Bacterium

“ The kind of bacterium to be destroyed, since some are more readily killed by a given disinfectant than others, even though no spores are present.
2. The age of the culture. Young bacteria less than twenty-four hours old are usually more readily killed than older ones since the cell wall is more delicate and more easily penetrated, though old growths may be weakened by the accumulation of their products and be more easily destroyed. ”

“ The bacterium is generally a jointed rod-like filament of living matter, and its native world seems to be any putrefying organic substance.
Bacteria are the smallest of microscopic organisms. They are widely diffused in the natural world, existing independently and also in a parasitical way, in connection with larger forms of organic life. They multiply with the greatest rapidity. On the whole, the bacterium fulfills its vital offices in two ways, or with two results; first, fermentation, and secondly, disease. ”

“ It would be difficult to say where bacterium germs do not exist. In air, in water, in the soil adhering to tiny particles of every kind, in every region of the earth, from the poles to the equator, they are found. In the substance of the tissues—nay, in the cells of almost all plants, and in the interstices of the tissues of many animals—bacteria germs exist. I know not what part of the body of man and the higher animals is entirely destitute of particles which under favorable circumstances develop into bacteria. ”

“ Having glanced hastily at the history of bacteriology, we may next consider some facts concerning the germs themselves. What are they? To the lay mind the words germ, microbe, bacterium, and bacillus often convey confused ideas of invisible, wriggling, worm-like creatures, enemies of mankind, ever on the watch to gain a stealthy entrance into our bodies, where they wreak harm and death. Scientifically considered, however, they are the smallest of living things yet known. They are not animals, but are members of the vegetable kingdom, and are possessed of definite yet varying shapes. ”

“ Now, as it requires only thirty minutes for one cell to divide, it has been estimated that a single bacterium will in twenty-four hours increase to the number of over sixteen million five hundred thousand, and in forty-eight hours to two hundred and eighty-one million five hundred thousand. At this rate of increase, in three days there would be a mass of bacteria weighing about sixteen million pounds. ”

“ Many pathological observations have proved, that certain micro-organisms require a so-called mixed infection, that is, that certain bacteria alter the cell substance of the host in such a way, that some other kind of bacterium finds conditions favourable for its existence. ”

“ Others consider the bacterium as formed of protoplasm containing granules capable of being colored, which are a part of the protoplasm itself, and not a nuclear substance. On the latter view, bacteria would consist of cell plasm enclosed in a membrane and destitute of a nucleus. Whatever be the nature of the granule-containing material, each bacterium is regarded as a cell, the minutest and simplest living particle capable of an independent existence that has yet been discovered. ”

“ Any agent which destroys the life of the bacteria, or prevents their multiplication, breaks this circle and renders a cure possible.
The influence of bacteria in fermentation is still undecided, but, for the sake of completeness, the different opinions should be mentioned. It is admitted by all chemists that these or similar organisms are invariably present in some fermentations—Bacterium termo, or rod bacterium, in putrefaction, and the yeast-plant in alcoholic fermentation, for example ”

“ The spore formation of bacteria is very simple, all or part of the living contents of the bacterium becomes surrounded by a tough wall and remains so surrounded till circumstances are favourable, when the wall bursts, its contents escapes and becomes a bacterium, capable of founding a new colony by the method of splitting we have already described. ”

“ The facts themselves by their remarkable variety have not aided classification. Names which a few years ago were applied to individual species, like Bacillus subtilis, or Bacterium termo, or Bacillus coli, are now representative, not of individuals, but of families and groups of species. Again, isolated characteristics of certain microbes, such as motility, power of liquefying gelatine, size, colour, and so forth, which at first sight might appear as likely to form a basis for classification, are found to vary not only between similar germs, but in the same germ. ”

“ These hostile conditions are produced perhaps in part by the secretions from the bacteria, for bacteria are unable to flourish in a medium containing much of their own secretions. The secretions which they produce are poisons to them as well as to the individual in which they grow, and after these have become quite abundant the further growth of the bacterium is checked and finally stopped. ”

“ A contributor to the ‘Medical Times and Gazette’ of February 2nd, 1878, advances the opinion that many of the bacteria are only parts of a plant which has other forms and other modes of growth and propagation when not confined to the living organism or to fluids, and regards the bacterium as a transitional or provisional and not as a permanent form, but an abnormal phase of life thrust upon the plant by accident. ”

“ As previously stated, most of the physiological activities of bacteria are due to the enzymes that they produce. It is evident that for action to occur on substances which do not diffuse into the bacterial cell—starches, cellulose, complex proteins, gelatin—the enzymes must pass out of the bacterium and consequently may be found in the surrounding medium. Substances like sugars, peptones, alcohol, which are readily diffusible, may be acted on by enzymes retained within the cell body. ”

“ Bacteria increase by bisection, and when the surrounding conditions are favorable their rate of production is marvellous. It has been computed that an individual bacterium will generate nearly 17,000,000 of its fellows within twenty-four hours. ”

“ On the outside is a cell membrane which encloses cytoplasm and nucleus; the latter, however, is not in a single mass, but the nuclear material is distributed through the cell. Many of the bacteria have the power of motion, this being effected by small hair-like appendages or flagellæ which may be numerous, projecting from all parts of the organisms or from one or both ends, the movement being produced by rapid lashing of these hairs. A bacterium grows until it attains the size of the species, when it divides by simple cleavage at right angles to the long axis forming two individuals. ”

