Localization of Viable Salmonella Typhimurium Internalized through the Surface of Green Onion during Preharvest

2013 ◽  
Vol 76 (4) ◽  
pp. 568-574 ◽  
Author(s):  
CHONGTAO GE ◽  
CHEONGHOON LEE ◽  
JIYOUNG LEE
Keyword(s):  
Water Stress ◽  
Salmonella Typhimurium ◽  
Laser Scanning ◽  
Plate Count ◽  
Contamination Level ◽  
High Concentration ◽  
Real Time Quantitative Pcr ◽  
Plate Count Method ◽  
Water Volumes ◽  
Different Parts

Internalization of pathogens poses a tremendous health risk in the consumption of raw fresh produce, because conventional washing cannot remove pathogens effectively after internalization occurs. We investigated (i) the pattern of Salmonella internalization in different parts of green onions when it was contaminated on their surfaces, and (ii) whether environmental factors (extreme weather) affect the extent of Salmonella internalization. Green onions were surface contaminated with three different levels of Salmonella Typhimurium (1, 3, and 5 log CFU per green onion). Each contamination group was irrigated with three different water volumes to mimic water stress and to determine if Salmonella Typhimurium internalization was localized in different parts of the plant. The plants were collected 2 days after contamination, and surface bacteria were inactivated with ethanol and silver nitrate. The plants were then cut into two parts, upper and lower. The internalized Salmonella Typhimurium in each part was visualized and confirmed with a laser scanning confocal microscope and was quantified with the plate count method and real-time quantitative PCR (qPCR). The results indicate that Salmonella Typhimurium can be taken up through the plant surface and transported from the upper to the lower part of the plant. The level of viable internalized Salmonella Typhimurium (plate count) was higher in the lower part than the level in the upper leafy part, especially when the leaves were contaminated with a high concentration of Salmonella (5 log CFU, P < 0.05), whereas the total internalized Salmonella Typhimurium (by qPCR) was higher in the upper part (P < 0.05) at the same contamination level. The discrepancy between these results suggests that most internalized Salmonella lost viability in the upper part but survived in the lower part. Water stress did not significantly change the extent of internalization in either location of green onion, whether detected via plate count or qPCR when the contamination occurred on the surface.

scholarly journals Reduction of Microbe Contamination through Steaming Process to Cocoa Beans Using Steaming Chamber

2014 ◽  
Vol 30 (1) ◽  
Author(s):  
Hendy Firmanto
Keyword(s):  
Microbial Contamination ◽  
Microbial Population ◽  
Plate Count ◽  
Cocoa Bean ◽  
Contamination Level ◽  
Cocoa Beans ◽  
Total Plate Count ◽  
Microbial Analysis ◽  
Plate Count Method ◽  
Nutrient Changes

Dry cocoa bean quality is also determined by its microbe contamination level. Steaming process for dried cocoa beans as a pretreatment process was selected because of less effect on organic compound inside the dried cocoa bean. This experiment aim was to study microbial contamination level of cocoa beans using steaming process, determining its microbial population and evaluate its chemical changes. Experiment was carried out in Postharvest Laboratory of Indonesian Coffee and Cocoa Research Institute. Cocoa beans for the experiment were lots collected from four farms in Jayapura, Papua with different microbial contamination level for each lot. Results of this experiment showed that optimum steaming process was 15 minutes at 100 O C with 10 minutes preheating time. Microbial analysis result of the four lots after complete steaming process by total plate count method showed the same result (<3.0 x 103 cfu). Most of the decrease in microbial contaminant appeared in the plate was 73.5% of Staphylococcus aureusand 0.058% of Penicilliumsp. Bean acidity (pH) after steaming increased (4.76 to 4.80) and free fatty acid increased (1.81% to 1.96%) while carbohydrate content decreased (17.5% to 15.9%) and as well as protein content (12.6% into 11.7%). Key words: cocoa bean, steaming process, microbe reduction, nutrient changes

scholarly journals Identification of Lactobacillus delbrueckii and Streptococcus thermophilus Strains Present in Artisanal Raw Cow Milk Cheese Using Real-time PCR and Classic Plate Count Methods

