Protein,enzyme and carbohydrate quantification using smartphone through colorimetric digitization technique

In this paper the utilization of smartphone as a detection platform for colorimetric quantification of biological macromolecules has been demonstrated. Using V‐channel of HSV color space, the quantification of BSA protein, catalase enzyme and carbohydrate (using D‐glucose) have been successfully investigated. A custom designed android application has been developed for estimating the total concentration of biological macromolecules. The results have been compared with that of a standard spectrophotometer which is generally used for colorimetric quantification in laboratory settings by measuring its absorbance at a specific wavelength. The results obtained with the designed sensor is found to be similar when compared with the spectrophotometer data. The designed sensor is low cost, robust and we envision that it could promote diverse fields of bio‐analytical investigations.

Schematic illustration of the smartphone sensing mechanism for colorimetric analysis of biomolecular samples.     

Understanding the effects of culture conditions in bacterial growth: A biochemical perspective using Raman microscopy

Rapid, sensitive and label‐free methods to probe bacterial growth irrespective of the culture conditions can shed light on the mechanisms by which bacteria adapt to different environmental stimuli. Raman spectroscopy can rapidly and continuously monitor the growth of bacteria under varied conditions. In this study, the growth of Escherichia coli in Luria broth (nutrient rich conditions) and minimal media with either glucose or glycerol as carbon source (nutrient limiting conditions) is profiled using Raman spectroscopy. Moreover, the study also gives insights into the altered bacterial biochemistry upon exposure to low‐ (25°C) and high‐temperature (45°C) stress. Raman spectral measurement was performed on bulk bacteria cultured under laboratory conditions. A detailed analysis of the spectra as a function of bacterial growth reveals changes in Raman band intensities/area of biomolecules such as DNA, proteins and lipids. We also report five novel ratiometric markers (I₈₃₀/I₈₁₀, I₁₁₂₆/I₁₁₀₀, I₁₃₄₀/I₁₄₄₀, I₁₂₀₇/I₁₂₄₀ and I₁₅₈₀/I₁₄₄₀) that can identify the phase of growth, independent of the culture condition. Unsupervised multivariate methods like Principal Component Analysis also corroborate the aforementioned markers of growth. Altogether, our findings highlight the potential of Raman spectroscopy in yielding universal biochemical signatures that may be indicative of stress and aging in a growth milieu.     

ESTIMATION OF MICROBIOLOGICAL QUALITY OF CHILLED BEEF USING AUTOMATED TURBIDIMETRY

Total bacterial counts on chilled beef samples were estimated by the standard plate count method and by an automated turbidimetric system. The latter method is based on product-specific calibration curves constructed by correlating growth curve parameters calculated for the turbidimeter to the log CFU values obtained by plate counts. A total of 74 beef samples was used to construct the calibration curves. Correlation analysis between turbidimetric parameters and plate count values showed that detection time was the best predictor to estimate microbial loads on fresh (r=0.91) and aged beef (r=0.94). Microbial loads for a different set of aged beef samples (n = 37) refrigerated for 7, 9, 10, 17 and 45 days were compared by turbidimetric measurements and plate counts. Mean total viable counts were log 5.92 ± 1.17 and log 5.54 ± 1.28 CFU/mL, respectively. Results showed that total bacterial counts on chilled beef could be estimated accurately from turbidimetric parameters. Furthermore, setting a cut-off value of log 6 CFU/mL allowed to accepting/rejecting samples according to their microbial condition in shorter periods of time compared to the traditional plate count method.     

