• Journal of Microbiology and Biotechnology
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• 제20권1호
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• pp.161-168
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• 2010

In this study, the metabolic activities of five strains of Pediococcus spp., in terms of the quantities they produced of lactic acid, hydrogen peroxide, exopolysaccharides, and proteolytic activity, were determined. Lactic acid levels produced by these strains were found to be in the range of 2.5-5.6 mg/ml. All strains produced hydrogen peroxide. The P. pentosaceus Z13P strain produced the maximum amount (0.25 mg/ml) of proteolytic activity. Exopolysaccharide (EPS) production by the Pediococcus strains during growth in MRS (de Man, Rogosa, and Sharpe) medium was in the range 25-64 mg/l. The susceptibility of 10 different antibiotics against these strains was also tested. All strains were found to be resistant to amoxicillin, gentamicin, and vancomycin. Antimicrobial effects of the Pediococcus spp. on pathogens were also determined by an agar diffusion method. All of the strains were able to inhibit L. monocytogenes. The tolerance of the strains to low pH, their resistance to bile salts of strains, and their abilities to autoaggregate and coaggregate with L. monocytogenes were also evaluated.

• Journal of Microbiology and Biotechnology
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• 제18권7호
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• pp.1227-1234
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• 2008

Pseudomonas aeruginosa is an opportunistic human pathogen that produces and secretes exopolysaccharides (EPS), in which cells are embedded to form a highly organized community structure called biofilm. Here, we characterized the role of cyclic diguanylate (c-di-GMP) and EPS (PEL) overproduction in the wspF mutant phenotypes of P. aeruginosa PA14 (wrinkly appearance, hyperadherence, impaired motilities, and reduced virulence in acute infections). We confirmed that the elevated c-di-GMP level plays a key role in all the wspF mutant phenotypes listed above, as assessed by ectopic expression of a c-di-GMP-degrading phophodiesterase (PvrR) in the wspF mutant. In contrast, PEL EPS, which is overproduced in the wspF mutant, was necessary for wrinkly appearance and hyperadherence, but not for the impaired flagellar motilities and the attenuated virulence of the wspF mutant. These results suggest that c-di-GMP affects flagellar motility and virulence, independently of EPS production and surface adherence of this bacterium.

• Journal of Microbiology and Biotechnology
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• 제34권7호
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• pp.1491-1500
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• 2024

Inflammation is a biodefense mechanism that provides protection against painful conditions such as inflammatory bowel disease, other gastrointestinal problems, and irritable bowel syndrome. Paraprobiotics have probiotic characteristics of intestinal modulation along with merits of safety and stability. In this study, heat-killed Lactiplantibacillus plantarum KU15122 (KU15122) was investigated for its anti-inflammatory properties. KU15122 was subjected to heat-killed treatment for enhancement of its safety, and its concentration was set at 8 log CFU/mL for conducting different experiments. Nitric oxide production was most remarkably reduced in the KU15122 group, whereas it was increased in the LPS-treated group. In RAW 264.7 cells, KU15122 inhibited the expression of inducible nitric oxide synthase, cyclooxygenase-2, interleukin (IL)-1β, IL-6, and tumor necrosis factor-α. ELISA revealed that among the tested strains, KU15122 exhibited the most significant reduction in PGE2, IL-1β, and IL-6. Moreover, KU15122 inhibited various factors involved in the nuclear factor-kappa B, activator protein-1, and mitogen-activated protein kinase pathways. In addition, KU15122 reduced the generation of reactive oxygen species. The anti-inflammatory effect of KU15122 was likely attributable to the bacterial exopolysaccharides. Conclusively, KU15122 exhibits anti-inflammatory potential against inflammatory diseases.

• Animal Bioscience
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• 제35권2호
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• pp.281-289
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• 2022

Objective: The aim of this study was to characterize the exopolysaccharides (EPS)-producing lactic acid bacteria from Taiwanese ropy fermented milk (TRFM) for developing a clean label low-fat fermented milk. Methods: Potential isolates from TRFM were selected based on the Gram staining test and observation of turbid suspension in the culture broth. Random amplified polymorphic DNA-polymerase chain reaction, 16S rRNA gene sequencing, and API CHL 50 test were used for strain identification. After evaluation of EPS concentration, target strains were introduced to low-fat milk fermentation for 24 h. Fermentation characters were checked: pH value, acidity, viable count, syneresis, and viscosity. Sensory evaluation of fermented products was carried out by 30 volunteers, while the storage test was performed for 21 days at 4℃. Results: Two EPS-producing strains (APL15 and APL16) were isolated from TRFM and identified as Lactococcus (Lc.) lactis subsp. cremoris. Their EPS concentrations in glucose and lactose media were higher than other published strains of Lc. lactis subsp. cremoris. Low-fat fermented milk separately prepared with APL15 and APL16 reached pH 4.3 and acidity 0.8% with a viable count of 9 log colony-forming units/mL. The physical properties of both products were superior to the control yogurt, showing significant improvements in syneresis and viscosity (p<0.05). Our low-fat products had appropriate sensory scores in appearance and texture according to sensory evaluation. Although decreasing viable cells of strains during the 21-day storage test, low-fat fermented milk made by APL15 exhibited stable physicochemical properties, including pH value, acidity, syneresis and sufficient viable cells throughout the storage period. Conclusion: This study demonstrated that Lc. lactis subsp. cremoris APL15 isolated from TRFM had good fermentation abilities to produce low-fat fermented milk. These data indicate that EPS-producing lactic acid bacteria have great potential to act as natural food stabilizers for low-fat fermented milk.

