Bacterial Habitats in the Antarctic Environment 539 



tion by actively metabolizing cells. Therefore it is possible that 

 algal acids may provide a nutrient source for marine bacteria as 

 well as serve as a protective mechanism against bacterial decay 

 of the metabolizing algal cell. 



A procedure similar to that used to isolate acrylic acid (21) 

 has been used to obtain the volatile fatty acid fraction from sea 

 water. Preliminary studies during winter phytoplankton blooms 

 in Narragansett Bay indicate that most of this fraction is acetic 

 acid and that values of 30 mg/liter of sea water are not uncom- 

 mon. Supplementation of artificial sea water with this level of 

 acetic acid and ammonium salts as a nitrogen source is sufficient 

 to support the growth of marine bacteria contained in natural 

 sea water inocula. Sea water media containing acetate, ammonium 

 salts and water soluble vitamins are capable of yielding counts of 

 10^ organisms/ml which equals or at low temperatures exceeds 

 the counts on ZoBell's medium (14). It is possible that further 

 studies will reveal that the apparent absence of marine bacteria in 

 the higher latitudes is due to a requirement for nutrients of algal 

 origin rather than of animal origin which support good growth in 

 tropic and sub-tropic areas (7). 



BACTERIAL CHANGES IN PENGUIN GUANO 

 UNDER NATURAL CONDITIONS 



Penguin feces which form guano deposits at rookeries ap- 

 parently undergo bacterial decomposition at ambient tempera- 

 tures ( <5 C) to yield a "humus" that supports a bryophytic 

 flora. In an attempt to characterize bacterial changes which occur 

 in penquin fecal material imder natural conditions, penguin 

 guano in various stages of decomposition as well as soil samples 

 were studied at penguin rookeries on three islands in the South 

 Shetland group. The samples were aseptically collected and im- 

 mediately brought back to the ship for pH determinations, for 

 cup antibacterial assays against Staphylococcus aureus and Sar- 

 cina Ititea, and for the enumeration of bacterial types. Tenth ml 

 aliquots of serial decimal dilutions in tryptose broth were used to 

 surface inoculate slants of heart infusion agar (Difco) (incubated 

 both aerobically and anaerobically by tlie method of Parker ( 15 ) 

 for total counts), tergitol-7 agar (for coliforms) and azide agar 