Superhydrophobic nanocarbon-based membrane with antibacterial characteristics

To overcome the biofouling challenge which faces membrane water treatment processed, the novel superhydrophobic carbon nanomaterials impregnated on/powder activated carbon (CNMs/PAC) was utilized to successfully design prepare an antimicrobial membrane. The research was conducted following a systematic statistical design of experiments technique considering various parameters of composite membrane fabrication. The impact of these parameters of composite membrane on Staphylococcus aureus growth was investigated. The bacteria growth was analyzed through spectrophotometer and SEM. The effect of CNMs' hydrophobicity on the bacterial colonies revealed a decrease in the abundance of bacterial colonies and an alteration in structure with increasing the hydrophobicity. The results revealed that the optimum preparative conditions for carbon loading CNMs/PAC was 363.04 mg with a polymer concentration of 22.64 g/100 g, and a casting knife thickness of 133.91 μm. These conditions have resulted in decreasing the number of bacteria colonies to about 7.56 CFU. Our results provided a strong evidence on the antibacterial effect and consequently on the antibiofouling potential of CNMs/PAC in membrane.     

Nanoplasmonic sensor for foodborne pathogens detection. Towards development of ISO‐SERS methodology for taxonomic affiliation of Campylobacter spp.

According to EU summary report on zoonoses, zoonotic agents and food‐borne outbreaks in 2017, Campylobacter was the most commonly reported gastrointestinal bacterial pathogen in humans in the EU. Unfortunately, the standard methods for the detection of thermotolerant Campylobacter spp. in foods are time‐consuming. Additionally, the qualified staff is obligatory. For this reason, new methods of pathogens detection are needed. The present work demonstrates that surface‐enhanced Raman scattering (SERS) is a reliable and fast method for detection of Campylobacter spp. in food samples. The proposed method combines the SERS measurements performed on an Ag/Si substrate with two initial steps of the ISO standard procedure. Finally, the principal component analysis (PCA) allows for statistical classification of the studied bacteria. By applying the proposed ISO‐SERS‐PCA method in the case of Campylobacter bacteria the total detection time may be reduced from 7 to 8 days required by ISO method to 3 to 4 days in the case of SERS‐based approach.     

Peptones from diverse sources: pivotal determinants of bacterial growth dynamics

Aims: In view of the major problems encountered by microbiologists in obtaining reproducible data on growth dynamics in complex media, we studied the effects of different peptones made from different biological sources and produced by numerous manufacturers. Methods and Results: Peptones (including casein, gelatin, meat, soy and yeast) were assessed as a constituent of the pre‐enrichment broth buffered peptone water (BPW). Generation times (g) and yields of Salmonella serovar Typhimurium were significantly affected by the type of peptone employed with yeast peptones generating yields of 7·04 × 10⁹ CFU ml^?1 and gelatin peptones producing 0·81 × 10⁹ CFU ml^?1. Medium sterilization was also found to have significant effects (P = 0·000) upon subsequent bacterial growth. Filter sterilization of BPW media produced lower generation times compared with those obtained after sterilization by autoclaving. Finally, it was observed that some peptones which produced good growth when inoculated with healthy organisms, showed relatively poor growth when inocula were sublethally injured by heating. Conclusions: Variation in peptone as a constituent of BPW has a significant effect on growth and enumeration of bacteria. Significance and Impact of the Study: Increased consideration with respect to culture media may significantly improve bacterial growth and experimental reproducibility.     

Colorimetric/fluorescent bacterial sensing by agarose-embedded lipid/polydiacetylene films

Aim: Development of a new chromatic (colorimetric/fluorescence) bacterial sensor, for rapid, sensitive and versatile detection of bacterial proliferation. Methods and Results: We constructed agarose‐embedded chromatic films which produce dramatic colour changes and fluorescence transformations in response to bacterial growth. The sensing constructs comprise glass‐supported Langmuir–Schaeffer phospholipid/polydiacetylene films that undergo both blue‐red transformations and induction of intense fluorescence following interactions with bacterially secreted amphiphilic compounds that diffuse through the agarose. The agarose matrix coating the sensor film further contains growth nutrients, facilitating signal amplification through promotion of bacterial culture proliferation. The agarose layer also constitutes an effective barrier for reducing background signals not associated with the bacteria. We demonstrate the applications of the new sensor for the detection of Gram‐negative and Gram‐positive bacteria, and for screening specimens of physiological fluids (blood and urine) and foods (meat) for bacterial contaminations. Conclusions: The experiments demonstrate that the new agarose‐embedded film constructs are capable of bacterial detection through visible colour transitions and fluorescence emission recorded in conventional apparatuses. Significance and Impact of the Study: This work demonstrated a new simple chromatic platform for bacterial detection, based on the generation of easily recorded colour and fluorescence changes. The new bacterial detection scheme is highly generic and could be employed for varied practical uses, in which, rapid reporting on bacterial presence is required.     

