Journal of Microbiology

Review

Recent Advances in CRISPR‑Cas Technologies for Synthetic Biology: Song Hee Jeong , Ho Joung Lee , Sang Jun Lee; J. Microbiol. 2023;61(1):13-36. Published online February 1, 2023; DOI: https://doi.org/10.1007/s12275-022-00005-5

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Abstract: With developments in synthetic biology, “engineering biology” has emerged through standardization and platformization based on hierarchical, orthogonal, and modularized biological systems. Genome engineering is necessary to manufacture and design synthetic cells with desired functions by using bioparts obtained from sequence databases. Among various tools, the CRISPR-Cas system is modularly composed of guide RNA and Cas nuclease; therefore, it is convenient for editing the genome freely. Recently, various strategies have been developed to accurately edit the genome at a single nucleotide level. Furthermore, CRISPR-Cas technology has been extended to molecular diagnostics for nucleic acids and detection of pathogens, including disease-causing viruses. Moreover, CRISPR technology, which can precisely control the expression of specific genes in cells, is evolving to find the target of metabolic biotechnology. In this review, we summarize the status of various CRISPR technologies that can be applied to synthetic biology and discuss the development of synthetic biology combined with CRISPR technology in microbiology.

Journal Articles

Role of melatonin in murine “restraint stress”-induced dysfunction of colonic microbiota: Rutao Lin , Zixu Wang , Jing Cao , Ting Gao , Yulan Dong , Yaoxing Chen; J. Microbiol. 2021;59(5):500-512. Published online February 25, 2021; DOI: https://doi.org/10.1007/s12275-021-0305-7

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Abstract: Intestinal diseases caused by physiological stress have become a severe public health threat worldwide. Disturbances in the gut microbiota-host relationship have been associated with irritable bowel disease (IBD), while melatonin (MT) has antiinflammatory and antioxidant effects. The objective of this study was to investigate the mechanisms by which MT-mediated protection mitigated stress-induced intestinal microbiota dysbiosis and inflammation. We successfully established a murine restraint stress model with and without MT supplementation. Mice subjected to restraint stress had significantly elevated corticosterone (CORT) levels, decreased MT levels in their plasma, elevated colonic ROS levels and increased bacterial abundance, including Bacteroides and Tyzzerella, in their colon tract, which led to elevated expression of Toll-like receptor (TLR) 2/4, p-P65 and p-IκB. In contrast, supplementation with 20 mg/kg MT reversed the elevation of the plasma CORT levels, downregulated the colon ROS levels and inhibited the changes in the intestinal microbiota induced by restraint stress. These effects, in turn, inhibited the activities of TLR2 and TLR4, p-P65 and p-IκB, and decreased the inflammatory reaction induced by restraint stress. Our results suggested that MT may mitigate “restraint stress”-induced colonic microbiota dysbiosis and intestinal inflammation by inhibiting the activation of the NF-κB pathway.

Phosphorylation of tegument protein pp28 contributes to trafficking to the assembly compartment in human cytomegalovirus infection: Jun-Young Seo , Jin Ah Heo , William J. Britt; J. Microbiol. 2020;58(7):624-631. Published online June 27, 2020; DOI: https://doi.org/10.1007/s12275-020-0263-5

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Abstract: Human cytomegalovirus (HCMV) UL99 encodes a late tegument protein pp28 that is essential for envelopment and production of infectious virus. This protein is localized to the endoplasmic reticulum-Golgi intermediate compartment (ERGIC) in transfected cells but it localizes to the cytoplasmic assembly compartment (AC) in HCMV-infected cells. Trafficking of pp28 to the AC is required for the assembly of infectious virus. The N-terminal domain (aa 1-61) of pp28 is sufficient for trafficking and function of the wild type protein during viral infection. However, residues required for authentic pp28 trafficking with the exception of the acidic cluster in the N-terminal domain of pp28 remain undefined. Monitoring protein migration on SDS-PAGE, we found that pp28 is phosphorylated in the virus-infected cells and dephosphorylated in the viral particles. By generating substitution mutants of pp28, we showed that three serine residues (aa 41–43) and a tyrosine residue (aa 34) account for its phosphorylation. The mutant forms of pp28 were localized to the plasma membrane as well as the ERGIC in transfected cells. Likewise, these mutant proteins were localized to the plasma membrane as well as the AC in virus-infected cells. These results suggested that phosphorylation of pp28 contributes to its intracellular trafficking and efficient viral assembly and incorporation.

