GROWTH AND SURVIVAL OF BACTERIA IN PEAT: I. POWDERED PEAT AND RELATED PRODUCTS

1947 ◽  
Vol 25c (1) ◽  
pp. 1-13 ◽  
Author(s):  
A. G. Lochhead ◽  
R. H. Thexton

Comparative tests of various powdered materials showed that well humified peat was superior to other preparations in maintaining the test bacteria in viable condition. Under the test conditions, sterilization of peat improved it as a medium for the maintenance of high numbers of viable cells. Neutralization was important, and more satisfactory following, than preceding, sterilization. Potassium carbonate was more suitable than sodium carbonate as neutralizing agent for promoting longevity of bacteria. Though peat allowed to dry immediately after inoculation did not permit the same high increase in bacterial numbers observed in peat kept at suitable moisture content, it was able to maintain large numbers of organisms in viable condition. Peat allowed to dry following the initial rise continued to support an increased load of living cells. After the initial increase at growth temperatures, peat stored at 4 °C. maintained numbers of bacteria better than at the higher temperature. Though immediate storage at 4 °C. resulted in a pronounced decline in numbers, subsequent removal to a temperature suitable for growth, even though delayed for as long as 12 wk., was followed by a rapid increase of bacteria to very high numbers.

The arc spectrum of cæsium was investigated with the object of finding whether any of its lines possessed hyperfine structure, resulting from a nuclear magnetic moment, due to a quantised nuclear spin. The lines belonging to the principal series should, owing to the greater degree of penetration of the electron in the (1 s or 6 1 ) orbit, and the correspondingly greater interaction, show the greatest effect. The lines of the principal series are very easily broadened if the vapour pressure of the metal becomes high, so that great care had to be used in obtaining the spectrum of cæsium at a sufficiently low temperature. The most satisfactory method of excitation was found to be the application by means of external electrodes of a very high frequency alternating current to a tube filled with helium at about 2 mm. pressure containing a small quantity of cæsium. The tube required slight heating to bring out the cæsium lines; without this the helium spectrum was very much stronger than the metallic spectrum. At a very low vapour pressures of cæsium the discharge was blue in colour. Under these conditions the lines of the principal series showed no broadening greater than that due to thermal agitation, but at a slightly higher temperature the colour of the discharge became purple and the lines broadened. The lines belonging to the principal series were found to be very close doublets with very nearly constant frequencies differences. A theory is worked out which explains the origin of these doublets, assuming a nuclear spin of one half quantum; by correlating the difference in the separation of the hyperfine structure doublets in the 1 s — m 2 p 3/2 lines and the 1 s — m 2 p 1/2 lines, it is shown that a ratio of the magnetic to the mechanical moment of the nucleus about twice as great as the corresponding ratio for the electron would account for the observed frequency differences. The spectral notation used throughout is that of Hund. The results are compared with those found for the hyperfine structure of some of the bismuth lines by Back and Goudsmid, and are found to be in satisfactory agreement. A selection principle is found which applies both to the bismuth and the cæsium spectrum.