抗感青枯病番茄的内生细菌数量动态分析及其对青枯病的生物防治

对番茄内生细菌数量动态及其对青枯病的生物防治研究结果表明:番茄内生细菌可来源于种子内部。番茄不同生育期,内生细菌数量最多在成株期,其中抗病品种根、茎分别为24.3×104CFU/g鲜重和22.9×104CFU/g鲜重,感病品种根、茎分别为9.8×104CFU/g鲜重和13.4×104CFU/g鲜重。抗病品种中具有拮抗青枯菌的内生细菌菌株为17个,感病品种中7个。部分内生细菌具促进番茄种子萌发和防治番茄青枯病的作用,其中5R和3R内生菌株的防病效果分别达91.7%和81.3%。     

A magnetoelastic resonance biosensor immobilized with polyclonal antibody for the detection of Salmonella typhimurium

Mass-sensitive, magnetoelastic resonance sensors have a characteristic resonant frequency that can be determined by monitoring the magnetic flux emitted by the sensor in response to an applied, time varying, magnetic field. This magnetostrictive platform has a unique advantage over conventional sensor platforms in that measurement is wireless and remote. A biosensor for the detection of Salmonella typhimurium was constructed by immobilizing a polyclonal antibody (the bio-molecular recognition element) onto the surface of a magnetostrictive platform. The biosensor was then exposed to solutions containing S. typhimurium bacteria. Binding between the antibody and antigen (bacteria) occurred and the additional mass of the bound bacteria caused a shift in the sensor's resonant frequency. Sensors with different physical dimensions were exposed to different concentrations of S. typhimurium ranging from 10(2) to 10(9)CFU/ml. Detection limits of 5x10(3) CFU/ml, 10(5) CFU/ml and 10(7) CFU/ml were obtained for sensors with the size of 2 mmx0.4 mmx15 microm, 5 mmx1 mmx15 microm and 25 mmx5 mmx15 microm, respectively. Good agreement between the measured number of bound bacterial cells (as measured by scanning electron microscopy (SEM)) and frequency shifts was obtained.     

Biological control of streptococcal infection in Nile tilapia Oreochromis niloticus (Linnaeus, 1758) using filter‐feeding bivalve mussel Pilsbryoconcha exilis (Lea, 1838)

Since bivalve mussels are able to graze heavily on bacteria, in this paper it is hypothesized that when mussels are cultured with fish, the filtering efficiency of the mussels will keep the bacterial population below a certain threshold and thus assist in reducing the risk of bacterial disease outbreaks. The ability of the filter‐feeding bivalve mussel Pilsbryoconcha exilis to control Streptococcus agalactiae was tested in a laboratory‐scale tilapia culture system. Juvenile Nile tilapia (Oreochromis niloticus), the bivalve mussel as well as the bacteria were cultured at different combinations using four treatments: treatment‐1: mussel and bacteria but no fish, treatment‐2: tilapia and mussel but no bacteria, treatment‐3: tilapia and bacteria but no mussel, and treatment‐4: tilapia, mussels, and bacteria. All treatments were run in three replicates; stocking rates were 10 tilapia juveniles; five mussels; and about 3.5 × 10⁵ colony forming units (CFU) ml^?1 of bacteria in 50‐L aquaria with 40‐L volume. The mussel reduced the bacterial population by 83.6–87.1% in a 3‐week period whereas in the absence of the mussel, the bacterial counts increased by 31.5%. Oresence of the mussel also resulted in significantly higher growth and lower mortality of tilapia juveniles than when the mussel was absent. The results of this experiment suggest that the freshwater mussel P. exilis could control the population of S. agalactiae in a laboratory‐scale tilapia culture system. Future studies should focus on the dynamic interactions among fish, mussels, and bacteria as well as on how input such as feed and other organic materials affect these interactions.     