Thermococcus indicus sp. nov., a Fe(III)-reducing hyperthermophilic archaeon isolated from the Onnuri Vent Field of the Central Indian Ocean ridge: Jae Kyu Lim , Yun Jae Kim , Jhung-Ahn Yang , Teddy Namirimu , Sung-Hyun Yang , Mi-Jeong Park , Yong Min Kwon , Hyun Sook Lee , Sung Gyun Kang , Jung-Hyun Lee , Kae Kyoung Kwon; J. Microbiol. 2020;58(4):260-267. Published online April 1, 2020; DOI: https://doi.org/10.1007/s12275-020-9424-9

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Abstract: A strictly anaerobic, dissimilatory Fe(III)-reducing hyperthermophilic archaeon, designated as strain IOH1T, was isolated from a new deep-sea hydrothermal vent (Onnuri Vent Field) area in the Central Indian Ocean ridge. Strain IOH1T showed > 99% 16S rRNA gene sequence similarity with Thermococcus celericrescens TS2T (99.4%) and T. siculi DSM 12349T (99.2%). Additional three species T. barossii SHCK-94T (99.0%), T. celer Vu13T (98.8%), and T. piezophilus (98.6%) showed > 98.6% of 16S rRNA gene sequence similarity, however, the maximum OrthoANI value is 89.8% for the genome of T. celericrescens TS2T. Strain IOH1T cells are coccoid, 1.2–1.8 μm in diameter, and motile by flagella. Growth was at 70–82°C (optimum 80°C), pH 5.4–8.0 (optimum pH 6.0) with 2–4% (optimum 3%) NaCl. Growth of strain IOH1T was enhanced by starch, pyruvate, D(+)-maltose and maltodextrin as a carbon sources, and elemental sulfur as an electron acceptor; clearly different from those of related species T. celecrescens DSM 17994T and T. siculi DSM 12349T. Strain IOH1T, T. celercrescence DSM 17994T, and T. siculi DSM 12349T reduced soluble Fe(III)-citrate present in the medium, whereas the amount of total cellular proteins increased with the concomitant accumulation of Fe(II). We determined a circular chromosome of 2,234 kb with an extra-chromosomal archaeal plasmid, pTI1, of 7.7 kb and predicted 2,425 genes. The DNA G + C content was 54.9 mol%. Based on physiological properties, phylogenetic, and genome analysis, we proposed that strain IOH1T (= KCTC 15844T = JCM 39077T) is assigned to a new species in the genus Thermococcus and named Thermococcus indicus sp. nov.

Salicibibacter halophilus sp. nov., a moderately halophilic bacterium isolated from kimchi: Young Joon Oh , Joon Yong Kim , Hyo Kyeong Park , Ja-Young Jang , Seul Ki Lim , Min-Sung Kwon , Hak-Jong Choi; J. Microbiol. 2019;57(11):997-1002. Published online October 28, 2019; DOI: https://doi.org/10.1007/s12275-019-9421-z

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Abstract: A Gram-stain-positive, rod-shaped, alkalitolerant, and halophilic bacterium–designated as strain NKC3-5T–was isolated from kimchi that was collected from the Geumsan area in the Republic of Korea. Cells of isolated strain NKC3-5T were 0.5–0.7􍾘μm wide and 1.4–2.8 μm long. The strain NKC3-5T could grow at up to 20.0% (w/v) NaCl (optimum 10%), pH 6.5–10.0 (optimum pH 9.0), and 25–40°C (optimum 35°C). The cells were able to reduce nitrate under aerobic conditions, which is the first report in the genus Salicibibacter. The genome size and genomic G + C content of strain NKC3-5T were 3,754,174 bp and 45.9 mol%, respectively; it contained 3,630 coding sequences, 16S rRNA genes (six 16S, five 5S, and five 23S), and 59 tRNA genes. Phylogenetic analysis based on 16S rRNA showed that strain NKC- 3-5T clustered with bacterium Salicibibacter kimchii NKC1-1T, with a similarity of 96.2–97.6%, but formed a distinct branch with other published species of the family Bacillaceae. In addition, OrthoANI value between strain NKC3-5T and Salicibibacter kimchii NKC1-1T was far lower than the species demarcation threshold. Using functional genome annotation, the result found that carbohydrate, amino acid, and vitamin metabolism related genes were highly distributed in the genome of strain NKC3-5T. Comparative genomic analysis revealed that strain NKC3-5T had 716 pan-genome orthologous groups (POGs), dominated with carbohydrate metabolism. Phylogenomic analysis based on the concatenated core POGs revealed that strain NKC3-5T was closely related to Salicibibacter kimchii. The predominant polar lipids were phosphatidylglycerol and two unidentified lipids. Anteiso- C15:0, iso-C17:0, anteiso-C17:0, and iso-C15:0 were the major cellular fatty acids, and menaquinone-7 was the major isoprenoid quinone present in strain NKC3-5T. Cell wall peptidoglycan analysis of strain NKC3-5T showed that meso-diaminopimelic acid was the diagnostic diamino acid. The phenotypic, genomic, phylogenetic, and chemotaxonomic properties reveal that the strain represents a novel species of the genus Salicibibacter, for which the name Salicibibacter halophilus sp. nov. is proposed, with the type strain NKC3-5T (= KACC 21230T = JCM 33437T).

