细菌与细菌学
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BACTERIA AND BACTERIOLOGY.
Bacteria are one-celled plants that sometimes
are so small they must be viewed with an electron microscope. Some
bacteria are free-living---they manufacture their own food. Others
live on dead or decaying matter or as parasites on other living
organisms. Still others cause disease. The science of bacteriology
deals with the properties and activities of bacteria.
细菌与细菌学。细菌是单细胞植物，有时是如此之小，必须用电子显微镜才能观察到它们。有些细菌是独立生活的---它们自己制造食物。另外一些细菌以死亡或腐烂的物质为生，或寄生在其它活生物体上。有些还会引发疾病。细菌学科学涉及的是细菌的属性和活动。
The bacteria constitute a useful and essential group in the
biological community. Although some bacteria prey on higher forms
of life, relatively few are pathogens (disease-causing organisms).
Certain microorganisms spoil food and fiber, but most of these are
subject to control. From the point of view of man these activities
are “antisocial,” but oth
er organisms derive many benefits from the existence of bacteria.
Life on earth depends on the activity of bacteria in mineralizing
organic compounds and on their ability to capture the free nitrogen
molecules in the air for use by plants. Also, bacteria are
important industrially for the conversion of raw materials into
useful products, such as the formation of organic chemicals,
including antibiotics, and the manufacture of cheese.
细菌在生物界构成了一种有用的和非常重要的群体。尽管一些细菌会捕食更高级的生命形式，但相对而言，很少是病原体（引发疾病的生物体）。特定的微生物会破坏食物和纤维，但它们大多数是可控的。从人的视角来看，这些活动都是“反社会的”，但其它生物体从存在的细菌中获得了许多好处。地球上的生命依赖于细菌矿化有机化合物的活动，并且依赖于它们的能力来捕获空气中的游离氮分子供植物使用。还有，在工业上细菌很重要，可将原料转变成有用的产品，比如，形成有机化学品，包括抗生素，以及制作奶酪。
1． Bacteriology As a
Science
History. Bacteria
were first described in 1676 by an amateur lens grinder named Anton
van Leeuwenhoek of Delft, Holland. They received little attention
for nearly 200 years until Louis Pasteur, a French chemist, became
interested in the “diseases” of beer and wine. From his researches
he concluded (1857) that such chemical compounds as lactic and
butyric acids are produced by specific organisms. This significant
concept was extended readily to the idea that a given disease may
be caused by a specific microorganism. Robert Koch, a German
physician, demonstrated this to be true (1876) for anthrax in
cattle. He isolated the causative organism, Bacillus
anthracis, from the blood of an infected animal and grew it in
pure culture, which he then used to infect another animal. This
demonstration, soon extended to other infectious diseases, marks
the beginning of bacteriology as a branch of science. (See DISEASE,
GERM THEORY OF.) Although bacteriology initially was concerned
chiefly with pathogenic bacteria and the diseases they cause, such
bacteria represent only a limited number of species. As the science
developed, attention was directed toward organisms important in
agriculture (soil and dairy bacteriology) and technology
(fermentation and food). Recently, bacteriology has been recognized
as an independent discipline, significant especially for its
contributions in the field of molecular biology, without reference
to its many important practical applications.
1．
细菌学是一门科学。
历史。1676年，荷兰代尔夫特的一位名叫安东·范·列文虎克的业余磨镜师第一次命名了细菌。在近200年里很少有人关注到它们，直到一位法国化学家路易·巴斯德对啤酒和葡萄酒中的“疾病”产生兴趣为止。从他的研究中他得出结论，像乳酸和丁酸这样的化合物是由特殊功能的生物体产生的。这一意义重大的概念很容易延伸到这种观念，即某种疾病可能是由一种特定的微生物引起的。德国内科医生罗伯特·科赫证实家牛中的炭疽热是真实存在的（1876年）。他从受感染的动物血液中分离出致病微生物炭疽杆菌，并在纯培养的环境中使其生长，然后他用它们感染了其它的动物。这一论证，很快扩展到其它感染的疾病中，标志着作为科学分支细菌学的开始。（可参阅疾病的微生物理论词条）。尽管细菌学最初主要是关注致病菌和它们引起的疾病，但这种细菌只代表了数量有限的种类。随着科学的发展，注意力直接引向了农业中（土壤和乳制品的细菌学）重要的生物体和技术（发酵和食物）。最近，细菌学被认为是一门独立学科，尤其重要的是它对分子生物学领域的贡献，但未提及它许多重要的实际应用。
Relation to Other Organisms.
