Plate Count Method Research Articles

Comparison of SYBR® Green qPCR assay and plate count method to describe growth of Weissella viridescens and Leuconostoc mesenteroides in pure and mixed cultivation

The current study was conducted to statistically compare the SYBR® Green quantitative polymerase chain reaction (qPCR) assay and the conventional plate counting (PC) method to construct growth curves of a cocktail of Weissella viridescens in pure culture under different isothermal storage conditions (4, 8, 14, and 30 °C) and in mixed culture with Leuconostoc mesenteroides at 8 °C. The efficiency and specificity of the qPCR standard curves were confirmed, and both methods were adequate to quantify the growth kinetics of W. viridescens at all isothermal temperatures, demonstrating a good correlation and agreement. The efficiencies of the standard curves varied between 98% and 102%. The SYBR® Green qPCR assay was also able to differentiate the growth curves of W. viridescens and L. mesenteroides in the mixed culture at 8 °C. Additionally, the SYBR® Green qPCR method was considered a faster and more sensitive alternative to construct growth curves under different isothermal conditions and differentiate morphologically similar lactic acid bacteria. Overall, the results suggest that the SYBR® Green qPCR method is a reliable and efficient tool to study microbial growth kinetics in pure and mixed cultures.

Probiotic and postbiotic analytical methods: a perspective of available enumeration techniques.

Probiotics are the largest non-herbal/traditional dietary supplements category worldwide. To be effective, a probiotic strain must be delivered viable at an adequate dose proven to deliver a health benefit. The objective of this article is to provide an overview of the various technologies available for probiotic enumeration, including a general description of each technology, their advantages and limitations, and their potential for the future of the probiotics industry. The current "gold standard" for analytical quantification of probiotics in the probiotic industry is the Plate Count method (PC). PC measures the bacterial cell's ability to proliferate into detectable colonies, thus PC relies on cultivability as a measure of viability. Although viability has widely been measured by cultivability, there has been agreement that the definition of viability is not limited to cultivability. For example, bacterial cells may exist in a state known as viable but not culturable (VBNC) where the cells lose cultivability but can maintain some of the characteristics of viable cells as well as probiotic properties. This led to questioning the association between viability and cultivability and the accuracy of PC in enumerating all the viable cells in probiotic products. PC has always been an estimate of the number of viable cells and not a true cell count. Additionally, newer probiotic categories such as Next Generation Probiotics (NGPs) are difficult to culture in routine laboratories as NGPs are often strict anaerobes with extreme sensitivity to atmospheric oxygen. Thus, accurate quantification using culture-based techniques will be complicated. Another emerging category of biotics is postbiotics, which are inanimate microorganisms, also often referred to as tyndallized or heat-killed bacteria. Obviously, culture dependent methods are not suitable for these products, and alternative methods are needed for their quantification. Different methodologies provide a more complete picture of a heterogeneous bacterial population versus PC focusing exclusively on the eventual multiplication of the cells. Alternative culture-independent techniques including real-time PCR, digital PCR and flow cytometry are discussed. These methods can measure viability beyond cultivability (i.e., by measuring cellular enzymatic activity, membrane integrity or membrane potential), and depending on how they are designed they can achieve strain-specific enumeration.

Sensitive detection of Mycobacterium bovis in spiked milk using polymerase chain reaction assay

Bovine tuberculosis is a chronic zoonotic disease that affects both animal and human health and imposes serious public health concerns in the world. Intake of non-pasteurized milk is considered the most probable vehicle for the transmission of pathogenic bacteria. In this study, the detection of Mycobacterium bovis BCG in spiked milk using a polymerase chain reaction was performed. The performance of two DNA extraction methods, CTAB/phenol:chloroform:isoamyl alcohol and EXTRAGENMB were also evaluated. In addition, Mycobacterial concentration was tried to determine using the Standard/ Viable Plate Count Method and Spectrophotometric (Turbidimetric) Method. PCR successfully detected M. bovis BCG in spiked milk, detecting approximately up to two bacilli per reaction. The two DNA extraction methods were effective in the isolation of amplifiable DNA, having the advantage of EXTRAGENMB in terms of (1) shorter duration of DNA extraction, (2) less sample manipulation, and (3) ease of execution of the procedure. Quantitative determination of the Mycobacterial population however failed to quantify the bacterial concentration per dilution, suggesting that CFU concentration should be considered an approximation. It is expected that this method can be used for the detection of M. bovis in raw milk samples.

