scholarly journals Fermentation tube test statistics for direct water sampling and comments on the Thomas formula

2010 ◽  
Vol 8 (3) ◽  
pp. 431-437
Author(s):  
M. Nawalany ◽  
M. Loga

This article describes a new interpretation of the Fermentation Tube Test (FTT) performed on water samples drawn from natural waters polluted by faecal bacteria. A novel general procedure to calculate the Most Probable Number of bacteria (MPN) in natural waters has been derived for the FTT for both direct and independent repetitive multiple water sampling. The generalization based on solving the newly proposed equation allows consideration of any a priori frequency distribution g(n) of bacterial concentration in analysed water as opposed to the unbounded uniform a priori distribution g(n) assumed in the standard procedures of the Standard Methods of Examining Water and Wastewater and ISO 8199:1988. Also a statistical analysis of the Thomas formula is presented. It is demonstrated that the Thomas formula is highly inaccurate. The authors propose, therefore, to remove the Thomas formula from the Standard Methods of Examining Water and Wastewater and ISO 8199:1988 altogether and replace it with a solution of the proposed generalized equation.

2017 ◽  
Vol 16 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Ray Petrisek ◽  
Jonathon Hall

Abstract This study compares the performance of a novel most probable number (MPN) method (Legiolert™/Quanti-Tray®) with Standard Methods for the Examination of Water and Wastewater 9260 J for the enumeration of Legionella pneumophila from potable and nonpotable waters. Data from the study showed that Legiolert exhibited higher sensitivity for the detection of L. pneumophila for potable water and equivalent sensitivity for nonpotable water. The Legiolert medium had a high specificity with no false positive signals reported for either water type. The new method represents a significant improvement in usability and accuracy in the enumeration of L. pneumophila.


2019 ◽  
Vol 9 (2) ◽  
pp. 112
Author(s):  
SAWIDYA FITRIYANI ◽  
I WAYAN DANA ATMAJA ◽  
NI NENGAH SONIARI

Algae Genus in Organic Rice Fields Planted with Local and Inhibrida Rice in Subak Jatiluwih, Tabanan. The abundance of microalgae in rice fields, especially microalgae from Cyanophyta division that are capable of fixing nitrogen, is very important helping maintain soil fertility. The aim of this study was to find out the genus of algae in organic rice fields of Subak Jatiluwih, Tabanan. The research was conducted from September 2018 to April 2019. Sampling was done in Subak Jatiluwih. Algae breeding were carried out at Biology and Physics Laboratory, Faculty of Agriculture, Udayana University. This research method uses descriptive quantitative. The implementation of the research included the determination of location, soil and water sampling, identification of algae, and analysis of algae genera. Enrichment algae was carried out using the MPN method, results of the analysis of algae genus were found in 37 genera from 3 divisions i.e Chlorophyta, Cyanophyta and Chrysophyta. Descriptive quantitative method Most Probable Number (MPN) calculation conclude that there are not much different from the Local and Inhibrida rice fields. The maximum population algae of local rice fields is 1.100 cell g-1 and Inhibrida rice fields is >1.100 cell g-1 of land. The minimum population is 3,6 cell g-1 of land in local rice fields, and 9,2 cell g-1 of land in Inhibrida rice fields.


2014 ◽  
Vol 4 (4) ◽  
pp. 714-719
Author(s):  
M. Mansoor Ahammed ◽  
Shilpa Dave

Water samples from four different sources of varying physico-chemical and microbial quality with their naturally occurring microorganisms were exposed to sunlight in polyethylene terephthalate bottles under similar conditions. Up to 3-log10 reduction of total coliforms (TC) was observed during a 6-h exposure period under weak/moderate radiation conditions (<600 W/m2). Complete inactivation of TC was not achieved in 6 h of exposure for waters with larger initial TC such as river water (1 × 103 most probable number [MPN]/100 mL) and treated municipal wastewater (2 × 105 MPN/100 mL) under these conditions. Heterotrophic bacteria showed lower inactivation rates than did TC. The inactivation rate for spiked Escherichia coli was faster than for naturally occurring coliforms. Further tests with compound parabolic collectors showed that complete inactivation of naturally occurring TC could be achieved within 6 h of exposure for all the natural waters tested. The results of the study thus indicate the need to use naturally occurring organisms in testing the effectiveness of solar disinfection, and the importance of source quality on the inactivation rates of microorganisms.