2017 ◽  
Vol 66 (4) ◽  
pp. 491-499 ◽  
Author(s):  
Milena A. Stachelska
Keyword(s):  
Real Time ◽  
Quantitative Pcr ◽  
Real Time Pcr ◽  
Streptococcus Thermophilus ◽  
Lactobacillus Delbrueckii ◽  
Cow Milk ◽  
Plate Count ◽  
Real Time Quantitative Pcr ◽  
Count Method ◽  
Plate Count Method

The aim of this paper was to detect Lactobacillus delbrueckii and Streptococcus thermophilus using real-time quantitative PCR assay in 7-day ripening cheese produced from unpasteurised milk. Real-time quantitative PCR assays were designed to identify and enumerate the chosen species of lactic acid bacteria (LAB) in ripened cheese. The results of molecular quantification and classic bacterial enumeration showed a high level of similarity proving that DNA extraction was carried out in a proper way and that genomic DNA solutions were free of PCR inhibitors. These methods revealed the presence of L. delbrueckii and S. thermophilus. The real-time PCR enabled quantification with a detection of 101–103 CFU/g of product. qPCR-standard curves were linear over seven log units down to 101 copies per reaction; efficiencies ranged from 77.9% to 93.6%. Cheese samples were analysed with plate count method and qPCR in parallel. Compared with the classic plate count method, the newly developed qPCR method provided faster and species specific identification of two dairy LAB and yielded comparable quantitative results.

Internalization of Bacterial Pathogens in Tomatoes and Their Control by Selected Chemicals

2004 ◽  
Vol 67 (7) ◽  
pp. 1353-1358 ◽  
Author(s):  
L. S. IBARRA-SÁNCHEZ ◽  
S. ALVARADO-CASILLAS ◽  
M. O. RODRÍGUEZ-GARCÍA ◽  
N. E. MARTÍNEZ-GONZÁLES ◽  
A. CASTILLO
Keyword(s):  
Lactic Acid ◽  
Salmonella Typhimurium ◽  
Tap Water ◽  
Plate Count ◽  
Bacterial Suspension ◽  
Enrichment Method ◽  
E Coli ◽  
Internal Ph ◽  
Plate Count Method ◽  
The Mean

The effect of different washing or sanitizing agents was compared for preventing or reducing surface and internal contamination of tomatoes by Salmonella Typhimurium and Escherichia coli O157:H7. The tomatoes were inoculated by dipping them in a bacterial suspension containing approximately 6.0 log CFU/ml of each pathogen and then rinsing them with tap water, hypochlorite solution (250 mg/liter), or lactic acid solution (2%, wt/vol). All treatments were applied by dipping or spraying, and solutions were applied at 5, 25, 35, and 55°C. With the exception of the lactic acid dip at 5°C, all treatments reduced both pathogens on the surfaces of the tomatoes by at least 2.9 cycles. No significantly different results were obtained (P &gt; 0.05) with the dipping and spraying techniques. For internalized pathogens, the mean counts for tomatoes treated with water alone or with chlorine ranged from 0.8 to 2.1 log CFU/g. In contrast, after lactic acid spray treatment, all core samples of tomatoes tested negative for Salmonella Typhimurium and, except for one sample with a low but detectable count, all samples tested negative for E. coli O157:H7 with a plate count method. When the absence of pathogens was verified by an enrichment method, Salmonella was not recovered from any samples, whereas two of four samples tested positive for E. coli O157:H7 even though the counts were negative. Few cells of internalized pathogens were able to survive in the center of the tomato during storage at room temperature (25 to 28°C). The average superficial pH of tomatoes treated with tap water, chlorine, or lactic acid was 4.9 to 5.2, 4.1 to 4.3, and 2.5, respectively (P &lt; 0.05), whereas no differences were observed in the internal pH (3.6 to 3.7) of the tomatoes treated with different sanitizers. The general practice in the tomato industry is to wash the tomatoes in chlorinated water. However, chlorine is rapidly degraded by organic matter usually present in produce. Therefore, lactic acid sprays may be a more effective alternative for decontaminating tomato surfaces. The use of warm (55°C) sprays could reduce pathogen internalization during washing.

