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Co ai biet cach nao de quan sat Bacillus subtillis xin hay chi cho tui voi. Toi dang rat quan tam den su thay doi cau truc cua cell trong moi truong co nong do muoi cao. Hay giup toi. Cam on cac ban rat nhieu.

Mua một ống giống Bacillus subtilis, nhuộm gram rồi đưa lên kính hiển vi xem. Cái này thực tập VSV năm 3 coi muốn mờ mắt rồi mà.
Muốn biết sự thay đổi cấu trúc tb trong mt nồng độ muối cao thì pha các dung dịch ưu trương trên 1%, rồi thả tế bào vô; nó biến đổi là sẽ thấy ngay. Còn nếu chỉ quan tâm chung chung thì mua sách về đọc, ví dụ như bài
Functional Significance of Cell Volume Regulatory Mechanisms
Physiol Rev, Jan 1998; 78: 247 - 306.
À quên, nhớ coi bằng kính hiển vi ở độ phóng đại x90, chứ 40 kô thấy được đâu
Ok, chuyện vặt có gì mà cảm ơn

Tôi chỉ giúp cho bạn mấy cái abstract này, còn tôi không thể post nguyên cái full text được;

Studies on the mechanism of the osmoresistance of spores of Bacillus subtilis.
AIMS: To determine the reason that spores of Bacillus species, in particular Bacillus subtilis, are able to form colonies with high efficiency on media with very high salt concentrations. METHODS AND RESULTS: Spores of various Bacillus species have a significantly higher plating efficiency on media with high salt concentration (termed osmoresistance) than do log or stationary phase cells. This spore osmoresistance is higher on richer media. Bacillus subtilis spores lacking various small, acid-soluble spore proteins (SASP) were generally significantly less osmoresistant than were wild-type spores, as shown previously (Ruzal et al. 1994). Other results included: (a) spore osmoresistance varied significantly between species; (b) the osmoresistance of spores lacking SASP was not restored well by amino acid osmolytes added to plating media, but was completely restored by glucose; (c) the osmoresistance of spores lacking SASP was restored upon brief germination in the absence of salt in a process that did not require protein synthesis; (d) significant amounts of amino acids generated by SASP degradation were retained within spores upon germination in a medium with high but not low salt; (e) slowing but not abolishing SASP degradation by loss of the SASP-specific germination protease (GPR) did not affect spore osmoresistance; (f) sporulation at higher temperatures produced less osmoresistant spores; and (g) spore osmoresistance was not decreased markedly by the absence of the stress sigma factor for RNA polymerase, sigmaB. CONCLUSIONS: Spore osmoresistance appears as a result of three major factors: (1) specific characteristics of spores and cells of individual species; (2) the precise sporulation con***ions that produce the spores; and (3) sufficient energy generation by the germinating and outgrowing spore to allow the spore to adapt to con***ions of high osmotic strength; the substrates for this energy generation can come from either the endogenous generation of amino acids by SASP degradation or from the spore''''s environment, in the form of a readily taken up and metabolized energy source such as glucose. SIGNFICANCE AND IMPACT OF STUDY: These results provide information on the mechanisms of spore osmoresistance, a spore property that can be of major applied significance given the use of high osmotic strength with or without high salt as a means of food preservation.
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Genome-wide transcriptional profiling analysis of adaptation of Bacillus subtilis to high salinity.
The gram-positive soil bacterium Bacillus subtilis often faces increases in the salinity in its natural habitats. A transcriptional profiling approach was utilized to investigate both the initial reaction to a sudden increase in salinity elicited by the ad***ion of 0.4 M NaCl and the cellular adaptation reactions to prolonged growth at high salinity (1.2 M NaCl). Following salt shock, a sigB mutant displayed immediate and transient induction and repression of 75 and 51 genes, respectively. Continuous propagation of this strain in the presence of 1.2 M NaCl triggered the induction of 123 genes and led to the repression of 101 genes. In summary, our studies revealed (i) an immediate and transient induction of the SigW regulon following salt shock, (ii) a role of the DegS/DegU two-component system in sensing high salinity, (iii) a high-salinity-mediated iron limitation, and (iv) a repression of chemotaxis and motility genes by high salinity, causing severe impairment of the swarming capability of B. subtilis cells. Initial adaptation to salt shock and continuous growth at high salinity share only a limited set of induced and repressed genes. This finding strongly suggests that these two phases of adaptation require distinctively different physiological adaptation reactions by the B. subtilis cell. The large portion of genes with unassigned functions among the high-salinity-induced or -repressed genes demonstrates that major aspects of the cellular adaptation of B. subtilis to high salinity are unexplored so far.
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KtrAB and KtrCD: two K+ uptake systems in Bacillus subtilis and their role in adaptation to hypertonicity.
