Growth Of Total Bacteria Research Articles

Utilization of Jatropha Leaf (Jatropa curcas) Extract as Immune System Enhancer of Vannamei Shrimp (Litopenaeus vannamei) Infected with Vibrio parahaemolyticus

The problem arises in vanamei shrimp cultivation is the emergence of diseases, such as vibriosis caused by Vibrio parahaemolyticus. Jatropha leaf extract can be used as an immunostimulant because it contains bioactive compounds namely flavonoid, tannins, saponins, and alkaloids. This research used a completely randomized design (CRD) with 5 treatments with 3 replications. The treatments used were; P1 (feed without extract and bacterial infection); P2 (feed without extract and NaCl injection); P3 : Feed + 1% + bacterial infection; P4 : Feed + 2% extract from feed and bacterial infection, P5 : Feed + 3% extract of feed and bacterial infection. Based on the results of the study, the administration of Jatropha leaf extract was able to increase the highest SR value of P2 by 88.3%, the highest THC value of P5 at 24.46 x 106 cells/ml, DHC values ​​such as hyaline cells ranged from 36.67-71%, granular cells ranged from 17-38.57%, and semigranular cells ranged from 12-24.67%, the highest AF value in P5 was 77.25%, and the lowest TBC value was at P2 of 6 x 108 CFU/ml, the lowest TVC value was at P2 of 0.56 x 106 CFU/ml. The higher the dose of extract given, the higher the THC and AF, besides that, Jatropha leaves were also able to increase the SR value and suppress the growth of total bacteria and total Vibrio in shrimp intestines.

Effect of hydraulic retention time on solid-phase denitrification reactor in recirculating aquaculture system

Hydraulic retention time (HRT) is one of the most critical operational parameters for solid-phase denitrification. The effect of HRT on solid-phase denitrification reactors (DR) packed with corrugated paperboard was investigated in recirculating aquaculture systems (RAS). Denitrification efficiencies of DR were 81.21–85.05% at HRTs of 0.5–2.0 h. The optimal HRT for denitrification was 2.0 h with a rate of 14.81 mg/(L substrate day). HRT significantly affected the bacterial community structure in DR by changing the population dynamics of the dominant bacteria and denitrifying functional bacteria such as Rhizobiaceae, Desulfovibrionaceae, and Arcobacteraceae. Moreover, the HRT of the DR showed a significant effect on the bacterial community in the nitrification reactor and culture water. Reducing HRT can promote the growth of total bacteria in the DR. However, it revealed a limiting effect on the abundance of key genes of the nitrogen cycle, including the amoA, nirK and nosZ. Under the condition of short HRT, the DR can also achieve a good denitrification effect, which provides feasible management measures for nitrogen removal in RAS.

Enhancement effect of nanoscale zero-valent iron addition on microbial degradation of BDE-209 in contaminated mangrove sediment

Chemical and biological methods have been employed to remedy polybrominated diphenyl ether contamination, but the removal of decabromodiphenyl ether (BDE-209) by either method still has limitations. The present study aims to evaluate the combined effect of nanoscale zero-valent iron (nZVI) (from 0.1 to 10%) reduction and microbial debromination on BDE-209 removal in mangrove sediments under an anaerobic condition. During the 12-months incubation, nZVI significantly enhanced BDE-209 removal, with 17.03% to 41.99% reduction in sterilized sediments. The reduction was even higher in non-sterilized sediments with living indigenous microorganisms, achieving 15.80%, 33.50%, 55.83% and 66.95% removal of BDE-209 at 0 (control without nZVI), 0.1%, 1% and 10% nZVI, respectively. In control sterilized sediments, no debromination was found, and debromination occurred according to spiked levels of nZVI, with BDE-153 being the dominant congener. The concentrations of debrominated congeners in non-sterilized sediments also increased with nZVI levels, but were significantly higher than the respective sterilized sediment. The relative proportions of different debrominated congeners in non-sterilized sediments depended on nZVI levels, with BDE-99 being the dominant congener in low nZVI amended sediments but shifted to BDE-153 under high nZVI. Higher concentrations of ferrous iron (Fe2+) were detected in both sterilized and non-sterilized sediments spiked with more nZVI, and their concentrations significantly correlated with BDE-209 removal. Growth of total bacteria in sediments with 1% and 10% nZVI was inhibited within first two months, but their numbers resumed to that in the control at the end of 12 months. The present study demonstrates the synergy between chemical and microbiological methods, and a combination of nZVI and indigenous microorganisms could be an efficient and feasible mean to remedy BDE-209 in contaminated sediments.