COUNTING TOTAL BACTERIA IN LAND ORGANIC WASTE HOUSEHOLD AND LAND INORGANIC WITH TOTAL PLATE COUNT METHOD (TPC)

2017 ◽  
Vol 4 (2) ◽  
pp. 87-91
Author(s):  
Ekamaida Ekamaida
Keyword(s):  
Soil Fertility ◽  
Bacterial Population ◽  
Organic Soil ◽  
Biological Properties ◽  
Plate Count ◽  
Bacterial Populations ◽  
Fertility Data ◽  
Plate Count Method ◽  
The Mean ◽  
Total Bacteria

The soil fertility aspect is characterized by the good biological properties of the soil. One important element of the soil biological properties is the bacterial population present in it. This research was conducted in the laboratory of Microbiology University of Malikussaleh in the May until June 2016. This study aims to determine the number of bacterial populations in soil organic and inorganic so that can be used as an indicator to know the level of soil fertility. Data analysis was done by T-Test that is by comparing the mean of observation parameter to each soil sample. The sampling method used is a composite method, which combines 9 of soil samples taken from 9 sample points on the same plot diagonally both on organic soil and inorganic soil. The results showed the highest bacterial population was found in total organic soil cfu 180500000 and total inorganic soil cfu 62.500.000

Pengaruh Suhu Penyimpanan terhadap Organoleptik, Derajat Keasaman dan Pertumbuhan Bakteri Coliform pada Susu Pasteurisasi

2016 ◽  
Vol 10 (1) ◽  
pp. 13-23 ◽  
Author(s):  
Agustina Arianita Cahyaningtyas ◽  
Wiwik Pudjiastuti ◽  
Ilham Ramdhan
Keyword(s):  
Storage Temperature ◽  
Total Coliform ◽  
Coliform Bacteria ◽  
Plate Count ◽  
Pasteurized Milk ◽  
Initial Analysis ◽  
Total Plate Count ◽  
Plate Count Method ◽  
Pathogenic Microbes ◽  
Total Coliform Bacteria

One attempt to reduce the number of pathogenic microbes in milk is through the pasteurization process. This research aims to determine the effect of storage temperature on the organoleptic, acidity (pH) and growth of coliform bacteria in pasteurized milk. Pasteurized milk is stored at the varies of temperature  4°C (observed for 14 days), 10°C-15°C (observed for 14 days) and 25°C-27°C (observed for 22 hours), as well as also conducted an initial analysis pasteurized milk. The parameters were observed among other organoleptic (smell, taste, color, texture), pH and total coliform bacteria. Testing acidity using pH paper, while the growth of coliform bacteria testing done using Total Plate Count method based on ISO 2897 in 2008. The results of this study indicate that storage at 4°C for 14 days, organoleptic pasteurized milk is still good until the day ke- 8, pH progressively decreases, and the growth of coliform bacteria obtained the highest score of 3100x101 CFU / ml. Storage at 10°C-15°C for 14 days, organoleptic pasteurized milk is still good until the 6th day, the pH progressively decreases, and the growth of coliform bacteria obtained the highest score of 5729x101 CFU / ml. Storage at 25°C-27°C for 22 days, organoleptic pasteurized milk is still good until the 9th, pH progressively decreases, and the growth of coliform bacteria obtained the highest score of 4.3 x106 CFU / ml.ABSTRAKSalah satu usaha untuk mengurangi jumlah mikroba patogen pada susu adalah melalui proses pasteurisasi. Penelitian ini bertujuan untuk mengetahui pengaruh suhu penyimpanan terhadap organoleptik, derajat keasaman (pH) dan pertumbuhan bakteri Coliform pada susu pasteurisasi. Susu pasteurisasi disimpan pada suhu yang bervariasi yaitu suhu 4°C (diamati selama 14 hari), suhu 10°C-15°C (diamati selama 14 hari) dan suhu 25°C-27°C (diamati selama 22 jam), serta dilakukan pula analisa awal susu pasteurisasi. Parameter yang diamati antara lain organoleptik (bau, rasa, warna, tekstur), pH dan jumlah bakteri Coliform. Pengujian derajat keasaman menggunakan kertas pH, sedangkan pengujian pertumbuhan bakteri Coliform dilakukan dengan menggunakan metode Total Plate Count berdasarkan SNI 2897 Tahun 2008. Hasil penelitian ini menunjukkan bahwa penyimpanan pada suhu 4°C selama 14 hari, organoleptik susu pasteurisasi masih baik sampai dengan hari ke-8, pH semakin lama semakin menurun, dan pertumbuhan bakteri Coliform didapatkan nilai tertinggi sebesar 3100x101 Cfu/ml. Penyimpanan pada suhu 10°C-15°C selama 14 hari, organoleptik susu pasteurisasi masih baik sampai hari ke-6, pH semakin lama semakin menurun, dan pertumbuhan bakteri Coliform didapatkan nilai tertinggi sebesar 5729x101 Cfu/ml. Penyimpanan pada suhu 25°C-27°C selama 22 hari, organoleptik susu pasteurisasi masih baik sampai jam ke-9, pH semakin lama semakin menurun, dan pertumbuhan bakteri Coliform didapatkan nilai tertinggi sebesar 4,3 x106 Cfu/ml.Kata kunci : bakteri coliform, derajat keasaman, suhu penyimpanan, organoleptik, susu pasteurisasi

