Plate Count Technique Research Articles

Microcalorimetric growth behavior of E. coli ATCC 25922 in an MCDSC

Isothermal microcalorimetry can provide a general analytical tool for the characterization of bacterial growth. Methodologies and equipment have been studied to expand the application and disseminate the use of the technique. The MCDSC is a microcalorimeter capable of measuring in the range of 0.2 μW that can operate at a temperature range of −20 to 140 °C or under isothermal conditions. Here, we present the first investigation of MCDSC for E. coli growth with the Baranyi and Roberts modeling application. This study presented the calorimetric E. coli fingerprint at MCDSC and compares it with the plate count technique, giving the data more biological meaning. The calorimeter was able to accurately detect growth metabolism and discriminate E. coli at different inoculum densities. Additionally, the MCDSC can offer a new point of view for evaluating microbial growth, such as the significant reduction in error due to dispersed data by the viable counting method.

Bacteriological quality of frozen chicken sold in the capital cities of the South Eastern States of Nigeria

Aims: To determine and compare the bacteriological quality of frozen chicken sold in the Capital cities of the South Eastern States of Nigeria. Method: A total of 150 samples (frozen chicken) were collected from different Capital cities (Abakaliki, Awka, Enugu, Owerri and Umuahia) of the five (5) South Eastern States of Nigeria, which were 30 samples each State. The Aerobic Plate Counts (APC), Total Coliform Counts (TCC), Psychrotrophic Plate Counts (PPC), Escherichia coli counts, Staphyococcus aureus counts and the presence of Salmonella spp were determined by plate count technique using the appropriate media. Colony counts were taken from the plates with the specified number of colonies. Results: For the Capital cities which are Abakaliki, Awka, Enugu, Owerri and Umuahia, the samples mean values for the Aerobic Plate Counts (APC) were 9.61×106, 8.50×106, 6.12×106, 8.10×106 and 6.46×106 respectively, the Total Coliform Counts (TCC) were 4.80×103, 5.59×103, 2.46×103, 2.62×103 and 3.72×103 respectively, the Psychrotrophic Plate Counts (PPC) were 5.71×106, 4.57×106, 4.22×106, 5.53×106 and 4.41×106 respectively, the Escherichia coli counts were 2.33×103, 2.68×103, 1.56×103, 1.80×103 and 2.12×103 respectively, the Staphyococcus aureus counts were 5.58×103, 3.93×103, 4.36×103, 4.16×103 and 4.11×103 respectively and the incidence of Salmonella spp were 19, 13, 6, 15 and 16 respectively. Abakaliki with the highest mean values counts and highest incidence was the Capital with the highest bacterial load/contamination. Awka was the Capital with second most bacterial load. Enugu was the Capital with the lowest bacterial load. Owerri and Umuahia were contaminated but had bacterial load lower than those of Abakaliki and Awka samples. The bacterial load of Owerri and Umuahia tends to be equivalent. The mean values of the Capital cities exceed the international permissible limits and there were presence of Salmonella spp Conclusion: The frozen chicken meats sold in the Capital cities of South Eastern States of Nigeria are highly contaminated and can cause food poisoning when eaten raw or under cooked. Therefore, proper cooking should be done before consumption.

Investigation of diverse biosynthetic secondary metabolites gene clusters using genome mining of indigenous Streptomyces strains isolated from saline soils in Iran.

