Effect of storage temperatures on Rhizobium meliloti survival in peat- and clay-based inoculants

1993 ◽  
Vol 73 (1) ◽  
pp. 101-110 ◽  
Author(s):  
V. O. Biederbeck ◽  
H. J. Geissler
Keyword(s):  
Storage Temperature ◽  
Rhizobium Meliloti ◽  
Most Probable Number ◽  
Soil Conditions ◽  
Extension Agents ◽  
Storage Duration ◽  
Probable Number ◽  
Plant Infection ◽  
Regulatory Testing ◽  
Before And After

Legume growers and extension agents require advice on optimum conditions under which inoculants may be stored without deterioration of rhizobia or the effectiveness of the inoculant. This study was conducted to determine effects of storage duration and temperature on survival of Rhizobium meliloti in two inoculant carriers, one with a peat base and the other with a clay base. Inoculant subsamples were placed in polyethylene bags, then packaged into plastic containers and stored in wooden boxes at either −23 °C (freezer), 4 °C (refrigerator), or room temperature (21–33 °C). Before and after storage for 0.5, 3, 6, 9, 12, 15 and 20 mo, samples were analyzed for surviving rhizobia by most probable number (MPN) plant-infection technique using plastic pouches with seedlings of alfalfa (Medicago sativa L. ’Algonquin’). These counts showed no significant reduction of rhizobial viability in either inoculant at any temperature over the 20-mo study. The surprising lack of population decreases was attributed partly to the wide span between the confidence limits of MPN estimates (at P = 0.05) and partly to the effectiveness of the protective packaging in preventing any desiccation or acidification of the inoculants. Throughout the experiment pH remained unchanged at 6.8 and 8.5 and moisture content at 12.3 and 3.0% in the peat-base and clay-base inoculants, respectively. Nodule color and size indicated that symbiotic effectiveness was not affected by storage temperature. Counts, when averaged across temperatures, showed rhizobial populations remained constant around 1.3 × 109 cells g−1 peat and 1.1 × 108 cells g−1 clay. Re-testing of R. meliloti inoculants stored for up to 10 yr at 4 °C, after earlier regulatory testing, showed no significant viability reductions in any product stored < 7 yr and in some products stored for as long as 10 yr. The results indicated that rhizobial populations could be maintained at levels much above the regulatory minimum MPN (103 seed−1), which would be of critical importance when forage legumes are grown under adverse soil conditions and inoculation is required. Key words: Rhizobium meliloti, inoculant storage, temperature effects, carrier effects, MPN plant-infection technique, inoculant quality control

Microbial Hazards Associated with Bean Sprouting

1982 ◽  
Vol 65 (2) ◽  
pp. 241-248 ◽  
Author(s):  
Wallace H Andrews ◽  
Philip B Mislivec ◽  
Clyde R Wilson ◽  
Verneal R Bruce ◽  
Paul L Poelma ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Plate Count ◽  
Most Probable Number ◽  
Probable Number ◽  
Before And After ◽  
Alternaria Species ◽  
Aerobic Plate Count ◽  
Yeasts And Molds ◽  
Mold Count ◽  
Total Yeast

Abstract The behavior of microorganisms was studied in mung beans and alfalfa seeds before and after germination in modified, commercially available bean-sprouting kits. The microorganisms were enumerated by the aerobic plate count (APC) and by total yeast and mold count procedures. Salmonella species were artificially inoculated into selected samples and were enumerated by the most probable number (MPN) method. After germination of the beans or seeds into mature sprouts, significant increases were noted in APCs and in MPN values of Salmonella species. Although counts of yeasts and molds did not increase significantly after germination, these samples showed an increase in toxic Aspergillus flavus and potentially toxic Alternaria species. The presence of toxic Penicillium cyclopium molds also increased substantially in 5 samples of a single brand of mung beans. Analysis of selected sprout samples, however, showed no presence of aflatoxin.

scholarly journals A Most-Probable-Number Assay for Enumeration of Infectious Cryptosporidium parvum Oocysts