Characteristics of intestinal microbiota and enzyme activities in mice fed with lily bulb.

The aim was to investigate the effect of lily bulbs on the microecological characteristics of intestinal microbiota and enzyme activities in normal mice. Thirty SPF Kunming mice were randomly divided into the control group, Lilium lancifolium (LL) group and Lilium davidii var. unicolor (LDU) group. Mice of the latter two groups were given 0.15g·mL-1 lily bulb solution, respectively, by gavage twice a day, while the control group was given the same volume of sterilized water. After 49days, intestinal contents and mucosa of all mice were collected and the characteristics of intestinal microbiota and enzyme activities were analyzed. Results showed that the number of Lactobacillus spp. and Bifidobacteria spp. in the LL group was significantly higher than that in the control group (t = 2.68 × 107, P = 0.000; t = 5.96 × 107; P = 0.000) and the LDU group (t = 6.12 × 107, P = 0.000; t = 2.71 × 107, P = 0.000), while the number of total bacteria was significantly lower (P = 0.040). Microbial activity in intestinal contents and mucosa of the LDU group (t = 0.43, P = 0.001; t = 0.69, P = 0.000) decreased, and microbial activity in intestinal mucosa of the LL group decreased significantly (t = 0.89, P = 0.000) but increased significantly in intestinal contents of the LL group (t = 0.81, P = 0.000). The activities of amylase (t = 455.73, P = 0.000; t = 206.56, P = 0.000) and protease (t = 52.32, P = 0.000) increased but the activities of lactase (t = 443.51, P = 0.000; t = 15.71, P = 0.000) and sucrase (t = 5.82, P = 0.000; t = 366.82, P = 0.000) decreased significantly in contents from the LL group and LDU group. Except for the sucrase activity, enzyme activities in mucosa of the LL group were completely opposite to those in contents (t = 44.15, P = 0.000; t = 1.25, P = 0.007; t = 14.64, P = 0.011). In conclusion, dietary lily bulbs increased intestinal contents amylase activities and mucosa lactase activity significantly. Lily bulbs, especially Lilium lancifolium, can promote the growth of Lactobacillus spp. and Bifidobacteria spp., and inhibit the growth of total bacteria in the intestines of normal mice. Lilium lancifolium bulbs have the potential to be a functional food.

Xylooligosaccharides from steam-exploded barley straw: Structural features and assessment of bifidogenic properties

The biorefinery concept integrates the production of energy and bioproducts from biomass. In this philosophy, barley straw samples were used as raw material for the production of xylooligosaccharides (XOS) mixtures from soluble hemicelluloses by steam-explosion pretreatment. This fraction was treated by ion-exchange (XOS1) and a combination of membrane filtration, enzymatic hydrolysis, and ion-exchange processes (XOS2) to produce prebiotic compounds. The afforded products were then characterized by using analytical techniques, including HPAEC-PAD, FTIR, and MALDI-TOF-MS. XOS2 is composed of a backbone of xylopyranosyl branched, which including acetyl-esterified oligosaccharides and feruloyl substituted arabino-oligosaccharides.Further, the prebiotic potential was evaluated by in vitro fermentation experiments using as inocula human fecal samples from volunteers in which the short-chain fatty acids production, total bacteria growth, and the bifidobacteria numbers were quantified and compared to the results obtained with commercial fructooligosaccharides.The accumulation of short-chain fatty acids was similar for XOS1 and XOS2 (102.7 and 117.2 mM). An increase of 1.50 and 1.43 log cell number/mL-fold was observed for media containing XOS1 and XOS2, respectively. Results obtained confirm that the production and use of XOS derived from steam-exploded barley straw such as functional ingredient is an alternative for the valorization of its hemicelluloses fraction into the “biorefinery” context.

