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Synthetic biology strategies for sustainable bioplastic production by yeasts
Huong-Giang Le, Yongjae Lee, Sun-Mi Lee
J. Microbiol. 2025;63(3):e2501022.   Published online March 28, 2025
DOI: https://doi.org/10.71150/jm.2501022
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AbstractAbstract PDF

The increasing environmental concerns regarding conventional plastics have led to a growing demand for sustainable alternatives, such as biodegradable plastics. Yeast cell factories, specifically Saccharomyces cerevisiae and Yarrowia lipolytica, have emerged as promising platforms for bioplastic production due to their scalability, robustness, and ease of manipulation. This review highlights synthetic biology approaches aimed at developing yeast cell factories to produce key biodegradable plastics, including polylactic acid (PLA), polyhydroxyalkanoates (PHAs), and poly (butylene adipate-co-terephthalate) (PBAT). We explore recent advancements in engineered yeast strains that utilize various synthetic biology strategies, such as the incorporation of new genetic elements at the gene, pathway, and cellular system levels. The combined efforts of metabolic engineering, protein engineering, and adaptive evolution have enhanced strain efficiency and maximized product yields. Additionally, this review addresses the importance of integrating computational tools and machine learning into the Design-Build-Test-Learn cycle for strain development. This integration aims to facilitate strain development while minimizing effort and maximizing performance. However, challenges remain in improving strain robustness and scaling up industrial production processes. By combining advanced synthetic biology techniques with computational approaches, yeast cell factories hold significant potential for the sustainable and scalable production of bioplastics, thus contributing to a greener bioeconomy.

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  • Advancing microbial engineering through synthetic biology
    Ki Jun Jeong
    Journal of Microbiology.2025; 63(3): e2503100.     CrossRef
Journal Articles
Enhanced Poly-γ-Glutamic Acid Production by a Newly Isolated Bacillus halotolerans F29
Xiaorong Sun, Yaoyu Cai, Dexin Wang
J. Microbiol. 2024;62(8):695-707.   Published online August 20, 2024
DOI: https://doi.org/10.1007/s12275-024-00153-w
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AbstractAbstract
Poly-γ-glutamic acid (γ-PGA) is a promising biopolymer for various applications. In this study, we isolated a novel γ-PGA-producing strain, Bacillus halotolerans F29. The one-factor-at-a-time method was used to investigate the influence of carbon sources, nitrogen sources, and culture parameters on γ-PGA production. The optimal carbon and nitrogen sources were sucrose and (NH4)2SO4, respectively. The optimal culture conditions for γ-PGA production were determined to be 37 °C and a pH of 5.5. Response surface methodology was used to determine the optimum medium components: 77.6 g/L sucrose, 43.0 g/L monosodium glutamate, and 2.2 g/L K2HPO4. The γ-PGA titer increased significantly from 8.5 ± 0.3 g/L to 20.7 ± 0.7 g/L when strain F29 was cultivated in the optimized medium. Furthermore, the γ-PGA titer reached 50.9 ± 1.5 g/L with a productivity of 1.33 g/L/h and a yield of 2.23 g of γ-PGA/g of L-glutamic acid with the optimized medium in fed-batch fermentation. The maximum γ-PGA titer reached 45.3 ± 1.1 g/L, with a productivity of 1.06 g/L/h when molasses was used as a carbon source. It should be noted that the γ-PGA yield in this study was the highest of all reported studies, indicating great potential for the industrial production of γ-PGA.