Hahyoungchilella caricis gen. nov., sp. nov., isolated from a rhizosphere mudflat of a halophyte (Carex scabrifolia), transfer of Thioclava arenosa Thongphrom et al. 2017 to Pseudothioclava as Pseudothioclava arenosa gen. nov., comb. nov. and proposal of Thioclava electrotropha Chang et al. 2018: Young-Ju Kim , Soon Dong Lee; J. Microbiol. 2019;57(12):1048-1055. Published online September 25, 2019; DOI: https://doi.org/10.1007/s12275-019-9260-y

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Abstract: A Gram-stain-negative, strictly aerobic, marine bacterium, designated GH2-2T, was isolated from a rhizosphere mudflat of a halophyte (Carex scabrifolia) in Gangwha Island, the Republic of Korea. The cells of the organism were oxidase- positive, catalase-positive, flagellated, short rods that grew at 10–40°C, pH 4–10, and 0–13% (w/v) NaCl. The predominant ubiquinone was Q-10. The major polar lipids were phosphatidylcholine, phosphatidylethanolamine, and phosphatidylglycerol. The major fatty acid is C18:1. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the novel isolate formed an independent lineage at the base of the radiation encompassing members of the genus Thioclava, except for Thioclava arenosa. The closest relatives were T. nitratireducens (96.03% sequence similarity) and T. dalianensis (95.97%). The genome size and DNA G+C content were 3.77 Mbp and 59.6 mol%, respectively. Phylogenomic analysis supported phylogenetic distinctness based on 16S rRNA gene sequences. Average nucleotide identity values were 73.6–74.0% between the novel strain and members of the genus Thioclava. On the basis of data obtained from a polyphasic approach, the strain GH2-2T (= KCTC 62124T = DSM 105743T) represents a novel species of a new genus for which the name Hahyoungchilella caricis gen. nov., sp. nov. is proposed. Moreover, the transfer of Thioclava arenosa Thongphrom et al. 2017 to Pseudothioclava gen. nov. as Pseudothioclava arenosa comb. nov. is also proposed. Finally, Thioclava electrotropha Chang et al. 2018 is proposed to be a later heterosynonym of Thioclava sediminum Liu et al. 2017.

Growth of cyanobacterial soil crusts during diurnal freeze-thaw cycles: Steven K. Schmidt , Lara Vimercati; J. Microbiol. 2019;57(4):243-251. Published online February 5, 2019; DOI: https://doi.org/10.1007/s12275-019-8359-5

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Abstract: Various Nostoc spp. and related cyanobacteria are able to survive extreme temperatures and are among the most successful colonists of high-elevation sites being exposed due to glacial retreat. It is unclear, however, if cyanobacteria can grow during the extreme freeze-thaw cycles that occur on a yearround basis at high-elevation, peri-glacial sites or if they only grow during the rare periods when freeze-thaw cycles do not occur. We conducted several experiments to determine if cyanobacteria that form biological soil crusts (BSCs) at highelevation sites (> 5,000 m.a.s.l.) in the Andes can grow during diurnal freeze-thaw cycles on a par with those that occur in the field. Here we show that a soil crust that had been frozen at -20°C for five years was able to increase from 40% to 100% soil coverage during a 45-day incubation during which the soil temperature cycled between -12°C and 26°C every day. In a second, experiment an undeveloped soil with no visible BSCs showed a statistically significant shift in the bacterial community from one containing few cyanobacterial sequences (8% of sequences) to one dominated (27%) by Nostoc, Microcoleus, and Leptolyngbya phylotypes during a 77-day incubation with daily freeze-thaw cycles. In addition, counts of spherical Nostoc-like colonies increased significantly on the soil surface during the experiment, especially in microcosms receiving phosphorus. Taken together these results show that freeze-thaw cycles alone do not limit the growth of BSCs in high-elevation soils, and provide new insight into how life is able to thrive in one of the most extreme terrestrial environments on Earth.