ANALISIS CEMARAN MIKROBIOLOGI BEBERAPA ASPEK PRODUKSI PADA PEDAGANG PENYEDIA MAKANAN DI SEKITAR KAMPUS UNIVERSITAS BUMIGORA MATARAM

Most health problems by food are caused by contamination of microorganisms. This contamination can due because cleanliness or improper implementation of sanitation and hygiene. The aim of this research is to identify microorganism contamination in the production aspects of food traders around the Campus of Bumigora University Mataram. Total microbial testing was carried out using the Total Plate Count (TPC) method for air, table, floor, equipment and water samples. Another method for testing coliforms in water use the principle of the Most Probably Number (MPN) method. The observation results show that the environmental quality as seen from the total microbes in the air is below the threshold, namely <700 col/m3, so it is said to be still safe. Meanwhile, table, floor and equipment samples showed that the total number of microbes was high enough to exceed the required threshold, especially those related to eating utensils such as plates, glasses and spoons. The total microbial test in the water sources used by the three traders showed that the two water sources used contained microbial colonies which were tested via TPC with colony numbers ranging from 87.7 – 99 x 10-5 CFU/ml. The results of the coliform estimation test using the MPN method principle showed that there was no suspicion of any coliform bacteria contamination in the two water samples, which indicated that both water sources also met the clean water requirements according to Minister of Health Regulation No. 492 of 2010.

The growth rate and antibacterial activity of lactic acid bacteria GMH2 and GMH3 in various salt concentration

Lactic acid bacteria (LAB) can be naturally found in fermented fish products that contain various salt concentrations. LAB is reported to produce proteinogenic antibacterial compounds named bacteriocin that can inhibit the growth of pathogenic and spoilage bacteria. In order to evaluate the performance of previously isolated LABs, namely GMH2 and GMH3, to inhibit the growth of these bacteria in fermented food systems, it is necessary to examine the effect of salt concentration on the growth rate and antibacterial activity. LAB GMH2 and GMH3 were inoculated on de man rogosa and sharp broth (MRSB) at various salt concentrations, including 0%, 7.5%, and 15%, followed by incubation at 37°C for 30 hours with observation every 6 hours. Bacterial growth was tested using the Total Plate Count (TPC) method, which was then further processed using the DMFit program to obtain growth rates, while antibacterial activity was tested using the macrodilution method against histamine-producing bacteria (HPB) Klebsiella pneumoniae (CK2). Both strains showed the highest growth rate at 0% NaCl, with 0.171 and 1.681 log CFU/hour for GMH2 and GMH3, respectively and remained steady until 7.5% salt concentration at 0,153 log CFU/hour for GMH2 and 0.044 log CFU/hour for GMH3. Antibacterial activity for both isolates showed the highest inhibitory value of 39.87±2.25% for GMH2 and 79.55±1.08 for GMH3. The addition of 7.5% and 15% interestingly did not show a significant reduction in antibacterial activity. The results of this study concluded that LAB GMH2 and GMH3 have the potency to be used as starters in fish fermented products, which possess up to 7.5% salt content.

The potential of Moringa oleifera extract as a phytobiotic candidate for the growth of Lactobacillus fermentum bacteria by in vitro

Moringa oleifera is used to explore the biodiversity of the ability of herbal plants as a candidate phytobiotic. The total carbohydrate content in the ethanol extract is 42% consisting of monosaccharides, disaccharides, and oligosaccharides which are gut micro-flora nutrient. The study aimed to discover the effect of moringa leaf extracts with different dosages to improve Lactobacillus fermentum bacteria’s growth. The study employed moringa leaf extracts and Lactobacillus fermentum bacteria then divided them into four groups, i.e., control group (P0), treatment P1 with moringa leaf extracts of 0.1% dosage, treatment P2 with moringa leaf extracts of 0.2%, and treatment P3 with moringa leaf extracts of 0.3% dosage. At the end of the treatment, each colony was calculated using the Total Plate Count method. Data obtained were analyzed using ANOVA and subjected to the Duncan test. The study results show that moringa leaf extracts with dosages of 0.1%, 0.2%, and 0.3% could improve Lactobacillus fermentum bacteria’s growth. The average growth log of Lactobacillus fermentum bacteria on treatment P0 was 3,532 log CFU/ml, 4,320 log CFU/ml for treatment P1, 4,368 log CFU/ml for treatment P2, and 4,480 log CFU/ml for treatment P3 as the highest value.