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  • Transcriptomics-guided rational engineering in Bacillus licheniformis for enhancing poly-γ-glutamic acid biosynthesis using untreated molasses
    Rui Han, Qian Zhong, Yifan Yan, Juan Wang, Yifan Zhu, Sha Li, Peng Lei, Rui Wang, Yibin Qiu, Zhengshan Luo, Hong Xu
    International Journal of Biological Macromolecules.2024; 282: 137514.     CrossRef
Cultivation of Diverse Novel Marine Bacteria from Deep Ocean Sediment Using Spent Culture Supernatant of Ca. Bathyarchaeia Enrichment
Sidra Erum Ishaq, Tariq Ahmad, Lewen Liang, Ruize Xie, Tiantian Yu, Yinzhao Wang, Fengping Wang
J. Microbiol. 2024;62(8):611-625.   Published online July 10, 2024
DOI: https://doi.org/10.1007/s12275-024-00145-w
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AbstractAbstract
Most microorganisms resist pure cultivation under conventional laboratory conditions. One of the primary issues for this un-culturability is the absence of biologically produced growth-promoting factors in traditionally defined growth media. However, whether cultivating microbes by providing spent culture supernatant of pivotal microbes in the growth medium can be an effective approach to overcome this limitation is still an under-explored area of research. Here, we used the spent culture medium (SCM) method to isolate previously uncultivated marine bacteria and compared the efficiency of this method with the traditional cultivation (TC) method. In the SCM method, Ca. Bathyarchaeia-enriched supernatant (10%) was used along with recalcitrant organic substrates such as lignin, humic acid, and organic carbon mixture. Ca. Bathyarchaeia, a ubiquitous class of archaea, have the capacity to produce metabolites, making their spent culture supernatant a key source to recover new bacterial stains. Both cultivation methods resulted in the recovery of bacterial species from the phyla Pseudomonadota, Bacteroidota, Actinomycetota, and Bacillota. However, our SCM approach also led to the recovery of species from rarely cultivated groups, such as Planctomycetota, Deinococcota, and Balneolota. In terms of the isolation of new taxa, the SCM method resulted in the cultivation of 80 potential new strains, including one at the family, 16 at the genus, and 63 at the species level, with a novelty ratio of ~ 35% (80/219). In contrast, the TC method allowed the isolation of ~ 10% (19/171) novel strains at species level only. These findings suggest that the SCM approach improved the cultivation of novel and diverse bacteria.

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  • Engineering the phycosphere: fundamental concepts and tools for the bottom-up design of microalgal-bacterial consortia
    Austin Semple, Jagroop Pandhal
    Applied Phycology.2025; 6(1): 21.     CrossRef
  • Uncertainty Analysis of Biogas Generation and Gas Hydrate Accumulations in the Baiyun Sag, South China Sea
    Pibo Su, Jinqiang Liang, Huai Cheng, Yaoyao Lv, Wei Zhang, Zuofei Zhu
    Microorganisms.2024; 13(1): 5.     CrossRef
Epidemiological Characteristics of Norovirus Outbreaks in Shenyang from 2017 to 2021
Ying Qi , Xinxin Dong , Xiaowei Cheng , Han Xu , Jin Wang , Bing Wang , Ye Chen , Baijun Sun , Linlin Zhang , Yan Yao
J. Microbiol. 2023;61(4):471-478.   Published online March 27, 2023
DOI: https://doi.org/10.1007/s12275-023-00033-9
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AbstractAbstract
Norovirus is one of the leading causes of acute gastroenteritis outbreaks worldwide. This study aimed to identify the epidemiological characteristics of norovirus outbreaks and to provide evidence for public health entities. Specimens and epidemiological survey data were collected to determine if there were differences in the attack rate of norovirus in terms of the year, season, transmission route, exposure setting, and region and to determine whether there were relationships between the reporting interval, the number of illnesses in a single outbreak and the duration of the outbreak. Norovirus outbreaks were reported throughout the year, with seasonal characteristics (i.e., high rates in spring and winter). Among all regions in Shenyang with the exception of Huanggu and Liaozhong, norovirus outbreaks had been reported, and the primary genotype was GII.2[P16]. Vomiting was the most common symptom. The main places of occurrence were childcare institutions and schools. The person-to-person route was the main transmission route. The median duration of norovirus was 3 days (IQR [interquartile range]: 2–6 days), the median reporting interval was 2 days (IQR: 1–4 days), the median number of illnesses in a single outbreak was 16 (IQR: 10–25); there was a positive correlation between these parameters. Norovirus surveillance and genotyping studies still need to be further strengthened to increase knowledge regarding the pathogens and their variant characteristics, to better characterize the patterns of norovirus outbreaks and to provide information for outbreak prevention. Norovirus outbreaks should be detected, reported and handled early. Public health entities and the government should develop corresponding measures for different seasons, transmission routes, exposure settings, and regions.

