• International journal of advanced smart convergence
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• v.4 no.1
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• pp.11-17
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• 2015

Fouling in heat exchanger becomes a major problem of dairy industry and it increases the production cost. These are lost productivity, additional energy, additional equipment, chemical, manpower, and environmental impact. Fouling also introduces the risk of food safety due to the improper heating temperature which allow the survival of pathogenic bacteria in milk, introducing biofilm formation of pathogenic bacteria in equipments and spreading the pathogenic bacteria to milk. The aim of this study is to determine the fouling rate during pasteurization process in heat exchanger of pasteurized milk produced by Village Cooperative Society (KUD) "X" in Malang, East Java Indonesia by using empirical modeling. The fouling rate is found as $0.3945^{\circ}C/h$ with the heating process time ranged from 0 to 2 hours and temperature difference (hot water inlet temperature and milk outlet temperature) ranged from 0.654 to $1.636^{\circ}C$. The fouling rate depends on type and characteristics of heat exchangers, time and temperature of process, milk type, age of milk, seasonal variations, the presence of microorganism and more. This results will be used to plan Cleaning In Place (CIP) and to design the control system of pasteurization process in order to maintain the milk outlet temperature as standard of pasteurization.

• Research in Plant Disease
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• v.23 no.3
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• pp.212-227
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• 2017

Pseudomonas chlororaphis O6, isolated from the roots of dryland, field-grown commercial wheat in the USA, enhances plant health and therefore it is used in agriculture as a biofertilizer and biocontrol agent. The metabolites produced by this pseudomonad stimulate plant growth through direct antagonism of pathogens and by inducing systemic resistance in the plant. Studies upon P. chlororaphis O6 identify the pathways through which defined bacterial metabolites generate protection against pathogenic microbes, insects, and nematodes. P. chlororaphis O6 also triggers plant resistance to drought and salinity stresses. The beneficial determinants are produced from bacterial cells as they form biofilms during root colonization. Molecular control these processes in P. chlororaphis O6 involves the global regulatory Gac/Rsm signaling cascade with cross-talk between other global regulatory pathways. The Gac/Rsm regulon allows for coordinate phasing of expression of the genes that encode these beneficial traits among a community of cells. This review provides insights on the Gac/Rsm regulon in expression of beneficial traits of the P. chlororaphis O6 which can contribute to help yield enhancement and quality in agricultural production.

• BMB Reports
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• v.44 no.1
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• pp.1-10
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• 2011

Inter-cellular communication via diffusible small molecules is a defining character not only of multicellular forms of life but also of single-celled organisms. A large number of bacterial genes are regulated by the change of chemical milieu mediated by the local population density of its own species or others. The cell density-dependent "autoinducer" molecules regulate the expression of those genes involved in genetic competence, biofilm formation and persistence, virulence, sporulation, bioluminescence, antibiotic production, and many others. Recent innovations in recombinant DNA technology and micro-/nano-fluidics systems render the genetic circuitry responsible for cell-to-cell communication feasible to and malleable via synthetic biological approaches. Here we review the current understanding of the molecular biology of bacterial intercellular communication and the novel experimental protocols and platforms used to investigate this phenomenon. A particular emphasis is given to the genetic regulatory circuits that provide the standard building blocks which constitute the syntax of the biochemical communication network. Thus, this review gives focus to the engineering principles necessary for rewiring bacterial chemo-communication for various applications, ranging from population-level gene expression control to the study of host-pathogen interactions.

