No abstract

The occurrence of Arcobacter spp. was studied in seawater and plankton samples collected from the Straits of Messina, Italy, during an annual period of observation by using cultural and molecular techniques. A PCR assay with three pairs of primers targeting the 16S and 23S rRNA genes was used for detection and identification of Arcobacter butzleri, Arcobacter cryaerophilus, and Arcobacter skirrowii in cultures and environmental samples. Only one of the Arcobacter species, A. butzleri, was isolated from seawater and plankton samples. With some samples the A. butzleri PCR assay gave amplified products when cultures were negative. A. cryaerophilus and A. skirrowii were never detected by culture on selective agar plates; they were detected only by PCR performed directly with environmental samples. Collectively, our data suggest that culturable and nonculturable forms of Arcobacter are present in marine environments. The assay was useful for detecting Arcobacter spp. both as free forms and intimately associated with plankton. This is the first report showing both direct isolation of A. butzleri and the presence of nonculturable Arcobacter spp. in the coastal environment of the Mediterranean Sea.

Aims: To determine the abundance of faecal and nonfaecal bacteria related to human and animal health, as free living or associated with small (>64 lm) and large (>200 lm) plankton, samples were collected monthly from the coastal zone at Messina (Italy). Methods and Results: Different enrichment and selective cultural methods were used to determine the abundance of bacteria in sea water and plankton. The bacteria were more frequently isolated from water and large plankton than from small plankton. Vibrio and Aeromonas spp. showed different distribution patterns in water and plankton. Faecal indicators were always present in water and the large size class plankton samples. Enterococci associated with large plankton were more abundant than E. coli in the winter. Vibrio species distributions were different in water and plankton samples. Among arcobacters only A. butzleri was isolated from water and plankton samples. Campylobacter spp. was always absent in small plankton and more frequent in large plankton than in water. Conclusions: The colonization of zooplankton by potentially pathogenic bacteria is a widespread phenomenon. Significance and Impact of the Study: The presence of potentially pathogenic bacteria in sea water and associated with plankton can have ecological and epidemiological implications.

No abstract

The aim of this study was to investigate the microbial community thriving at two shallow hydrothermal vents off Panarea Island (Italy). Physico-chemical characteristics of thermal waters were examined in order to establish the effect of the vents on biodiversity of both Bacteria and Archaea. Water and adjacent sediment samples were collected at different times from two vents, characterised by different depth and temperature, and analysed to evaluate total microbial abundances, sulphur-oxidising and thermophilic aerobic bacteria. Total microbial abundances were on average of the order of 10(5) cells ml(-1), expressed as picoplanktonic size fraction. Picophytoplanktonic cells accounted for 0.77-3.83% of the total picoplanktonic cells. The contribution of bacterial and archaeal taxa to prokaryotic community diversity was investigated by PCR-DGGE fingerprinting method. The number of bands derived from bacterial DNA was highest in the DGGE profiles of water sample from the warmest and deepest site (site 2). In contrast, archaeal richness was highest in the water of the coldest and shallowest site (site 1). Sulphur-oxidising bacteria were detected by both culture-dependent and -independent methods. The primary production at the shallow hydrothermal system of Panarea is supported by a complex microbial community composed by phototrophs and chemolithotrophs.