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  • Surge of acute gastroenteritis outbreaks due to rising norovirus GII.4 transmission in Seoul childcare centers and kindergartens in 2022 compared to 2019–2021
    Euncheol Son, Young-Hoon Kim
    Archives of Virology.2024;[Epub]     CrossRef
  • Development and Evaluation of a Rapid GII Norovirus Detection Method Based on CRISPR-Cas12a
    Xinyi Hu, Pei He, Tong Jiang, Jilu Shen
    Polish Journal of Microbiology.2024; 73(1): 89.     CrossRef
  • Improving knowledge, attitude and practice on norovirus infection diarrhea among staff of kindergartens and schools: a before-after study
    Hongxin Lyu, Dongmei Liang, Riyan Luo, Yunlong Feng, Lei Liu, Sixia Yang, Fuling Cai, Zhen Zhang, Huawei Xiong
    BMC Public Health.2024;[Epub]     CrossRef
  • Epidemiological and Molecular Genetic Analysis of Outbreaks of Acute Intestinal Infections in the Khabarovsk Krai in 2022
    Elena Yu. Sapega, Liudmila V. Butakova, Olga E. Trotsenko, Tatyana A. Zaitseva, Tatyana N. Karavyanskaya
    ЗДОРОВЬЕ НАСЕЛЕНИЯ И СРЕДА ОБИТАНИЯ - ЗНиСО / PUBLIC HEALTH AND LIFE ENVIRONMENT.2023; : 74.     CrossRef
  • Dual-responsive amplification strategy for ultrasensitive detection of norovirus in food samples: Combining magnetic relaxation switching and fluorescence assay
    Tao Wang, Sha Liu, Zixuan Zhou, Weiya Wang, Shuyue Ren, Baolin Liu, Zhixian Gao
    Sensors and Actuators B: Chemical.2023; 396: 134573.     CrossRef
Activation of the SigE-SigB signaling pathway by inhibition of the respiratory electron transport chain and its effect on rifampicin resistance in Mycobacterium smegmatis
Yuna Oh , Hye-In Lee , Ji-A Jeong , Seonghan Kim , Jeong-Il Oh
J. Microbiol. 2022;60(9):935-947.   Published online August 1, 2022
DOI: https://doi.org/10.1007/s12275-022-2202-0
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AbstractAbstract
Using a mutant of Mycobacterium smegmatis lacking the major aa3 cytochrome c oxidase of the electron transport chain (Δaa3), we demonstrated that inhibition of the respiratory electron transport chain led to an increase in antibiotic resistance of M. smegmatis to isoniazid, rifampicin, ethambutol, and tetracycline. The alternative sigma factors SigB and SigE were shown to be involved in an increase in rifampicin resistance of M. smegmatis induced under respiration-inhibitory conditions. As in Mycobacterium tuberculosis, SigE and SigB form a hierarchical regulatory pathway in M. smegmatis through SigE-dependent transcription of sigB. Expression of sigB and sigE was demonstrated to increase in the Δaa3 mutant, leading to upregulation of the SigB-dependent genes in the mutant. The phoU2 (MSMEG_1605) gene implicated in a phosphatesignaling pathway and the MSMEG_1097 gene encoding a putative glycosyltransferase were identified to be involved in the SigB-dependent enhancement of rifampicin resistance observed for the Δaa3 mutant of M. smegmatis. The significance of this study is that the direct link between the functionality of the respiratory electron transport chain and antibiotic resistance in mycobacteria was demonstrated for the first time using an electron transport chain mutant rather than inhibitors of electron transport chain.

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  • Rel-dependent decrease in the expression of ribosomal protein genes by inhibition of the respiratory electron transport chain in Mycobacterium smegmatis
    Na-Kyeong Kim, Jong-Eun Baek, Ye-Jin Lee, Yuna Oh, Jeong-Il Oh
    Frontiers in Microbiology.2024;[Epub]     CrossRef
  • MoaB2, a newly identified transcription factor, binds to σ A in Mycobacterium smegmatis
    Barbora Brezovská, Subhash Narasimhan, Michaela Šiková, Hana Šanderová, Tomáš Kovaľ, Nabajyoti Borah, Mahmoud Shoman, Debora Pospíšilová, Viola Vaňková Hausnerová, Dávid Tužinčin, Martin Černý, Jan Komárek, Martina Janoušková, Milada Kambová, Petr Halada,
    Journal of Bacteriology.2024;[Epub]     CrossRef
  • Enhanced hypoxanthine utilization for cAMP salvage synthesis efficiently by Arthrobacter sp. CCTCC 2013431 via xanthine oxidase inhibition
    Baofeng Chen, Hai Tan, Chang Li, Linbo Li, Zhonghua Zhang, Zhigang Li
    Biotechnology Letters.2024; 46(6): 1095.     CrossRef