The separation of all living things into two
kingdoms—the animal and the vegetable—remained satisfactory until
significant study of microorganisms began in the early part of the
19th century. As information developed, it became
apparent that bacteria, molds, yeasts, algae, and protozoa could
not categorically be classified as either plants or animals. For
example, bacteria have rigid cell walls, as do plants, but some are
motile and most use organic foods, as animal do; algae have
chlorophyll, as do plants, but some are motile; yeasts have a rigid
cell wall, but some share with animals the ability to make fats;
and some protozoa and bacteria have chlorophyll. Ernst Haeckel
solved this dilemma (1866) by proposing an additional kingdom the
Protista, to include protozoa, molds, yeasts, bacteria, and the
simplest algae. This suggestion achieved little acceptance and
today, as a result of work done primarily in the 19th
century, protozoa are assigned to the animal kingdom, while
bacteria, molds, yeasts, and algae are allocated to the vegetable
kingdom. In recent years, viruses (the smallest known
microorganisms) and the rickettsiae (intermediate in size between
viruses and bacteria) have also been included in the plant
category.
与其它生物体的关系。所有生物可分为两个王国---动物王国和植物王国---一直是令人满意的，直到开始于19世纪早期对微生物的重要研究为止。随着信息的发展，很明显细菌、霉菌、酵母、藻类和原生动物既无法被明确地归为植物，也无法归为动物。例如，细菌像植物一样具有坚硬的细胞壁，但一些细菌是活动的，而且大多数像动物一样食用有机食物；藻类像植物一样含有叶绿素，但一些藻类是能动的；酵母拥有坚硬的细胞壁，但一些酵母与动物一样有制造脂肪的能力；而一些原生动物和细菌都拥有叶绿素。恩斯特·黑克尔通过建议增加一个额外的原生生物王国，包括原生动物、霉菌、酵母、细菌以及最简单的藻类解决了这一难题（1866年）。几乎没有人接受这一建议，而今天，作为19世纪主要完成的工作成果，原生动物被归入动物王国，而细菌、霉菌、酵母和藻类都被归入了植物王国。在最近几年中，病毒（已知最小的微生物）和立克次体（在病毒和细菌之间中等大小的）已被包括在植物种类中。
Classification.
Bacteria are classified according to the
following criteria: microscopic appearance and staining reaction;
appearance of growth on the surface of solid media or in liquid
media; physiological characteristics, including the effects of the
bacteria upon the environment; the ability to produce disease; and,
for some, serological reactions. The nomenclature of bacteria is
binomial, using the genus and species names; for example,
Escherichia coli. An International Code of Nomenclature of
Bacteria and Viruses has been developed and adopted by the
International Association of Microbiological societies. It should
be emphasized that this is an artificial classification and not a
natural one such as is attempted for higher plants and animals. For
efforts to classify bacteria there are few such guidelines of
sexual reproduction or evolutionary development as are used for the
higher forms. Sexual reproduction has been demonstrated in only a
few bacteria; since bacteria have no parts that fossilize, little
can be learned about their evolutionary development from
paleontology. Thus, classification of bacteria is actually an
arbitrary key to identification, such as that followed in
Bergey’ Manual of Determinative Bacteriology.
分类。细菌是根据下列标准分类的：显微镜下的外观和染色反应；固体介质或在液体介质表面生长的外观；生理特性，包括细菌对环境的影响；产生疾病的能力；以及对一些血清的反应。细菌的命名法是双项式的，使用属和种来命名；例如，大肠杆菌。《国际微生物学会联合会》已制定并采纳了《细菌和病毒的国际命名规则》。需要强调的是，这是一种人为的分类，而非对高等植物和动物进行的自然分类。在对细菌进行分类的尝试中，很少有用于高级形式的这种对有性繁殖或进化发展的指导方针。有性繁殖只在少数细菌中得到证实；因为细菌没有变成化石的部分，从古生物学中很难了解到有关它们的进化发展。因此，对确认来说，细菌分类实际上是一种随意的答案，比如在《伯杰氏鉴定细菌学手册》中出现的情况。
The bacteria have been assigned to the Protophyta, a special
division of the vegetable kingdom that has THREE classes: Class I,
Schizophyceae, the blue-green algae; Class II, Schizomycetes, the
bacteria; and Class III, Microtatobiotes, including the rickettsiae
and viruses.
细菌已归入到原生植物类中，一种特殊的植物王国分支，它有三个种类：种类I，裂殖藻类，兰绿藻；种类II，裂殖菌类，细菌；和种类III，极微菌类，包括立克次体和病毒。
The class Schizomycetes may be divided into 10 orders. The
orders Eubacteriales and Pseudomonadales
contain the largest number of species and include most of the
bacteria important to man. These orders embrace the simplest rod,
spiral, and spherical form that most laymen would regard as
bacteria. The order Actinomycetales embodies forms that have a
mold-like appearance, with hyphae (thread-like extensions) and
conidiospores (asexual spores), and are common in soil. Also
included in this order are the microorganisms that cause
tuberculosis, as well as many that produce antibiotics. The order
Spirochaetales contains spiral-shaped forms that have flexible cell
walls and resemble protozoa; important members of this order are
those that produce syphilis and relapsing fever. The order
Mycoplasmatales includes organisms that are highly pleomorphic—that
is, they occur in more than one distinct form during their life
cycles. The organisms are characterized by filaments that break up
into coccoid (spherical) bodies. These cell bodies, which are soft
and fragile, can cause disease; they are called
pleuropneumonia-like organisms. In the order chlamydobacteriales
are found the iron bacteria, present in water, which deposit oxides
or carbonates of iron in sheaths surrounding the cells. The order
Hyphomicrobiales contains organisms that multiply by budding or by
longitudinal fission and occur in aggregates that have a common
stalk; these are also to be found in fresh water.