Comparison of chlorine dioxide and chlorhexidine 2% antiseptic in reducing bacterial colony counts as an alternative to DUWLs cleaning: a quasi-experimental study

ABSTRACTIntroduction: The inner surfaces of dental unit waterlines (DUWLs) possess an accumulation of any bacteria. Microorganisms can enter dental unit waterlines from water reservoirs. Antiseptics are substances that inhibit the growth of bacteria. Chlorine dioxide is effective in decontaminating microbes in the DUWLs and has a beneficial effect on reducing nosocomial infections. Chlorhexidine effectively prevents the growth of Streptococcus bacteria. The addition of antiseptic agents to the water source contributed to a significant reduction of the cultivable microbial counts in the aerosol. The purpose of this study was to analyze the difference between Chlorine Dioxide 0,1% and Chlorhexidine 2% antiseptics on the number of bacterial colonies in the Dental Unit Waterline. Methods: This study was a quasi-experimental study with a total sample size of 8 dental units that have water tanks in the oral surgery clinic. The sampling technique was total sampling, where the sample was divided into 2 groups, group I using Chlorine Dioxide and group II using 2% Chlorhexidine calculation of colony counts unit using the plate count method. Results: The difference in the number of colonies before being given Chlorine Dioxide was 13,153 CFU/mL and after being given Chlorine Dioxide antiseptic was 6,070 CFU/mL, while before being given 2% Chlorhexidine antiseptic was 12,917 CFU/mL and after being given 2% Chlorhexidine antiseptic was 2,823 CFU/mL. There is a significant difference in the number of bacterial colonies before and after being given Chlorine Dioxide and Chlorhexidine 2% antiseptic with ρ=0.001; Conclusion: Chlorhexidine 2% reduces bacterial colony forming unit in DUWLs much more than using Chlorine dioxide for the alternative of DUWLs Cleaning Agents.Keywords: DUWLs, chlorine dioxide, chlorhexidine 2%, bacterial colony counts

Comparison of new and old BacT/ALERT aerobic bottles for detection of Candida species.

A new version of aerobic blood culture media has been developed for the BacT/ALERT (bioMérieux) blood culture system. We evaluated the time to detection and yeast cell counts in positive blood cultures for each Candida spp. according to changes in media. Isolates from defibrinated horse blood were inoculated into three types of bottles: the old version of aerobic bottle, new version of aerobic bottle, and anaerobic bottle. All bottles were incubated in the BacT/ALERT Virtuo blood culture system. The time to detection was monitored for each bottle, and yeast cell counts were performed immediately after testing positive, determined via the plate count method. Clinical retrospective data of the candidemia samples before and after aerobic bottle change also were analyzed. The median time to detection was 52.47 hours in the old aerobic bottles versus 19.92 hours in the new aerobic bottles (P < 0.001) for Candida glabrata, and standard and clinical strains showed similar results. C. albicans (27.6 to 24.95 hours) and C. guilliermondii (28.92 to 26.9 hours) had shorter time to detection. However, C. auris (25.43 to 28.25 hours) had a longer time to detection in the new aerobic bottle. The retrospective clinical analysis showed a significant decrease in time to detection (45.0 to 19.4 hours) for C. glabrata, which is consistent with our simulated study result for C. glabrata. As a result of analysis including all blood specimens, C. tropicalis showed a significant delay in time to detection in new aerobic bottles. In an analysis limited to peripheral blood specimens, the time to detection of C. parapsilosis was longer in new aerobic bottles than in old aerobic bottles. Most Candida species did not show remarkable TTD differences, but TTD of C. glabrata was markedly reduced in the New FA Plus bottle. The reduction of time to detection enables faster detection and therapeutic approach for C. glabrata infections.