Feasibility of Determination of Foodborne Microbe Contamination of Fresh-Cut Shredded Cabbage Using SW-NIR

Shredded cabbage is widely used in much ready-to-eat food. Therefore, rapid methods for detecting and monitoring the contamination of foodborne microbes is essential. Short wavelength near infrared (SW-NIR) spectroscopy was applied on two types of solutions, a drained solution from the outer surface of the shredded cabbage (SC) and a ground solution of shredded cabbage (GC) which were inoculated with a mixture of two bacterial suspensions, Escherichia coli and Salmonella typhimurium. NIR spectra of around 700 to 1100 nm were collected from the samples after 0, 4, and 8 h at 37 °C incubation, along with the growth of total bacteria, E. coli and S. typhimurium. The raw spectra were obtained from both sample types, clearly separated with the increase of incubation time. The first derivative, a Savitzky–Golay pretreatment, was applied on the GC spectra, while the second derivative was applied on the SC spectra before developing the calibration equation, using partial least squares regression (PLS). The obtained correlation (r) of the SC spectra was higher than the GC spectra, while the standard error of cross-validation (SECV) was lower. The ratio of prediction of deviation (RPD) of the SC spectra was higher than the GC spectra, especially in total bacteria, quite normal for the E. coli but relatively low for the S. typhimurium. The prediction results of microbial spoilage were more reliable on the SC than on the GC spectra. Total bacterial detection was best for quantitative measurement, as E. coli contamination could only be distinguished between high and low values. Conversely, S. typhimurium predictions were not optimal for either sample type. The SW-NIR shows the feasibility for detecting the existence of microbes in the solution obtained from SC, but for a more specific application for discrimination or quantitation is needed, proving further research in still required.

Oligosaccharides Profile and Prebiotic Potential of Gembolo Tuber (Dioscorea bulbifera)

Indonesia has many potential tubers that not yet utilized, whereas the tubers can be utilized in functional food. Dioscorea bulbifera contains oligosaccharides which can be used as functional food prebiotics based. This research aim was to analyze the content of oligosaccharides from Dioscorea bulbifera tuber flour and its prebiotics potential. The extraction of oligosaccharides from Dioscorea bulbifera flour was done using ethanol 70% and analyze the content of oligosaccharides using HPLC (High-Performance Liquid Chromatography). The inoculum of colonic microbial used from volunteer infants aged less than 6 months and only consume breast milk. The prebiotic index was determined by enumerating the growth of total bacteria, microbial probiotics (Bifidobacteria and Lactobacillus) and microbial pathogens (Bacteroids and Clostridium) in anaerobic conditions at 0, 24 and 48 hours. The results showed that oligosaccharides profile of Dioscorea bulbifera flour were Inulin 0.76; Raffinose 0.07; and Lactulose 0.09% b/v. The prebiotics index value of oligosaccharide of extracts of Dioscorea bulbifera flour at 48th hour is 1.2045. It can be concluded that the oligosaccharide from Dioscorea bulbifera tuber flour has potential as a prebiotic.

Influence of glycated nitrosohaemoglobin prepared from porcine blood cell on physicochemical properties, microbial growth and flavour formation of Harbin dry sausages

Glycated nitrosohaemoglobin (G-NO-Hb) prepared from porcine blood cells was used in natural fermented Harbin dry sausages to evaluate their possible as an alternative for sodium nitrite (SN). The results show that the G-NO-Hb had no significant effect on the pH, water activity, and growth of total bacteria and lactic acid bacteria counts (P > 0.05). G-NO-Hb inhibited Enterobacteriaceae growth (P < 0.05), but this inhibition was lower than SN. The redness of sausages with 2 g/kg G-NO-Hb were almost the same as SN sausages (P > 0.05). The thiobarbituric acid reactive substances of G-NO-Hb samples had no differences when compared to SN samples except at 12 days. Residual nitrite in G-NO-Hb sausages was lower than SN samples. The content of individual volatile compounds, such as hexanal (lipid oxidation marker), was nearly three times lower for SN than for G-NO-Hb samples. Overall, G-NO-Hb reduced nitrite residue and inhibited lipid oxidation and Enterobacteriaceae growth of sausages, demonstrating great potential as a substitute for sodium nitrite in meat products.

Influence of hydrolysis rate of urea on ruminal bacterial diversity level and cellulolytic bacteria abundance in vitro.