裂殖菌类可分为10目。真细菌目和假单胞菌目，包含数量最多的种类，并包括了大多数对人重要的细菌。这些目包括最简单的棒状、螺旋状和球状形式，因此，大多数外行会认为是细菌。放线菌目包括了霉菌样外观的形式，带有菌丝（线状延伸）和孢子（无性孢子），这在土壤中很常见。在这个目中还包括引起结核病的微生物，以及产生抗生素的许多微生物。螺旋体目包括那些拥有柔韧的细胞壁和类似于原生动物的螺旋状形式；该目的重要成员是那些产生梅毒和回归热的成员。枝原体目包括高度多形的有机体---换言之，在它们的生命周期内，它们不只一次地以不同的形式出现。这些有机体以丝状为特征，可分裂成球状（球形）体。这些细胞体柔软而易碎，会引发病症；它们被称为类胸膜肺炎生物体。在鞘杆菌目中，发现了出现在水中的铁细菌，它在细胞周围的鞘中沉积了氧化物或碳酸盐。生丝微菌目，包含了通过发芽或通过纵向裂变繁殖的生物体，并出现在具有共同茎的聚合物中；在淡水中也发现了它们。
The order Caryophanales embraces very large bacteria (6
microns in diameter by 20 microns in length) that are found in the
intestinal tracts of animals; in these larger cells a nucleus can
be clearly discerned. The order Beggiatoales contains rod-shaped
forms that move by a gliding motion, though they appear to lack
flagella or other organs of locomotion; some contain granules of
sulfur. The order Myxobacteriales includes the flexible rods that
produce slime; resting cells originate in fruiting bodies that are
formed by the aggregation of a large number of vegetative
cells.
显核细菌目，包括在动物肠道中发现的非常大的细菌（直径6微米，长度大约20微米）；在这些较大的细胞中，可以清晰地看出细胞核心。贝日阿托氏菌目，包含一种滑行方式移动的杆状形式，虽然它们好像没有鞭毛，或者其它移动的器官；有些包含着硫磺粒。粘液菌目，包括产生粘液的柔软棒；静息细胞产生于大量的植物生长细胞聚合物形成的子实体。
2. Bacterial Anatomy
Methods of Investigation.
Becauseof their microscopic size, cytological study of
bacteria for many years was limited to application of staining
methods to reveal size, shape and such few specialized structures
as flagella and spores. The predominant bacterial forms, ranging
from 0.5 to 10 microns in length (1 micron=0.001 millimeter), are
spheres (cocci), rods (bacilli), and spirals (spirilla). The
development of more powerful phase and electron microscopes and
such specialized auxiliary techniques as slicing sections from a
single cell with a delicate microtome have facilitated more
intimate knowledge of the fine structure of the bacterial cell.
Finally, methods that involve breaking the cells and separating the
parts into various fractions by differential centrifugation reveal
associations between structure and function at the molecular
level.
2、细菌解剖学
研究方法。由于它们极小的尺寸，多年来对细菌的细胞学研究被限制在应用染色法来显示尺寸、形状以及像鞭毛和孢子这样很少的特殊结构。从长度0.5到10微米（1微米等于0.001毫米）的主要细菌形式是球形（菌球），棒条体（杆菌）和螺旋形（螺旋菌）。更强大的相位和电子显微镜的发展和用精密的切片机从单个细胞切片的专业辅助技术促进了对细菌细胞精细结构更深入的了解。最后，涉及打破细胞的方法和通过差速离心法将部件分离成不同的片段，在分子层面揭示了结构与片段之间的联系。
Structure and Function.
The typical bacterial cell has on the outside
a coating termed a slime layer or capsule. In many, this structure
is a high-molecular-weight polymer (a long molecule made up of
repeating structural units) of a simple hexose sugar such as
glucose (dextrans) or levulose (levans). In others, the structure
is chemically much more complex, being formed of units of simple
sugars (glucose, mannose, and galactose), derived sugars (amino
sugars), and sugar acids (gluconic and glucuronic). Probably the
cells of this type most widely studied are those associated with
the pneumococci. The capsular material confers type specificity on
the organism, which is to say that the type of pneumonia developing
in the host depends on the molecular composition of the capsule. In
Bacillus anthracis the capsule is a polymer of D-glutamic
acid, the unnatural form of this amino acid.