The Microbiological Quality of Honey as Determined by Aerobic Colony Counts

1993 ◽  
Vol 56 (4) ◽  
pp. 336-337 ◽  
Author(s):  
JOSEP SERRA BONVEHI ◽  
ROSSEND ESCOLÁ JORDÁ
Keyword(s):  
Membrane Filter ◽  
Microbiological Quality ◽  
Plate Count ◽  
Filter Method ◽  
Filter Methods ◽  
Plate Counts ◽  
Multifloral Honey ◽  
Plate Count Method ◽  
Membrane Filter Method

The number of mesophilic aerobic colonies was determined in 72 samples of mono- and multifloral honey from various sources by the plate count and the membrane filter methods. The presence of motile colonies made the plate counts unreliable. The microorganism producing these colonies was identified as Bacillus alvei. Colony counts could only be carried out in 27 of the samples when using the plate count method, while with the membrane filter method the number of colonies was counted in all the samples.

scholarly journals Graphene-Modulated Removal Performance of Nitrogen and Phosphorus Pollutants in a Sequencing Batch Chlorella Reactor

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2181 ◽  
Author(s):  
Gonghan Xia ◽  
Wenlai Xu ◽  
Qinglin Fang ◽  
Zishen Mou ◽  
Zhicheng Pan
Keyword(s):  
Optical Microscopy ◽  
Sewage Treatment ◽  
Ammonia Nitrogen ◽  
Pollutant Removal ◽  
Plate Count ◽  
Nitrogen And Phosphorus ◽  
Removal Rates ◽  
Practical Support ◽  
Plate Count Method ◽  
The Impact

In this work, the influence of graphene on nitrogen and phosphorus in a batch Chlorella reactor was studied. The impact of graphene on the removal performance of Chlorella was investigated in a home-built sewage treatment system with seven identical sequencing batch Chlorella reactors with graphene contents of 0 mg/L (T1), 0.05 mg/L (T2), 0.1 mg/L (T3), 0.2 mg/L (T4), 0.4 mg/L (T5), 0.8 mg/L (T6) and 10 mg/L (T7). The influence of graphene concentration and reaction time on the pollutant removal performance was studied. The malondialdehyde (MDA) and total superoxide dismutase (SOD) concentrations in each reactor were measured, and optical microscopy and scanning electron microscopy (SEM) characterizations were performed to determine the related mechanism. The results show that after 168 h, the total nitrogen (TN), ammonia nitrogen (AN) and total phosphorus (TP) removal rates of reactors T1–T7 become stable, and the TN, AN and TP removal rates were gradually reduced with increasing graphene concentration. At 96 h, the concentrations of both MDA and SOD in T1–T7 gradually increased as the graphene concentration increased. In optical microscopy and SEM measurements, it was found that graphene was adsorbed on the surface of Chlorella, and entered Chlorella cells, deforming and reducing Chlorella. Through the blood plate count method, we estimated an average Chlorella reduction of 16%. According to the water quality and microscopic experiments, it can be concluded that the addition of graphene causes oxidative damage to microalgae and destruction of the Chlorella cell wall and cell membrane, inhibiting the nitrogen and phosphorus removal in Chlorella reactors. This study provides theoretical and practical support for the safe use of graphene.