The objective of this experiment was to evaluate the effects of urea hydrolysis rate on ruminal bacterial diversity level and cellulolytic bacteria abundance in vitro. To control urea hydrolysis rate, urea and urease inhibitor (acetohydroxamic acid, AHA) were supplemented to a 2 × 2 factorial design, with urea supplemented at 0 or 20 g/kg dry matter (DM) of substrate, and AHA equivalent to 0 or 450 mg/kg DM of substrate. Ruminal fluid was collected from three Chinese Holstein dairy cows, fed a TMR, and incubated at 39 °C for 12 h after the addition of urea and AHA. Rumen fermentation parameters, which indicated the rate of ammonia formation (including ammonia-nitrogen (NH3-N) and urea-nitrogen concentrations, urease activity, and microbial crude protein) were measured by chemical analysis. Bacterial diversity was analyzed by denaturing gradient gel electrophoresis (DGGE). Total bacteria and cellulolytic bacteria abundance was detected by quantitative PCR. Results showed that AHA addition significantly decreased the rate of ammonia formation when urea was supplemented. Urea and AHA supplementation significantly increased the bacterial community diversity level according to the Shannon–Weiner index of 16S DGGE images. Furthermore, ruminal bacterial profiles were separated by ammonia release rate when urea was supplemented, according to the DGGE and hierarchical cluster analysis. Urea supplementation reduced the abundance of cellulolytic bacteria, such as Ruminococcus albus, R. flavefaciens, Fibrobacter succinogenes, and Butyrivibrio fibrosolvens, but inhibition of urea hydrolysis by AHA addition alleviated the reductions during the early period of incubation. In conclusion, slow release of ammonia induced by urease inhibitor influenced the ruminal bacterial diversity level and lessened the inhibition of total bacteria growth at the incubation of 12 h and F. succinogenes during the early period of incubation.

Dynamics of microbial community and enzyme assay as influenced by green manuring and weed control measures in rice-groundnut cropping system

A long-term experiment was commenced (2011) and conducted at the Research Farm of Dapoli (Maharashtra) during Kharif and Rabi season in rice-groundnut cropping system, to evaluate the effect of green manuring and different weed control measures on the survival and growth of total bacteria, total fungi, total free living nitrogen fixers and total phosphate solubilizers in rhizospheric soil. Results emerged out from the conduct during 2011 to 2014 indicated that, green manuring (in-situ application of Sesbania rostrata 45 DAS) and without green manuring (control) as a main plot treatment and among the weed control measures and sub plot treatments comprising, comparative effects of hand weeding, fixed herbicide pretilachlor (pre-emergence) for rice crop and pendimethalin (pre-emergence) for groundnut crop, and different rotational herbicides (for rice crop, pyrazosulfuron 0.030 kg/ha at 8–10 DAT (1 year), fenoxaprop-p-ethyl 0.056 kg/ha at 25–30 DAT (2 year), oxadiargyl 0.100 kg/ha at 0–5 DAT (3 year), and for groundnut crop oxadiargyl 0.12 kg/ha at 0–2 DAS-1 year, butachlor 1.0 kg/ha at 0–3 DAS-2 year, alachlor1.5 kg/ha at 0–3 DAS3 year) application to both the crops were significantly tested along with weedy check. The results concluded that the green manuring significantly increased in microbial populations than without green manuring. There were no adverse effects of herbicidal use on all the estimated microbial population at all the stages of both the crops. In contrast to use of fixed herbicide pretilachlor-S 0.75 kg/ha for rice and pendimethalin 1.00 kg/ha and different rotational herbicides had no long-term adverse effects on rhizosphere micro-flora of rice-groundnut cropping system.

The Early Intestinal Microbiota of Healthy Korean Newborns.

Background:The microflora hypothesis may be the underlying explanation for the growth of inflammatory disease. In addition to many known affecting factors, knowing the gut microbiota of healthy newborns can help to understand the gut immunity and modulate it.Objectives:This study examined the microbiota of healthy newborns from urban regions.Patients and Methods:We enrolled 128 full-term newborns, born at Seoul St. Mary and St. Paul hospital from January 2009 to February 2010. All 143 samples of feces were cultivated in six culture plates to determine the amounts of total bacteria, anaerobes, gram-positive bacteria, coliforms, lactobacilli, and bifidobacteria. The samples were evaluated with a bivariate correlation between coliforms and lactobacilli. Terminal restriction fragment length polymorphism (T-RFLP) analysis with HhaI and MspI and a clustering analysis were performed for determination of diversity.Results:Bacteria were cultured in 61.5% of feces in the following order: anaerobes, gram-positive bacteria, lactobacilli, coliform, and bifidobacteria. The growth of total bacteria and lactobacilli increased in feces defecated after 24 hours of birth (P < 0.001, P = 0.008) and anaerobes decreased (P = 0.003). A negative correlation between the growth of lactobacilli and coliforms was found (r = -463, P < 0.001).Conclusions:This study confirms that bacterial colonization of healthy newborns born in cities is non-sterile, but has early diversification and inter-individuality.