结构与功能。典型的细菌细胞在外部拥有一层称为沾液层或囊的涂层。在许多方面，这种结构是一种简单的已糖高分子量聚合物（由重复结构单元组成的长分子）诸如葡萄糖（葡萄聚糖）或果糖（果聚糖）。在其它方面，该结构在化学结构上要复杂的多，是由单糖（葡萄糖，甘露糖和半乳糖），衍生糖（氨基糠）和糖酸（糖酸和糖醛）的单元组成。很可能这类被最广泛研究的细胞与肺炎双球菌有关。该囊状材料赋予了有机体的类型特异性，这就是说，在宿主中发展的肺炎类型取决于胶囊的分子成分。在碳疽杆菌中，胶囊是一种D-谷氨酸的聚合物，是这种氨基酸的非自然形式。
In general, bacterial cell walls appear to be double- or
triple-layered structures, each layer having a thickness of perhaps
0.002 to 0.003 micron. The chemical composition of the walls of
“true” bacterial seems to be related to the gram-staining
characteristics of the cell. The cell walls most studied are those
of the gram-positive Staphylococcus aureus. (See GRAM, HANS
CHRISTIAN JOACHIM.) They are a complex polymer of
N-acetylglucosamine (the basic structural unit in chitin from
insect exoskeletons), N-acetylglucosamine with a lactic acid
molecule connected to it (muramic acid), and a small number of
amino acids linked to the lactic acid molecule. Muramic
acid—indeed, the entire polymer of the cell wall—is unique to
bacterial cells; the antibiotic penicillin inhibits cell wall
synthesis in gram-positive cells, whereas it does not interfere
with growth of gram-negative bacteria, which contain very little of
this unique polymer. The cell walls of gram-negative bacteria are
more complex in that they contain true protein, polysaccharides,
and lipid material.
一般而言，细菌细胞壁显示为双层-或三层结构，每层拥有或许0.002到0.003微米的厚度。“真正的”细菌壁的化学成分似乎与细胞的革兰氏染色特性有关。研究最多的细胞壁是那些革兰氏阳性的金黄色酿脓葡萄球菌。（参阅革兰氏，汉斯·克里斯蒂安·约阿希姆词条）。它们是N-乙酰氨基葡糖（来自昆虫外骨骼甲壳素中的基本结构单元）的一种复杂的聚合物，N-乙酰氨基葡糖与乳酸分子相接（胞壁酸）---实际上，细胞壁的整个聚合物---对于细菌细胞是独一无二的；在革兰氏阳性细胞中，抗生素青霉素抑制了细胞壁合成，然而它并不干扰含有很少的这种独特聚合物，革兰氏阴性细菌的生长。革兰氏阴性细菌的细胞壁更为复杂，因为它们包含真正的蛋白质，多糖类和脂类物质。
Next to the cell wall lies a membrane composed of proteins
and lipids. In addition to acting as part of the osmotic barrier
between the external and internal environments of the cell, it
contains many of the oxidation-reduction enzyme systems concerned
with energy metabolism. In the cells of higher plants and animals,
these systems are located in specialized structures called the
mitochondria, scattered throughout the cytoplasm (defined as the
material inside the cell membrane). Within the bacterial cytoplasm
are the granules that act as reservoirs for food, pigments, and
nucleic acids. Food can be stored both as carbohydrate polymers
(such as starch and glycogen) and as true fats. It is noteworthy
that, among the bacilli and some other species, the stored lipid is
a simple polymer of beta-hydroxybutyric acid. The polymers of
ribonucleic acid include a protein-synthesizing fraction analogous
to the ribosomes found in cells of higher plants and
animals.
紧挨着细胞壁的是由蛋白质和脂类组成的膜。除了作为细胞内、外环境之间渗透屏障的一部分外，它包含了许多涉及能量代谢的氧化还原酶系统。在高等植物和动物的细胞中，这些系统位于称为线粒体的特殊结构中，分散在细胞质中（定义为细胞膜内部的物质）。在细菌的细胞质内是些充当食物、色素和核酸储存器的颗粒。食物既可贮存为碳水化合物的聚合物（如淀粉和糖原），也可贮存为真正的脂肪。值得注意的是，在杆菌和一些其它物种中，贮存的脂类是一种β-羟丁酸的简单聚合物。核糖核酸的聚合物包括蛋白质合成的部分，类似于在高级植物和动物的细胞中发现的核糖体。
Many bacteria possess one or more fine threadlike structures,
called the flagella, which are used for locomotion. These are
composed of a protein similar to myosin, the protein of muscle
fiber.