1913 ◽  
Vol 17 (2) ◽  
pp. 117-131
Author(s):  
Hans Zinsser

The experiments recorded in this paper confirm the observations of Friedberger that acutely toxic bodies can be produced from typhoid bacilli by the action of sensitizer and complement and that, when small quantities of bacteria are used, an excess of sensitization either interferes with the formation of the poisons or leads to a cleavage of the bacterial proteid beyond the poisonous intermediate products spoken of as anaphylatoxins. Unlike the experience of other workers with poisons of this nature, however, our experiments have shown that the action of complement upon typhoid bacilli strongly sensitized or not at all sensitized may be carried on, at body temperature, for considerably longer than twelve hours without leading to a destruction of the poisons, and that this is true when the quantities of the bacteria used vary within the wide range of from one to twelve agar slants. It has been found, in fact, that in the case of this microorganism prolonged exposure at the higher temperature of considerable quantities of bacteria constitutes an unfailing method of regularly obtaining powerful poisons. The results obtained by the use of smaller quantities and the less vigorous complement action at low temperatures are far less regular or satisfactory. It would appear from this that complement action of considerable vigor is required to obtain from this bacillus any appreciable yield of anaphylatoxin, and that the poison, once formed, is not as unstable as that found in other microorganisms by Neufeld and Dold and others. In fact, although we have never observed complete lysis in vitro of the typhoid bacilli treated with antibody and complement, the sensitized bacteria exposed to the action of complement for as long as fifteen hours at 37.5° C. showed, in our experiments, much disintegration, and yet powerful poisons were present. Were the influence of lysis or of the too vigorous action of the serum bodies as rapidly poison-destroying in the case of this bacillus as it has been shown to be in the case of some other bacteria, it would be hard to understand how anaphylatoxins could play any part in the toxemia of typhoid fever. This phase of our experiments, however, seems to indicate that the conditions prevailing in the infected body at the height of this disease would furnish ideal criteria for anaphylatoxin production, since, in such cases, vigorously sensitized bacilli, in large numbers, are under the prolonged influence of considerable quantities of complement, conditions exactly comparable to those prevailing in our experiments. Granted that this state of affairs is actually the case, then the subsidence of the disease might depend merely upon limitation of the supply of antigen, as the increasing bactericidal action of the blood constituents come into play, and upon the consequent diminution of the anaphylatoxin. For as the bacteria diminish and the sensitizer increases, a changed proportion between them is established which, finally, as experiment has shown, results in a failure of anaphylatoxin production. For although our experiments have shown that, within a wide latitude of relative proportions of bacteria and antibody, anaphylatoxin can be formed, beyond this range an excess of one or the other element eventually will prevent their formation. It is not, however, the purpose of this paper to discuss the mechanism of the subsidence of the disease since this phase of the work will necessitate further experimental study. In regard to the experiments with kaolin, we were unable to confirm the contention of Keysser and Wassermann, though it is more than likely that toxic bodies could be formed by the action of complement upon any foreign proteid rendered amenable to its action. We are not inclined to attribute too much importance to these negative results, recording them merely as they occurred. However, should it be found subsequently that anaphylatoxins can be formed in this way, it seems unlikely that they are formed from the sensitizer or amboceptor as matrix, since this was not specifically adsorbed out of concentrated serum by the kaolin in our experiments. On the basis of experiments with so called endotoxins, ,we feel that the existence of such preformed intracellular poisons as an element in typhoid toxemia has not been proved, and is not absolutely necessary for the explanation of the phenomena occurring in this disease. However, the diarrhea, the hemorrhagic lesions, and the protracted symptoms following the injection of extracts and filtrates of the bacillus, differing so strikingly from the acute illness with rapid death or equally rapid recovery resulting from anaphylatoxin poisoning, would justify the assumption that poisons of this nature may still play a part in the disease, adding an additional specific characteristic to the clinical picture. As stated before, however, it is not improbable that all these characteristics may represent merely a more protracted or subacute state of anaphylatoxin toxemia. The experiments with autolysates, although none of them were fatal in their results upon guinea pigs, have sufficiently indicated that poisons comparable to anaphylatoxins can be formed in this way. This would indicate that a reaction of proteolysis, which may take place slowly by autolysis, is hastened by the action of complement, and its velocity is still further augmented by the increase, within certain limits, of the sensitization,—a conception which would attribute to the combined action of complement and sensitizer a function not incomparable to that of the bodies spoken of as catalytic agents.


2016 ◽  
Vol 5 (4) ◽  
pp. 13 ◽  
Author(s):  
Daud Kassam ◽  
Marcus Sangazi

<p>Most fish farmers in Malawi culture unimproved fish strains whose growth is slow and mature while still small. Four strains of <em>Oreochromis</em>, namely; selectively-bred/improved <em>O. shiranus</em> (F<sub>8</sub>), two reciprocal F<sub>1</sub> <em>Oreochromis</em> hybrids, and <em>O. karongae</em> as a control (mean weight 2.5 ± 0.7 g) were stocked at a density of 5fish/m<sup>2 </sup>in 9m<sup>2 </sup>hapas replicated three times, and cultured for 90 days at Bunda Fish Farm. Fish were fed twice a day with feed formulated using maize bran and soybean containing 30% crude protein throughout the experimental period. The final mean weights were significantly different (p&lt;0.05) across the treatments whereby; hybrid <em>O. shiranus</em> (male) X <em>O. karongae</em> (female) was 12.09g, hybrid <em>O. shiranus</em> (female) X <em>O. karongae</em> (male) was 9.72g, improved <em>O. shiranus</em> (F<sub>8</sub>) registered 9.23g, and <em>O. karongae</em> was the least with 9.00g. Apparent food conversion ratio was also statistically different (p&lt;0.05) across the treatments whereby; <em>O. karongae</em> was 3.63, hybrid <em>O. shiranus</em> (female) X <em>O. karongae</em> (male) was 3.25, improved <em>O. shiranus</em> (F<sub>8</sub>) was 3.16 and hybrid <em>O. shiranus</em> (male) X <em>O. karongae</em> (female) was lowest with 2.26. There were no significant differences on the water quality parameters across the treatments throughout the experimental period and were within the required ranges for growth and survival of tilapias fish species. The results suggest that <em>Oreochromis</em> hybrids may be suitable candidates for aquaculture in terms of production as they performed better than the improved <em>O. shiranus</em> and the control <em>O. karongae</em>.</p>