1999 ◽  
Vol 65 (9) ◽  
pp. 3936-3941 ◽  
Author(s):  
Theresa R. Slifko ◽  
Debra E. Huffman ◽  
Joan B. Rose
Keyword(s):  
Cell Culture ◽  
Most Probable Number ◽  
Recreational Waters ◽  
Probable Number ◽  
Cell Monolayers ◽  
Water Testing ◽  
Before And After ◽  
A Cell ◽  
Cryptosporidium Parvum Oocysts ◽  
Focus Detection

ABSTRACT Cryptosporidium is globally established as a contaminant of drinking and recreational waters. A previously described cell culture infectivity assay capable of detecting infectious oocysts was adapted to quantify viable oocysts through sporozoite invasion and clustering of foci. Eight experiments were performed by using oocysts less than 4 months of age to inoculate host HCT-8 cell monolayers. Oocysts were diluted in a standard 5- or 10-fold multiple dilution format, levels of infection and clustering were determined, and the most probable number (MPN) of infectious oocysts in the stock suspension was calculated. The MPN was compared to the initial oocyst inoculum to determine the level of correlation. For oocysts less than 30 days of age, the correlation coefficient (r) was 0.9726 (0.9306 to 0.9893; n = 20). A two-tailed Pvalue (alpha = 0.05) indicated that P was less than 0.0001. This strong correlation suggests that the MPN can be used to effectively enumerate infectious oocysts in a cell culture system. Age affected the degree of oocyst infectivity. Oocyst infectivity was tested by the focus detection method (FDM)-MPN assay and in BALB/c mice before and after treatment with pulsed white light (PureBrite). The FDM-MPN assay and animal infectivity assays both demonstrated more than a 4 log10 inactivation. Municipal water systems and a host of other water testing organizations could utilize the FDM-MPN assay for routine survival and disinfection studies.

scholarly journals Salmonella spp. Isolated by Miniaturized Most Probable Number and Conventional Microbiology in Poultry Slaughterhouses

2018 ◽  
Vol 44 (1) ◽  
pp. 5
Author(s):  
Ligiani Mion ◽  
Luana Parizotto ◽  
Lilian Andriva dos Santos ◽  
Bruna Webber ◽  
Isabel Cristina Cisco ◽  
...  
Keyword(s):  
Bacterial Resistance ◽  
Low Frequency ◽  
Automated System ◽  
Most Probable Number ◽  
Salmonella Spp ◽  
Heterogeneous Distribution ◽  
Probable Number ◽  
Poultry Products ◽  
Before And After ◽  
Positive Rate

Background: Salmonella spp. are frequently isolated from fowls, and their detection in poultry products varies according to the breeding system and the slaughtering process, bringing risks to the consumer and compromising the marketability. The control of Salmonella in poultry slaughterhouses is based on the detection of bacteria, but the quantification of the agent would be important in assessing risk, as well as in obtaining data to determine the capacity of each step of the process to decrease or increase bacterial contamination. The aims of this study were to propose a method for the quantification of Salmonella in poultry slaughterhouses, frequency of isolation and serovars identified.Materials, Methods & Results: Twenty-one broiler flocks from seven federally inspected slaughterhouses in southern Brazil, totaling 1,071 samples, were assessed by miniaturized most probable number (mMPN) and conventional microbiology. The samples were collected in triplicate at 17 points, which included cloacae, transportation cages before and after sanitization, water (scald tank, supply, pre-chiller and chiller), and carcasses (before and after scalding, defeathering, rinsing, evisceration, final rinsing, chilling at 4ºC, and freezing at -12°C for 24 h, 30 and 60 days). Typical Salmonella colonies were submitted to TSI, LIA, SIM, urea, and polyvalent anti-O antiserum tests, and to final identification by Microarray by Check&Trace. Nine of the 1,071 (0.83%) samples analyzed by mMPN and by conventional microbiology were positive for Salmonella and the following serovars were identified: Anatum, Brandenburg, Agona, Tennessee, Bredeney, Schwarzengrund and Infantis.Discussion: This positive rate was lower than that described by other authors, whose rates ranged from 3% and 39% for the isolation of Salmonella spp. from different sources, such as slaughterhouses and retail sales in samples collected in Brazil. The low frequency of isolation of Salmonella in this study can be attributed to the efficiency of control systems used from the field to the slaughterhouse, such as Good Manufacturing Practices (GMP) and Sanitation Standard Operating Procedures (SSOP), which are HACCP requirements. Also, when slaughtering technology actions are properly managed, such as water replacement and temperatures lower than 4ºC in the chiller, the initial contamination by Salmonella spp. can be reduced, with a decline in contamination from 70% to 20%, and with a reduction in the contamination of broiler carcasses after chilling from 15.8% to 3.3%. On the other hand the contamination of carcasses by Salmonella before pre-chilling and in post-chilling might be due to the automated system, inadequate temperatures during chilling, and inappropriate water chlorination in the assessed meat-packing plant. Of the 17 points evaluated, seven were positive for Salmonella, especially the cages after sanitization and frozen carcasses. The contamination by Salmonella spp. in transportation cages after sanitization indicates inefficiency of the automated system as well as possible bacterial resistance to the sanitizers used in SSOP while the isolation in carcasses frozen for 24 h and 60 days demonstrates the thermal resistance of the bacterium to a conservation method widely used in the food industry. In this work, just one of the nine positive samples for Salmonella was identified by conventional methods (CM) and mMPN. The discrepancy between methods can be explained by the heterogeneous distribution of Salmonella and other bacteria in naturally contaminated samples. Samples that were positive in the qualitative test but negative in the mMPN protocol could have had a number of Salmonella below the detection amount.