许多细菌都具有一种或多种被称为鞭毛的，用于移动的精密丝状结构。这些是由类似于肌球蛋白的蛋白质组成，是种肌纤维的蛋白质。
Members of the Bacillaceae family of the order Eubacteriales,
species of both aerobicBacillus living only in the presence
of oxygen and anaerobic Clostridium flourishing only in the
absence of free oxygen, form endospores. These are highly
refractile bodies that are extremely resistant to heat, to drying,
and to many chemical agents. Their size, shape, and position within
the mother cell are criteria employed for classification.
Chemically, spores differ in several respects from vegetative
cells, notably in having less water but more calcium. One compound,
dipicolinic acid, is unique to spores, and it may account for from
10 to 15 percent of their dry weight. Endospores also contain fewer
active enzymes than does the vegetative cell, but have dormant
enzymes that can be detected only after activation by heat or
chemical agents. This breaking of the dormancy is accompanied by
intake of water; by increase in permeability; and by losses of
refractility, heat resistance, and calcium dipicolinate. The spores
coat break, and a new cell emerges. Since only one spore is formed
per cell, this is not a method of reproduction, but a means of
surviving adverse conditions.
真细菌目的芽胞杆菌科成员，既是一种只生活在有氧环境中的好氧芽孢杆菌，又是一种只有在缺乏游离氧的情况下才会长势好，形成内孢子的厌氧芽孢梭菌。这些都是有高度折射力的物体，极耐热，耐干，并且耐受许多化学药剂。它们在母细胞中的大小、形状和位置是用于分类的标准。在化学上，孢子与植物细胞在几个方面有所不同，特别是缺水而多钙。一种吡啶二羧酸的化合物是孢子独有的，它可能占它们干重量的10%到15%。内孢子也比植物细胞包含更少的活性霉，但拥有休眠霉，只有在加热或化学药剂激活后才能检测到。这种对休眠的打破是伴随着水的摄入；通过增加渗透性；而且通过折射率、耐热性和二吡啶酸钙的损失。孢子衣破裂，新的细胞出现。由于每个细胞只形成一个孢子，因此这不是繁殖的方法，而是不利条件的生存手段。
3. Bacterial Physiology
Nutritional Types.
Bacteria conveniently can be classified into THREE major groups
according to the materials they employ as sources of energy: (1)
chemoorganotrophs that use organic compounds; (2) photoautotrophs
that utilize radiant energy; and (3) chemolithotrophs that oxidize
inorganic molecules. The two last groups usually use carbon dioxide
as the major source of carbon. In all groups, energy is obtained
either aerobically, by employing molecular oxygen as the terminal
electron acceptor, or anaerobically, in the absence of oxygen, by
oxidation-reductions between organic compounds in the process known
as fermentation. So-called facultative anaerobes can use either
mechanism.
2． 细菌生理学
营养类型。根据细菌利用的能源资料，可方便地将它们分成三大群体：（1）使用有机化合物的化能异养型；（2）利用辐射能的光能自养型；以及（3）氧化无机分子的化能无机营养型。后两个大群通常使用二氧化碳作为碳的主要来源。在所有大群中，既可通过使用氧分子作为末端的电子受体，以有氧的方式来获得能量，也可在缺氧的情况下通过称为发酵过程中有机化合物间的氧化还原，以厌氧的方式来获得能量。所谓兼性厌氧菌可使用该机制中的任何一种。
As do other forms of life, bacteria require water, minerals,
vitamins, and sources of carbon and of nitrogen for growth. In
culture these nutrients are conveniently provided for many species
by a bouillon containing from 1 to 2 percent peptone, a hydrolyzed
protein made from beef or casein; for colonial growth, a
solidifying agent such as agar is added. For precise study of
bacterial physiology, however, a synthetic medium made from known
constituents is preferable.
正如生命生长的其它形式一样，细菌生长也需要水、矿物质、维生素和碳，及氮的来源。在细菌的培养中，用含有1%到2%的胨汤，一种来自牛肉或酪蛋白的水解蛋白质可为许多物种方便地提供这些营养物；为菌群的生长增加如琼脂一样的固化剂。然而，为精确地研究细菌的生理机能，一种由已知成分制成的合成介质更为合适。
Sources of Carbon and Nitrogen. The
source of carbon in synthetic media is usually glucose, but other
carbohydrates can be used, for example, in a diagnostic test. Sugar
alcohols in the form of glycerol or mannitol are suitable for most
species; others, such as the Bacillaceae, possess amylase that
enables them to use starch. A few specialized forms have the enzyme
systems necessary to break down cellulose, usually anaerobically
and at temperatures greater than 45゜C.
Since few species form lipases, enzymes capable of hydrolyzing
fats, generally they do not use fats as such. But many can utilize
the salts, including the four carbon dicarboxylic acids, especially
succinic and malic acids. Since nitrogen is required mainly for
synthesis of cell protein, a mixture of amino acids is suitable.
