Buried in time: culturable fungi in a deep-sea sediment core from the Chagos Trench, Indian Ocean

• Published in: Deep-sea research. Part I, Oceanographic research papers Vol. 51; no. 11; pp. 1759 - 1768
• Main Authors: Raghukumar, Chandralata, Raghukumar, Seshagiri, Sheelu, G., Gupta, S.M., Nagender Nath, B., Rao, B.R.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.11.2004; Elsevier; Pergamon Press Inc
• Subjects: Ancient fungi; Aspergillus sydowi; Bacteria; Central Indian Ocean; Chagos Trench; Earth, ocean, space; Exact sciences and technology; External geophysics; Fungi; Hydrography; Marine; Oceans; Palaeoclimate; Physics of the oceans; Sediment core; Sediments; ISW, Indian Ocean, Chagos Trench; Sediment core; Ancient fungi; Chagos Trench; Central Indian Ocean; Palaeoclimate; Total organic carbon; Indian Ocean; microorganisms; Long term
• DOI: 10.1016/j.dsr.2004.08.002
• ISSN: 0967-0637

The recovery of culturable microorganisms from ancient materials, ranging from a few thousand to several million years old, has generated interest in the long-term survival capabilities of micrororganisms. We report the occurrence of such paleobes for the first time from a deep-sea sediment core obtained from a depth of 5904m from the Chagos trench in the Indian Ocean. Culturable fungi, direct counts of bacteria, age of the sediments based on the radiolarian assemblage, total organic carbon, Eh and CaCO3 were determined in these sediments. Culturable fungi were obtained from subsections up to 370cm depth. The age of the sediments from which fungi were isolated was estimated to range from>0.18 to 0.43 million years (Ma), being the oldest recorded age for recovery of culturable fungi. Colony forming units of fungi ranged from 69 to 2493g−1 dry weight sediment with a maximum abundance recorded at 160cm depth of the core, corresponding to ∼0.18Ma. Bacterial numbers in the core showed oscillations corresponding to cycles of approximately 100ka (kilo years). The fungi comprised non-sporulating forms and a sporulating form identified to be Aspergillus sydowii. Germination of spores of A. sydowii at 100, 300 and 500bar hydrostatic pressures at 5°C confirmed its barotolerance and its nativity to deep-sea sediments. We propose that deep-sea sediments are a source of paleobes, which could be useful in studies on palaeoclimate, long-term microbial survival and biotechnology.