Development of Antimicrobial Poly(∊-caprolactone)/Poly(lactic acid)/Silver Exchanged Montmorillonite Nanoblend Films with Silver Ion Release Property for Active Packaging Use

Abstract Biodegradable PCL/PLA/Ag-MMT nanoblends with a strong antibacterial activity and a silver ion release property were successfully prepared by melt blending process for active packaging use. The presence of silver exchanged montmorillonite and its interaction with PCL/PLA matrix was evidenced by ATR/FTIR. The morphology was investigated by both XRD and TEM analyses. It was suggested the formation of mainly exfoliated structures with a random dispersion of spherical silver nanoparticles within their composite matrices. The thermal and mechanical properties of these nanomaterials were thoroughly investigated and compared to those of the unfilled blends. The potential of the silver ion release from the PCL/PLA/Ag-MMT film was estimated after immersion in water for several periods of time. The results showed an increase of the amount of silver ions released with growing immersion time of PCL/PLA/Ag-MMT nanoblends. Due to the presence of silver nanoparticles in their matrices, PCL/PLA/Ag-MMT nanoblends showed a total bacteria growth inhibition.

Inhibitory effect of a quercetin-based soaking formulation and modified atmospheric packaging (MAP) on muscle degradation of Pacific white shrimp (Litopenaeus vannamei)

Effects of quercetin, cinnamic acid and 4-hexylresorcinol on the quality changes of Pacific white shrimp (Litopenaeus vannamei) during cold storage for 12 days were investigated. Fresh shrimp were immersed into a quercetin-based preservative formulation containing 0.05 g/L quercetin incorporating 0.025 g/L cinnamic acid and 0.025 g/L 4-hexylresorcinol (4-HR), then stored in air or under modified atmosphere (MA, 80% CO2/10% O2/10% N2) at 4 °C. The preservatives prevented melanosis and protein degradation of shrimp to some extent, but their inhibitory effect on the growth of total bacteria and total volatile basic nitrogen (TVB-N) and K-value was limited. After 12 days of storage, the samples treated by the combination of soaking and MA packaging treatment not only had higher whiteness value, but also lower values of total viable count (TVC), K- and TVB-N values. The SDS-PAGE profiles of sarcoplasmic and myofibrillar proteins and histological analysis also indicated that the shrimp muscle treated with the combined treatment was less likely to be degraded.

Effect of Methylcellulose Coating Enriched with Pimpinella affinis Oil on the Quality of Silver Carp Fillet during Refrigerator Storage Condition

The effects of methylcellulose (MC) coating enriched with Pimpinella affinis essential oil (PAO) on quality and shelf life of fresh silver carp fillets during refrigerated storage (4 ± 1C) were examined over a period of 16 days. MC solution (3%) and MC enriched with PAO (1.5% v/v concentration) were prepared for coating of the fish samples. The control and the treated fish samples were analyzed periodically for microbiological (total viable count), chemical (pH, thiobarbituric acid [TBA], total volatile basic nitrogen [TVB-N], free fatty acid [FFA] and pv) and sensory characteristics. According to results (pv, FFA, TBA, TVB-N, pH), color and odor on MC contain 1.5% PAO and have less change in comparison to other treatments (P < 0.05), and it could inhibit a total bacteria growth and psychrophilic counts of fillet. The results indicated that MC contains 1.5% PAO, a good antioxidant activity, so it can be used for fish preservation without any undesirable changes in antimicrobial and sensorial attributes. Practical Applications The main practical application behind the development of chitosan coating is used to preserve fish quality with the fact that these polysaccharides represent a renewable source of natural biodegradable polymers and meet with the emergence of more and more food safety problems. The results of this study are a useful tool for the development of new environment-friendly and healthier commercial applications in the food processing industry because of its antimicrobial and antioxidative characteristics.

Effect of Fresh Garlic on Lipid Oxidation and Microbiological Changes of Pork Patties during Refrigerated Storage.