2005 ◽  
Vol 488-489 ◽  
pp. 287-290 ◽  
Author(s):  
Tadayoshi Tsukeda ◽  
Ken Saito ◽  
Mayumi Suzuki ◽  
Junichi Koike ◽  
Kouichi Maruyama

We compared the newly developed heat resistant magnesium alloy with conventional ones by Thixomolding® and aluminum alloy by die casting. Tensile properties at elevated temperatures of AXEJ6310 were equal to those of ADC12. In particular, elongation tendency of AXEJ6310 at higher temperature was better than those of the other alloys. Creep resistance of AXEJ6310 was larger than that of AE42 by almost 3 orders and smaller than that of ADC12 by almost 2 orders of magnitude. Fatigue limits at room temperature and 423K of AXEJ6310 was superior among conventional magnesium alloys.


1962 ◽  
Vol 15 (3) ◽  
pp. 525-534 ◽  
Author(s):  
M. Rabinovitch ◽  
W. Plaut

The incorporation of tritiated thymidine in Amoeba proteus was reinvestigated in order to see if it could be associated with microscopically detectable structures. Staining experiments with basic dyes, including the fluorochrome acridine orange, revealed the presence of large numbers of 0.3 to 0.5 µ particles in the cytoplasm of all cells studied. The effect of nuclease digestion on the dye affinity of the particles suggests that they contain DNA as well as RNA. Centrifugation of living cells at 10,000 g leads to the sedimentation of the particles in the centrifugal third of the ameba near the nucleus. Analysis of centrifuged cells which had been incubated with H3-thymidine showed a very high degree of correlation between the location of the nucleic acid-containing granules and that of acid-insoluble, deoxyribonuclease-sensitive labeled molecules and leads to the conclusion that cytoplasmic DNA synthesis in Amoeba proteus occurs in association with these particles.


Author(s):  
S. C. Knowles

The development of the letter code desk is described, particular reference being made to the necessity for the characteristics to be suited to the operating personnel. An explanation is given of the design features introduced as a result of this unit being required in relatively large numbers for this class of work. The development of the special printing unit for code application is described, with particular emphasis on the very high reliability required. An indication is given of probable future trends.


2009 ◽  
Vol 5 (S268) ◽  
pp. 463-468
Author(s):  
Ko Nakamura ◽  
Takashi Yoshida ◽  
Toshikazu Shigeyama ◽  
Toshitaka Kajino

AbstractType Ic supernova (SN Ic) is the gravitational collapse of a massive star without H and He layers. It propels several solar masses of material to the typical velocity of 10,000 km/s, a very small fraction of the ejecta nearly to the speed of light. We investigate SNe Ic as production sites for the light elements Li, Be, and B, via the neutrino-process and spallations. As massive stars collapse, neutrinos are emitted in large numbers from the central remnants. Some of the neutrinos interact with nuclei in the exploding materials and mainly 7Li and 11B are produced. Subsequently, the ejected materials with very high energy impinge on the interstellar/circumstellar matter and spall into light elements. We find that the ν-process in the current SN Ic model produces a significant amount of 11B, consistent with observations if combined with B isotopes from the following spallation production.


1990 ◽  
Vol 53 (8) ◽  
pp. 652-655 ◽  
Author(s):  
DONALD E. CONNER ◽  
VIRGINIA N. SCOTT ◽  
DANE T. BERNARD

Growth and survival of four strains of Listeria monocytogenes under acidic conditions were investigated. Tryptic soy broth with yeast extract (TSBYE) was acidified with acetic, citric, hydrochloric, lactic, or propionic acid to pH 4.0–6.0, inoculated with L. monocytogenes and incubated at 30 or 4°C. The minimum test pH at which L. monocytogenes did not grow (inhibitory pH) was determined for each acid. In the pH range tested, this inhibitory pH was 5.0 for propionic acid, 4.5 for acetic and lactic acids, and 4.0 for citric and hydrochloric acids. All four strains gave similar results. Subsequent studies were conducted at 10 and 30°C to determine changes in cell populations in TSBYE adjusted to each inhibitory pH. Initial populations of viable cells (104 CFU/ml) were reduced to &lt;10 CFU/ml within 1–3 weeks at 30°C, whereas at 10°C, L. monocytogenes survived for 11–12 weeks in acetic, citric, or propionic acid-adjusted media and for 6 weeks in media adjusted with hydrochloric or lactic acid. The concentration of undissociated lactic acid was 0.002 M at pH 4.5.


