without its chemical decomposition. We also found that the optimal cell concentration for Chl determination ranged from 1.44 × 104 to 3.60 × 105 cells/mL and the extraction efficiency was lower when the cell density of the culture was out of this range. These results highlight the importance of the optimization of the pigment extraction for the studied algal species.

Arundinibacter roseus gen. nov., sp. nov., a new member of the family Cytophagaceae.

Three Gram-stain-negative, aerobic, non-motile, oxidase- and catalase positive, rod-shaped, pink-coloured bacterial strains, DMA-K-7aT, DMA-K-1 and DMG-N-1, were isolated from water sampled at Lake Ferto/Neusiedler See (Hungary). Phylogenetic analysis based on the 16S rRNA gene sequences revealed that the strains form a distinct linage within the family Cytophagaceae of the phylum Bacteroidetes, and their closest relatives are Rhabdobacter roseus R49T (95.66 %) and Dyadobacter sediminis Z12T (95.38 %). The assembled genome of strain DMA-K-7aT had a total length of 5.8 Mb and a DNA G+C content of 45.7 mol%. The major isoprenoid quinone was menaquinone-7 (MK-7). The major cellular fatty acids were C16 : 1 ω7c, iso-C15 : 0, C16 : 1 ω5c, C16 : 0 and iso-C17 : 0 3-OH. The polar lipid profile contained phosphatidylethanolamine, phosphatidylserine, an unknown aminolipid, an unknown glycolipid and five unknown lipids. Flexirubin-type pigments were absent. Strain DMA-K-7aT (=DSM 106737T=NCAIM B.02641T) is proposed as the type strain of a new genus and species in the family Cytophagaceae, for which the name Arundinibacter roseus gen. nov., sp. nov. is proposed.

Presence of potential bacterial pathogens in a municipal drinking water supply system.

The quality of drinking water is a major public concern, but the detection of most potential pathogens is not always included in drinking water hygienic monitoring or is only assessed with highly biased cultivation-based methods. In this study, the occurrence of Pseudomonas aeruginosa and Legionella spp. was examined with taxon-specific PCRs in samples taken at ten points of a municipal drinking water supply system in three months. Sequence analysis confirmed the positivity of samples and revealed a diverse community of legionellae. The results showed that chlorination was an important and effective disinfection method against pathogenic bacteria in drinking water, but pathogenic bacteria could reoccur in the system farther away from the chlorination point. No strong correlation was found between the presence of the investigated potentially pathogenic bacteria and the measured abiotic and biotic parameters within the investigated range. It is hypothesized that instead of physicochemical parameters, the main factors influencing the presence of pathogens in the drinking water were rather the composition of the microbial community, the biotic interactions between individual non-pathogenic and pathogenic microorganisms (competition or promotion of growth) and the structure of biofilm grown on the inner surface of the supply system.

Detection of potentially pathogenic bacteria in the drinking water distribution system of a hospital in Hungary.

The drinking water distribution system of a hospital was investigated using standard cultivation techniques, taxon-specific PCRs targeting pathogenic bacteria, denaturing gradient gel electrophoresis, cloning and sequencing. The results obtained verify the higher sensitivity of PCR compared to cultivation for detecting Legionella and Pseudomonas aeruginosa. Moreover, several other opportunistic pathogenic bacteria, such as Escherichia albertii, Acinetobacter lwoffi and Corynebacterium tuberculostrearicum, were detected, emphasizing that drinking water systems, especially those with stagnant water sections, could be the source of nosocomial infections.