  • Mycobacterial Regulatory Systems Involved in the Regulation of Gene Expression Under Respiration-Inhibitory Conditions
    Yuna Oh, Ha-Na Lee, Eon-Min Ko, Ji-A Jeong, Sae Woong Park, Jeong-Il Oh
    Journal of Microbiology.2023; 61(3): 297.     CrossRef
The transcription factor Cas5 suppresses hyphal morphogenesis during yeast-form growth in Candida albicans
Jong-Myeong Kim , Hye Yun Moon , Dong Wook Lee , Hyun Ah Kang , Jeong-Yoon Kim
J. Microbiol. 2021;59(10):911-919.   Published online September 7, 2021
DOI: https://doi.org/10.1007/s12275-021-1326-y
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AbstractAbstract
Candida albicans is an opportunistic human pathogen that exists as yeast, hyphal or pseudohyphal forms depending on pH, nutrients, and temperature. The morphological transition from yeast to hyphae, which is required for the complete virulence of C. albicans, is controlled by many transcription factors that activate or repress hypha-specific genes. The C. albicans transcriptional factor Cas5, a key regulator of genes involved in cell wall integrity, affects the susceptibility of C. albicans to fluconazole, an inhibitor of ergosterol synthesis. In this study, we found that deletion of CAS5 in C. albicans decreased the expression levels of a set of ergosterol biosynthesis genes, such as ERG2, ERG3, ERG5, ERG6, ERG11, and ERG24,
result
ing in the accumulation of lanosterol and zymosterol, which are intermediate metabolites in the ergosterol biosynthesis pathway. Interestingly, it was observed that the cas5Δ/Δ mutant could not maintain the yeast form under non-hyphainducing conditions, while the CAS5-overexpressing cells could not form hyphae under hypha-inducing conditions. Consistent with these observations, the cas5Δ/Δ mutant highly expressed hypha-specific genes, ALS3, ECE1, and HWP1, under non-hypha-inducing conditions. In addition, CAS5 transcription was significantly downregulated immediately after hyphal initiation in the wild-type strain. Furthermore, the cas5Δ/Δ mutant reduced the transcription of NRG1, which encodes a major repressor of hyphal morphogenesis, while Cas5 overexpression increased the transcription of NRG1 under hyphainducing conditions. Collectively, this study suggests the potential role of Cas5 as a repressor of hypha-specific genes during yeast-form growth of C. albicans.

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  • The Role of Sfp1 in Candida albicans Cell Wall Maintenance
    Che-Kang Chang, Min-Chi Yang, Hsueh-Fen Chen, Yi-Ling Liao, Chung-Yu Lan
    Journal of Fungi.2022; 8(11): 1196.     CrossRef
Paenibacillus albilobatus sp. nov., isolated from acidic soil on Jeju Island
Jae-Won Lee , Ye-Eun Kim , Myung-Suk Kang , Ki-Eun Lee , Eun-Young Lee , Soo-Je Park
J. Microbiol. 2018;56(6):393-398.   Published online June 1, 2018
DOI: https://doi.org/10.1007/s12275-018-8158-4
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AbstractAbstract
A rod-shaped, white color colony with lobate architectures, strain h2T was isolated from a moderately acidic soil on Jeju Island, Republic of Korea. Comparative analysis of the 16S rRNA gene sequence showed that the strain h2T is closely related to Paenibacillus relictisesami DSM 25385T (97.4%, 16S rRNA gene sequence similarity), Paenibacillus azoreducens KACC 11244T (97.2%), and Paenibacillus cookii LMG 18419T (97.0%). DNA-DNA hybridization indicated that the strain h2T has relatively low levels of DNA-DNA relatedness with respect to P. relictisesami DSM 25385T (10.2%) and P. azoreducens KACC 11244T (13.7%). Additionally, the genomic DNA G + C content of h2T is 51.5 mol%. The isolated strain grew at pH 4.0–9.0 (optimum, pH 6.0–7.0) and 0–5% (w/v) NaCl (optimum, 0%) and a temperature of 15–45°C (optimum 35°C). The quinones in the strain are MK-6 and MK-7, and the predominant fatty acid is C15:0 anteiso (32.1%) followed by C17:0 anteiso (26.5%), and C16:0 iso (21.0%). Based on its phenotypic properties, genotypic distinctiveness, and chemotaxonomic features, strain h2T is proposed as a novel species in the genus Paenibacillus, for which the name Paenibacillus albilobatus sp. nov. is proposed (= KCCM 43269T = JCM 32395T = LMG 30408T). The type strain of Paenibacillus albilobatus is h2T.