• Microbiology and Biotechnology Letters
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• v.22 no.4
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• pp.415-422
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• 1994

The biodegradation of aromatic compounds by a mixed culture GE1 was investigated in an artificial wastewater containing 250 mg/l of benzene, toluene, and phenol in semicontinuous culture. In the control group (no strains) with an aeration rate of 75 ml/l/min, 37% of phenol and 83% of benzene were volatilized during early 24 hrs and toluene was disappeared from the medium within 12 hrs. The biodegradation of benzene and toluene was effective in SB (strains + biofilm) treatment, while phenol was degraded more quickly in SG (strains + glucose) treatment including glucose as an additional carbon source. aromatic compounds added at a concentration of 250 mg/l were completely removed by SG treatment after 16 hrs or 32 hrs, respectively. The removal rate of COD was high as much as 80 mg/l/h in SG treatment during early period, but COD revealed a stable value of 116~140 mg/l after 12 hrs caused by increased biomass. Therefore, it is concluded that the mixed GE1 could be used for the wastewater treatment including aromatic compounds such as benzene, toluene, and phenol.

• Journal of Environmental Science International
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• v.16 no.7
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• pp.813-821
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• 2007

Laboratory scale experiments were conducted to investigate the removal characteristics of nitrogen and phosphorus in two sequencing batch biofilm reactors (SBBRs). SBBR1 had a short first non-aeration period and SBBR2 had a long first non-aeration period. The removal characteristics of nitrogen and phosphorus in each SBBR were precisely observed according to the variation of influent TOC concentration, and the operation control parameters (pH, DO concentration, ORP) in each reactor were measured. In biological nitrogen removal, there was little difference between SBBR1 and SBBR2 and the nitrogen removal efficiencies were very low. The nitrogen and phosphorus removal characteristics in high influent TOC concentration were different from those in low TOC. Nitrogen removals by simultaneous nitrification/denitrification (SND) were occurred in both SBBR1 and SBBR2. The P removal in SBBR1 was superior to that in SBBR2. The second P release was observed in SBBR1 which had long second non-aeration period.

• Environmental Engineering Research
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• v.19 no.3
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• pp.185-195
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• 2014

Despite the enormous technical and economic efforts to improve environmental conditions, currently about 40% of the global population (or 2 billion people) are still lack access to safe water supply and adequate sanitation facilities. Pollution problems and transmission of water- related diseases will continue to proliferate. The rapid population growth and industrialization will lead to a reduction of arable land, thus exacerbating the food shortage problems and threatening environmental sustainability. Natural systems in this context are a transdisciplinary approach which employs the activities of microbes, soil and/or plants in waste stabilisation and resource recovery without the aid of mechanical or energy-intensive equipments. Examples of these natural systems are: waste stabilisation ponds, aquatic weed ponds, constructed wetlands and land treatment processes. Although they require relatively large land areas, the natural systems could achieve a high degree of waste stabilisation and at the same time, yield potentials for waste recycling through the production of algal protein, fish, crops, and plant biomass. Because of the complex interactions occurring in the natural systems, the existing design procedures are based mainly on empirical or field experience approaches. An integrated kinetic model encompassing the activities of both suspended and biofilm bacteria and some important engineering parameters has been developed which could predict the organic matter degradation in the natural systems satisfactorily.

• Korean Journal of Materials Research
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• v.16 no.10
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• pp.639-646
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• 2006

Over the last two decades, microbiologically influenced corrosion (MIC) of metallic materials has received considerable attention due to its serious effects on industrial field. In this context, it is important to devise control methods which inhibit biofilm formation on various metallic compounds and are compatible with environment. It was change of various conditions (duty cycle, current density, $AgNO_3$ concentration and pH) for injection of Ag particles in anodized Aluminum alloy pore using pulsed current. Optimal condition was obtained by means of FE-SEM, ICP analysis etc. The antibacterial metal's specimen were manufactured under optimal condition and this specimen were tested the antibacterial characterization and anticorrosion characterization. In result of test, we can confirmed that the antibacterial characterization and anticorrosion characterization of the specimens of injected Ag particles in anodized Aluminum alloy pore using pulsed current were better than the anodized Aluminum alloy specimens.