• Journal of Microbiology and Biotechnology
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• 제17권1호
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• pp.44-51
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• 2007

Marine bacterial strains were isolated trom coastal regions of Goa and screened for the strains that produce the highest amount of mucous expolysaccharide (EPS). Our screening resulted in the identification of the strain Vibrio furnissii VB0S3 (hereafter called VB0S3), as it produced the highest EPS in batch cultures during the late logarithmic growth phase. The isolate was identified as VB0S3 based on morphological and biochemical properties. Growth and EPS production were studied in mineral salts medium supplemented with NaCl (1.5%) and glucose (0.2%). The exopolymer was recovered from the culture supernatant by using three volumes of cold ethanol precipitation and dialysis procedure. Chemical analyses of EPS revealed that it is primarily composed of neutral sugars, uronic acids, and proteins. Fourier-transform infrared (FT-IR) spectroscopy revealed the presence of carboxyl, hydroxyl, and amide groups, which correspond to a typical heteropolymeric polysaccharide, and the EPS also possessed good emulsification activity. The gas chromatographic analysis of an alditol-acetate derivatized sample of EPS revealed that it was mainly composed of galactose and glucose. Minor components found were mannose, rhamnose, fucose, ribose, arabinose, and xylose. EPS was readily isolated from culture supernatants, which suggests that the EPS was a slime-like exopolysaccharide. This is the first report of exopolysaccharide characterization that describes the isolation and characterization of an EPS expressed by Vibrio surnissii strain VB0S3. The results of the study contribute significantly and go a long way towards an understanding of the correlation between growth and EPS production, chemical composition, and industrial applications of the exopolysaccharide in environmental biotechnology and bioremediation.

• Journal of Veterinary Science
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• 제25권2호
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• pp.30.1-30.16
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• 2024

Background: Biofilms, such as those from Staphylococcus epidermidis, are generally insensitive to traditional antimicrobial agents, making it difficult to inhibit their formation. Although quercetin has excellent antibiofilm effects, its clinical applications are limited by the lack of sustained and targeted release at the site of S. epidermidis infection. Objectives: Polyethylene glycol-quercetin nanoparticles (PQ-NPs)-loaded gelatin-N,O-carboxymethyl chitosan (N,O-CMCS) composite nanogels were prepared and assessed for the on-demand release potential for reducing S. epidermidis biofilm formation. Methods: The formation mechanism, physicochemical characterization, and antibiofilm activity of PQ-nanogels against S. epidermidis were studied. Results: Physicochemical characterization confirmed that PQ-nanogels had been prepared by the electrostatic interactions between gelatin and N,O-CMCS with sodium tripolyphosphate. The PQ-nanogels exhibited obvious pH and gelatinase-responsive to achieve on-demand release in the micro-environment (pH 5.5 and gelatinase) of S. epidermidis. In addition, PQ-nanogels had excellent antibiofilm activity, and the potential antibiofilm mechanism may enhance its antibiofilm activity by reducing its relative biofilm formation, surface hydrophobicity, exopolysaccharides production, and eDNA production. Conclusions: This study will guide the development of the dual responsiveness (pH and gelatinase) of nanogels to achieve on-demand release for reducing S. epidermidis biofilm formation.

• 생명과학회지
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• 제14권1호
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• pp.51-56
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• 2004

장수상황버섯(Phellinus baumii)의 균사체 성장 및 세포외 다당체(exopolysaccharides) 생산을 위한 액체배양의 최적 배지 및 배양조건에 관한 실험을 수행한 결과, 최적배양 온도와 초기 pH는 각각 3$0^{\circ}C$와 5.0으로 결정되었다. 탄소원의 경우, cellobiose와 maltose가 균사체 성장에는 양호하였으나 저조한 세포외 다당체 생산을 보였으며, 반면에 fructose 와 mannitol 은 상대적으로 높은 수율의 세포외 다당체 생산과 균사체 성장 또한 양호하였다. 최적 질소원으로는 yeast extract가 균사체 성장뿐만 아니라 세포외 다당체 생산에 효과적인 것으로 결정되었다. 최적 배지의 조성은 fructose 20 g/L, yeast extract 20 g/L 및 $CaCl_2$ 0.55 g/L이었으며, 최적 배양조건 하에서 5-L 교반 발효조를 운전한 결과, 최대 균사체 성장(17.43 g/L)과 최대 세포외 다당체 생산(3.6 g/L)을 얻을 수 있었다. 회수된 세포외 다당체는 glycoprotein이었으며 그 조성은 amino acid분석 결과 주로 arginine (14.1%)과 glycin (12.0%)이었으며, cabohydrate의 경우는 mannose (48.7%)와 arabinose (38.4%)이 주성분이었다.