A-Factor as a selective agent for isolation of the soil Gram-negative bacterium strain--the producent of an antibacterial antibiotic]

It was shown the stimulating role of A-factor on soil prokaryotes growth. Soil sample culturing on agar medium, containing A-factor, resulted in the colony forming units (CFU) increasing in comparison with culturing on the medium without this regulator. Gram-negative bacteria were the reason of CFU increasing; previously the effect of A-factor on bacteria of this group was not shown. Gram-negative rod bacterial strain No. 35 was isolated and shown that CFU number was approximately twice increased at A-factor concentration in agar medium 2 and 7 mcg/ml; high A-factor concentration up to 28 mcg/ml was not effective. Isolated strain No. 35 is the producer of antibiotic, effective against gram-positive bacteria.     

Modeling bacterial contamination of fuel ethanol fermentation

The emergence of antibiotic‐resistant bacteria may limit the effectiveness of antibiotics to treat bacterial contamination in fuel ethanol plants, and therefore, new antibacterial intervention methods and tools to test their application are needed. Using shake‐flask cultures of Saccharomyces cerevisiae grown on saccharified corn mash and strains of lactic acid bacteria isolated from a dry‐grind ethanol facility, a simple model to simulate bacterial contamination and infection was developed. Challenging the model with 10⁸ CFU/mL Lactobacillus fermentum decreased ethanol yield by 27% and increased residual glucose from 6.2 to 45.5 g/L. The magnitude of the effect was proportional to the initial bacterial load, with 10⁵ CFU/mL L. fermentum still producing an 8% decrease in ethanol and a 3.2‐fold increase in residual glucose. Infection was also dependent on the bacterial species used to challenge the fermentation, as neither L. delbrueckii ATCC 4797 nor L. amylovorus 0315‐7B produced a significant decrease in ethanol when inoculated at a density of 10⁸ CFU/mL. In the shake‐flask model, treatment with 2 µg/mL virginiamycin mitigated the infection when challenged with a susceptible strain of L. fermentum (MIC for virginiamycin ≤2 ppm), but treatment was ineffective at treating infection by a resistant strain of L. fermentum (MIC = 16 ppm). The model may find application in developing new antibacterial agents and management practices for use in controlling contamination in the fuel ethanol industry. Biotechnol. Bioeng. 2009;103: 117–122. Published 2008 Wiley Periodicals, Inc.     

The microbial threat: Can rare earths help?

Despite an ever increasing demand for reliable and cheap methods in the detection and quantification of microbes, surprisingly few investigations have explored or utilized the luminescence of rare earths in the microbial context, neither in conventional, that is, plating and microscopic imaging techniques, nor in advanced methods like fluorescence flow cytometry. We have thus investigated the potential of some rare earth complexes and hybrid materials for microbiological analysis. We found fairly simple procedures for internal staining (dyes inside the bacterial cell) and external staining (dyes on the cell surface). The present paper is predominantly relying on microscopic imaging and luminescence spectroscopies (excitation, emission, decay times), but also evaluates model rare earth microspheres to estimate an eventual rare earth based stain for a fast and sensitive bacteria enumeration with luminescence flow cytometry.     

Specific labeling and identification of bacteria based on concentration-dependent carbon dot staining combined with hyperspectral imaging

Concentration-dependent carbon dot (CD) fluorescence was developed and utilized alongside hyperspectral microscopy as a specific labeling and identification technique for bacteria. Staining revealed that the CD concentration within cells depended on the characteristic intracellular environment of the species. Therefore, based on the concentration dependence of the CD fluorescence, different bacterial species were specifically labeled. Hyperspectral microscopy captured subtle fluorescence variations to identify bacteria. Method validation using Bacillus subtilis and Bacillus licheniformis succeeded with an identification accuracy of 99%. As a simple, rapid method for labeling and identifying bacterial species in mixtures, this technique has excellent potential for bacterial community studies.     