Recently, a new type of K+ transporter, Ktr, has been identified in the bacterium Vibrio alginolyticus (T. Nakamura, R. Yuda, T. Unemoto, and E. P. Bakker, J. Bacteriol. 180:3491-3494, 1998). The Ktr transport system consists of KtrB, an integral membrane subunit, and KtrA, a subunit peripherally bound to the cytoplasmic membrane. The genome sequence of Bacillus subtilis contains two genes for each of these subunits: yuaA (ktrA) and ykqB (ktrC) encode homologues to the V. alginolyticus KtrA protein, and yubG (ktrB) and ykrM (ktrD) encode homologues to the V. alginolyticus KtrB protein. We constructed gene disruption mutations in each of the four B. subtilis ktr genes and used this isogenic set of mutants for K+ uptake experiments. Preliminary K+ transport assays revealed that the KtrAB system has a moderate affinity with a Km value of approximately 1 mM for K+, while KtrCD has a low affinity with a Km value of approximately 10 mM for this ion. A strain defective in both KtrAB and KtrCD exhibited only a residual K+ uptake activity, demonstrating that KtrAB and KtrCD systems are the major K+ transporters of B. subtilis. Northern blot analyses revealed that ktrA and ktrB are cotranscribed as an operon, whereas ktrC and ktrD, which occupy different locations on the B. subtilis chromosome, are expressed as single transcriptional units. The amount of K+ in the environment or the salinity of the growth medium did not influence the amounts of the various ktr transcripts. A strain with a defect in KtrAB is unable to cope with a sudden osmotic upshock, and it exhibits a growth defect at elevated osmolalities which is particularly pronounced when KtrCD is also defective. In the ktrAB strain, the osmotically mediated growth defect was associated with a rapid loss of K+ ions from the cells. Under these con***ions, the cells stopped synthesizing proteins but the transcription of the osmotically induced proHJ, opuA, and gsiB genes was not impaired, demonstrating that a high cytoplasmic K+ concentration is not essential for the transcriptional activation of these genes at high osmolarity. Taken together, our data suggest that K+ uptake via KtrAB and KtrCD is an important facet in the cellular defense of B. subtilis against both suddenly imposed and prolonged osmotic stress.
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Salt stress is an environmental signal affecting degradative enzyme synthesis in Bacillus subtilis.
Growth under con***ions of salt stress has important effects on the synthesis of degradative enzymes in Bacillus subtilis. Salt stress strongly stimulates the expression of sacB, encoding levansucrase (about ninefold), and downregulates the expression of aprE, encoding alkaline protease (about sixfold). It is suggested that the DegS-DegU two-component system is involved in sensing salt stress. Moreover, it has been shown that the level of sacB expression strongly depends on the growth con***ions; its expression level is about eightfold higher in cells grown on agar plates than in cells grown in liquid medium.
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High-salinity-induced iron limitation in Bacillus subtilis.
Proteome analysis of Bacillus subtilis cells grown at low and high salinity revealed the induction of 16 protein spots and the repression of 2 protein spots, respectively. Most of these protein spots were identified by mass spectrometry. Four of the 16 high-salinity-induced proteins corresponded to DhbA, DhbB, DhbC, and DhbE, enzymes that are involved in the synthesis of 2,3-dihydroxybenzoate (DHB) and its modification and esterification to the iron siderophore bacillibactin. These proteins are encoded by the dhbACEBF operon, which is negatively controlled by the central iron regulatory protein Fur and is derepressed upon iron limitation. We found that iron limitation and high salinity derepressed dhb expression to a similar extent and that both led to the accumulation of comparable amounts of DHB in the culture supernatant. DHB production increased linearly with the degree of salinity of the growth medium but could still be reduced by an excess of iron. Such an excess of iron also partially reversed the growth defect exhibited by salt-stressed B. subtilis cultures. Taken together, these findings strongly suggest that B. subtilis cells grown at high salinity experience iron limitation. In support of this notion, we found that the expression of several genes and operons encoding putative iron uptake systems was increased upon salt stress. The unexpected finding that high-salinity stress has an iron limitation component might be of special ecophysiological importance for the growth of B. subtilis in natural settings, in which bioavailable iron is usually scarce.
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Salt stress is an environmental signal affecting degradative enzyme synthesis in Bacillus subtilis.
Growth under con***ions of salt stress has important effects on the synthesis of degradative enzymes in Bacillus subtilis. Salt stress strongly stimulates the expression of sacB, encoding levansucrase (about ninefold), and downregulates the expression of aprE, encoding alkaline protease (about sixfold). It is suggested that the DegS-DegU two-component system is involved in sensing salt stress. Moreover, it has been shown that the level of sacB expression strongly depends on the growth con***ions; its expression level is about eightfold higher in cells grown on agar plates than in cells grown in liquid medium.
Được concay sửa chữa / chuyển vào 03:35 ngày 15/04/2004