Inhibition of Listeria monocytogenes and Salmonella by Natural Antimicrobials and High Hydrostatic Pressure in Sliced Cooked Ham

2005 ◽  
Vol 68 (1) ◽  
pp. 173-177 ◽  
Author(s):  
TERESA AYMERICH ◽  
ANNA JOFRÉ ◽  
MARGARITA GARRIGA ◽  
MARTA HUGAS
Keyword(s):  
Listeria Monocytogenes ◽  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Storage Temperature ◽  
Detection Methods ◽  
Most Probable Number ◽  
Probable Number ◽  
Cooked Ham ◽  
Potassium Lactate ◽  
Microbial Enumeration

The effectiveness of nisin, lactate salts, and high hydrostatic pressure to inhibit the growth of Listeria monocytogenes and Salmonella in sliced cooked ham was studied through a combination of PCR-based detection methods, most probable number, and classical microbial enumeration techniques (International Organization for Standardization protocols). A synergistic effect to inhibit a cocktail of Listeria monocytogenes CTC1010, CTC1011, and CTC1034 was observed between potassium lactate, high hydrostatic pressure (400 MPa, 17°C, 10 min), and low storage temperature when sliced cooked ham was stored for 84 days at 1°C. The high hydrostatic pressure treatment also proved to be useful to inhibit a cocktail of Salmonella enterica serotypes London CTC1003, Schwarzengrund CTC1015, and Derby CTC1022.

scholarly journals Pengaruh Pencucian Permukaan Kaleng Minuman terhadap Keberadaan Bakteri Koliform-Fecal

2018 ◽  
Vol 17 (1) ◽  
pp. 26
Author(s):  
Muhammad Asril ◽  
R.A. Hoetary Tirta Amallia
Keyword(s):  
Most Probable Number ◽  
Test Design ◽  
Fecal Bacteria ◽  
Probable Number ◽  
Experiment Method ◽  
Before And After ◽  
Post Test ◽  
Storage Location ◽  
Univariate Test ◽  
Beverage Packaging

