An improved selection technique and medium for the isolation and enumeration of Azospirillum brasilense

1985 ◽  
Vol 31 (10) ◽  
pp. 947-952 ◽  
Author(s):  
Yoav Bashan ◽  
Hanna Levanony
Keyword(s):  
Azospirillum Brasilense ◽  
Sodium Deoxycholate ◽  
Selective Medium ◽  
Most Probable Number ◽  
Streptomycin Sulphate ◽  
Triphenyltetrazolium Chloride ◽  
Wheat Roots ◽  
Semisolid Medium ◽  
Probable Number ◽  
Selection Technique

An improved selection technique for isolation and enumeration of Azospirillum brasilense was developed. The technique is based on successive liquid enrichments in nitrogen-free semisolid medium supplemented with streptomycin, followed by the most probable number counting method and verification on a selective medium. The latter is based on Okon's nitrogen-free medium supplemented with cycloheximide (250 mg/L), streptomycin sulphate (200 mg/L), sodium deoxycholate (200 mg/L), 2,3,5-triphenyltetrazolium chloride (15 mg/L), and Congo red (1000 mg/L). This medium was found to be superior to other available diagnostic media. The technique was readily applied to detect and count A. brasilense Cd in inoculated wheat roots.

Application of Triphenyltetrazolium Chloride in Microbial Limit Test of Pharmaceuticals and Cosmetics

1995 ◽  
Vol 78 (6) ◽  
pp. 1525-1529 ◽  
Author(s):  
Mjtsuko Taba Ohara ◽  
Takako Saito
Keyword(s):  
Microbial Growth ◽  
Culture Medium ◽  
Inhibitory Effect ◽  
Most Probable Number ◽  
Triphenyltetrazolium Chloride ◽  
Probable Number ◽  
Alternative Method ◽  
Coefficients Of Variation ◽  
Limit Test ◽  
Microbial Contaminants

Abstract An alternative method was developed for counting viable microbial contaminants in pharmaceuticals and cosmetics with insoluble materials and low bioburden. The method uses triphenyltetrazolium chloride (TTC). The inhibitory effect of TTC on microbial growth observed by others was eliminated by adding it as an overlay, after incubation of sample in culture medium for 48 h. Six samples of pharmaceutical suspensions and 6 samples of cosmetics were evaluated by most-probable number (MPN) and pour-plate techniques with TTC in comparison with MPN with subculturing. The equivalence between MPN technique with TTC and subculturing was demonstrated for all samples and between pour-plate and subculturing for 10 samples. The differences were probably due to some error inherent to both techniques and not from application of TTC. Comparison of coefficients of variation showed that plate countings were more precise than the MPN method, as expected.

Evaluation of Most-Probable-Number–PCR Method with Internal Amplification Control for the Counting of Total and Pathogenic Vibrio parahaemolyticus in Frozen Shrimps

2012 ◽  
Vol 75 (1) ◽  
pp. 150-153 ◽  
Author(s):  
S. COPIN ◽  
A. ROBERT-PILLOT ◽  
P. MALLE ◽  
M. L. QUILICI ◽  
M. GAY
Keyword(s):  
Vibrio Parahaemolyticus ◽  
Direct Detection ◽  
Selective Medium ◽  
Internal Amplification Control ◽  
Most Probable Number ◽  
Probable Number ◽  
Pathogenic Vibrio ◽  
Biochemical Identification ◽  
Pcr Method ◽  
Frozen Shrimp

The most-probable-number (MPN) method is often time-consuming for the isolation, detection, and quantification of Vibrio parahaemolyticus from natural sources. MPN counting of V. parahaemolyticus bacteria usually involves the isolation of typical V. parahaemolyticus colonies on selective medium, with subsequent confirmation by biochemical identification. In this study, we evaluated the use of a PCR on MPN enrichment cultures (MPN-PCR) for the direct detection of total and pathogenic V. parahaemolyticus cells in frozen shrimp. This reaction targeted the R72H, tdh, and trh sequences. An internal amplification control was added to the samples before R72H amplification. There was an excellent correlation between the results of the two methods for artificially inoculated and natural shrimp samples. Of 36 natural samples, 28 tested positive for the presence of V. parahaemolyticus, with an MPN value of 2 × 10−1 to 9.2 × 101 per g. No pathogenic V. parahaemolyticus cells were detected. The test had a detection limit of one V. parahaemolyticus organism per g and was completed within two working days. These results support the use of the combination of PCR with MPN for the detection of total or potentially pathogenic V. parahaemolyticus cells in frozen shrimp.