Ngoài ra tôi còn giới thiệu bạn một chương về Bacillus trong bộ
Encyclopedia of Molecular Biology, Volumes 1-4
©1999 trang 243-259
có đầy đủ những gì bạn cần tìm hiểu về Bacillus
BACILLUS
COLIN R. HARWOOD
KEITH STEPHENSON
University of Newcastle upon Tyne
Newcastle upon Tyne, UK
OUTLINE
Introduction
Distribution and Taxonomy
Preservation of Strains
Culture Collections
Genetic Manipulation
Mutagenesis
Transformation
Genome Analysis and Manipulation
Cloning and Expression Systems
Protein Secretion
Gene Expression
Sporulation
Phosphate
Carbon
Nitrogen
Products
Enzymes
Metabolites
Peptide Antibiotics
Heterologous Proteins
Insecticides
Safety
Growth
Laboratory Culture Con***ions
Commercial Culture Con***ions

Cam on bac concay rat nhieu vi su nhiet tinh giup do. background cua tui khong ve CNSH nen tui khong that su hieu tot ve may van de nay. Ah, ma â?ouu truongâ? nghia la gi vay bac conco.
Cac ban co the chi cho tui cach gram stain B.subtillis duoc khong? Ten hoa chat thi lam on viet bang tieng anh nhe.
Cam on cac ban .

Nhuộm gram VSV không phải là kiến thức của CNSH mà là của SINH HỌC, kỹ thuật nhuộm này có nhiếu trong các sách thực tập Vi Sinh do các tác giả Việtnam viết như Nguyễn lân Dũng, Trần Linh Thước, Lê Duy Linh, ... bạn chịu khó dò tìm.
Nếu không, bạn có thể vào google đánh keyword gram staining bacterial là có đầy đủ.
Khái niệm dung dịch ưu trương, nhược trương là khái niệm cơ bản mà khi học sinh học tế bào, mọi SV đều phải biết. Đại khái có thể hiểu dd ưu trương là dd chứa các chất hòa tan (ion, đường, chất hữu cơ) tạo ra một nồng độ áp suất thẩm thấu cao hơn nồng độ áp suất thẩm thấu tế bào, khiến cho nước từ trong tb đi ra (để cân bằng áp suất thẩm thấu) làm cho tế bào bị co lại (gọi là co nguyên sinh).
Với tế bào sống, dd đẳng trương là dd muối NaCl 0,85%: nồng độ dưới 0,85% là nhược trương, nước đi vào tb, làm tb căng phòng, đến 1 ngưỡng nhất định thì tb bị bể. Trên 0,85% là ưu trương như đã nói.