Latar belakang: Tempat dan kondisi penyimpanan produk minuman kemasan yang baik merupakan salah satu penentu adanya kualitas pada produk minuman kemasan/ kaleng. Keberadaan bakteri akibat kondisi yang tidak sesuai tidak hanya terdapat di air dalam kemasan, tetapi juga terdapat di permukaan kaleng minuman sehingga perlu ada penanganan lebih lanjut pada permukaan kaleng yang akan dikonsumsi. Tujuan dari penelitian ini untuk mengetahui pengaruh pencucian permukaan kaleng minuman terhadap keberadaan bakteri koliform-fecal pada produk minuman yang dijual dipinggir jalan.Metode: Penelitian ini bersifat deskriptif analitik dengan desain Quasy experiment dengan rancangan one group design pre-test and post-test design. Pengujian ini menggunakan sampel air yang terdapat dipermukaan kaleng minuman dan dilakukan uji mikrobiologis menggunakan metode Most Probable Number (MPN) dengan perlakuan sebelum dan setelah dilakukan pencucian dengan air mengalir.Hasil: Hasil uji univariat menunjukkan bahwa dari 10 sampel kaleng minuman yang diuji terdapat penurunan jumlah rata-rata angka koliform dan koliform fecal sebanyak 78 cfu/ml menjadi 7 cfu/ml. Uji bivariat menunjukkan bahwa terdapat perbedaan yang signifikan terhadap keberadaan bakteri koliform (p<0,05, p=0,02) dan koliform fecal (p<0,05, p= 0,008) sebelum dan setelah dilakukan pencucian.Simpulan: Terdapat penurunan secara signifikan keberadaan bakteri koliform-fecal pada permukaan kaleng minuman yang dijual dipinggir jalan setelah dicuci dengan air mengalir sehingga mampu menurunkan resiko kontaminasi. ABSTRACT Title: The Effect of Washing the Cans Suface on the Presence of the Coliform-Fecal BacteriaBackground: The storage location and condition of good beverage packaging products is one of the determinants of the beverage packaging products/cans quality. The presence of bacteria due to unsuitable conditions is not only found in the water in packs, but also on the surface of the beverage cans so that there must be advanced treatment on the surface of the cans to be consumed. The purpose of this study is to observe the effect of washing the drink cans surface towards the presence of coliform-fecal bacteria in beverage products sold on the sidewalk.Method: This research is analytical descriptive with Quasy experiment method (one group of pre-post test design). These tests uses water samples on the surface of the can and performed microbiological tests using the Most Probable Number (MPN) method with pre and post treatment which washing with fresh water.Result: The result of univariate test showed from 10 samples of beverage cans tested there was a decrease of the average number of coliform -fecal counted 78 cfu/ml to 7 cfu/ml. Bivariate tests showed significant differences in coliform bacterial (p<0.05, p= 0.02) and coliform fecal (p<0.05, p= 0.008) existence before and after washing.Conclusion: Therefore, it can be concluded that there is a significant decrease in the presence of coliform-fecal bacteria on the surface of the drink can after being washed with fresh water.

Aspects of the Microbiological Quality and Safety of Ready-to-Eat Foods in Sharjah Supermarkets in the United Arab Emirates

2010 ◽  
Vol 73 (7) ◽  
pp. 1328-1331 ◽  
Author(s):  
NAJLA A. ALMUALLA ◽  
LOUIS C. LALEYE ◽  
AISHA A. ABUSHELAIBI ◽  
RASHA A. AL-QASSEMI ◽  
ABDULKADAR A. WASESA ◽  
...  
Keyword(s):  
United Arab Emirates ◽  
Storage Temperature ◽  
Microbiological Quality ◽  
Aerobic Bacteria ◽  
Most Probable Number ◽  
Grocery Stores ◽  
Probable Number ◽  
E Coli ◽  
Plate Counts ◽  
Total Bacteria

Over the last few years, ready-to-eat (RTE) foods have become popular in grocery stores all over the world. This study was conducted to evaluate the microbiological safety and shelf life of some RTE salads sold in supermarkets in Sharjah Emirate, United Arab Emirates. Samples of four RTE salads, tabbouleh, hummus, Greek salad, and coleslaw, were obtained from supermarkets and examined for aerobic bacteria, Escherichia coli, Staphylococcus aureus, Salmonella, and Listeria monocytogenes. The results indicated significant differences (P ≤ 0.05) for the aerobic bacteria count among the RTE salad types. In tabbouleh, hummus, Greek salad, and coleslaw, E. coli counts of 0.9, 0.50, 0.27, and 0.25 log most probable number (MPN)/g and total aerobic bacterial plate counts of 3.57, 2.71, 2.76, and 2.52 log CFU/g, respectively, were found after preparation (day 0). At day 0, all RTE salads tested except tabbouleh contained an acceptable count of total bacteria, but the aerobic bacteria count for all the RTE salads increased rapidly during storage from day 2 to day 6, regardless of the storage temperature (5, 25, and 40°C). Twenty percent of all samples contained E. coli, although the numbers were as low as 1 log MPN/g. No S. aureus, L. monocytogenes, or Salmonella serotypes were detected in any of the RTE salads tested in this study.