Food grade disinfectants based on hydrogen peroxide/peracetic acid and sodium hypochlorite interfere with the adhesion of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Listeria monocytogenes to stainless steel of differing surface roughness

This study aimed to evaluate the potential of the bacterium Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Listeria monocytogenes to adhere to stainless steel discs with differing degrees of surface roughness (Ra = 25.20–961.90 nm). Stainless steel is a material commonly used in the food industry for processing equipment, which is regularly exposed to cleaning procedures. The investigation included the commercial disinfectants hydrogen peroxide/peracetic acid and sodium hypochlorite which were evaluated for their antibacterial and anti-adhesion activity. The adhesion was assessed by the standard plate count method, while the broth microdilution method CLSI M07-A10 was used to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the disinfectants. Based on the MIC values, both disinfectants exerted significant inhibitory effects with MIC values for hydrogen peroxide/peracetic acid and sodium hypochlorite of 250 µg ml−1 and 500 µg ml−1, respectively. Whereas the MBC values were equal to the MIC for all bacteria except for E. coli with values 2-fold higher than the MIC. Obtained results also revealed that all tested bacteria were able to adhere to stainless steel surfaces, although differences were found for strains and surface roughness. The lowest adhesion rate of each strain was recorded on the roughest stainless steel disc at a Ra of 961.90 nm. Further, at a concentration of 1 MIC, the disinfectant sodium hypochlorite reduced initial bacterial adhesion to stainless steel surfaces to a significantly greater extent than the disinfectant hydrogen peroxide/peracetic acid. These findings are consistent with the results obtained by Scanning Electron Microscopy (SEM) analysis, which indicates the great applicability of the tested disinfectants for the control of bacterial adhesion in the food industry.

Isolation, Characterisation and Evaluation of Plastic Degrading Properties of Soil Biofilms Collected from Chennai District

Environmental pollution due to accumulation of synthetic polymers namely plastics is a growing concern which threatens the terrestrial marine flora and fauna. Traditional methods of plastic disposal include incineration and disposal into landfills or water bodies. Incineration of polyethylene, polystyrene leads to emission of a large amount of carbon monoxide which is toxic if inhaled and also a potent greenhouse gas. Degradation of plastic by microorganisms is an efficient and eco-friendly method employed for rapid rate of disintegration. The biofilm present in the contaminated soil survives by adapting to harsh environment by secreting hydrolysing enzymes which are potent in degradation of the accumulated plastics. The present study deals with the isolation, characterisation and evaluation of plastic degrading properties of microorganisms isolated from various soil samples collected from Chennai district. Soil samples were collected aseptically from various locations &amp; isolated by standard plate count method. The isolated organisms were identified by staining methods and characterized by phylogenetic analysis. The organism Pseudomonas aeruginosa and Streptomyces fulvissimus were further subjected to plastic degradation testing. The present study demonstrates the ability of Pseudomonas aeruginosa and Streptomyces fulvissimus to degrade polyethylene sheets.

Microbial Profile of Fresh and Semicooked Nile Tilapia (Oreochromis niloticus) and Hygienic Practice of Fish Handlers in Hawassa, Ethiopia.

Despite its high nutritional quality, fish is a highly perishable food item. This study aimed at assessing the microbial quality and safety of fresh and semicooked Nile tilapia fish fillets and the food safety practices of fish handlers in Hawassa City. The microbial load of 40 for each of raw and semicooked fillet samples was estimated by the standard plate count method, and the dominant flora as well as common bacterial pathogens were identified following phenotypic procedures. Moreover, a survey was conducted to assess the hygienic conditions and food safety practices of 30 fish handlers. The mean microbial load of the raw fillet samples in log10CFUg-1 was 8.42 for aerobic mesophilic bacteria (AMBC), 2.52 for total coliforms (TCC), and 3.41 for a count of staphylococci (CS). On the other hand, the respective parameters for the semicooked fillets in log10CFUg-1 were 6.68 (AMBC), 2.52 (TCC), and 3.17 (CS). The mean AMBC of all the fresh raw fillet samples exceeded the recommended maximum permissible limits. The mean SC of raw fillets from three of the eight vendors and one semicooked fillet were at a potentially hazardous level (>4 log units). Moreover, Salmonella species were isolated from 30% to 25% of raw and semicooked samples, respectively. The mesophilic bacterial flora of both types of samples was dominated by Bacillus species, Salmonella species, E coli, and Staphylococcus species. Most fish handlers did not practice hygienic food handling and lacked basic sanitation amenities like clean water and soap for hand washing. Moreover, nearly all the fish handlers did not have any formal education. These findings call for public health intervention measures like the provision of training in good hygienic practices and certification for fish vendors in the chain.