Salicibibacter kimchii gen. nov., sp. nov., a moderately halophilic and alkalitolerant bacterium in the family Bacillaceae, isolated from kimchi: Ja-Young Jang , Young Joon Oh , Seul Ki Lim , Hyo Kyeong Park , Changsu Lee , Joon Yong Kim , Mi-Ai Lee , Hak-Jong Choi; J. Microbiol. 2018;56(12):880-885. Published online October 25, 2018; DOI: https://doi.org/10.1007/s12275-018-8518-0

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Abstract: A moderately halophilic and alkalitolerant bacterial strain NKC1-1T was isolated from commercial kimchi in Korea. Strain NKC1-1T was Gram-stain-positive, aerobic, rod-shaped, non-motile, and contained diaminopimelic acid-type murein. Cell growth was observed in a medium containing 0–25% (w/v) NaCl (optimal at 10% [w/v]), at 20–40°C (optimal at 37°C) and pH 6.5–10.0 (optimal at pH 9.0). The major isoprenoid quinone of the isolate was menaquinone-7, and the major polar lipids were phosphatidylglycerol and unidentified phospholipids. Cell membrane of the strain contained iso-C17:0 and anteiso-C15:0 as the major fatty acids. Its DNA G + C content was 45.2 mol%. Phylogenetic analysis indicated the strain to be most closely related to Geomicrobium halophilum with 92.7–92.9% 16S rRNA gene sequence similarity. Based on polyphasic taxonomic evaluation with phenotypic, phylogenetic, and chemotaxonomic analyses, the strain represents a novel species in a new genus, for which the name Salicibibacter kimchii gen. nov., sp. nov. is proposed (= CECT 9537T; KCCM 43276T).

Identification of trehalose as a compatible solute in different species of acidophilic bacteria: Pedro A. Galleguillos , Barry M. Grail , Kevin B. Hallberg , Cecilia S. Demergasso , D. Barrie Johnson; J. Microbiol. 2018;56(10):727-733. Published online September 28, 2018; DOI: https://doi.org/10.1007/s12275-018-8176-2

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Abstract: The major industrial heap bioleaching processes are located in desert regions (mainly Chile and Australia) where fresh water is scarce and the use of resources with low water activity becomes an attractive alternative. However, in spite of the importance of the microbial populations involved in these processes, little is known about their response or adaptation to osmotic stress. In order to investigate the response to osmotic stress in these microorganisms, six species of acidophilic bacteria were grown at elevated osmotic strength in liquid media, and the compatible solutes synthesised were identified using ion chromatography and MALDI-TOF mass spectrometry. Trehalose was identified as one of, or the sole, compatible solute in all species and strains, apart from Acidithiobacillus thiooxidans where glucose and proline levels increased at elevated osmotic potentials. Several other potential compatible solutes were tentatively identified by MALDITOF analysis. The same compatible solutes were produced by these bacteria regardless of the salt used to produce the osmotic stress. The results correlate with data from sequenced genomes which confirm that many chemolithotrophic and heterotrophic acidophiles possess genes for trehalose synthesis. This is the first report to identify and quantify compatible solutes in acidophilic bacteria that have important roles in biomining technologies.