“ Not only does the close resemblance of the Bacteria to unquestionable plants, such as the Oscillatorioe and the lower forms of Fungi, justify this conclusion, but the manufacturing test settles the question at once. It is only needful to add a minute drop of fluid containing Bacteria, to water in which tartrate, phosphate, and sulphate of ammonia are dissolved; and, in a very short space of time, the clear fluid becomes milky by reason of their prodigious multiplication, which, of course, implies the manufacture of living Bacterium-stuff out of these merely saline matters. ”

“ Or media in which certain organisms thrive and others not, so that the former soon “crowd out” the latter (unsterilized milk for lactic acid bacteria, inorganic media in soil bacteriology) may be used. A combination of the general methods (b) and (c) is much used in the separation of the organisms of the “intestinal group” in human practice. (d) The inoculation of a susceptible animal with a mixture suspected to contain a given pathogenic bacterium frequently results in the development of the latter in pure culture in the body of an animal, from which it may be readily recovered. ”

“ Bacteria are those minute creatures the mode of origin of which in sealed infusions has been so much of late disputed, but the activity of which in promoting the decomposition of dead substances is undisputed. A bacterium is a particle of protoplasmic matter, either spheroidal or oblong, or like a short rod, or shaped like a corkscrew, and bacteria may also be in the form of a short chain of spheroids, or of oblong particles, or of rods united in a zigzag manner. ”

“ Just as an unidentified disease in an animal may be determined by testing its serum as above described against known kinds of bacteria, so unknown bacteria isolated from an animal, from water, etc., may be identified by testing them against the blood sera of different animals, each of which has been properly inoculated with a different kind of known bacteria. If the unknown organism is agglutinated by the blood of one of the animals in high dilution, and not by the others, evidently the bacterium is the same as that with which the animal has been inoculated, or immunized, as is usually stated. ”

“ Therefore, wherever we find bacteria in the active processes of growth, that is, multiplication, we may be assured that they have found matter that should be rescued from waste and converted into useful food for plants. It follows that when we find a bacterium actively growing in any part of our bodies, it has found some197 form of decaying matter that is not only no longer useful to our bodies, but is in fact harmful and should be removed. ”

“ The tissues and fluids are treated by various histological methods, but, to speak generally, examination is made either in films smeared on thin cover-glasses and allowed to dry, or in thin sections cut by the microtome after suitable fixation and hardening of the tissue. In the case of any bacterium discovered, observation must be made in a long series of instances in order to determine its invariable presence.
In cultivating bacteria outside the body various media to Cultivation. serve as food material must be prepared and sterilized by heat. ”

“ According to this view, then, a part at least of the directly toxic substance is produced in the living body by enzymes present in the so-called toxin obtained from the bacterial culture. Recent researches go to show that enzymes play a greater part in fermentation by living ferments than was formerly supposed, and by analogy it is likely that they are also concerned in the processes of disease. But this has not been proved, and hitherto no enzyme has been separated from a pathogenic bacterium capable of forming, by digestive or other action, the toxic bodies from proteids outside the body. ”

“ In studying under the microscope the development of these little organisms, in the preparations of which they have taken possession, a very curious evolution of one of the microbes of the air is revealed. The organism is a bacterium, which presents at first sight the characteristics of a very long, filamentous bacillus. M. Miquel affirms that he has seen this organism afterward divide itself into segments of unequal size, in such a way as to form strings of micrococci. The observation deserves consideration, for, if it is confirmed, and the ”

“ Other bacterial cultures such as Bacillus subtilus, Pseudomonas aeruginosa, Micrococcus roseus, and Mycobacterium smegmatis (SI>0.80) serve as suitable blind QC cultures. MEASUREMENT: 13.
Set gas chromatograph according to manufacturer’s recommendations and to conditions given on page 0801-1. Inject a 2-μL sample aliquot with an autosampler. 14. ”

“ Simonson, in rubber jacket and similar galoshes, bound with whip-cord over woolen socks (he was a vegetarian and did not use the skin of animals) , was also awaiting the departure of the party. He stood near the entrance of the house, writing down in a note-book a thought that occurred to him. “If,” he wrote, “a bacterium were to observe and analyze the nail of a man, it would declare him an inorganic being. Similarly, from an observation of the earth’s surface, we declare it to be inorganic. ”

“ We have already seen how many organisms exhibit their energy in the formation of many coloured pigments. They are, as a rule, "innocent" microbes. Oxygen is required for some, darkness for others, and they all vary according to the medium upon which they are growing. Red milk, yellow milk, and green pus afford examples of pigment produced by bacteria.
2. Gas. Quite a number of the common bacteria, like Bacillus coli, produce gas in their growth; hydrogen (H) , carbonic acid (CO2) , methane (CH4) , and even nitrogen (N) being formed by different bacteria. ”

“ These properties explain the regular distribution of bacteria in liquids exposed to the air. Thus, in water in which plants have been macerated the surface of the liquid is occupied by Bacillus subtilis. which has need of free oxygen in order to live, while in the bulk of the liquid, in the vegetable tissues, we find other bacteria, notably B. amylobacter, which lives very well by consuming oxygen in a state of combination. Bacteria, then, can only live in organic matters, now in the presence and now in the absence of air. ”

“ The recommendation of sanitarians that water or milk or food suspected of being contaminated by pathogenic bacteria should be exposed to a boiling temperature before it is used is based upon the experimental data referred to; and the knowledge that organic liquids can be sterilized by heat constitutes the foundation upon which the bacteriology of the present day has been established. To obtain reliable information with reference to the biological characters of any particular micro-organism it is necessary to experiment with pure cultures, and this requires a sterile culture medium. ”