Biodegradable and pH-Responsive Amphiphilic Poly(succinimide) Derivatives for Triggered Release of Antibiotics for Management of Infected Wounds.

Wound infection has become a healthy economic burden globally. Current wound management mainly relies on the use of antibiotics; however, the misuse and overuse of antibiotics can easily result in antibiotic resistance. This study proposes a biodegradable, biocompatible, and pH-responsive amphiphilic 11-aminoundecanoic acid-grafted polysuccinimide (AUA-PSI) as a nanocarrier for drug encapsulation via nanoprecipitation. The succinimide groups in the backbone of PSI allow facile postfunctionalization via an aminolysis reaction. The degree of substitution of AUA can be modulated to adjust the degradation rate, pH sensitivity, and drug-release profile. Antibiotic rifampicin was incorporated with AUA-PSI to form Rif-AUA-PSI nanoparticles and demonstrated pH-responsiveness and antimicrobial activity. Because of the elevation of the pH value from pH = ∼ 5.5 in healthy skin to pH > 7 in an infected wound, Rif-AUA-PSI nanoparticles begin to decompose and release Rif upon the hydrolysis of succinimide/amide and deprotonation of carboxyl groups. The effective suppression of bacterial growth by Rif-AUA-PSI nanoparticles was demonstrated using a plate count method. More importantly, Rif-AUA-PSI nanoparticles were physically deposited on cotton gauze bandages as an antibiotic wound dressing. The Rif-AUA-PSI-modified gauze was applied to infected wounds on rats for wound management. The results show fast wound healing and inhibition of bacterial growth, which demonstrate that the method promotes modulable amphiphilicity, biodegradability, biocompatibility, pH-responsiveness, and facile modification for nanomedicine and medical devices.

Recalls of tattoo and permanent makeup inks in the United States and a follow-up microbiological survey of inks with a previous recall history.

In this study, we collected voluntary recall records of tattoo and permanent makeup ink from the U.S. Food and Drug Administration (US FDA) Enforcement Report Database. The recall records contain information, such as recall date, manufacturer, ink color, reason for recall, and the microorganisms detected from the ink samples. Between 2003 and 2021, a total of 15 voluntary tattoo ink recalls occurred in the U.S. market, involving over 200 tattoo inks marketed by 13 manufacturers and one distributor. Fourteen recalls were due to microbial contamination, and one recall was due to allergic reaction. As follow-up, a microbiological survey of 28 tattoo inks of new batches from seven manufacturers having products that were previously recalled was conducted. Aerobic plate count (APC) and enrichment culture methods based on the FDA's Bacteriological Analytical Manual (BAM) were used to detect microbial contamination. The results revealed that six out of 28 tattoo inks were contaminated with bacteria and were produced by two manufacturers. The level of microbial contamination was less than 250 CFU/g in three of the tattoo inks and between 1 × 103 and 1 × 105 CFU/g in the other three inks. Eleven bacterial isolates were identified, including spore-forming Bacillus-related species and potentially pathogenic species. Overall, this study shows that some tattoo ink products produced by manufacturers with a recall history continue to be contaminated with microorganisms. This highlights the need for ongoing monitoring and quality control of such products.