Bioactive secondary metabolites are the products of microbial communities adapting to environmental challenges, which have yet remained anonymous. As a result of demands in the pharmaceutical, agricultural, and food industries, microbial metabolites should be investigated. The most substantial sources of secondary metabolites are Streptomyces strains and are potential candidates for bioactive compound production. So, we used genome mining and bioinformatics to predict the isolates secondary metabolites, biosynthesis, and potential pharmaceuticals. This is a bioinformatics part of our previous experimental research. Here, we aimed to inspect the underlying secondary metabolite properties of 20 phylogenetically diverse Streptomyces species of saline soil by a rationalized computational workflow by several software tools. We examined the Metabolites' cytotoxicity and antibacterial effects using the MTT assay and plate count technique, respectively. Among Streptomyces species, three were selected for genome mining and predicted novel secondary metabolites and potential drug abilities. All 11 metabolites were cytotoxic to A549, but ectoine (p≤0.5) and geosmin (p≤0.001) significantly operated as an anti-cancer drug. Metabolites of oxytetracycline and phosphinothricin (p≤0.001), 4Z-annimycin and geosmin (p≤0.01), and ectoine (p≤0.5) revealed significant antibacterial activity. Of all the 11 compounds investigated, annimycin, geosmin, phosphinothricin, and ectoine had antimicrobial properties, but geosmin also showed very significant anti-cancer properties.

Viability droplet digital polymerase chain reaction accurately enumerates probiotics and provides insight into damage experienced during storage.

Probiotics are typically enumerated by agar plate counting (PC) techniques. PC has several limitations including poor specificity, high variability, inability to enumerate dead cells, viable but non-culturable cells and cells in complex matrices. Viability droplet digital polymerase chain reaction (v-ddPCR) is an emerging enumeration technique with improved specificity, precision, and the ability to enumerate cells in varying states of culturability or in complex matrices. Good correlation and agreement between v-ddPCR and PC is well documented, but not much research has been published on the comparison when enumerating freeze-dried (FD) probiotics during storage. In this study, v-ddPCR utilizing PE51 (PE51-ddPCR), a combination of propidium monoazide (PMA) and ethidium monoazide (EMA), was evaluated as alternative enumeration technique to PC on blends of four FD probiotic strains over the course of a 3-month storage study with accelerated conditions. When PMA and EMA are combined (PE51), this study demonstrates agreement (bias = 7.63e+9, LOA = 4.38e+10 to 5.9e+10) and association (r = 0.762) between PC and v-ddPCR, at or above levels of an accepted alternative method. Additionally, v-ddPCR with individual dyes PMA and EMA provide insight into how they individually contribute to the viable counts obtained by PE51-ddPCR and provide a more specific physiological understanding of how probiotics cope with or experience damage during storage.

Synergistic effect of copper, silver nanoparticles and hydrogen peroxide on Xanthomonas axonopodis pv. punicae

Bacterial blight disease of pomegranate caused by Xanthomonas axonopodis pv. punicae decrease crop productivity. X. axonopodis was isolated from infected fruits, stem and leaves collected from Pravara area on NAS medium. Pure culture was obtained by regular subculture and maintained on NAS medium. Trichoderma harizanium fungal biomass was generated for nanoparticle synthesis on liquid PDA medium. The aqueous cell free culture filtrate (CFCF) obtained by filtration. Nanoparticles were synthesized using 50 ml of aqueous CFCF in flasks by stirring appropriate amount of, CuSO4 (1–2 mM) solution in dark at 45 °C. Silver nanoparticles were synthesized using Trichoderma viride. SEM analysis proved silver nanoparticle size in the range 5–10 µm. Spread plate and colony count techniques proved significant antibacterial activity of silver nanoparticles against Xanthomonas axonopodis.

Biocontrol Activity of Yeasts against Alternaria solani and Plant Growth Promotion of Tomato Plants

