M.I. Ansari, M. Harb, B. Jones, P.-Y. Hong
Scientific Reports 5, 9001, (2015)
Molecular-based approaches were used to characterize the coastal
microbiota and to elucidate the trophic state of Red Sea. Nutrient
content and enterococci numbers were monitored, and used to correlate
with the abundance of microbial markers. Microbial source tracking
revealed the presence of >1 human-associated Bacteroides spp.
at some of the near-shore sampling sites and at a heavily frequented
beach. Water samples collected from the beaches had occasional
exceedances in enterococci numbers, higher total organic carbon (TOC,
1.48–2.18 mg/L) and nitrogen (TN, 0.15–0.27 mg/L) than that detected in
the near-shore waters. Enterococci abundances obtained from
next-generation sequencing did not correlate well with the cultured
enterococci numbers. The abundance of certain genera, for example Arcobacter, Pseudomonas and unclassified Campylobacterales,
was observed to exhibit slight correlation with TOC and TN. Low
abundance of functional genes accounting for up to 41 copies/L of each Pseudomonas aeruginosa and Campylobacter coli were detected. Arcobacter butzleri
was also detected in abundance ranging from 111 to 238 copies/L.
Operational taxonomic units (OTUs) associated with cyanobacteria, Prochlorococcus, Ostreococcus spp. and Gramella
were more prevalent in waters that were likely impacted by urban
runoffs and recreational activities. These OTUs could potentially serve
as quantifiable markers indicative of the water quality.