1、Designation:F 488 95An American National StandardStandard Test Method forOn-Site Screening of Heterotrophic Bacteria in Water1This standard is issued under the fixed designation F 488;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,t
2、he year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This screening test method covers the detection andenumeration of bacteria contained in a water sample employin
3、ga commercial device specifically designed for that purpose.This test method applies only to the enumeration of thoseviable bacteria that will grow under the test conditions speci-fied(for example,medium,temperature,time,etc.).It is notapplicable to the detection of anaerobic bacteria.1.2 No bacteri
4、al culture technique can enumerate all theviable bacteria in a sample,since bacteria occur singly,in pairs,chains,or clusters and no single set of growth conditions ormedia can satisfy the physiological requirements of all bacteriain a sample.Therefore,this test method cannot provide a totalbacteria
5、l count,but can only strive to achieve a relative countof viable aerobic and facultative anaerobic bacteria present ina sample.1.3 The test method applies to samples in which the numberof culturable bacteria per millilitre exceeds at least 10 and nomore than 160 bacteria/mL in the sample or sample d
6、ilution.1.4 This test method is intended to be used as a simplifiedfield method where bacteriological laboratory facilities are notreadily available.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this stan
7、dard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:D 1129 Terminology Relating to Water2D 1193 Specification for Reagent Water2D 3370 Practices for Sampling Water from Closed Con-
8、duits23.Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method,referto Terminology D 1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 dynamic systema system or container in which thewater contained is in motion.3.2.2 estimated bacterial countthe number of bac
9、teriapresent in a 1.0-mLsample that can be cultured into individual,countable colonies by the technique described in this testmethod.3.2.3 static systema system or container in which thewater is not in motion.Water held in a bottle or storage tank isan example of a static system.3.2.4 CFUcolony form
10、ing units.3.2.4.1 DiscussionExamples are a pump-driven watercirculating system and a flowing-water purification line.4.Summary of Test Method4.1 A commercially available water sampler device3(SPCSampler)is immersed in a water sample.A1.0-mL volume isautomatically drawn through a 0.45-um pore size ba
11、cteriaretentive membrane filter into a backing pad of absorbentmaterial.The absorbent pad,sealed to the back of the filtercontains a dehydrated nutrient medium which hydrates anddiffuses through the filter.The water sampler is then incubated,and the bacteria trapped on the filter surface grow into v
12、isiblecolonies.The colonies may be counted directly or preferablywith low-power magnification.4.2 With high bacterial count samples,a suitable dilution isprepared prior to conducting the test described in 4.1.5.Significance and Use5.1 This test method provides a means for locating thesource of bacte
13、rial contaminations in a system.5.2 This is a screening test method that should be limited touse in estimating levels of bacterial contamination in a system.This test method is intended to provide a simple field techniquetoward estimating the bacteria count in samples of water.Sincethe method employ
14、s a 1-mL sample,it is not statisticallysignificant unless the culturable bacteria are present in greaterthan 10 cfu/mL.1This test method is under the jurisdiction of ASTM Committee D-19 on Waterand is the direct responsibility of Subcommittee D19.24 on Water Microbiology.Current edition approved Apr
15、il 15,1995.Published August 1995.Originallypublished as F 488 76 T.Last previous edition F 488 79e1.2Annual Book of ASTM Standards,Vol.11.01.3A SPC Sampler,available from Millipore Corp.,Bedford,MA 01730,or itsequivalent,has been found suitable for this purpose.1Copyright ASTM International,100 Barr
16、 Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.5.3 This test method is applicable to the detection ofculturable,aerobic,and facultative anaerobic bacteria in water.6.Apparatus6.1 Expendable Apparatus:6.1.1 SPC Samplera presterilized bacteriological field-test device comprised of a 0.45-um pore size membrane filterand absorbent pad with a dehydrated nutrient medium of thetype described as follows.The filter and nutrient medium-containing pad are sealed together in a paddl