Aim: Yeasts have emerged as a single celled biocontrol agent which are applicable in controlling many disease causing pathogens in plants. These yeasts also have growth promoting substances that help in the growth and development of plants.
 Materials and Methods: Yeast on tomato plants were isolated using standard plate count technique and observed under microscope for their cell shape and sizes. Biocontrol activity of yeast was evaluated by measuring diameter of zone of inhibition (mm) and estimating mycelial dry weights of pathogen. IAA production by yeasts was estimated in vitro and the plant growth and development was evaluated by measuring plant heights, number of leaves, number of days for flower initiation, shoot biomass, root mass, disease incidence and severity in pot culture experiments.
 Results: Yeast isolate TPL-I isolated from tomato plants was most effective in inhibiting Alternaria solani with diameter of zone of inhibition of 9.00 mm. Reduced mycelial dry weight of pathogen viz., 40.07 mg was exhibited by TPL-I under in vitro conditions. The maximum concentration of IAA was produced by TPL- I (0.11 μg/ml). The highest plant height, number of leaflets and number of days taken for flower initiation was recorded highest in T4 (Trichoderma harzianum) followed by T7 (Foliar spray of Alternaria solani + TPL- I + Trichoderma harzianum) at 30, 45 and 60 days after transplanting. Maximum dry weight of shoot (12.32 g/plant) and root (5.18 g/plant) was recorded in T4 (Foliar spray of Trichoderma harzianum) whereas, minimum dry weight of shoot (8.26 g/plant) and root (2.80 g/plant) was recorded in T2 (Foliar spray of Alternaria solani). Lowest disease incidence (33.33%) and disease severity (24.25%) was recorded in T5 (Foliar spray of Alternaria solani + TPL- I).

Minimum Inhibitory Concentration (MIC) and minimum bactericidal concentration of beluntas leaf ethanol extract against streptococcus mutans

bjective: The purpose of this study was to determine the exact values of MBC (Minimum Bactericidal Concentration) and MIC (Minimum Inhibitory Concentration) of beluntas leaf extract against Streptococcus mutans colonies.
 Material and Methood: This study used Streptococcus mutans ATCC 25175 and ethanol extract of beluntas leaves with concentrations: 250 g/ml, 125 g/ml, 62.5 g/ml, 31.3 g/ml, 15.6 g/ml, 7.8 g /ml, 3.9 g/ml and 1.95μg/ml. This study used two methods, Broth Microdilution and Total Plate Count techniques as the designated method for the purpose of counting bacteria. Furthermore, the data analysis test was carried out to analyze normality using the Kolmogorov-Smirnov test. If the data distribution shows normal, then one way ANOVA parametric test is performed to determine the significance between the beluntas leaf extract and the number of streptococcus mutans bacteria, which will then be further examined using the Post-Hoc Test with the Tuckey method to find out which dataset is the most significantly different in among others.
 Results: The beluntas leaf extract showed significant bacterial properties against Streptococcus mutans (P-Value = 0.00) which was expressed through definite MBC and MIC values. The results showed that the MIC and MBC values were 62.5 g/ml and 125 g/ml, respectively against Streptococcus mutans colonies.
 Conclusion: The conclusion of this study was that the ethanol extract of the leaves of beluntas (Pluchea Indica L) showed antibacterial properties as indicated by the MIC value at a concentration of 62.5μg/ml and the MBC at a concentration of 125μg/ml against streptococcus mutans.

Applied Research Note: Combination of probiotic and prebiotic impacts Salmonella Enteritidis infection in layer pullets

Mitigation of food pathogens such as Salmonella continues to be a focus in poultry production, whether on shell eggs or meat products. No single approach is fully able to eliminate the risk of Salmonella contamination, but rather comprehensive programs are used in a multi-faceted approach. Targeted in-feed additives are a component of a food safety program and may help to reduce Salmonella infection. This study was aimed to evaluate the efficacy of a probiotic and prebiotic combination feed-additive product to reduce Salmonella Enteritidis (S.E.) infection in layer pullets. A total of 192 day-old pullets were placed in cages in two treatments (Control and pre-probiotic combination product at 1.5 lb/ton/of complete feed). Birds were challenged with 1.8 × 10 9 colony forming units (CFU) per bird of S.E. on Day 21 of the trial. Twenty-four birds from each treatment were sampled 6, 10, 14 and 18 days post infection (dpi). Cecal pouches were collected for enumeration of S.E. using plate counting technique. S.E. counts were numerically lower in Treatment 2 compared to Treatment 1 at 14 and 18 dpi, as Salmonella shedding in the course of infection was declining. Mean S.E. count in the ceca of pullets in Treatment 2 was 0.54 log 10 lower than that of Treatment 1 (3.36 log10) at 18 dpi. Samples below the detection limit of the counting method were significantly (p=0.021) higher in 10/24 (41.7%) of the pullets in Treatment 2 compared to 3/24 (12.5%) Treatment 1 at 18 dpi. Therefore, addition of the dietary pre- and probiotic combination product resulted in lower S.E. shedding in layer pullets challenged with S.E.