1991 ◽  
Vol 74 (3) ◽  
pp. 526-529 ◽  
Author(s):  
Stephen C Edberg ◽  
Martin J Allen ◽  
Darrell B Smith

Abstract The defined substrate technology (DST) method Is a reagent system designed to enumerate specific target microbes(s) from a mixture of bacteria. The system simultaneously enumerates total coliforms and Escherichia coll directly from a water sample. The reagent contains o-nitrophenyl-β-D-galactopyranoside (ONPG), which is hydrolyzed by total conforms to produce a yellow chromogen, and 4-methylumbelllferyl-β-D-glucuronide (MUG), which is hydrolyzed and fluoresces when E. coll organisms grow. Noncoliform bacteria are suppressed and cannot metabolize the indicator nutrients. Nine laboratories participated in a field evaluation of the method, which covered a wide range of surface and subsurface water sources and water-processing modalities, including the examination of natural samples. The DST system was compared to multiple-tube fermentation (MTF) (quantitative) and presence-absence (P-A) (qualitative) Standard Methods formats. Comparison of water samples from natural sources by using the most probable number (MPN) procedure showed that the DST test was equivalent to the currently used MTF test. Results from the DST and the qualitative P-A procedure showed that these tests agreed with each other in 94% of the water samples analyzed. Specificity of the DST method was established by subculturing a species consistent with a total conform or E. coll from each positive tube. Eight laboratories participated in a collaborative study of the method. Each laboratory received 3 concentrations of E. coll (organisms/100 mL): 10 (low); 60 (medium); and 120 (high). The DST test was inoculated from a split sample of each bacterial density In parallel with Standard Methods brilliant green lactose broth. Statistical analyses for repeatability and reproducibility showed the DST system to be equivalent to currently used standard methods. The DST method has been adopted official first action by AOAC for detection and enumeration of total coliforms and E. coll in water.


2009 ◽  
Vol 92 (1) ◽  
pp. 165-174 ◽  
Author(s):  
Erin S Crowley ◽  
Patrick M Bird ◽  
Marianne K Torontali ◽  
James R Agin ◽  
David G Goins ◽  
...  

Abstract The automated system for enumeration of total viable count (TVC) in foods, TEMPO® TVC, uses a dehydrated culture medium and an enumeration card containing 48 wells across 3 different dilutions for the automatic determination of the most probable number (MPN). The alternative method was compared in a multilaboratory collaborative study to AOAC Method 966.23 for determination of aerobic plate count for nondairy products and the Standard Methods for the Examination of Dairy Products (SMEDP) Standard Plate Count for dairy products. Five food types, raw ground beef, raw ground chicken, cooked whitefish fillets, bagged lettuce, and milk, were analyzed for TVC by 14 collaborating laboratories throughout the United States and Canada. Three lots of naturally contaminated food products representing a wide range of counts were tested for each of the 5 food types. The study demonstrated that the overall repeatability, reproducibility, and mean log counts of the TEMPO TVC method were statistically comparable to those of the 2 standard methods at the 5 level.


2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Wanda Aulya ◽  
Fadhliani Fadhliani ◽  
Vivi Mardina

Water is the main source for life and also the most severe substance caused by pollution. The mandatory parameters for determining microbiological quality of drinking water are total non-fecal Coliform bacteria and Coliform fecal (Escherichia coli). Coliform bacteria are a group of microorganisms commonly used as indicators, where these bacteria can be a signal to determine whether a water source has been contaminated by bacteria or not, while fecal Coliform bacteria are indicator bacteria polluting pathogenic bacteria originating from human feces and warm-blooded animals (mammals) . The water inspection method in this study uses the MPN (Most Probable Number) method which consists of 3 tests, namely, the presumption test, the affirmation test, and the reinforcement test. The results showed that of 15 drinking water samples 8 samples were tested positive for Coliform bacteria with the highest total bacterial value of sample number 1, 15 (210/100 ml), while 7 other samples were negative. From 8 positive Coliform samples only 1 sample was stated to be negative fecal Coliform bacteria and 7 other samples were positive for Coliform fecal bacteria with the highest total bacterial value of sample number 1 (210/100 ml).


2015 ◽  
Vol 1 (1) ◽  
pp. 44
Author(s):  
Rafika Sari ◽  
Pratiwi Apridamayanti

Latar Belakang: Makanan laut merupakan salah satu jenis makanan yang banyak dikonsumsi oleh masyarakat selain sebagai komoditi ekspor. Mengkonsumsi makanan laut yang telah terkontaminasi bakteri hidup atau toksin yang dihasilkannya dapat menyebabkan keracunan makanan. Tujuan penelitian ini adalah untuk mengetahui adanya kontaminasi bakteri koliform E.coli sebagai indikator pencemaran pada makanan laut dan memberikan informasi kelayakan dan keamanan konsumsi dari makanan laut di dua pasar tradisional terbesar di daerah Pontianak. Metode: Sampel yang digunakan adalah ikan, sotong dan udang. Penelitian terhadap sampel dilakukan menggunakan uji Most Probable Number (MPN) yang dilengkapi dengan uji biokimia untuk mengidentifikasi jenis bakteri pada sampel melalui penanaman bakteri pada media agar Lactose Broth (LB) dan Briliant Green Lactose Bile Broth (BGLB). Hasil: Hasil penelitian menunjukkan bakteri koliform E.coli terdeteksi pada 100% sampel dengan nilai MPN yang tidak memenuhi kriteria kelayakan konsumsi, yakni >3/g. Kesimpulan: Makanan yang ada tidak memenuhi kriteria kelayakan konsumsi.


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