• Journal of Microbiology and Biotechnology
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• v.30 no.4
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• pp.571-582
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• 2020

Quorum sensing (QS)-mediated infections cause severe diseases in human beings. The control of infectious diseases by inhibiting QS using antipathogenic drugs is a promising approach as antibiotics are proving inefficient in treating these diseases. Marine fungal (Pestalotiopsis sydowiana PPR) extract was found to possess effective antipathogenic characteristics. The minimum inhibitory concentration (MIC) of the fungal extract against test pathogen Pseudomonas aeruginosa PAO1 was 1,000 ㎍/ml. Sub-MIC concentrations (250 and 500 ㎍/ml) of fungal extract reduced QS-regulated virulence phenotypes such as the production of pyocyanin, chitinase, protease, elastase, and staphylolytic activity in P. aeruginosa PAO1 by 84.15%, 73.15%, 67.37%, 62.37%, and 33.65%, respectively. Moreover, it also reduced the production of exopolysaccharides (74.99%), rhamnolipids (68.01%), and alginate (54.98%), and inhibited the biofilm formation of the bacteria by 90.54%. In silico analysis revealed that the metabolite of P. sydowiana PPR binds to the bacterial QS receptor proteins (LasR and RhlR) similar to their respective natural signaling molecules. Cyclo(-Leu-Pro) (CLP) and 4-Hydroxyphenylacetamide (4-HPA) were identified as potent bioactive compounds among the metabolites of P. sydowiana PPR using in silico approaches. The MIC values of CLP and 4-HPA against P. aeruginosa PAO1 were determined as 250 and 125 ㎍/ml, respectively. All the antivirulence assays were conducted at sub-MIC concentrations of CLP (125 ㎍/ml) and 4-HPA (62.5 ㎍/ml), which resulted in marked reduction in all the investigated virulence factors. This was further supported by gene expression studies. The findings suggest that the metabolites of P. sydowiana PPR can be employed as promising QS inhibitors that target pathogenic bacteria.

• The Plant Pathology Journal
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• v.25 no.1
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• pp.62-69
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• 2009

In this study, we characterized the bacterial strain KJ2C12 in relation with its biocontrol activity against Phytophthora capsici on pepper, and identified this strain using morphological, physiological, biochemical, fatty acid methyl ester, and 16S rRNA gene sequence analyses. Strain KJ2C12 significantly (P=0.05) reduced both final disease severity and areas under the disease progress curves of 5-week-old pepper plants inoculated with P. capsici compared to buffer-treated controls. As for the production of antibiotics, biofilms, biosurfactant, extracellular enzyme, HCN, and swarming activity, strain KJ2C12 produced an extracellular enzyme with protease activity, but no other productions or swarming activity. However, Escherichia coli produced weak biofilm only. Strain KJ2C12 could colonize pepper roots more effectively in a gnotobiotic system using sterile quartz sand compared to E. coli over 4 weeks after treatments. However, no bacterial populations were detected in 10 mM $MgSO_4$ buffer-treated controls. Strain KJ2C12 produced significantly higher microbial activity than the $MgSO_4$-treated control or E. coli over 4 weeks after treatments. Bacterial strain KJ2C12 was identified as Bacillus luciferensis based on morphological, physiological, and biochemical characteristics as well as FAME and 16S rRNA gene sequence analyses. In addition, these results suggested that B. luciferensis strain KJ2C12 could reduce Phytophthora blight of pepper by protecting infection courts through enhanced effective root colonization with protease production and an increase of soil microbial activity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.10
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• pp.2990-2996
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• 2009

S. mutans, one of a major causal agents of dental caries, is component of the dental plaque and produces various organic acids such as lactic acid as the end-product of glycolysis. In this study, we are interested in comparing the gene expression of acid-shocked and control cells of S. mutans isolated from Korean with caries. Expression levels of gtfB, gtfC, gtfD and ftf were analyzed by Real-time PCR, when the cells were grown under 20 mM lactic acid stress in the exponential phase. The data showed reduced expression of these genes. S. mutans is known to have developed a variety of mechanisms to tolerate acid sterss. A more detailed analysis of the functions and interactions of acid stress proteins connecting the growth, stress tolerance, biofilm formation is under way.