Some species, including many of the Bacillaceae, produce
proteinases (enzymes that can digest protein), a faculty that
allows them to use native protein as a source of these acids.
Others utilize ammonia, urea, and nitrates, as do green plants, and
a few can “fix” molecular nitrogen. See also section 5.
Ecology (The Nitrogen Cycle).
碳和氮的来源。在合成介质中的碳来源通常是葡萄糖，但也能利用其它的碳水化合物，例如，在诊断测试中。以甘油或甘露醇形式存在的糖醇适合大多数物种；其它的，诸如芽胞杆菌科，拥有淀粉酶，因此能使它们利用淀粉。有些特殊的形式拥有分解纤维素所必需的淀粉酶系统，通常以厌氧的方式，并且温度大于45度。因为，很少有物种能形成脂肪酶，酶类能够水解脂肪，一般来说，它们不使用脂肪本身。但许多物种可以利用盐，包括四种碳二羧酸，尤其是琥珀酸和苹果酸。由于氮主要是用于合成细胞蛋白质所需要的，一种氨基酸的混合物便是合适的。一些物种，包括许多的芽胞杆菌科，产生蛋白酶（能消化蛋白质的酶类），允许它们利用天然蛋白质作为这些酸来源的一种机能。其它的物种利用氨、尿素和硝酸盐，就像绿色植物那样，而有些物种能“固定”分子氮。也可参阅第五部分生态学（氮循环）。
Minerals and Growth Factors. Bacteria use
the same types of mineral ions as do higher plants and for much the
same purposes, but in relatively much smaller quantities; tap water
will often meet their mineral needs. Mineral ions needed include
such trace elements as molybdenum, manganese, and cobalt.
Phosphates are frequently added to a medium, both as a source of
phosphorus for synthesis of nucleic acids and to buffer the medium
against excessive acidity through their capacity to neutralize
acids.
矿物质和生长因素。细菌就像高等植物那样，而且出于同样的目的使用相同类型的矿物离子，但数量相对较少；自来水会时常满足它们对矿物质的需求。需要的矿物离子包括钼、锰和钴这样的微量元素。磷酸盐经常被添加到介质中，既可作为用于合成核酸的磷的来源，也可通过它们中和酸的能力用于防止酸度过高的缓冲介质。
The chief vitamin requirement is for the constituents of the
B complex: riboflavin, thiamine, biotin, and pantothenic acid. Many
organisms, including the Enterobacteriaceae that live in the
intestinal tracts of man and animals, can synthesize their own
vitamins; when the bacteria die, these are released to the host.
Biological assay methods based on these requirements for specific
vitamins or minerals by specific strains of bacteria have been
developed. Furthermore, bacteria have been widely used to study the
functions of these vitamins in metabolism as coenzymes required to
maintain the activity of specific enzyme systems. Perhaps half of
the vitamins in the B complex were originally discovered through
studies of the nutritional needs of bacteria. See also
VITAMINS.
主要的维生素需求是对复合维生素B的成分：核黄素（维生素B2），硫胺素（维生素B1），生物素（维生素H），以及泛酸（维生素B5）。许多有机体，包括生活在人和动物肠道道中的肠杆菌，能够合成它们自己的维生素；当细菌死亡时，它们被释放给宿主。目前已开发出基于这些特定维生素需求或特定细菌株的生物测定方法。此外，细菌已被广泛用于研究这些维生素作为维持特定酶系统活性所需要的辅酶在新陈代谢中的作用。可能复合维生素B有一半的维生素，最初是通过研究细菌的营养需求发现的。也可参阅维生素词条。
When an animal cell anaerobically breaks down glucose sugar,
it combines the glucose molecule with phosphates, and this
phosphorylated sugar is split into two molecules of glyceraldehydes
phosphate; this, in turn, is converted into lactic acid via pyruvic
acid. Many bacteria use this Embden-Meyerhof-Parnas glycolytic
pathway, named after the chief investigators of this process, but
others have alternative pathways to pyruvic acid. For example,
Leuconostoc mesenteroides successively converts hexose
phosphate to phosphogluconic acid, to ribulose phosphate, to
glyceraldehydes phosphate, and then to pyruvic acid. Regardless of
the pathway, however, the liberated energy is stored in the
phosphate portion of a molecule called adenosine triphosphate
(ATP), where it can be drawn on for use when needed by converting
ATP into the diphosphate (ADP). Species of the Lactobacillus and
Leuconostoc form lactic acid, but the clostridium and the
enterobacteria convert the pyruvate into various organic compound,
among which are the following: ethyl, isopropyl, and butyl
alcohols; formic, acetic, propionic, butyric, and succinic acids;
and acetone, acetoin, and 2,3-butylene glycol. Gases produced
include carbon dioxide, hydrogen, and methane. The “will-o’-the-wisp” results when
fermenting anaerobes in a marsh or bog form hydrogen and methane
and these gases ignite.