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  • Description of Paenibacillus dokdonensis sp. nov., a new bacterium isolated from soil
    Jayoung Paek, Lu Bai, Yeseul Shin, Hongik Kim, Joong-Ki Kook, Young-Hyo Chang
    International Journal of Systematic and Evolutionary Microbiology .2019;[Epub]     CrossRef
Research Support, Non-U.S. Gov'ts
Effect of Light and Reductones on Differentiation of Pleurotus ostreatus
Seung-Rock Lee , Woo-Jeong Joo , Yong-Un Baek , Inyoung Kim , Kee-Oh Chay , Seung-Hyun Cho , Seung-Jae Lee , Sa-Ouk Kang
J. Microbiol. 2011;49(1):71-77.   Published online March 3, 2011
DOI: https://doi.org/10.1007/s12275-011-0507-5
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AbstractAbstract
Vegetative mycelia of Pleurotus ostreatus were differentiated into primordia and subsequently into fruit bodies in synthetic sucrose-asparagine medium when exposed to light at low temperature. During photomorphogenesis, L-ascorbic acid-like substances called reductones were produced. L-Ascorbic acid, D-erythroascorbic acid, 5-O-(α-D-glucopyranosyl)-D-erythroascorbic acid, 5-O-(α-D-xylopyranosyl)-D-erythroascorbic acid, 5-methyl-5-O-(α-D-glucopyranosyl)-D-erythroascorbic acid and 5-methyl-5-O-(α-D-xylopyranosyl)-D-erythroascorbic acid were accumulated initially in the illuminated mycelia before the initiation of fruiting. The content of glycosides of erythroascorbic acid and their methylated compounds increased again in the primordia and the fruit bodies. Exogenous L-ascorbic acid induced the formation of primordia from the mycelia in the dark in a dose-dependent manner. Thus, this suggests that these reductones might play a role in mediating the light stimulus in photomorphogenesis.
Intracellular Substrates of a Heme-Containing Ascorbate Oxidase in Pleurotus ostreatus
Seung-Rock Lee , Woo-Jeong Joo , Yong-Un Baek , Youn-Kyong Lee , Seong-Woon Yu , Yeon-Ran Kim , Kee-Oh Chay , Seung-Hyun Cho , Sa-Ouk Kang
J. Microbiol. 2009;47(2):178-186.   Published online May 2, 2009
DOI: https://doi.org/10.1007/s12275-008-0307-8
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AbstractAbstract
A novel heme-containing ascorbate oxidase isolated from oyster mushroom, Pleurotus ostreatus, catalyzes oxidation of ascorbic acid (Kim et al., 1996). In this report, we describe the identification of intracellular substrates of the enzyme in the mushroom. Six compounds, which can serve as substrate of the heme-containing ascorbate oxidase, were identified as L-ascorbic acid, D-erythroascorbic acid, 5-O-(α-D-glucopyranosyl)-D-erythroascorbic acid, 5-O-(α-D-xylopyranosyl)-D-erythroascorbic acid, 5-methyl-5-O-(α-D-glucopyranosyl)-D-erythroascorbic acid, and 5-methyl-5-O-(α-D-xylopyranosyl)-D-erythroascorbic acid. All of the compounds were oxidized at a significant rate by the heme-containing ascorbate oxidase. Oxidation of the compounds produced equimolar amounts of hydrogen peroxide per mole of substrate.
Enhanced Production of Exopolysaccharides by Fed-batch Culture of Ganoderma resinaceum DG-6556
Hyun Mi Kim , Soon-Young Paik , Kyung Soo Ra , Kwang Bon Koo , Jong Won Yun , Jang Won Choi
J. Microbiol. 2006;44(2):233-242.
DOI: https://doi.org/2360 [pii]
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AbstractAbstract
The objectives of this study were to optimize submerged culture conditions of a new fungal isolate, Ganorderma resinaceum, and to enhance the production of bioactive mycelial biomass and exopolysaccharides (EPS) by fed-batch culture. The maximum mycelial growth and EPS production in batch culture were achieved in a medium containing 10 g/l glucose, 8 g/l soy peptone, and 5 mM MnCl2 at an initial pH 6.0 and temperature 31°C. After optimization of culture medium and environmental conditions in batch cultures, a fed-batch culture strategy was employed to enhance production of mycelial biomass and EPS. Five different EPS with molecular weights ranging from 53,000 to 5,257,000 g/mole were obtained from either top or bottom fractions of ethanol precipitate of culture filtrate. A fed-batch culture of G. resinaceum led to enhanced production of both mycelial biomass and EPS. The maximum concentrations of mycelial biomass (42.2 g/l) and EPS (4.6 g/l) were obtained when 50 g/l of glucose was fed at day 6 into an initial 10 g/l of glucose medium. It may be worth attempting with other mushroom fermentation processes for enhanced production of mushroom polysaccharides, particularly those with industrial potential.