Counts, Serovars, and Antimicrobial Resistance Phenotypes of Salmonella on Raw Chicken Meat at Retail in Colombia

2014 ◽  
Vol 77 (2) ◽  
pp. 227-235 ◽  
Author(s):  
PILAR DONADO-GODOY ◽  
VIVIANA CLAVIJO ◽  
MARIBEL LEÓN ◽  
ALEJANDRA AREVALO ◽  
RICARDO CASTELLANOS ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Storage Temperature ◽  
Retail Store ◽  
Most Probable Number ◽  
Department Of Agriculture ◽  
Probable Number ◽  
Risk Assessment Models ◽  
Paratyphi B ◽  
Inspection Service ◽  
Integrated Or

The objective of this study was to determine Salmonella counts, serovars, and antimicrobial-resistant phenotypes on retail raw chicken carcasses in Colombia. A total of 301 chicken carcasses were collected from six departments (one city per department) in Colombia. Samples were analyzed for Salmonella counts using the most-probable-number method as recommended by the U.S. Department of Agriculture, Food Safety Inspection Service protocol. A total of 378 isolates (268 from our previous study) were serotyped and tested for antimicrobial susceptibility. The overall Salmonella count (mean log most probable number per carcass ± 95% confidence interval) and prevalence were 2.1 (2.0 to 2.3) and 37%, respectively. There were significant differences (P &lt; 0.05) by Salmonella levels (i.e., counts and prevalence) by storage temperature (i.e., frozen, chilled, or ambient), retail store type (wet markets, supermarkets, and independent markets), and poultry company (chicken produced by integrated or nonintegrated company). Frozen chicken had the lowest Salmonella levels compared with chicken stored at other temperatures, chickens from wet markets had higher levels than those from other retail store types, and chicken produced by integrated companies had lower levels than nonintegrated companies. Thirty-one Salmonella serovars were identified among 378 isolates, with Salmonella Paratyphi B tartrate-positive (i.e., Salmonella Paratyphi B dT+) the most prevalent (44.7%), followed by Heidelberg (19%), Enteritidis (17.7%), Typhimurium (5.3%), and Anatum (2.1%). Of all the Salmonella isolates, 35.2% were resistant to 1 to 5 antimicrobial agents, 24.6% to 6 to 10, and 33.9% to 11 to 15. Among all the serovars obtained, Salmonella Paratyphi B dT+ and Salmonella Heidelberg were the most antimicrobial resistant. Salmonella prevalence was determined to be high, whereas cell numbers were relatively low. These data can be used in developing risk assessment models for preventing the transmission of Salmonella from chicken to humans in Colombia.

Listeria monocytogenes Occurrence and Growth at Refrigeration Temperatures in Fresh Blue Crab (Callinectes sapidus) Meat

1995 ◽  
Vol 58 (11) ◽  
pp. 1219-1221 ◽  
Author(s):  
DAFNE RAWLES ◽  
GEORGE FLICK ◽  
MERLE PIERSON ◽  
ALPHA DIALLO ◽  
ROBERT WITTMAN ◽  
...  
Keyword(s):  
Growth Rate ◽  
Blue Crab ◽  
Storage Temperature ◽  
Callinectes Sapidus ◽  
Growth Curves ◽  
Most Probable Number ◽  
Probable Number ◽  
Log10 Unit ◽  
Unit Increase ◽  
Crab Meat

In this study, 126 samples of freshly cooked and picked blue crab (Callinectes sapidus) meat collected from different processing facilities were analyzed for the presence of Listeria spp. Thirteen samples (10%) were positive for Listeria, with 10 samples positive for L. monocytogenes and 3 samples positive for L. innocua. Fraser broth was used in a 5-tube most probable number (MPN) enumeration, in duplicate, of Listeria in 25-g samples incubated at 36°C for 24 h and plated in modified Oxford agar and blood agar with API strip confirmation. The levels of Listeria cells found in fresh blue crab meat were always less than 100/g with only one exception, in which the MPN index was 1,100/g. A L. monocytogenes strain (168) isolated from fresh blue crab meat was inoculated (less than 50 CFU/g) into pasteurized crab meat and incubated at 1.1, 2.2, and 5°C for 21 days. Growth curves were obtained by analyzing 2-g samples at intervals of 0, 8, 10, 12, 14, 16, 19, and 21 days. When inoculated into pasteurized blue crab meat, L. monocytogenes had an increased growth rate as the storage temperature increased, with approximately a 7-log10-unit increase in population at 5°C and only a 2.5-log10-unit increase in population at 1.1 °C after the 21 days of incubation.