当动物的细胞以厌氧方式分解葡萄糖时，它就是将葡萄糖分子与磷盐酸结合在一起，而这种磷酸化的糖分解为两个甘油醛磷酸盐分子；反过来，通过丙酮酸转变成乳酸。许多细菌使用这种以这一过程的主要研究者命名的糖酵解途径，但其它的细菌有替代丙酮酸的途径。例如，肠系膜明串珠菌先后将磷酸己糖转变成磷酸葡萄糖酸、磷酸核酮糖、磷酸甘油醛，然后是丙酮酸。然而，不管路径如何，摆脱了束缚能力储存在称为三磷酸腺苷（ATP）分子的磷酸部分，当需要时，它在那里就可将ATP转换成二磷酸（ADP）。乳酸菌和明串珠菌的种类便形成乳酸，但梭状芽胞杆菌和肠杆菌能使丙酮酸盐转化成各种有机化合物，其中包括：乙烷基、异丙基以及丁醇；甲酸、乙酸、丙酸和琥珀酸；还有丙酮、乙偶姻以及2，3—丁二醇。产生的气体包括二氧化碳、氢气和甲烷。当在沼泽或泥塘中的厌氧菌发酵时就会形成氢气和沼气，而且这些气体会燃烧，产生“鬼火”现象。
Aerobically, the animal cell oxidizes lactic acid by
returning it to pyruvic acid, which is oxidized to the acetyl
group. The acetyl group, in turn, is condensed with a 4-carbon
dicarboxylic (oxalacetic) acid. Citric acid goes through a series
of reactions that eventually end with oxalacetic acid. The net
result of this tricarboxylic acid (TCA) cycle is that a molecule of
pyruvic acid is completely oxidized to carbon dioxide and water,
with the liberated energy stored in the APT-ADP reservoir. Many
bacteria use the TCA cycle in oxidizing pyruvic acid, but other
have developed alternative pathways.
以有氧的方式，动物细胞通过将乳酸还原成丙酮酸来氧化乳酸，把乳酸氧化成乙酰基。反过来，乙酰基与4-碳二羧酸凝结（草酸）。柠檬酸通过一系列反应，最终生成草酸。这种三羧酸（TCA）循环的最终结果是丙酮酸分子被完全氧化成二氧化碳和水，包括将释放的能量贮存在APT-ADP的储层中。许多细菌在氧化丙酮酸中都利用TCA循环，但其它的细菌已发展出替代途径。
The photoautotrophs belong to THREE families: Thiorhodaceae,
the purple sulfur bacteria; Athiorhodaceae, the brown and purple
nonsulfur bacteria; and Chlorobacteriaceae, the green sulfur
bacteria. Their classification is based in part on the source of
hydrogen used to reduce carbon dioxide. Photoautotrophs have a
bacteriochlorophyll similar to that of green plants, but one that
absorbs light of longer wavelengths. It is contained in structures
called chromatophores and is completely obscured in the purple
forms by pigments that color the cells yellow, brown, red, and
purple. In contrast to the process in green plants, bacterial
photosynthesis is obligately anaerobic.
光合自养生物归属三科：色硫菌科，紫色硫菌；红色无硫菌科，棕色和紫色的非硫菌；以及绿硫细菌科，绿色硫菌。它们的分类在一定程度上是基于用于减少二氧化碳的氢的来源。光合自养生物有类似于绿色植物的那种细菌叶绿素，而且能吸收波长较长的光。它包含在被称为色素细胞的结构中，并且完全被遮蔽在将细胞涂成黄色、棕色、红色以及紫色的，由色素形成的紫色中。与绿色植物的过程形成对照，细菌的光作用完全是厌氧的。
Chemolithotrophic organisms include the following:
Hydrogenomonas, the Knallgas bacterium, oxidizes hydrogen to
water; Nitrosomonas and Nitrobacter, the nitrifiers,
respectively oxidize ammonia to nitrite and nitrite to nitrate;
Thiobacillus oxidizes sulfur or hydrogen sulfide to
sulfate.
无机化能营养的有机体包括如下：氢单胞菌，氢氧混合气细菌，将氢气氧化进水中；亚硝化单胞菌和硝化菌属，硝化细菌，分别将氨氧化成亚硝酸盐，并将亚硝酸盐氧化成硝酸盐。
The Growth Curve. The
energy liberated in the reactions described above is directed
primarily toward biosynthesis of cell materials. Such growth is
assayed by such methods as measuring turbidity or the amount of
such formed products as carbon dioxide and lactic acid. These
indirect methods are standardized against actual cell counts
obtained by making suitable dilutions of the bacterial culture and
plating (distributing) a measured quantity into an appropriate agar
medium. After a period of incubation, colonies arising from the
individual cells are readily counted.