Development of a Bottle-Free Multipurpose Incubator for Generating Various Bacterial Culture Conditions
Nam Woong Yang , Yong Lim
J. Microbiol. 2005;43(1):28-33.
DOI: https://doi.org/2142 [pii]
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AbstractAbstract
The purpose of this study was to develop a multipurpose incubator, without the gas cylinders (bottles) which are required for H_2 and CO_2 supplementation. In our bottle-free multipurpose incubator, the H_2 and CO_2 were generated by chemical reactions induced within the chamber. The reaction between sodium borohydride and acetic acid at a molar ratio of 1:1 was used to generate H_2, according to the following formula: 4NaBH_4 + 2CH_3COOH + 7H_2O → 2CH_3COONa + Na_2B_4O_7 + 16H_2, whereas the other reaction, citric acid and sodium bicarbonate at a 1:1 molar ratio, was used to generate CO_2, according to the following formula: C_6H_8O_7 + 3NaHCO_3 → Na_3(C_6H_5O_7) + 3H_2O + 3CO_2. Five species of obligate anaerobic bacteria, one strain of capnophilic bacterium, and one strain of microaerophilic bacterium were successfully cultured in the presence of their respective suitable conditions, all of which were successfully generated by our bottle-free multipurpose incubator. We conclude that, due to its greater safety, versatility, and significantly lower operating costs, this bottle-free multipurpose incubator can be used for the production of fastidious bacterial cultures, and constitutes a favorable step above existing anaerobic incubators. <br>
Purification and Characterization of Dehydroascorbate Reductase from Pleurotus ostreatus
Kim, Yeon Ran , Kang, Sa Ouk
J. Microbiol. 1998;36(3):164-170.
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AbstractAbstract
Dehydroascorbate reductase was purified 93-fold relative to the crude cell extracts from the cytosolic fraction of the mycelia of Pleurotus ostreatus with an overall yield of 5%. The molecular mass of the native enzyme determined by gel filtration chromatography was 86 kDa. Sodium dodecylsulfate-polyacrylamide gel electrophoresis revealed that the enzyme is a single polypeptide. Dehydroascorbate kreductase from P. ostreatus contained relatively quite a lot of lysine and a relatively small amount of glutamate/glutamine. The enzyme was optimally active at pH 7.5 and at 45℃. Apparent K_m values of dehydroascorbate reductase were 2.5 mM and 0.7 mM for dehydroascorbate and glutathione. The enzyme was significantly unstable under acidic and highly alkaline conditions. The absorption spectrum of the purified enzyme showed an unusual flavin peak, the result of which suggests that the enzyme might form flavin adduct.
Reduction of Hexavalent Chromium by Escherichia coli ATCC 33456 in Batch and Continuous Cultures
Woo Chul Bae , Tae Gu Kang , In Kyong Kang , You Jung Won , Byeong Chul Jeong
J. Microbiol. 2000;38(1):36-39.
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AbstractAbstract
Toxic hexavalent chromium, Cr(VI), was reduced to a less toxic trivalent chromium form by E. coli ATCC 33456. The suitable electron donor for Cr(VI) reduction was glucose. E. coli ATCC 33456 was more resistant to metal cations than other reported Cr(VI) reducing microorganisms. Cell growth was inhibited by the presence of Cr(VI) in a liquid medium and Cr(VI) reduction accompanied cell growth. With a hydraulic retention time of 20 h, Cr(VI) reducing efficiency was 100% to 84% when Cr(VI) concentration in the influent was in the range of 10 to 40 mg L^-1. Specific rate of Cr(VI) concentration in the influent was 2.41 mg Cr(VI) g DCW^-1 h^-1 when 40 mg :^-1 of Cr(VI) influent was used. This result suggested the potential application of E. coli ATCC 33456 for the detoxification of Cr(VI) in Cr(VI) contaminated wastewater.

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