Magnetic polymeric nanoparticles functionalized by mannose‐rhodamine conjugate for detection of E. coli

Mannose‐rhodamine (Rh) conjugate (80% yield) was synthesized in a one‐pot reaction and immobilized onto magnetic polymeric nanoparticles (MPNP; 43% magnetic content) of poly(styrene/divinyl benzene/acrylic acid). The resulting nanoparticles contained MPNP as a substrate, mannose as an E. coli receptor and Rh as a fluorescent signaling unit. TEM imaging clearly demonstrated that multiple mannose‐Rh MPNPs could be captured by E. coli strain ORN178. The fluorescent signal from captured nanoparticles was emitted at 580 nm. These results indicate that mannose‐Rh MPNP offers a simple and rapid strategy for bacterial detection. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40012.     

Antioxidative activity and functional properties of protein hydrolysate of yellow stripe trevally (Selaroides leptolepis) as influenced by the degree of hydrolysis and enzyme type

Antioxidative activity and functional properties of protein hydrolysates from yellow stripe trevally (Selaroides leptolepis) meat, hydrolyzed by Alcalase 2.4L (HA) and Flavourzyme 500L (HF) with different degrees of hydrolysis (DH) were investigated. As the DH increased, DPPH radical-scavenging activity and reducing power of HA decreased (p < 0.05) but no differences were observed for HF (p > 0.05). Metal chelating activity of both HA and HF increased with increasing DH (p < 0.05). HF generally had a higher (p < 0.05) chelating activity than had HA at the same DH tested. At low DH (5%), HA exhibited a better DPPH radical-scavenging activity while, at high DH (25%), HF had a higher (p < 0.05) reducing power. For the functional properties, hydrolysis by both enzymes increased protein solubility to above 85% over a wide pH range (2–12). When the DH increased, the interfacial activities (emulsion activity index, emulsion stability index, foaming capacity, foam stability) of hydrolysates decreased (p < 0.05), possibly caused by the shorter peptide chain length. At the same DH, the functionalities of protein hydrolysate depended on the enzyme used. The results reveal that antioxidative activity and functionalities of protein hydrolysates from yellow stripe trevally meat were determined by the DH and by the enzyme type employed.     

Characteristics and Use of Yellow Stripe Trevally Hydrolysate as Culture Media

ABSTRACT:  Characteristics and the use as culture media of protein hydrolysate from yellow stripe trevally (HF₂₅) were determined in comparison with Bacto Peptone. HF₂₅ had the higher contents of ash (45.73%), lipid (0.77%), and moisture (4.34%) but lower protein content (42.11%) than did Bacto Peptone ( P  < 0.05). HF₂₅ powder was slightly darker than Bacto Peptone ( P  < 0.05). HF₂₅ contained a higher amount of essential amino acids (44.05%) than did Bacto Peptone (19.34%). HF₂₅ and Bacto Peptone consisted of several minerals at varying levels and had an excellent solubility over a wide pH range. At water activity (a_w) greater than 0.75, the much higher moisture sorption was found in HF₂₅ ( P  < 0.05). HF₂₅ showed the higher bacterial productivity ratio than did Bacto Peptone ( P  < 0.05). When HF₂₅ and commercial Bacto Peptone were used as microbial media to determine microbial load of environmental and food samples and pathogenic bacteria, HF₂₅ generally exhibited similar potential in culturing those microorganisms ( P  > 0.05). Thus, the conversion of low market value species to fish protein hydrolysate, which can be used as the nitrogenous substrate for microbial growth, could be achieved.     

Enhancement of γ-aminobutyric acid (GABA) in Nham (Thai fermented pork sausage) using starter cultures of Lactobacillus namurensis NH2 and Pediococcus pentosaceus HN8

The aim was to produce Nham that was enriched with γ-aminobutyric acid (GABA); therefore two GABA producing lactic acid bacteria (Pediococcus pentosaceus HN8 and Lactobacillus namurensis NH2) were used as starter cultures. By using the central composite design (CCD) we showed that addition of 0.5% monosodium glutamate (MSG) together with an inoculum size of roughly 6 log CFU/g of each of the two strains produced a maximal amounts of GABA (4051 mg/kg) in the ‘GABA Nham’ product. This was higher than any current popular commercial Nham product by roughly 8 times. ‘GABA Nham’ with the additions of both starters and MSG (T_SM) supported maximum populations of lactic acid bacteria (LAB) with a minimum of yeasts and no staphylococci or molds when compared to the controls that had no addition of any starters or MSG (T_NN), or only the addition of MSG (T_NM), or with only the starter (T_SN). Based on proximate analysis among the Nham sets, ‘GABA Nham’ was low in fat, carbohydrate and energy although its texture and color were slightly different from the control (T_NN). However, sensory evaluations of ‘GABA Nham’ were more acceptable than the controls and commercial Nham products for all tested parameters. Hence, a unique novel ‘GABA Nham’ fermented pork sausage was successfully developed.     