Virgibacillus kimchii sp. nov., a halophilic bacterium isolated from kimchi: Young Joon Oh , Ja-Young Jang , Seul Ki Lim , Min-Sung Kwon , Jieun Lee , NamHee Kim , Mi-Young Shin , Hyo Kyeong Park , Myung-Ji Seo , Hak-Jong Choi; J. Microbiol. 2017;55(12):933-938. Published online December 7, 2017; DOI: https://doi.org/10.1007/s12275-017-7386-3

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Abstract: A Gram-stain-positive, halophilic, rod-shaped, non-motile, spore forming bacterium, strain NKC1-2T, was isolated from kimchi, a Korean fermented food. Comparative analysis based on 16S rRNA gene sequence demonstrated that the isolated strain was a species of the genus Virgibacillus. Strain NKC1- 2T exhibited high level of 16S rRNA gene sequence similarity with the type strains of Virgibacillus xinjiangensis SL6-1T (96.9%), V. sediminis YIM kkny3T (96.8%), and V. salarius SA-Vb1T (96.7%). The isolate grew at pH 6.5–10.0 (optimum, pH 8.5–9.0), 0.0–25.0% (w/v) NaCl (optimum, 10–15% NaCl), and 15–50°C (optimum, 37°C). The major menaquinone in the strain was menaquinone-7, and the main peptidoglycan of the strain was meso-diaminopimelic acid. The predominant fatty acids of the strain were iso-C14:0, anteisio-C15:0, iso- C15:0, and iso-C16:0 (other components were < 10.0%). The polar lipids consisted of diphosphatidylglycerol and phosphatidylglycerol. The genomic DNA G + C content of NKC1-2T was 42.5 mol%. On the basis of these findings, strain NKC1- 2T is proposed as a novel species in the genus Virgibacillus, for which the name Virgibacillus kimchii sp. nov. is proposed (=KACC 19404T =JCM 32284T). The type strain of Virgibacillus kimchii is NKC1-2T.

Review

MINIREVIEW] Global transcriptional regulator TrmB family members in prokaryotes: Minwook Kim , Soyoung Park , Sung-Jae Lee; J. Microbiol. 2016;54(10):639-645. Published online September 30, 2016; DOI: https://doi.org/10.1007/s12275-016-6362-7

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Abstract: Members of the TrmB family act as global transcriptional regulators for the activation or repression of sugar ABC transporters and central sugar metabolic pathways, including glycolytic, gluconeogenic, and other metabolic pathways, and also as chromosomal stabilizers in archaea. As a relatively newly classified transcriptional regulator family, there is limited experimental evidence for their role in Thermococcales, halophilic archaeon Halobacterium salinarum NRC1, and crenarchaea Sulfolobus strains, despite being one of the extending protein families in archaea. Recently, the protein structures of Pyrococcus furiosus TrmB and TrmBL2 were solved, and the transcriptomic data uncovered by microarray and ChIP-Seq were published. In the present review, recent evidence of the functional roles of TrmB family members in archaea is explained and extended to bacteria.

Journal Article

Gracilibacillus kimchii sp. nov., a halophilic bacterium isolated from kimchi§: Young Joon Oh , Hae-Won Lee , Seul Ki Lim , Min-Sung Kwon , Jieun Lee , Ja-Young Jang , Hae Woong Park , Young-Do Nam , Myung-Ji Seo , Hak-Jong Choi; J. Microbiol. 2016;54(9):588-593. Published online August 31, 2016; DOI: https://doi.org/10.1007/s12275-016-6349-4

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Abstract: A novel halophilic bacterium, strain K7T, was isolated from kimchi, a traditional Korean fermented food. The strain is Gram-positive, motile, and produces terminal endospores. The isolate is facultative aerobic and grows at salinities of 0.0–25.0% (w/v) NaCl (optimum 10–15% NaCl), pH 5.5–8.5 (optimum pH 7.0–7.5), and 15–42°C (optimum 37°C). The predominant isoprenoid quinone in the strain is menaquinone- 7 and the peptidoglycan of the strain is meso-diaminopimelic acid. The major fatty acids of the strain are anteisio- C15:0, iso-C15:0, and, C16:0 (other components were < 10.0%), while the major polar lipids are diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, and three unidentified lipids. A phylogenetic analysis of 16S rRNA gene sequence similarity showed that the isolated strain was a cluster of the genus Gracilibacillus. High levels of gene sequence similarity were observed between strain K7T and Gracilibacillus orientalis XH-63T (96.5%), and between the present strain and Gracilibacillus xinjiangensis (96.5%). The DNA G+C content of this strain is 37.7 mol%. Based on these findings, strain K7T is proposed as a novel species: Gracilibacillus kimchii sp. nov. The type strain is K7T (KACC 18669T; JCM 31344T).

