Fecal pollution source tracking and thalassogenic diseases: The temporal-spatial concordance between maximum concentrations of human mitochondrial DNA in seawater and Hepatitis A outbreaks among a coastal population

Fecal pollution source tracking (FST) studies the origin of fecal contamination and promotes action to eliminate it to improve human health and environmental sustainability. This work presents the temporal and spatial relations of human mitochondrial DNA (HmtDNA), fecal coliforms (FC) and live microbial biomass (ATP) in seawater during a hepatitis A outbreak among a human coastal population. The study area is approximately 100 km along the coastline of the Biobío Region in the southeastern Pacific (Humboldt Current System, Chile). Total data from the swash zone from summer 2015 to autumn 2016 show there were significant positive log-log correlations between FC and HmtDNA (R = 0.32) and ATP (R = 0.31). These correlations were highest during the austral spring of 2015 (R = 0.53 and 0.58 respectively), when HmtDNA also correlated significantly with ATP (R = 0.86). Maximum average values of the parameters measured in this season showed a temporal-spatial concordance with the peak in the number of hepatitis A cases among the nearby coastal population. FC correlated significantly with HmtDNA (R = 0.98) in the water column of the coastal zone close to Concepción Bay during the austral summer of 2016 and in the swash zone of the bay (R = 0.68) throughout the study period. Hepatitis A virus (HAV) has also been detected in organisms and seawater in Concepción Bay, which is consistent with the high incidence of hepatitis A among the coastal population. The concordance between human fecal pollution in the study area and a seasonal hepatitis A outbreak strongly suggests that HmtDNA and its relation with FC and ATP in the coastal zone of marine environments can be used as a proxy to evaluate the risk of outbreaks of thalassogenic diseases.

The Marine Fungi Rhodotorula sp. (Strain CNYC4007) as a Potential Feed Source for Fish Larvae Nutrition

Fish oil is used in the production of feed for cultured fish owing to its high polyunsaturated fatty acid content (PUFA). The over-exploitation of fisheries and events like “El Niño” are reducing the fish oil supply. Some marine microorganisms are considered potentially as alternative fatty acid sources. This study assesses a strain of Rhodotorula sp. (strain CNYC4007; 27% docosahexaenoic acid (DHA) of total fatty acids), as feed for fish larvae. The total length and ribonucleic acid (RNA)/deoxyribonucleic acid (DNA) ratio of Danio rerio larvae was determined at first feeding at six and 12 days old (post-yolk absorption larvae). Larvae fed with microencapsulated Rhodotorula sp. CNYC4007 had a significantly higher RNA/DNA ratio than control group (C1). At six days post-yolk absorption group, the RNA/DNA ratio of larvae fed with Rhodotorula sp. bioencapsulated in Brachionus sp. was significantly higher than control group fed with a commercial diet high in DHA (C2-DHA). Finally, at 12 days post-yolk absorption, the RNA/DNA ratio was significantly higher in larvae fed with Rhodotorula sp. CNYC4007 and C2-DHA (both bioencapsulated in Artemia sp. nauplii) than in control group (C1). These results suggest that Rhodotorula sp. CNYC4007 can be an alternative source of DHA for feeding fish at larval stage, providing a sustainable source of fatty acids.