Prevalence and distribution of antimicrobial resistance profile of Escherichia coli isolated from various local fish markets in Dhaka city, Bangladesh

Considering the importance of the fish and fish products as a vital part of the human diet in Bangladesh, the study aimed to estimate the microbial load, identify the E. coli and observe the isolates antibiogram pattern. Standard plate count technique, as well as the 3-tube most probable number (MPN) method, were applied to estimate the total viable bacteria (TVB) and total coliforms (TC), total fecal coliforms (TFC), and E. coli, respectively. Approximately 61.91% of samples fell into the marginally acceptable limit for TVB count, while 66.67% and 95.25% of examined species exceeded the threshold limit for TC and TFC, respectively (p<0.05). Around 90% of samples were contaminated with E. coli. A culture sensitivity test revealed that cent percent strains harbored resistance to penicillin, rifampicin, and erythromycin. Multiple antibiotic resistance (MAR) index above 0.2 may indicate the misuse or overuse of antibiotics. The findings highlight the potential food safety hazards associated with fish concerning the random use of antibiotics. J. Bangladesh Acad. Sci. 46(1); 9-18: June 2022

Development and validation of a triplex real-time qPCR for sensitive detection and quantification of major rat bite fever pathogen Streptobacillus moniliformis

Streptobacillus (S.) moniliformis is the most important pathogen causing rat bite fever (RBF) worldwide. This zoonotic pathogen is understudied mainly due to difficulties in culturing S. moniliformis as a fastidious microorganism. Therefore, advances in molecular detection techniques are highly needed, especially with regard to the widespread availability of real-time quantitative (q) PCR in laboratories. In this study, we aimed to develop a qPCR for the identification of Streptobacillus species and quantification of S. moniliformis in clinical samples, especially those derived from tissue samples of animal origin. We optimized a previously described PCR protocol in order to develop a qPCR, which can detect different Streptobacillus species with high specificity and is simultaneously able to quantitate S. moniliformis in different clinical matrices. The qPCR exhibited a limit of detection (LOD) of 21 copies/reaction representing ~4–5 streptobacilli, while the limit of quantification (LOQ) was 2.1 × 103 copies/reaction. It was also more sensitive than conventional PCR by two orders of magnitude and proved to have a substantial agreement (Kappa 0.74) compared to it with a superior detection rate in 374 samples from wild rats, laboratory rats and animals from holdings of wild-trapped rats.To conclude, the qPCR described in this study is an important molecular tool that is able to quantify S. moniliformis in tissue samples of animal origin. It represents a suitable tool for future establishment and evaluation of other molecular assays that are highly needed for a better understanding of epidemiology and pathophysiology of RBF. In experimental studies, it will also be useful for titration purposes since the quantification of the organism using classical plate counting technique is problematic and inaccurate.