scholarly journals Cadmium (Cd) Resistance of Isolate Bacteria from Poboya Gold Mining in Palu, Central Sulawesi

2020 ◽  
Vol 20 (2) ◽  
pp. 298
Author(s):  
Fahruddin Fahruddin ◽  
Syahruddin Kasim ◽  
Eka Ummi Rahayu
Keyword(s):  
Heavy Metals ◽  
Mining Industry ◽  
Plate Count ◽  
Resistance Testing ◽  
Bacterial Isolates ◽  
Bacterial Isolation ◽  
Cadmium Resistance ◽  
Cadmium Metal ◽  
Plate Count Method ◽  
Central Sulawesi

The mining industry in Indonesia is growing rapidly, giving an environmental impact from the waste produced because it contains dangerous heavy metals, one of which is cadmium metal (Cd). The purpose to know the ability of cadmium resistance in bacterial isolates. Bacterial isolates were obtained from soil samples from the Poboya Gold Mine field, Palu. Bacterial isolation and selection were carried out by the plate count method, resistance testing using nutrient broth media containing heavy metals Cd, analysis of Cd concentrations using atomic absorption spectrophotometers. From the results of the study, four types of Cd resistant isolates were obtained based on macroscopic and microscopic characterization results, namely isolates EK1, EK2, EK3 and EK4. The two best isolates of Cd resistance, EK2 and EK4 isolates were tested on media containing 20 ppm Cd, showing that both of these isolates were able to significantly reduce Cd concentrations in the supernatant and pellets.

scholarly journals Relative and quantitative rhizosphere microbiome profiling result in distinct abundance patterns

2021 ◽  
Author(s):  
Hamed Azarbad ◽  
Julien Tremblay ◽  
Luke D. Bainard ◽  
Etienne Yergeau
Keyword(s):  
Water Stress ◽  
Relative Abundance ◽  
Its Region ◽  
Cost Effective ◽  
Amplicon Sequencing ◽  
Rrna Gene ◽  
Real Time Quantitative Pcr ◽  
Rhizosphere Microbiome ◽  
History Of ◽  
Almost All

AbstractNext-generation sequencing is recognized as one of the most popular and cost-effective way of characterizing microbiome in multiple samples. However, most of the currently available amplicon sequencing approaches are inherently limited, as they are often presented based on the relative abundance of microbial taxa, which may not fully represent actual microbiome profiles. Here, we combined amplicon sequencing (16S rRNA gene for bacteria and ITS region for fungi) with real-time quantitative PCR (qPCR) to characterize the rhizosphere microbiome of wheat. We show that the increase in relative abundance of major microbial phyla does not necessarily result in an increase in abundance. One striking observation when comparing relative and quantitative abundances was a substantial increase in the abundance of almost all phyla associated with the rhizosphere of plants grown in soil with no history of water stress as compared with the rhizosphere of plants growing in soil with a history of water stress, which was in contradiction with the trends observed in the relative abundance data. Our results suggest that the estimated absolute abundance approach gives a different perspective than the relative abundance approach, providing complementary information that helps to better understand the rhizosphere microbiome.

Comparison between the EC plate count test at 21 °C and an accelerated plate count method for assessing the keeping quality of pasteurized milk

1992 ◽  
Vol 59 (3) ◽  
pp. 431-436 ◽  
Author(s):  
Sarah A. Langford ◽  
Rohan G. Kroll
Keyword(s):  
Plate Count ◽  
Gram Negative ◽  
Rapid Methods ◽  
Pasteurized Milk ◽  
Psychrotrophic Bacteria ◽  
Commercial Interest ◽  
Count Method ◽  
Keeping Quality ◽  
Plate Count Method

The keeping quality of properly refrigerated pasteurized milk and cream is primarily determined by post-pasteurization contamination by Gram-negative psychrotrophic bacteria (Phillips et al. 1981; Schröder et al. 1982). Reliable and rapid methods of assessing the levels of contamination by these organisms are therefore of commercial interest.

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