title: Chemical and biochemical parameters of cultured diatoms and bacteria from the Adriatic Sea as possible biomarkers of mucilage production.
abstract: Bacteria and diatom strains from the Adriatic Sea were investigated, under standard and altered environmental conditions, for carbohydrate production and for the presence of specific biomarkers. Algae from P-depleted cultures showed an increase in extracellular carbohydrate production, a significantly lower chlorophyll a content and unchanged total lipid levels. However, the fatty acid composition of algal cultures was severely affected by low P levels, in that, total saturated and monounsaturated fatty acids increased and total polyunsaturated fatty acids decreased. Marine heterotrophic bacteria resulted enriched by 4 to 6 orders of magnitude in mucilage samples respect to surrounding seawater, unlike other groups of bacteria such as the non-halophylic heterotrophs. The major fatty acids detected in bacteria were 16:0 and 18:1n-7; the uneven fatty acids 17:0i, 17:0 and 17:1 also constituted an important component of various strains and, as a result, the total monounsaturated fraction represented the main component of total fatty acids. All the mucilage samples analysed shared the same general fatty acid composition features with a high amount of saturated components, especially 16:0; typical marine polyunsaturated fatty acids, such as 20:5n-3 and 22:6n-3, were found at very low levels. With regard to the sterol composition, the analysed algal species and bacteria showed that different compounds prevailed in the different species, and under P-deprivation sterol distribution resulted differently affected in the various algal species. In mucilage samples an overall prevalence of cholesterol was observed and, among 4alpha-methylsterols, constantly present, dinosterol prevailed in all samples. Vibrational IR spectroscopic analyses confirmed the main results obtained with the GC analysis: a higher unsaturation degree in nutrient replete diatom cultures than in P-depleted ones, a lower amount of P-containing compounds in the latter, bacterial lipid profiles with a high amount of free carboxylic acids and/or ketones and a low unsaturation degree and, finally, mucilage samples with a very low unsaturation degree. All these results allowed some speculations on the involvement of the various microbial and phytoplankton components in mucilage genesis.
authors.affiliation: Centro Interdipartimentale di Ricerca per le Scienze Ambientali (CIRSA), Università di Bologna, Via Sant'Alberto 163, 48100 Ravenna, Italy. rossella.pistocchi@unibo.it
authors.forename: R
authors.initials: R
authors.lastname: Pistocchi
authors.forename: G
authors.initials: G
authors.lastname: Trigari
authors.forename: G P
authors.initials: GP
authors.lastname: Serrazanetti
authors.forename: P
authors.initials: P
authors.lastname: Taddei
authors.forename: G
authors.initials: G
authors.lastname: Monti
authors.forename: S
authors.initials: S
authors.lastname: Palamidesi
authors.forename: F
authors.initials: F
authors.lastname: Guerrini
authors.forename: G
authors.initials: G
authors.lastname: Bottura
authors.forename: P
authors.initials: P
authors.lastname: Serratore
authors.forename: M
authors.initials: M
authors.lastname: Fabbri
authors.forename: M
authors.initials: M
authors.lastname: Pirini
authors.forename: V
authors.initials: V
authors.lastname: Ventrella
authors.forename: A
authors.initials: A
authors.lastname: Pagliarani
authors.forename: L
authors.initials: L
authors.lastname: Boni
authors.forename: A R
authors.initials: AR
authors.lastname: Borgatti
mesh_terms: D001419:Bacteria / Q000737:chemistry*; D015415:Biomarkers / Q000378:metabolism; D002241:Carbohydrates / Q000032:analysis; D002478:Cells, Cultured; D002734:Chlorophyll / Q000032:analysis; D000077194:Chlorophyll A; D002849:Chromatography, Gas; D017377:Diatoms / Q000737:chemistry*; D008055:Lipids / Q000032:analysis; D008386:Marine Biology / Q000706:statistics & numerical data*; D008522:Mediterranean Sea; D010839:Phytoplankton / Q000737:chemistry*; D012623:Seawater / Q000737:chemistry; D013045:Species Specificity; D013055:Spectrophotometry, Infrared; D013261:Sterols / Q000032:analysis
chemical_list: D015415:Biomarkers; D002241:Carbohydrates; D008055:Lipids; D013261:Sterols; D002734:Chlorophyll; D000077194:Chlorophyll A