A comprehensive study on population dynamics of microbial enrichment of Organic manures

An experiment was conducted in Department of Agriculture, Karunya Institute of Technology and Sciences,Coimbatore to study the population dynamics of microbially enriched organic manures and their nutrientcomposition. Organic manures such as vermicompost, FYM, and coir pith compost were enriched with thelignite based microbial strains of Rhizobium leguminosorum, Bacillus megatherium and its combined inoculumat a rate of 1 kg per ton of manure and its moisture content was maintained at 50 per cent and incubated for180 days. After their enrichment, the microbial load in the organic manures was enumerated using thestandard plate count technique. The microbial results revealed that the maximum microbial populationwas attained on the 90th day after enrichment. The total microbial population in combined bio fertilizers(Rhizobium and Phosphobacteria) inoculated vermicompost was high during the initial phases and thentotal microbial population declined towards the end. Among the enriched organic manures, the highestpopulation was observed in combined microbial strains enriched with vermicompost (6.52 log10 CFU g-1)whereas, after 3 months the enriched organic manure shows the very less population density.

Antibacterial Activity of Nanoparticles of Garlic (Allium sativum) Extract against Different Bacteria Such as Streptococcus mutans and Poryphormonas gingivalis

To combat the threat of antimicrobial resistance, it is important to discover innovative and effective alternative antibacterial agents. Garlic has been recommended as a medicinal plant with antibacterial qualities. Hence, we conducted this study to evaluate the antibacterial activity of ultrasonicated garlic extract against Escherichia coli, Staphylococcus aureus sub. aureus, Streptococcus mutans, and Poryphyromonas gingivalis. Aqueous ultrasonicated garlic extract was tested against these strains, and their antibacterial activity quantified using both agar disk diffusion and agar well diffusion methods; the plate count technique was used to estimate the total viable count. Moreover, Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and microplate spectrophotometry were used to characterize garlic nanoparticles. The results confirmed that all tested bacteria were sensitive to both sonicated and non-sonicated garlic extracts. Streptococcus mutans was the most susceptible bacteria; on the other hand, Escherichia coli was the most resistant bacteria. Furthermore, characterization of the prepared garlic nanoparticles, showed the presence of organosulfur and phenolic compounds, carboxyl groups, and protein particles. Based on the obtained results, ultrasonicated garlic extract is a potent antibacterial agent. It can come in handy while developing novel antibiotics against bacteria that have developed resistance.

Characterization of plant growth promoting bacteria isolated from water in mangrove ecosystem

Mangrove is a unique and dynamic coastal ecosystem that is characterized by high salinity. It creates an ecological niche with varied environmental conditions and microbial communities, including Nitrogen Fixing Bacteria (NFB) and Phosphate Solubilizing Bacteria (PSB), which have great potential as Plant Growth Promoting Bacteria (PGPB). The study aims to obtain isolates of indigenous bacteria in a varied saline environment of the mangrove ecosystem that has the characteristics to promote plant growth or potential as PGPB. The bacteria were isolated from the mangrove ecosystem, which is the water of brackish zone using specific media with total plate count (TPC) technique. Furthermore, the PGPB characterization was analyzed using nitrogenase, ACC-deaminase, cellulose, salinity, Indole-3-Acetic Acid (IAA), dissolved P, and phosphatase (PME-ase) indicators in triplicate. The results showed that water salinity and pH in the mangrove ecosystem ranged from 1.12 to 1.73 ppt and 6.56 to 7.44, respectively. Furthermore, the bacteria isolated from water in the mangrove ecosystem produced IAA (6 isolates), dissolved P, acid and alkaline PMEase (11 isolates), saline tolerance (33 isolates), cellulose (14 isolates), nitrogenase (18 isolates), and ACC-deaminase (2 isolates) activity. One of the isolates (AZT5.1) identified as Bacillus cereus has potential as PGPB with the value of IAA production (18.61 ppm), 1.1cm P halo zone dissolved, 569.45 ppm dissolved P, 11.2 μg/pnitrofenol g− 1h−1 acid, and 12.85 μg/pnitrofenol g− 1h−1 alkaline PME-ase production, 1.30 cm cellulose halo zone, saline tolerance, nitrogenase, and ACC-deaminase activity. Therefore, the PGPB from this bacterium was the highest compared to other isolates.