Use of Protein Hydrolysate from Yellow Stripe Trevally (<Emphasis Type="Italic">Selaroides leptolepis</Emphasis>) as Microbial Media

The objective of this study was to investigate the potential use of protein hydrolysate from yellow stripe trevally as a nitrogen source for the growth of different microorganisms. Protein hydrolysates from yellow stripe trevally with different degrees of hydrolysis (5, 15 and 25%) prepared using Alcalase (HA) or Flavourzyme (HF) were determined in comparison with commercial Bacto Peptone. For bacteria, Staphylococcus aureus and Escherichia coli, HF with 25% DH (HF₂₅) yielded the highest cell density and specific growth rate (μ _max) and the lowest generation time (t _d) (p?Saccharomyces cerevisiae and Candida albicans, Bacto Peptone yielded the higher growth rate than did HA and HF (p?μ _max and t _d were observed for fungus, Aspergillus oryzae (p?>?0.05). The pH of culture broth containing HF₂₅ decreased markedly during the first 8 hours of cultivation of S. aureus and E. coli (p?S. aureus (p?25 rendered the similar growth and colony size of S. aureus (p?>?0.05), compared with that containing Bacto Peptone. Scanning electron microscopic study revealed no differences in size and shape of microorganisms cultured in HF₂₅ and Bacto Peptone (p?>?0.05).     

Encapsulation of Rhodopseudomonas palustris KTSSR54 using beads from alginate/starch blends

Alginate beads are a promising carrier for biofertilizer delivery, but still possess drawbacks of low mechanical strength and bead shrinkage that result in poor appearance and inadequate cell protection. Blending alginate with starch was proposed as a solution to these problems, and here alginate hydrogels were prepared using a 2% (w/v) alginate dispersion blended with varying contents of gelatinized starch (0–5% w/v). The interaction produced a viscosity synergism that increased the complexity of the matrix network in the alginate/starch blends, producing a more suitable matrix for cell entrapment. Hydrogen bonding between alginate and starch influenced the viscosity of the various solutions in a way that was consistent with the FTIR spectra. The starch content also helped beads retain their spherical shape after drying. The starch supported the entrapment of bacterial cells (plant growth-promoting bacterium Rhodopseudomonas palustris KTSSR54 as biofertilizer) in the matrix, which reduced cell loss. The highest entrapment efficiency of 70.83% was obtained at 4% (w/v) starch, while the entrapment efficiency of control beads was 50.56%. Overall, the appropriate content of starch mixed with alginate is conducive to changes in the morphology of microcapsules and increases in the amount of biological encapsulation.     

Process monitoring for correlated gamma‐distributed data using generalized‐linear‐model‐based control charts

A model‐based scheme is proposed for monitoring multiple gamma‐distributed variables. The procedure is based on the deviance residual, which is a likelihood ratio statistic for detecting a mean shift when the shape parameter is assumed to be unchanged and the input and output variables are related in a certain manner. We discuss the distribution of this statistic and the proposed monitoring scheme. An example involving the advance rate of a drill is used to illustrate the implementation of the deviance residual monitoring scheme. Finally, a simulation study is performed to compare the average run length (ARL) performance of the proposed method to the standard Shewhart control chart for individuals. Copyright © 2003 John Wiley & Sons, Ltd.     

Model‐based control chart for autoregressive and correlated data

In recent years, statistical process control for autocorrelated processes has received a great deal of attention. This is due in part to the improvements in measurement and data collection that allow processes to be sampled at higher frequency rates and, hence, data autocorrelation. A method for monitoring autocorrelated processes based on regression adjustment is presented in this paper. The performance of the residual‐based control chart in terms of the average run length is compared to observation‐based control charts via Monte Carlo simulations. In general, the observation‐based control charts perform very poorly when data are correlated over time. Under the assumption that the model is correct, the residual‐based control charts are superior for all cases considered here. This suggests using a residual‐based control chart to detect the mean shift. This is recommended particularly for chemical processes where there are often cascade processes with several inputs but only a few outputs, and where many of the variables are highly autocorrelated. Copyright © 2002 John Wiley & Sons, Ltd.     

Detection of Campylobacter DNA using magnetic nanoparticles coupled with PCR and a colorimetric end-point system

Food Science and Biotechnology - Campylobacter is an important food-borne pathogen causing acute gastroenteritis worldwide. Magnetic nanoparticle-based PCR coupled with streptavidin-horseradish...