2021 ◽  
Vol 9 (1) ◽  
pp. 01-12
Author(s):  
Charvia Ismi Zahrani ◽  
Setia Pramana

AbstractCOVID-19 is a serious problem that faced by almost all countries in the world. Since announced as a pandemic by WHO on March, the number of positive COVID-19 cases in Indonesia has reached 287,008 patients until the end of September 2020. COVID-19 cases dispersion depends on the local government policies and the awareness of the public to obey. About 60 percent of positive cases and 65 percent of death cases were in Java. Therefore, the aim of this study is to analyze the growth of the COVID-19 case in Java from March to September 2020 in relation to the local government policies. The results showed that six provinces in Java had the same pattern. The large-scale social restriction (PSBB), which was implemented since April 10 2020, seen to be able to contain the dispersion of cases because from April to June the positive cases did not increase significantly. A very high increase occurred in August and September, this was probably due to the easing of the PSBB become new-normal where various public places and facilities have been reopened. Meanwhile, death cases, the number is very high in mid-April and June and late July to September 2020. For cured cases, there was a significant increase in late August to September 2020. The importance of information about the growth of the COVID-19 cases can help government to formulate strategies and policies to prevent the dispersion of COVID-19.Keyword: COVID-19, Pandemic, Java, cases growth AbstrakCOVID-19 merupakan suatu masalah serius yang sedang dihadapi oleh hampir seluruh negara. Sejak diumumkan sebagai pandemi oleh WHO pada Maret lalu, jumlah kasus positif COVID-19 di Indonesia mencapai 287.008 pasien hingga akhir September. Penyebaran kasus COVID-19 sangat bergantung pada kebijakan yang ditetapkan oleh pemerintah serta kesadaran masyarakat untuk mematuhinya. Sebesar 60 persen kasus positif dan 65 persen kasus meninggal berada di Pulau Jawa. Oleh karena itu, tujuan penelitian ini adalah menganalisis perkembangan kasus COVID-19 di Pulau Jawa sejak Bulan Maret-September 2020 dikaitkan dengan kebijakan pemerintah setempat. Hasil penelitian menunjukkan bahwa keenam provinsi memiliki pola yang sama. Pembatasan Sosial Berskala Besar (PSBB) yang dilakukan sejak 10 April 2020 terlihat dapat menahan penyebaran kasus karena pada bulan April-Juni 2020 kasus positif tidak mengalami kenaikan yang signifikan. Kenaikan yang sangat tinggi terjadi pada bulan Agustus dan September 2020, hal ini mungkin disebabkan oleh dilonggarkannya kebijakan PSBB menjadi PSBB Transisi dimana berbagai tempat dan fasilitas umum telah dibuka kembali. Sementara untuk kasus meninggal, angka tertinggi terjadi pada pertengahan April dan Juni serta akhir Juli hingga September 2020. Untuk kasus sembuh, terjadi peningkatan yang signifikan pada akhir Agustus hingga September 2020. Pentingnya informasi tentang perkembangan kasus COVID-19 ini dapat membantu pemerintah daerah untuk membuat strategi dan kebijakan untuk mencegah penyebaran rantai virus COVID-19.Kata Kunci: COVID-19, Pandemi, Jawa, perkembangan kasus 


2007 ◽  
Vol 4 (4) ◽  
pp. 542-548
Author(s):  
Baghdad Science Journal

The ability of single and mixed bacterial culture to utilize Dora-refineries petroleum wastes was compared. Pseudomonas aeruginosa and Serratia ficaria mixed culture consumed the wastes better than the single bacterial cultures. The highest log. number of viable cells in mixed culture was 6.842 , while in single bacterial cultures it was 6.683 and 5.631, respectively. after 3 days in API medium containing the refinery wastes. The effect of some environmental conditions on the degradation of petroleum wastes was studied included aeration , NaCl concentration , pH and temperature. The growth of bacteria in the agitated culture was higher than stagnant culture the log. of cell no. was 6.021 in the first culture. The highest log. of cell no. stagnant culture was 5.771. Pseudomonas aeruginosa AA22 and Serratia ficaria AA39 were able to grow in medium containing 5 , 7 % NaCl , they favorite pH 7. The mixed culture of the two bacteria grew well of 45 oC.


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