CARRIER DEVELOPMENT FOR PGPR-BIOFERTILIZER AND ITS EXPLOITATION UNDER CADMIUM AND LEAD STRESSED CONDITION

Worldwide overpopulation needs progressive crop yield creating environmental pollution. Low cost and easily available biofertilizer development is the best alternative for a sustainable agricultural system. In this study different agricultural waste such as wheat bran, sesame bran and bagasse were used as a carrier for the isolated PGPR. Two most potent cadmium and lead tolerant PGPR were isolated from Indian agricultural soil and identified as Lysinibacillus varians strain KUBM17 (accession number MG976681) and Pseudomonas putida strain KUBM18 (accession number MG976684). PGPRs were inoculated in different possible combinations of carrier materials. The growth and survivability of PGPRs were checked with plate count technique frequently up to 120 days. The best carrier was selected for PGPR application on radish and gram plants to check their plant growth-promoting ability. Sesame bran showed higher CFU count (7.8 x106/gm) for the PGPRs from the early days. Whereas, wheat bran and bagasse individually showed slower but sustainable nutrient availability for both the PGPRs. Wheat bran, sesame bran and bagasse in 1:1:1 ratio produced decent performance throughout the time period. The carrier mixture as biofertilizer showed higher plant biomass, germination percentage, chlorophyll content and other growth parameters on radish and gram plant under cadmium and lead stress. Carrier grown Lysinibacillus varians and Pseudomonas putida were able to nullify the toxicity of cadmium or lead and significantly (p < 0.05) enhanced almost all the plant growth parameters of both the plants. So, wheat bran, sesame bran and bagasse can be used for cheap PGPR-biofertilizer development.

MICROBIOLOGICAL ANALYSIS OF KUNUN-ZAKI: A FERMENTED MILLET DRINK IN BENIN CITY, EDO STATE, NIGERIA

Microbiological and physicochemical analyses were carried out on samples of fermented millet drink Kunun Zaki. Fifteen samples were obtained from Ikpoba Hill Market and Aduwawa Quarters. The microbiological analysis was carried out using the standard plate count technique to determine the total microbial population. The mean count of bacteria and fungi was 2.57x10 7 cfu/ml and 0.98x10 7 cfu/ml respectively. Microorganisms identified were Lactobacillus sp, Bacillius sp, Staphylococcus aureus, Streptococcus sp, Escherichia coli, Pseudomonas sp, Mucor sp and Fusarium sp. The mean value of the pH and titrable acidity was 4.26±0.09 and 2.73±0.08ml 0.1M NaOH respectively. The moisture content was high with a mean of 85.90±0.95 and mean solid content of 14.1±0.95. This study has shown that kunun-zaki sold in Ikpoba Hill Market and Aduwawa Quarters is highly contaminated with microorganisms. Practices of good hygiene are therefore necessary in an environment where kunun-zaki is produced, stored, prepared and packaged.

Determination of Salmonella enterica Leaf Internalization Varies Substantially According to the Method and Conditions Used to Assess Bacterial Localization.

In a previous study, comparing the internalization of S. enterica serovar Typhimurium in various leaves by confocal microscopy, we have demonstrated that the pathogen failed to internalize tomato leaves. Numerous reasons may account for these findings, yet one such factor might be the methodology employed to quantify leaf internalization. To this end, we have systematically studied leaf localization of a Green-fluorescent protein-labeled Salmonella strain in tomato, lettuce, and Arabidopsis leaves by surface sterilization and enumeration of the surviving bacteria, side by side, with confocal microscopy observations. Leaf sterilization was performed using either sodium hypochlorite, silver nitrate, or ethanol for 1 to 7min. The level of internalization varied according to the type of disinfectant used for surface sterilization and the treatment time. Treatment of tomato leaves with 70% ethanol for up to 7min suggested possible internalization of Salmonella, while confocal microscopy showed no internalization. In the case of in lettuce and Arabidopsis leaves, both the plate-count technique and confocal microscopy demonstrated considerable Salmonella internalization thought different sterilization conditions resulted in variations in the internalization levels. Our findings highlighted the dependency of the internalization results on the specific disinfection protocol used to determine bacterial localization. The results underscore the importance of confocal microscopy in validating a particular surface sterilization protocol whenever a new pair of bacterial strain and plant cultivar is studied.