The effects of two levels (1.4 vs 2.8%) of fresh garlic on lipid oxidation and microbial growth in pork patties were evaluated. Hunter color (L, a, b), pH, thiobarbituric acid reactive substances (TBARS), oxidative volatile compounds, total bacteria and Enterobacteriaceae in the pork patties with or without fresh garlic were measured during storage at 4℃. Addition of fresh garlic decreased redness (a), while increased pH and yellowness (b) values of the fresh pork patties were observed, regardless of the levels added. The TBARS values of the pork patties were increased with the addition of fresh garlic (p<0.05). Similar results were observed in oxidative volatile compounds. A total of 13 volatile compounds were detected in the patties (5 sulfur-containing compounds, including allyl mercaptan, allyl methyl sulfide, diallyl sulfide, methyl-(E)-propenyl-disulfide, and diallyl disulfide, and the 8 other oxidative compounds, including 1-pentanol, hexanal, 1-hexanol, heptanal, (E)-2-heptenal, 1-octen-3-ol, (E)-2-octenal and nonanal). Fresh garlic accelerated development of oxidative products in the pork patties, especially hexanal and the total oxidative volatile compounds. However, the addition of 1.4 and 2.8% of fresh garlic inhibited the growth of total bacteria and Enterobacteriaceae, indicating low total bacterial counts and Enterobacteriaceae than the controls.

Prebiotic Oligosaccharides: Comparative Evaluation Using In Vitro Cultures of Infants' Fecal Microbiomes.

The objective of this study was to systematically assess the bifidogenic effect of three commonly used prebiotic products using in vitro cultures of infant fecal samples. Fresh stool samples collected from six term infants, each exclusively fed human milk (n = 3) or infant formula (n = 3), at 28 days of age were used as inocula. The following prebiotic products were added at concentrations applicable to infant formula: Vivinal GOS 15 (containing 28.5% galacto-oligosaccharide [GOS]) at 7.2 g/liter, Beneo HP (99.5% long-chain inulin [IN]) at 0.8 g/liter, Beneo Synergy 1 (enriched oligofructose and inulin [OF-IN]) at 4 g/liter, and a combination of Vivinal GOS 15 (7.2 g/liter) and Beneo HP (0.8 g/liter) (GOS-IN). The growth of total bacteria, Bifidobacterium, Bacteroides, Bifidobacterium longum, and Escherichia coli was quantified using specific quantitative PCR (qPCR). Bifidobacterium was also enumerated on selective Beerens agar plates, with representative colonies identified by sequencing of their 16S rRNA genes. Volatile fatty acids (VFA) and pH in the cultures were also determined. Irrespective of the feeding methods, the GOS product, either alone or in combination with Beneo HP, resulted in substantially higher growth of total bifidobacteria, and much of this growth was attributed to growth of B. longum. Beneo Synergy 1 also increased the abundance of total bifidobacteria and B. longum. Corresponding to the increases in these two bacterial groups, acetic acid concentrations were higher, while there was a trend of lower E. coli levels and pH. The lower pH and higher acetic acid concentration might be directly responsible for the lower E. coli population. At the concentrations studied, the GOS product was more bifidogenic and potent in inhibiting E. coli than the other products tested. These results suggest that supplementation of infant formula with GOS may increase intestinal bifidobacteria and benefit infant health.

Tobermolite effects on methane removal activity and microbial community of a lab-scale soil biocover

Three identical lab-scale biocovers were packed with an engineered soil (BC 1), tobermolite only (BC 2), and a mixture of the soil and tobermolite (BC 3), and were operated at an inlet load of 338-400g-CH4m(-2)d(-1) and a space velocity of 0.12h(-1). The methane removal capacity was 293±47g-CH4m(-2)d(-1) in steady state in the BC 3, which was significantly higher than those in the BC 1 and BC 2 (106±24 and 114±48g-CH4m(-2)d(-1), respectively). Quantitative PCR indicated that bacterial and methanotrophic densities (6.62-6.78×10(7) 16S rDNA gene copy numberg-dry sample(-1) and 1.37-2.23×10(7) pmoA gene copy numberg-dry sample(-1) in the BC 1 and BC 3, respectively) were significantly higher than those in the BC 2. Ribosomal tag pyrosequencing showed that methanotrophs comprised approximately 60% of the bacterial community in the BC 2 and BC 3, while they only comprised 43% in the BC 1. The engineered soil favored the growth of total bacteria including methanotrophs, while the presence of tobermolite enhanced the relative abundance of methanotrophs, resulting in an improved habitat for methanotrophs as well as greater methane mitigation performance in the mixture. Moreover, a batch experiment indicated that the soil and tobermolite mixture could display a stable methane oxidation level over wide temperature (20-40°C, at least 38μmolg-dry sample(-1)h(-1)) and pH (5-8, at least 61μmolg-dry sample(-1)h(-1)) ranges. In conclusion, the soil and tobermolite mixture is promising for methane mitigation.