Review

MINIREVIEW] Microbial Leaching of Metals from Solid Industrial Wastes: Debaraj Mishra , Young Ha Rhee; J. Microbiol. 2014;52(1):1-7. Published online January 4, 2014; DOI: https://doi.org/10.1007/s12275-014-3532-3

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Abstract: Biotechnological applications for metal recovery have played a greater role in recovery of valuable metals from low grade sulfide minerals from the beginning of the middle era till the end of the twentieth century. With depletion of ore/minerals and implementation of stricter environmental rules, microbiological applications for metal recovery have been shifted towards solid industrial wastes. Due to certain restrictions in conventional processes, use of microbes has garnered increased attention. The process is environmentally-friendly, economical and cost-effective. The major microorganisms in recovery of heavy metals are acidophiles that thrive at acidic pH ranging from 2.0–4.0. These microbes aid in dissolving metals by secreting inorganic and organic acids into aqueous media. Some of the well-known acidophilic bacteria such as Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, Leptospirillum ferrooxidans and Sulfolobus spp. are wellstudied for bioleaching activity, whereas, fungal species like Penicillium spp. and Aspergillus niger have been thoroughly studied for the same process. This mini-review focuses on the acidophilic microbial diversity and application of those microorganisms toward solid industrial wastes.

Research Support, Non-U.S. Gov'ts

Identification of an Extracellular Thermostable Glycosyl Hydrolase Family 13 α-Amylase from Thermotoga neapolitana: Kyoung-Hwa Choi , Sungmin Hwang , Hee-Seob Lee , Jaeho Cha; J. Microbiol. 2011;49(4):628-634. Published online September 2, 2011; DOI: https://doi.org/10.1007/s12275-011-0432-7

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Abstract: We cloned the gene for an extracellular α-amylase, AmyE, from the hyperthermophilic bacterium Thermotoga neapolitana and expressed it in Escherichia coli. The molecular mass of the enzyme was 92 kDa as a monomer. Maximum activity was observed at pH 6.5 and temperature 75°C and the enzyme was highly thermostable. AmyE hydrolyzed the typical substrates for α-amylase, including soluble starch, amylopectin, and maltooligosaccharides. The hydrolytic pattern of AmyE was similar to that of a typical α-amylase; however, unlike most of the calcium (Ca2+)-dependent α-amylases, the activity of AmyE was unaffected by Ca2+. The specific activities of AmyE towards various substrates indicated that the enzyme preferred maltooligosaccharides which have more than four glucose residues. AmyE could not hydrolyze maltose and maltotriose. When maltoheptaose was incubated with AmyE at the various time courses, the products consisting of maltose through maltopentaose was evenly formed indicating that the enzyme acts in an endo-fashion. The specific activity of AmyE (7.4 U/mg at 75°C, pH 6.5, with starch as the substrate) was extremely lower than that of other extracellular α-amylases, which indicates that AmyE may cooperate with other highly active extracellular α-amylases for the breakdown of the starch or α-glucans into maltose and maltotriose before transport into the cell in the members of Thermotoga sp.

Rescue of a Cold-Sensitive Mutant at Low Temperatures by Cold Shock Proteins from Polaribacter irgensii KOPRI 22228: Ji-hyun Uh , Youn Hong Jung , Yoo Kyung Lee , Hong Kum Lee , Hana Im; J. Microbiol. 2010;48(6):798-802. Published online January 9, 2011; DOI: https://doi.org/10.1007/s12275-010-0402-5

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Abstract: Exposure to low temperatures induces the biosynthesis of specific sets of proteins, including cold shock proteins (Csps). Since many of the specific functions of pychrophilic Csps are unknown, the roles of Csps from an Arctic bacterium, Polaribacter irgensii KOPRI 22228, were examined. The genes encoding CspA and CspC of P. irgensii were cloned in this study. Sequence analysis showed that these proteins have cold shock domains containing two RNA-binding motifs, RNP1 and RNP2. Both proteins bound oligo(dT)-cellulose resins, suggesting single-stranded nucleic acid-binding activity. When the P. irgensii Csps were overexpressed in Escherichia coli, the cold-resistance of the host was increased by more than five-fold. The P. irgensii Csps also rescued a cold-sensitive E. coli csp-quadruple deletion strain, BX04, at low temperatures. These results suggest that Csps from P. irgensii play a role in survival in polar environments.

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