Effectiveness of Quaternary Ammonium in Reducing Microbial Load on Eggs.

Table eggs are an affordable yet nutritious protein source for humans. Unfortunately, eggs are a vector for bacteria that could cause foodborne illness. This study aimed to investigate the effectiveness of a quaternary ammonium compound (quat) sanitizer against aerobic mesophilic bacteria, yeast, and mold load on the eggshell surface of free-range and commercial farms and the post-treatment effect on microbial load during storage. Total aerobic mesophilic bacteria, yeast, and molds were enumerated using plate count techniques. The efficacy of the quaternary ammonium sanitizer (quat) was tested using two levels: full factorial with two replicates for corner points, factor A (maximum: 200 ppm, minimum: 100 ppm) and factor B (maximum: 15 min, minimum: 5 min). Quat sanitizer significantly (p < 0.05) reduced approximately 4 log10 CFU/cm2 of the aerobic mesophilic bacteria, 1.5 to 2.5 log10 CFU/cm2 of the mold population, and 1.5 to 2 log10 CFU/cm2 of the yeast population. However, there was no significant (p ≥ 0.05) response observed between individual factor levels (maximum and minimum), and two-way interaction terms were also not statistically significant (p ≥ 0.05). A low (<1 log10 CFU/cm2) aerobic mesophilic bacteria trend was observed when shell eggs were stored in a cold environment up to the production expiry date. No internal microbial load was observed; thus, it was postulated that washing with quat sanitizer discreetly (without physically damaging the eggshell) does not facilitate microbial penetration during storage at either room temperature or cold storage. Current study findings demonstrated that the quat sanitizer effectively reduced the microbial population on eggshells without promoting internal microbial growth.

Ethnic food: A microbiological evaluation of black shellfish ceviche that is sold in typical restaurants

Ceviches are part of the cuisine in different countries of the Pacific coastal zone, they have become icons of the local cuisine. Despite the high consumption of black shellfish ceviche, there are no studies that evaluate the microbiological load in this type of preparation. Thus, the purpose of the study is focused on (i) conducting a microbiological analysis of back shellfish ceviche; and (ii) analyzing the habits of food handlers in charge of preparing ceviche. Data were collected in three typical restaurants called “Las huecas” located in Guayaquil-Ecuador. Samples of black shellfish ceviche were evaluated using the microbial plate count technique. The results highlight the absence of Salmonella in all replicates. However, food handling practices non-compliance were observed in the count of Aerobic mesophiles microorganisms; and Total coliforms should be controlled. Likewise, it is necessary to take corrective measures regarding handling and cooking the black shellfish ceviche. Finally, it is suggested to examine the ecosystems where the black shellfish is extracted.