Effect of silver nanoparticles on the morphological, antibacterial activity and performance of graphene oxide-embedded polyvinylidene fluoride membrane

In this work, a different ratio of silver nanoparticles (Ag NPs) was used as a nanofiller on graphene oxide (GO)-embedded polyvinylidene fluoride (PVDF) membranes fabrication through a non-solvent induced phase separation method. The morphology of fabricated membranes was investigated using FTIR, XRD, and SEM-EDX techniques. The fabricated membranes were tested for Bovine Serum Albumin (BSA) rejection and Molecular Weight Cut Off (MWCO) with various initial concentrations of 100 – 400 ppm and 6 – 145 kDa, respectively using a crossflow method, as well as antibacterial activity against four strains bacteria via total plate counting and Kirby-Bauer method. The incorporation of hydrophilic GO and Ag NPs obviously alters membrane morphology, enhances membrane’s porosity and hydrophilicity. Moreover, it improves membrane crystallinity (> 70%) as indicated by the higher XRD peaks intensity. Based on the crossflow measurements, the membrane fabricated with GO and Ag ratio of 1: 3 (PVDF/GO/AgNPs – 3) demonstrated the highest BSA flux of 83.81 L/m2 h, which was third-fold higher than that of PVDF membrane as well as high BSA rejection (> 94%) and MWCO of ∼3 kDa. According to the observation, PVDF/GO/AgNPs – 3 also possessed a high bacteria killing ratio of > 94% and a large inhibition zone of ≥ 1.5 mm toward all bacteria strains. These results inferred that PVDF/GO/Ag membrane has great potential as antibiofouling membranes.

Development of PMA-qPCR assay to accurately and reproducible quantify viable bacteria of Paenibacillus polymyxa.

Paenibacillus polymyxa is an important biocontrol bacterium. The combination of propidium monoazide (PMA) and quantitative polymerase chain reactionq (qPCR) has proven effective in quantifying live bacteria from various microorganisms. The objective was to create a PMA-qPCR assay to precisely and consistently measure the number of living bacteria of biocontrol P. polymyxa. The primers were designed for the spo0A gene of P. polymyxa HY96-2. The optimal conditions for treating the target strain with PMA were a PMA concentration of 15 μg/mL, an incubation time of 5 min, and an exposure time of 10 min. The PMA-qPCR method had a limit of quantification (LOQ) of 1.0×103 CFU/mL for measuring the amount of viable P. polymyxa bacteria. The PMA-qPCR method is more sensitive than the qPCR method in detecting viable bacteria in the mixtures of viable and dead bacteria. The accuracy and reproducibility of quantifying viable P. polymyxa bacteria using the PMA-qPCR method were higher compared to the plate count method.

Efektivitas Ekstrak Edamame (Glycine Max L. Merril) terhadap Streptococus Mutans pada Kawat Orthodontik Berbahan Nikel Titanium

Tooth movement in Orthodontic is brought about orthodontic archwire, which generate the biomechanical forces, transmit these forces via brackets to bring about tooth movement. Niti wire are the most commonly used in orthodontic treatment. These devices have characteristics that can lead to plaque accumulation. This study aims to assess the effectiveness of edamame extract (Glycine max L. Merril) Against Streptococcus Mutans (S. mutans) on orthodontic Nickel Titanium (NiTi). This study was an in vitro laboratory experimental study with a posttest only control group design. Edamame were extracted using the maceration method using 70% ethanol. NiTi immersed in artificial saliva in order to form pellicles for bacterial adhesion. NiTi that has been formed pellicles are then contaminated with S. mutans bacterial suspension, then cleaning is done by immersing in distilled water and edamame extract (Glycine Max L. Merril) with a concentration of 50, 75 and 100mg/ ml then observation is carried out by counting the number of colonies. with the Total Plate Count (TPC) method. The results showed that the smallest average number of S. mutans colonies was found in the edamame extract concentration of 75 and 100mg/ml. The statistical results showed that there was a significant difference between the 75 mg / ml edamame extract group and the negative control. Edamame extract with concentration of 50 mg/ml is an effective concentration in inhibiting the growth of S.Mutans bacteria.