A method to assess the bacterial content of refrigerated meat

A new method has been developed to estimate the levels of gram-negative bacteria on refrigerated meat. The method is based on the aminopeptidase activity of these bacteria, which cleaves L-alanine-p-nitroanilide to yield p-nitroaniline, which is easily determined spectrophotometrically. This method allows the determination of levels around 10(6) to 10(7) CFU cm-2 in about 3 h. Because of the yellow color of p-nitroaniline, bacterial loads around 10(7) CFU cm-2 develop a color intense enough to be detected with the naked eye.     

A method to assess the bacterial content of refrigerated meat.

A new method has been developed to estimate the levels of gram-negative bacteria on refrigerated meat. The method is based on the aminopeptidase activity of these bacteria, which cleaves L-alanine-p-nitroanilide to yield p-nitroaniline, which is easily determined spectrophotometrically. This method allows the determination of levels around 10(6) to 10(7) CFU cm-2 in about 3 h. Because of the yellow color of p-nitroaniline, bacterial loads around 10(7) CFU cm-2 develop a color intense enough to be detected with the naked eye.     

A Thin‐Layer Liquid Culture Technique for the Growth of Helicobacter pylori

Background and Aims: Several attempts have been successful in liquid cultivation of Helicobaccter pylori. However, there is a need to improve the growth of H. pylori in liquid media in order to get affluent growth and a simple approach for examining bacterial properties. We introduce here a thin‐layer liquid culture technique for the growth of H. pylori. Methods: A thin‐layer liquid culture system was established by adding liquid media to a 90‐mm diameter Petri dish. Optimal conditions for bacterial growth were investigated and then viability, growth curve, and released proteins were examined. Results: Maximal growth of H. pylori was obtained by adding 3 mL of brucella broth supplemented with 10% horse to a Petri dish. H. pylori grew in both DMEM and RPMI‐1640 supplemented with 10% fetal bovine serum and 0.5% yeast extract. Serum‐free RPMI‐1640 supported the growth of H. pylori when supplemented with dimethyl‐β‐cyclodextrin (200 μg/mL) and 1% yeast extract. Under optimal growth, H. pylori grew exponentially for 28 hours, reaching a density of 3.4 OD₆₀₀ with a generation time of 3.3 hours. After 24 hours, cultures at a cell density of 1.0 OD₆₀₀ contained 1.3 ± 0.1 × 10⁹ CFU/mL. γ‐Glutamyl transpeptidase, nuclease, superoxide dismutase, and urease were not detected in culture supernatants at 24 hours in thin‐layer liquid culture, but were present at 48 hours, whereas alcohol dehydrogenase, alkylhydroperoxide reductase, catalase, and vacuolating cytotoxin were detected at 24 hours. Conclusions: Thin‐layer liquid culture technique is feasible, and can serve as a versatile liquid culture technique for investigating bacterial properties of H. pylori.     

Airborne Bacteria in the Atmospheric Surface Layer: Temporal Distribution above a Grass Seed Field