• 한국식품과학회지
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• 제47권4호
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• pp.438-445
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• 2015

L. plantarum K154 고정화와 C. lacerata 균사체 배양물을 이용한 혼합발효를 통해서 다당류, ${\beta}$-glucan과 같은 생리활성물질과 기능성 GABA 생산을 최적화 하고자 하였다. C. lacerata 균사체의 최적 배양 조건으로 glucose 3%, soybean flour 3%, $MgSO_4$ 0.15%를 혼합하여 배지로 사용하였고, 5 L jar fermentor를 이용하여 $25^{\circ}C$에서 7일간 진탕 배양하였다. 배양물은 균사체 함량 29.7 g/L, 다당류 함량 3.1 g/L, ${\beta}$-glucan 2% (w/w), protease 활성 68.96 unit/mL, ${\alpha}$-amylase 활성 10.37 unit/mL로 매우 높게 나타났다. C. lacerata 균사체 배양물을 이용하여 젖산세균 고정화에 의한 혼합발효물의 생균수를 측정한 결과, 배양 1일 째 비드 내에서 젖산세균의 수는 $3.13{\time}10^9CFU/mL$로 높게 나타났고, 배지에 유리된 젖산세균의 수는 배양기간 동안 $1.48{\time}10^8CFU/mL$로 유지하였다. 알지네이트 1.5%를 사용하여 비드를 제조하였을 때, GABA 함량을 측정한 결과 배양 7일 째 비드 내에서 6.30 mg/mL, 배지에서 9.96 mg/mL로 높게 나타났다. 젖산세균 고정화의 재사용 가능성을 확인하기 위해 고정화 비드를 5회간 재사용하여 $30^{\circ}C$에서 15일간 혼합발효한 결과, GABA 생산이 급격히 증가하여 배양 기간 동안 유지하였다. 결론적으로 C. lacerata 균사체 배양물로부터 고정화된 젖산세균을 이용한 혼합발효는 고농도 GABA를 포함된 기능성 소재를 생산할 수 있었으며, 이는 식품 및 생물 산업의 원료로 활용이 기대된다.

• 한국미생물·생명공학회지
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• 제44권3호
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• pp.229-235
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• 2016

우리나라는 예전부터 전통적인 방법으로 누룩을 제조하고, 이를 발효제로 막걸리를 만들어 왔다. 막걸리는 여과 또는 살균 과정없이 다양한 미생물을 살아 있는 상태로 섭취하기 때문에 영양학적으로나 기능적인 측면에서 가치가 높다. 최근 많은 연구에서 막걸리로부터 미생물을 분리동정하고 다양한 기능성에 대해 스크리닝한 결과, 높은 프로바이오틱스 활성과 다양한 스펙트럼의 항균활성을 가진 균주들이 선별되었다. 특히 일부 유산균들은 GABA와 EPS 등의 기능성 물질을 생성하기도 했다. 또한, 일부 유산균과 효모의 경우 각각 bacteriocin 및 killer toxin을 통해 항균활성을 나타내는 것으로 여겨진다. 이러한 막걸리 유래 기능성 미생물과 그 대사산물은 기능성 식품 소재나 안전한 식품첨가물 및 다양한 산업분야에서 활용될 수 있을 것이다.

• 한국미생물·생명공학회지
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• 제34권1호
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• pp.1-6
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• 2006

Harmful algal blooms (HABs or red tides), caused by uncontrolled proliferation of marine phytoplankton, impose a severe environmental problem and occasionally threaten even public health. We sequenced the genome of an EPS-producing marine bacterium Hahella chejuensis that produces a red pigment with the lytic activity against red-tide dinoflagellates at parts per billion level. H. chejuensis is the first sequenced species among algicidal bacteria as well as in the order Oceanospirillales. Sequence analysis indicated a distant relationship to the Pseudomonas group. Its 7.2-megabase genome encodes basic metabolic functions and a large number of proteins involved in regulation or transport. One of the prominent features of the H. chejuensis genome is a multitude of genes of functional equivalence or of possible foreign origin. A significant proportion (${\sim}23%$) of the genome appears to be of foreign origin, i.e. genomic islands, which encode genes for biosynthesis of exopolysaccharides, toxins, polyketides or non-ribosomal peptides, iron utilization, motility, type III protein secretion and pigment production. Molecular structure of the algicidal pigment was determined to be prodigiosin by LC-ESI-MS/MS and NMR analyses. The genomics-based research on H. chejuensis opens a new possibility for controlling algal blooms by exploiting biotic interactions in the natural environment and provides a model in marine bioprospecting through genome research.