Zinc oxide coated regenerated spent FCC catalyst for water purification

Introduction: Zeolites are microporous aluminosilicates, commonly used as commercial adsorbents and catalysts. As an adsorbent, zeolite can adsorb gram-positive bacteria when compared with gram-negative bacteria (1,2). Ultrafine zinc oxide nanoparticles in colloidal medium is toxic to E. coli bacteria (3). ZnO-coated zeolite adsorbent can effectively remove of humic acid and E. coli from water when compared to zeolite adsorbent (4-5). The spent FCC (SFCC) catalyst is very harmful to the human health by being absorbed mainly into the respiratory tract and lungs due to its tiny particles of size 60-100 micrometer (1). Most of the spent FCC catalysts are currently disposed as landfills, which leads to the wastage of valuable metal resources and the environmental pollution. In this work the spent zeolite catalyst is regenerated and coated with zinc oxide and this zinc oxide coated regenerated spent FCC catalyst (ZOCRSC) is used to remove E. coli from water. Methods: In this work, decoking is done to burning off the deposited carbon by roasting in air at 550°C for 2 hours. Then SFCC catalyst is leached with HCl and oxalic acid. Activated SFCC catalyst, obtained as a leaching residue is separated. Zinc oxide is coated on the regenerated catalyst to develop zinc oxide coated zeolite adsorbents. Coating procedure follows activated catalyst modified by HNO3 and then Zn(NO3)2 solution. To characterize crystal structure of zeolite and ZOCRSC, XRD, SEM, and BET analysis were carried out. The water from the treatment plant after secondary treatment was used for the experiments and the E. coli content was estimated using plate counting technique. ZOCZ is added to the E-coli containing water and after proper mixing the suspension is allowed to settle. Sample is collected from treated water at different intervals for determining E. coli content. The treatment procedure was also done using the spent coated sample, acid activated sample and spent FCC catalyst and are used as a comparison with ZOCZ. Results & Discussions: The XRD pattern shows that the ZOCRSC exhibited similar characteristic diffraction peaks to that of the uncoated samples which indicates that the modification did not affect the mineralogy of the zeolite and in addition it also exhibited similar characteristic diffraction peaks to those of ZnO. Thus, the XRD pattern and the SEM images of ZnO coated spent catalyst and ZnO coated regenerated catalyst shows that coatings of ZnO on zeolites were done effectively. The surface area and pore volume of zinc oxide coated regenerated spent FCC catalyst is determined from BET analysis. The removal of E. coli from water was quantified by plate counting. The E. coli count of the untreated water sample is 560 cfu/ml and treated sample after 30 minutes is less than 1 cfu/ml. Water treated using spent FCC catalyst without any modification did not show any change in the E. coli count. The acid activated catalyst and spent FCC catalyst coated with ZnO reduce the E. coli content in the water to 11 cfu/ml and 6 cfu/ml respectively after 90 minutes. Conclusions: ZnO coated regenerated spent FCC catalyst is developed from waste spent catalysts is utilized for the removal of E. coli from water. The ZOCRSC removes E. coli effectively when compared with spent FCC catalyst coated with ZnO, acid activated catalyst, and spent FCC catalyst in a short period. The spent FCC catalyst coated with ZnO cannot be directly used for treating purpose as it contains various contaminant metals which should not be present in treated water. Keywords: Escherichia coli, Spent FCC catalyst, Zinc oxide, ZOCRSC

Diversity and plant growth-promoting potential of actinomycetes associated with the rhizosphere of Arnebia euchroma from Himachal Pradesh (India)

Aim: The present study aimed to explicate the diversity and plant growth promoting (PGP) potential of actinomycetes present in the rhizosphere of an endangered medicinal plant, Arnebia euchroma. Methodology: Rhizospheric soil samples of A. euchroma collected from trans-Himalayan region of Himachal Pradesh were processed for elucidating actinomycetes diversity and load by employing Standard Plate Count Technique. All recovered isolates were screened for their PGP potential using standard protocols. The potential strains were identified through 16SrRNA ribotyping and were deposited in the National Culture Collection Centre, NCMR, Pune, (India). Results: The rhizosphere of A. euchroma harboured a great deal of actinomycetes diversity (33 diverse morphotypes). Starch casein agar was best for isolating the actinomycetes. The same actinomycete isolate showed variations in their morphological features including pigments production on different isolation media. They exhibited multifarious plant growth-promoting activities like P- solubilization, phytase activity, N- fixation, siderophore production etc. The potential isolates were identified as Streptomyces silaceus CA7 (MK836019) and Streptomyces rectiviolaceus NA8 (MK836018). Interpretation: The actinomycetes evinced a considerable plant growth promoting potential that might be helpful in the adaptation and perpetuation of A. euchroma under prevailing harsh environmental conditions of Himachal Pradesh.