Temporal airborne bacterial concentrations and meteorological conditions were measured above a grass seed field in the Willamette River Valley, near Corvallis, Oreg., in the summer of 1993. The concentration of airborne bacteria had a maximum of 1,368.5 CFU/m(sup3), with a coefficient of variation of 90.5% and a mean of 121.3 CFU/m(sup3). The lowest concentration of bacteria occurred during the predawn hours, with an average of 32.2 CFU/m(sup3), while sunrise and early evening hours had the highest averages (164.7 and 158.1 CFU/m(sup3), respectively). The concentrations of bacteria in the atmosphere varied greatly, with a maximum difference between two 2-min samples of 1,995 CFU/m(sup3). The concentrations of bacteria in the atmosphere could be divided into five time periods during the day that were thought to be related to the local diurnal sea breeze and Pacific Coast monsoon weather conditions as follows: (i) the nighttime minimum concentration, i.e., 2300 to 0600 h; (ii) the sunrise peak concentration, i.e., 0600 to 0800 h; (iii) the midday accumulating concentration, i.e., 0800 to 1515 h; (iv) the late-afternoon sea breeze trough concentration, i.e., 1515 to 1700 h; and (v) the evening decrease to the nighttime minimum concentration, i.e., 1700 to 2300 h. The sunrise peak concentration (period ii) is thought to be a relatively general phenomenon dependent on ground heating by the sun, while the afternoon trough concentration is thought to be a relatively local phenomenon dependent on the afternoon sea breeze. Meteorological conditions are thought to be an important regulating influence on airborne bacterial concentrations in the outdoor atmosphere in the Willamette River Valley.     

The efficacy of smartphone‐based mental health interventions for depressive symptoms: a meta‐analysis of randomized controlled trials

The rapid advances and adoption of smartphone technology presents a novel opportunity for delivering mental health interventions on a population scale. Despite multi‐sector investment along with wide‐scale advertising and availability to the general population, the evidence supporting the use of smartphone apps in the treatment of depression has not been empirically evaluated. Thus, we conducted the first meta‐analysis of smartphone apps for depressive symptoms. An electronic database search in May 2017 identified 18 eligible randomized controlled trials of 22 smartphone apps, with outcome data from 3,414 participants. Depressive symptoms were reduced significantly more from smartphone apps than control conditions (g=0.38, 95% CI: 0.24‐0.52, p<0.001), with no evidence of publication bias. Smartphone interventions had a moderate positive effect in comparison to inactive controls (g=0.56, 95% CI: 0.38‐0.74), but only a small effect in comparison to active control conditions (g=0.22, 95% CI: 0.10‐0.33). Effects from smartphone‐only interventions were greater than from interventions which incorporated other human/computerized aspects along the smartphone component, although the difference was not statistically significant. The studies of cognitive training apps had a significantly smaller effect size on depression outcomes (p=0.004) than those of apps focusing on mental health. The use of mood monitoring softwares, or interventions based on cognitive behavioral therapy, or apps incorporating aspects of mindfulness training, did not affect significantly study effect sizes. Overall, these results indicate that smartphone devices are a promising self‐management tool for depression. Future research should aim to distil which aspects of these technologies produce beneficial effects, and for which populations.     

Taxonomic relatedness shapes bacterial assembly in activated sludge of globally distributed wastewater treatment plants

Activated sludge (AS), which has been in use for 100 years, has been the most popular biological process in various wastewater treatment plants (WWTPs), in which bacteria plays central roles in pollutant removal. However, the potential relationship between bacteria taxa and the niches occupied by specific functional bacteria in AS are largely unknown. Here, correlation‐based network analysis was applied to a 16S rRNA gene pyrosequencing dataset containing > 760 000 sequences of 50 AS samples from globally distributed full‐scale WWTPs. The results showed that (i) bacterial assembly in AS was nonrandomly arranged by taxonomic relatedness and (ii) intra‐ and inter‐phylum/class co‐occurrence higher than expected by chance was induced by multiple deterministic processes, such as habitat filtering and competition. Moreover, based on bacterial occupancy, a prevalent core set of cosmopolitan functional bacteria (e.g. multiple nitrogen‐cycling‐related bacteria) was widely distributed in the AS of different WWTPs, showing strong ecological associations among them. Additionally, the AS network has statistical and structural characteristics similar to those of previously reported ecological networks, such as power‐law connectivity distribution and nonrandomly connected properties. Overall, this work provides novel insights into the bacterial associations within AS and sheds light on the ecological rules guiding bacterial assembly in WWTPs.