生长曲线。在上述反应中释放的能量主要是指细胞材料的生物合成。这种生长是通过测量混浊度的方法或形成如二氧化碳和乳酸产品这样的数量来分析的。这些间接方法是对细菌培养液进行适当的稀释，根据实际的细胞计数标准化的，并将测定量镀到（分配）合适的琼脂培养基中。一段潜伏期后，便很容易计算产生自单个体细胞的菌群。
If a suitable liquid medium is inoculated, little or no
growth occurs for a period called the lag phase until the bacterial
become adjusted to the new environment. This is followed by a
period of accelerating growth that reaches its maximum in the log
phase, during which growth is exponential. Soon the rate of
multiplication decreases as cultural conditions become less
favorable for maximum growth; exhaustion of nutrient, a deficient
supply of oxygen, or an accumulation of toxic end product may be
responsible. During the period of exponential growth many species
have a generation time of from 10 to 60 minutes. This means that,
with an initial inoculum of 100 cells per milliliter (ml) and a
generation time of 20 minutes, the population might reach 100
billion cells/ml in 10 hours. Usually, however, maximum populations
of 100 to 1,000 million/ml are the rule. The rate of death also
increases and often becomes exponential, especially if the culture
is exposed to factors deleterious either chemically or
physically.
如果接种了合适的液体介质，在一段称为迟滞期中，几乎不会出现生长的情况，直到细菌适应了新的环境。随后是达到其最大的对数阶段，在此期间，生长是指数级的。很快，随着培养条件变得不利于最大限度的生长，增殖率就会减少；耗尽养分，供氧不足，或毒物的最终积累可能是原因。在指数增长期间，许多物种都有10到60分钟的生成时间。这意味着，最初接种量为每毫升100个细胞，生成时间为20分钟，10小时内种群数量可达每毫升1000个细胞。然而，通常的情况是最大的种群数量为每毫升1亿至10亿。死亡率也在增加，常常变成指数级，尤其当培养物暴露在化学或物理上有害的因素下时。
The death phase has been studies intensively because of man’s
desire to control the activities of microorganisms either to
encourage or to inhibit growth. Except for the spores, which can be
extremely resistant, bacteria are readily killed by heat. Another
means of destruction is radiation by ultraviolet light. Often
control is achieved by excluding contaminants through the use of
cotton or sintered-glass filters. Chemical used for inhibiting
growth include sugar and salt for raising the osmotic pressure, as
well as antiseptics and disinfectants. The latter exert their
effect through destruction of the cell membrane, as by phenol or
detergents; or by interference with the enzymes concerned neither
with an energy-liberating reaction, as by mercuric chloride, carbon
monoxide, and cyanide, or with biosynthesis, as by sulfonamides and
penicillin.
由于人类希望控制微生物的活动，既可鼓励其生长，又能抑制其生长，已对死亡阶段进行了深入细致的研究。除了具有极强抵抗力的孢子外，通过加热很容易杀死细菌。另一种杀菌手段是用紫外光辐射。控制通常是用棉花或烧结玻璃过滤器来排除污染物。用于抑制生长的化学物质包括提高渗透压的糖和盐，以及防腐剂和消毒剂。后者通过破坏细胞膜发挥它们的作用，如用苯酚或洗涤剂；或通过干扰与能量释放反应无关的酶，如用氯化汞，一氧化碳和氰化物，或者与生物合成无关的，如磺胺类药和青霉素。
The rate and extent of bacterial growth are also markedly
affected by factors in the environment other than food, water, and
inhibiting substances. Two important ones are temperature and
acidity. Most bacteria prefer a temperature range of from
25゜to 37゜C.,
but some species known as psychrophiles grow near the freezing
point, while others known as thermophiles prefer temperatures as
high as 60゜to
70゜C. The majority of bacteria prefer a
neutral medium neither markedly acid nor alkaline, but the
thiobacilli will develop in media with pH near 0, roughly
equivalent to that of 5 percent sulfuric acid.
除了食物、水和抑制物质外，细菌生长的速率和程度明显受环境因素的影响。两个重要因素是温度和酸度。大多数细菌更喜欢摄氏25度到摄氏37度的温度范围，但一些被称为嗜冷菌的物种就生长在冰点附近，而另外的被称为嗜热菌，更喜欢温度高达摄氏60度到摄氏70度。大多数细菌更喜欢中性介质，既不是明显的酸性，也不是明显的碱性，但硫杆菌属会在pH值接近零的介质中生长，大约相当于pH值为5%的硫酸。
2023年1月12日译
（该词条位列《大美百科全书》1985年版，第3卷，第30页至34页）
待续部分：4.
Technology（技术）；5.
Ecology（生态学）；6. Bacteriophage and
Bacteriogenetics（噬菌体与细菌遗传学)。