Analysis of Yeast Mold Contamination in Commercialized Chicken Sempol in Karanganyar District, Karanganyar Regency, Central Java

This research wants to find out if there is yeast mold in chicken sempol in Karanganyar Regency. The scientists used 10 chicken meat samples and a special kind of food for the bacteria to grow on. They also used water that had been purified. We did a study by watching how yeast mold grows, and then describing the results. The yeast mold test was done using the Total Plate Count (TPC) method. The samples were kept at a warm temperature for 7 days, and information was recorded on the 3rd, 5th, and 7th day. We compared the results with regulations from the Food and Drug Supervisory Agency (BPOM) No. In 2019, a new rule was made about how much yeast mold is allowed in processed meat. Please re-write this text using simpler words. The research found that samples A, B, and C had the most mold and yeast between the 3rd and 7th days of observation. At that time, sample G had the least amount of mold and yeast. Keywords:chicken sempol, yeast mold contamination, TPC.

A calibration-free, non-invasive, and accurate total viable count detection method based on tunable diode laser absorption spectroscopy combined with most probable number counting

Total viable count (TVC), as an important indicator in the microbiological detection. A calibration-free, non-invasive, and accurate TVC detection method was developed using the most probable number (MPN) method and tunable diode laser absorption spectroscopy (TDLAS). In the experiment, a tunable distributed feedback (DFB) laser with a center wavelength of 4989.97 cm−1 was used to measure CO2 emitted from the microorganisms in a sealed culture bottle. Then, the thresholds of negative and positive culture bottles in the MPN-TDLAS method were established by the features of the Staphylococcus aureus (S. aureus) growth curve. The experimental results revealed that the MPN-TDLAS method has a good correlation (R2 = 0.99) with the TVC of the ISO:4833:2013 standard plate counting method, and the result of the quality control (QC) sample was satisfactory (Z-score was less than 2), which demonstrated that this method is well-suited for food microbiology testing applications.

In-vitro effectiveness of a novel herboclean herbal solution in removing pesticides, heavy metals and microbial agents from fruits and vegetables

In recent years, the incidence of undesirable heavy metals, pesticide residues and microbial contaminants in fruits and vegetables has caused severe worldwide public health concerns. In this investigation, we intended to investigate the in-vitro effectiveness of a novel herboclean herbal solution in eliminating pesticides, heavy metals and microbes from the fruits and vegetables collected from various markets. The collected fruits and vegetables were immersed separately in a beaker containing an already prepared herboclean herbal solution for 30 min. The efficacy of the herboclean herbal solution in removing the pesticides and heavy metals was studied using Liquid Chromatography-Mass Spectrometry (LC-MS), and Inductively Plasma Mass Spectrometry (ICPMS), respectively. The reduction in microbes was analyzed by the plate count method. From the result, it was clear that the average removal rate of pesticide residues from fruits and vegetables was 89.89±7.21%. In the case of heavy metals average removal rate was 94.74±9.12%. Whereas in the case of microbes, the removal rate was 90.98±8.38% after washing with Herboclean herbal solution. These results clearly demonstrated that the herboclean herbal solution was very effective in eliminating various pesticides, heavy metals and microbial agents from fresh fruits and vegetables without interfering with their integrity or sensorial parameters. Moreover, this is the first report regarding the efficacy of natural herboclean herbal solutions.

The Effect of Corn (Zea mays) Cob Extract on the Growth of Bifidobacteria

Corncob is a source of dietary fiber, contains xylan polysaccharides (12.4%–31.94%), and is classified as the highest xylan-producing source compared to other agricultural wastes. Human digestive enzymes cannot degrade xylan but can be enzymatically degraded by lactic acid bacteria (LAB) through fermentation. This research aimed to evaluate the effect of corncob extract on the growth of Bifidobacterium. Corncob extract is obtained through alkaline extraction. The growth of Bifidobacterium bifidum FNCC 0462 and Bifidobacterium longum FNCC 0463 was observed through in vitro fermentation for 48 h using the total plate count (TPC) method. Bifidobacterium bifidum FNCC 0462 showed the ability to ferment corn cob extract for 48 h of fermentation with the highest growth at 8 h of fermentation (4,08 log10 CFU/mL) while B. longum FNCC 0463 was able to grow up to 16 h of fermentation only. The results indicated that corncob extract could support B. bifidum FNCC 0462 growth.