Current Methods to Detect Stressed Staphylococci

1979 ◽  
Vol 42 (4) ◽  
pp. 362-367 ◽  
Author(s):  
RUSSELL S. FLOWERS ◽  
Z. JOHN ORDAL
Keyword(s):  
Food Processing ◽  
Normal Growth ◽  
Selective Medium ◽  
Most Probable Number ◽  
Probable Number ◽  
Direct Plating ◽  
Selective Media ◽  
Selective Agents ◽  
Increased Sensitivity ◽  
Stressed Cells

Many of the operations employed in food processing can sublethally damage staphylococci, temporarily rendering the cells incapable of growth on selective media commonly employed for their enumeration. Stressed staphylococci are, under the proper conditions, capable of recovery and subsequently normal growth, including enterotoxin production by some strains. Therefore, to ensure the safety of foods, alternative enumeration methods designed to include stressed cells should be employed. Several methods have been proposed which employ a period of preincubation in/on a non-selective medium (liquid or solid) to allow recovery before exposing the cells to selective agents. In addition, recent findings have indicated that the increased sensitivity of stressed staphylococci is at least partially due to hydrogen peroxide toxicity: based on these findings direct plating and most-probable-number techniques containing catalase to degrade peroxide have been proposed. Greatly improved enumeration of stressed cells is possible, employing these methods without the use of a preincubation period.

Development and Evaluation of a 24-Hour Method for the Detection and Quantification of Listeria monocytogenes in Meat Products

2000 ◽  
Vol 63 (3) ◽  
pp. 347-353 ◽  
Author(s):  
SHANNON A. CARROLL ◽  
LEWIS E. CARR ◽  
EDWARD T. MALLINSON ◽  
CHINTA LAMICHANNE ◽  
BRANDT E. RICE ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Meat Products ◽  
Correlation Study ◽  
Selective Medium ◽  
Most Probable Number ◽  
Probable Number ◽  
Meat Samples ◽  
Detection And Quantification

A 24-h filter monitor-based test, Listeria-SELeCT, has been developed to quantify Listeria monocytogenes organisms in meat samples with a sensitivity of ≤1.0 CFU/g. The technique comprises a filter monitor–based system and a colony lift immunoassay to identify and enumerate the target organism. Meat homogenates were centrifuged and the eluate was filtered to trap and immobilize the microorganisms on the filter. Fraser broth was then added to the filter apparatus to allow the organisms to become established overnight and to inhibit contaminants, after which the filters were transferred onto Modified Oxford medium agar, a selective medium for L. monocytogenes. After 10 to 12 h, a colony lift immunoassay was used to confirm and enumerate suspect colonies on the filter. A correlation study between the Listeria-SELeCT method and the most probable number technique showed the Listeria-SELeCT to be considerably more accurate than the most probable number for quantitatively determining the number of viable organisms in meat samples. Because of ease and speed of testing, the Listeria-SELeCT system also provided major advantages over the most probable number technology.

Analysis of Coliform and Colifecal Total Pollution Test on Various Types of Drinking Water Using the MPN (Most Probable Number) Method

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Wanda Aulya ◽  
Fadhliani Fadhliani ◽  
Vivi Mardina
Keyword(s):  
Drinking Water ◽  
Fecal Coliform ◽  
Pathogenic Bacteria ◽  
Microbiological Quality ◽  
Coliform Bacteria ◽  
Most Probable Number ◽  
Inspection Method ◽  
Sample Number ◽  
Probable Number ◽  
Fecal Coliform Bacteria

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).

Cemaran Eshericia coli dalam makanan laut yang beredar di pasar tradisional Kota Pontian

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

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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