scholarly journals Uji Cemaran Mikroba Pada Air Yang Digunakan Untuk Mencuci Peralatan Makan Oleh Pedagang Kaki Lima di Sekitar UIN Sunan Ampel Surabaya

2021 ◽  
Vol 5 (2) ◽  
pp. 101-115
Author(s):  
Fahimatul Ula ◽  
Misbakhul Munir ◽  
Hanik Faizah
Keyword(s):  
Escherichia Coli ◽  
Water Sample ◽  
Plate Count ◽  
Most Probable Number ◽  
Food Hygiene ◽  
Street Vendors ◽  
Probable Number ◽  
Total Plate Count ◽  
Before And After ◽  
Mpn Test

The condition of eating places such as street vendors will determine the level of food hygiene, including the water used to wash food utensils. This study aimed to determine the number of microbes and identify Escherichia coli and Salmonella sp. on the water that was used to wash tableware by street vendors around UIN Sunan Ampel Surabaya. Water samples before and after being used to wash tableware were obtained from 4 street vendors. The number of microbes in the sample was tested by the Total Plate Count (TPC) and Most Probable Number (MPN) methods, Escherichia coli was identified using Eosin Methylene Blue Agar (EMB) media, and Salmonella sp. was identified using Salmonella-Shigella agar (SSA) and Triple Sugar Iron agar (TSIA) media. Based on the results of TPC test, the water sample before being used to wash tableware had the lowest and highest values that were 3.0 x 102 Cfu/ml and 9.8 x 105 Cfu/ml, respectively, while the water sample after being used to wash tableware had the lowest and highest values that were 4.0 x 102 Cfu/ml and 3.5 x 105 Cfu/ml, respectively. In the MPN test, the water sample before being used to wash tableware had the lowest and highest values that were 15/100ml and 26 100/ml, respectively, while the water sample after being used to wash tableware had the lowest and highest values that were 72/100 ml and 271/ 100 ml, respectively. Escherichia coli was detected in all samples 1&3 while in sample 2 Escherichia coli was detected in the water before it was detected the genus Enterobacter and in samples 4 the genus Enterobacter was detected and all samples water used to wash tableware of street vendors was positive for Salmonella.

scholarly journals Survey of Magneto-tactic Properties of Escherichia coli Under Static Magnetic Fields

2020 ◽  
Vol 7 (1) ◽  
pp. 14-19
Author(s):  
Ghorban Asgari ◽  
Ramin Khoshniyat ◽  
Mojtaba Moradi Golrokhi
Keyword(s):  
Escherichia Coli ◽  
Magnetic Fields ◽  
Most Probable Number ◽  
Gram Negative Bacteria ◽  
Static Magnetic Fields ◽  
Probable Number ◽  
E Coli ◽  
Before And After ◽  
The Mean ◽  
Coated Wires

Some of the microorganisms such as Escherichia coli have the ability to migrate to areas in which the intensity of magnetic fields (MFs) is higher, which is called magnetotactic properties. Magnetotaxis is a process implemented by a group of gram-negative bacteria that involves orienting and coordinating movement in response to magnetic fields. This study was conducted to investigate these properties of Escherichia coli in laboratory conditions. By means of coated wires (30 rounds) placed in two parts of the reactor (with five zones and a volume of 250 mL) and direct current (DC), an intensity of 0.18 mT for 42 minutes has been prepared. The most probable number of E. coli per 100 mL (MPN/100 mL) in each zone of the reactor, before and after exposure, was estimated. According to the results of this study, E. coli has magnetotactic properties, and the mean density of these bacteria in higher MFs (0.18 mT) is higher compared to the other zones in the reactor.

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