THE SPREAD PLATE AS A METHOD FOR THE ENUMERATION OF MARINE BACTERIA1, 2

摘要: A comparison was made of agar plates spread with glass rods and poured for the enumeration bacteria in waters Fisher’s Island Sound, salinity 30&. Spread were shown to he markedly superior. Highest counts obtained by spreading, using treated Desicotc (a silicone solution) incubating at 25”C, rather than 16”C, air CO2 content increased. INTBODUCI’ION For marine waters, extensive use is plate. The possibility that some organisms indigenous less 20°C killed even short exposure 45°C might grow more promptly on surface an plate suggested a challenge pour against technique. variations conditions commonly employed also effect incubation different temperatures atmosphere increased COz. METHODS AND MATERIALS Water various tidal during summer fall 1958, from one location Latimer Reef, which about 6 miles off coast Noank, Conneticut, east East Point, Island, New York. Top samples collected sterile 500 ml wide-mouth reagent bottles. Samples iced until examination laboratory, within 2 hours. Preliminary studies Sound showed could be decimal dilutions 10-l lo-“. Dilution blanks (9 99 sea water) sterilized autoclave. Pipettes 1.1 (milk) pipettes, oven, stored cans. 1 Supported part Grand #E-706, National Institutes Health. Contribution #l Marinc Research Laboratory, University Connecticut, Connecticut. plating medium used Woods Hole Oceanographic Institute reported ZoBell (1946) had following composition: water tap Noank Marine Laboratory ( 30X0 ) ; peptone Gelysate, Baltimore Biological Laboratory), 0.1%; glucose, K2HP0.*, 0.005%; Bacto-agar Digestive Ferments Company), 1.5%; final pH 7.6. It necessary filter through cheesecloth. All “platings” duplicate. plates, melted tempered 45”C, then mixed sample or dilution. technique, 15 into prior use. Dilutions so deposition 0.1 resulted desired Using separate rod each, inoculum evenly over entire rotary twirling motion under rod. 5 mm Pyrex, formed spreading portion handle as follows: 90” bend near center 25 cm length, another made, thus producing crank parallel but opposite legs; third ‘upward” gave 8.0 length. oven-sterilized Pour incubated 16”+-1°C; lS”*l”C 25”*l”C. lower temperature chosen approximate sampled, while 25°C upper limit 1954). COZ, in78 ENUMERATION OF MARINE BACTERIA BY THE SPREAD PLATE TABLE 1. Comparison colony (X 102) 16°C 79 Air nntc saE-plc RiYs Ratios EllKl Ratio . Tide (S) (1’) S/P S air/S P air/P