PRELIMINARY STUDY OF GEOCHEMICAL CHARACTERISTICS OF SOILS AND THEIR BACTERIAL ISOLATES FOR ANTIBIOTIC ACTIVITY: CASE STUDY FROM ELLIS ISLAND, NEW YORK

The increasing resistance to antibiotics in human populations is alarming. Isolating organisms hardwired to make new novel antibiotics is crucial. Every 2016 incoming biology student at NJCU worked at discovering antibiotic producers from soil with Small World Initiative. We were inspired by an historic local landmark of biomedical interest and the 2012 work of Bhullar and others who discovered intense antibiotic in a cave that had been isolated for over 4 ma. Our aim was to discover antibiotic producers from the grounds of the abandoned hospital complex on Ellis Island. Ellis Island in Upper New York Bay was used as an entry point for millions of immigrants from 1892 to 1954. The island is originally a glacial deposit that was extensively expanded with fill from the excavation of the NYC subway and other sources. Nine top-soil samples from the hospital complex were analyzed for physical and chemical characteristics, including particle size distribution, pH, EC, heavy metal composition (pXRF & ICP-MS), and CNS. The samples were also analyzed for their microbial attributes, such as culturable bacterial abundance, bacterial diversity and any antibiotic production against safe relatives of the clinically relevant ESKAPE pathogens.

The samples were collected from an open-central area, a disease-ward isolation unit, the morgue and the coal depot for the hospital furnace. The pH of the soils ranged from 6.47 to 7.73, while the EC ranged from 1 to 16 µS/cm. The sand: mud (silt+clay) ratio ranged from 19: 1 to 3:1. Heavy metal content of the samples vary noticeably- i.e., Pb range from 124 to 5441 mg/kg whereas Cu and Zn range from 69 to 500 mg/kg and 117 to 593 mg/kg, respectively. Antibiotic producing organisms were isolated from each zone. The coal depot area providing the highest percentage of antibiotic producers- 42 % against Staphylococcus epidermidis Gram (+) and 25 % against Erwinia carotovora Gram (-). It also included a species whose growth on LB agar or TSA agar matured to a deep purple color. This organism may be the quorum sensing, violacein pigment producing Chromobacterium violeceum whose genome has been shown by others to contain heavy-metal-resistance proteins. The apparent correlation between geochemical signatures and bacteria sets needs to be investigated further for a predictive discovery algorithm.