Taxonomic and functional analyses reveal existence of virulence and antibiotic resistance genes in beach sand bacterial populations.

Coastal sands are important natural recreational facilities that have become hotspots for tourism and economic development. However, these sands harbour diverse microbial assemblages that play a critical role in the balance between public health and ecology. In this study, targeted high-throughput sequencing analysis was used to identify sand-borne bacterial populations at four public beaches in Durban. The effect of heavy metal in shaping the distribution of bacterial metacommunities was determined using canonical correspondence analysis (CCA), while the functional gene profiles were predicted using PICRUSt2 analysis. Sequences matching those of the bacterial phylum Proteobacteria were the most abundant in all samples, followed by those of the phyla Firmicutes, Actinobacteria, Bacteroidetes, and Gemmatimonadetes. Genus-level taxonomic analysis showed the presence of 1163 bacterial genera in all samples combined. The distribution of bacterial communities was shaped by heavy metal concentrations, with the distribution of Flavobacteria, Bacteroidia, and Deltaproteobacteria influenced by Pb and Zn, while B and Cr influenced the distribution of Clostridia and Gammaproteobacteria, respectively. Identified antibiotic resistance genes included the peptidoglycan biosynthesis gene II, III, IV, and V, as well as the polymyxin resistance gene, while the virulence genes included the sitA, fimB, aerobactin synthase, and pilL gene. Our findings demonstrate that beach sand-borne bacteria are reservoirs of virulence and antibiotic resistance genes. Contamination of beach sands with heavy metals selects for both heavy metal resistance and antibiotic resistance in beach sand bacterial communities. Children and immunocompromised people engaging in recreational activities on beaches may be exposed to higher risk of infection.

Physicochemical characterization of the pelotherapeutic and balneotherapeutic clayey soils and natural spring water at Isinuka traditional healing spa in the Eastern Cape Province of South Africa.

Isinuka Springs at Port St Johns in the Eastern Cape Province of South Africa is a traditional spa sacred to the AmaMpondo tribe of the Xhosa speaking people. The bathing pond is considered to have healing powers both spiritually and therapeutically. Hundreds of people flock into the spiritual pond every weekend for both recreational and its spiritual healing power. In this study, we present the metal concentrations of the bathing pond (sediments and water samples), the hole drinking water as well as sediments from a cave situated at the bottom of the hill harbouring the bathing pond. Our results show that the geophagic clays from the cave and bathing pond has elevated concentrations of earth metals (up to 134,506 mg kg-1 for calcium), trace metals (up to 36,272 mg kg-1 for iron) and toxic metals (up to 25 mg kg-1 for lead). The levels of both essential and toxic metals in the drinking water were above the recommended daily limits except for zinc and copper. Aluminium, a metal with antibacterial activity was as high as 71,792 mg kg-1 in pond sediments. Even though the results show elevated concentrations especially for toxic metals, the study observes that the spa remains limited in potential for metal toxipathy because the frequency of contact with the pond is minimal estimated at once a week by traditional healers and once a month for locals while visitors from other parts of the province rarely come back.