백련초 추출물 첨가 김치의 품질특성 및 중학교 급식에서의 수응도 평가

This research studied the effects of Backryeoncho (Opuntia ficus-indica var. saboten) extract as an additive in kimchi in various amounts (0%, 0.4%, 0.8%, 1.2%), and its acceptance by middle school students in the Jeonju area. The treated kimchi had a higher pH than the untreated kimchi without extract, and the titratable acidity of the kimchi decreased with the addition of the Backryeoncho extract. The degree of salinity decreased in kimchi with the added Backryeoncho extract in a dose-dependent manner. The cutting force and compression force were higher in kimchi where the extract was added during the fermentation period resulting in improved texture of the kimchi. The addition of the extract slowed growth of total bacteria (1.83~2.12 log CFU/mL) and lactic acid bacteria (1.4 log CFU/mL) as compared with the control sample. In the sensory evaluation of overall taste, kimchi with 0.8% extract added demonstrated higher evaluation in overall categories. The acceptability of Backryeoncho extract as an additive in kimchi among middle school students was higher than in the control sample, with an optimum additive of 0.4% extract, based on the lowest volume of leftovers.

Modeling to predict growth/no growth boundaries and kinetic behavior of Salmonella on cutting board surfaces.

This study developed models to predict the growth probabilities and kinetic behavior of Salmonella enterica strains on cutting boards. Polyethylene coupons (3 by 5 cm) were rubbed with pork belly, and pork purge was then sprayed on the coupon surface, followed by inoculation of a five-strain Salmonella mixture onto the surface of the coupons. These coupons were stored at 13 to 35°C for 12 h, and total bacterial and Salmonella cell counts were enumerated on tryptic soy agar and xylose lysine deoxycholate (XLD) agar, respectively, every 2 h, which produced 56 combinations. The combinations that had growth of ≥0.5 log CFU/cm(2) of Salmonella bacteria recovered on XLD agar were given the value 1 (growth), and the combinations that had growth of <0.5 log CFU/cm(2) were assigned the value 0 (no growth). These growth response data from XLD agar were analyzed by logistic regression for producing growth/no growth interfaces of Salmonella bacteria. In addition, a linear model was fitted to the Salmonella cell counts to calculate the growth rate (log CFU per square centimeter per hour) and initial cell count (log CFU per square centimeter), following secondary modeling with the square root model. All of the models developed were validated with observed data, which were not used for model development. Growth of total bacteria and Salmonella cells was observed at 28, 30, 33, and 35°C, but there was no growth detected below 20°C within the time frame investigated. Moreover, various indices indicated that the performance of the developed models was acceptable. The results suggest that the models developed in this study may be useful in predicting the growth/no growth interface and kinetic behavior of Salmonella bacteria on polyethylene cutting boards.

Effects of green tea extract on reducing Vibrio parahaemolyticus and increasing shelf life of oyster meats

This study investigated effects of tea extract on growth of pathogenic Vibrio parahaemolyticus and potential utilization in post-harvest treatment to extend shelf life of Pacific oysters (Crassostrea gigas). Longjing Tea, which exhibited strong bactericidal activity against V. parahaemolyticus, was selected to use in this study. Tea extract containing equal or higher than 4.6 g/l total phenolic contents (TPC) as gallic acid equivalents (GAE) determined by Folin-Ciocalteau method could reduce a mixture of five clinical V. parahaemolyticus strains in tryptic soy broth plus 1.5% NaCl from 4.5 log CFU/ml to non-detectable level (<1 log CFU/ml) within 8 h. A treatment of shucked oysters with tea extract containing 9.1 g/l TPC as GAE for 2 h at 23 ± 1 °C with oyster/tea extract ratio of approximate 0.9 g/ml resulted in greater (p < 0.05) V. parahaemolyticus reductions (0.8 log MPN/g) compared to controls (0.2 log MPN/g). The following shelf life study indicated that green tea treatment at oyster/tea extract ratio of approximate 0.7 g/ml could enhance reducing V. parahaemolyticus while retarding the growth of total bacteria in oysters during 5 ± 1 °C storage. Therefore, green tea might be utilized as a natural antimicrobial agent to inactivate V. parahaemolyticus in oysters and extend the shelf life during refrigeration storage.