Classification according to the Bergey's Manual

Group I (Section 13. Vol. 2) Although there are only three genera listed in this group. Section 13 in Bergey's Manual lists three additional genera. one of which is Sporocarcina. a coccus-shaped organism

(see Group V). Most members of Group I are motile and differentiation is based primarily on oxygen needs.

Bacillus Although most of these organisms are aerobic. some are facultative anaerobes. Catalase is usually produced. For comparative characteristic of the 34 species in this genus refer to Table 13.4 on pages ll22and 1123.

Clostridium While most of members of this genus are strict anaerobes. some may grow in the presence of oxygen. Catalse is not usually produced. An excellent key for presumptive species identification is provided on pages 1143—1148. Species characterization tables are also provided on pages 1149—1154.

Sporolactobacillus Microaerophilic and catalase-negative. Nitrates are not reduced and indole is not formed. Spore formation occurs very infrequently (1% of cells).
Since there is only one species in this genus, one needs only to be certain that the unknown is definitely of this genus. Table 13.1 I on page 1140 can be used to compare other genera that are similar to this one.

Group 11 (Section 16. bl. 2) This group consists of Family Mycobacteriaceae. with only one genus:
Mvcobacterium. Fifty-four species are listed in Section 16. Differentiation of species within this group depends to some extent on whether the organism is classified as a slow or a fast grower. Tables on pages 1439—1442 can be used for comparing the characteristics of the various species.

Group III (Section 14. bl. 2) Of the seven diverse genera listed in Section 14. only three have been included here in this group.

LactobaciIlus Non-spore-forming rods, varying from long and slender to coryneform (club- shaped) coccobacilli. Chain formation is common. Only rarely motile. Facultative anaerobic or microaerophilic. Catalase-negative. Nitrate usually not reduced. Gelatin not liquefied. Indole and H2S not produced.

Lisreria Regular, short rods with rounded ends; occur singly and in short chains. Aerobic and facultative anaerobic. Motile when grown at 20—25°
C. Catalase-positive and oxidase-negative. Methyl red positive. Voges-Proskauer positive. Negative for citrate utilization. indole product ion, urea hydrolysis. gelatinase production. and casein hydrolysis. Table 14.12 on page 1241 provides information pertaining to species differentiation in this genus.

Kurthia Regular rods. 2-4 micrometers long with rounded ends; in chains in young cultures: coccoidal in older cultures. Strictly aerobic. Clatalase-positive. Oxidase-negative. Also negative for gelatinaseproduction and nitrate reduction. Only two, species in this genus.

Group IV (Section 15, Vol. 2)Although there are 21 genera listed in this section of Bergey's Manual. only three genera are described here.

Corvnebacterium Straight to sligbily curved rods with tapered ends. Sometimes club-shaped. Palisade arrangements common due to snapping division of cells. Metachromatic granules formed. Facultative anaerobic. Catalase.positive. Most species produce acid from glucose and some other sugars. Often produce pellicle in broth.Table I5.3on page 1269 provides information for species charactcrization.

Proprionihacrcnum Pleomorphic rods, often diphtheroid or club-shaped with one end rounded and the other tapered or pointed. Cells may he coccoid, bifid (forked, divided), or even branchcd. Nonmotile. Some produce clumps of cells with “Chinese character” arrangements. Anaerobic to acrototerant. Generally catalase-positive. Produce large amounts of proprionic and acetic acids. All produce acid from glucose.

Arthrobacter Gram-positisc rod and coccoid forms. Pleomorphic. Growth often starts out as rods, followed by shortening as growth continues. and finally becoming coccoidal. Some V and angular forms: branching by some. Rods usually nonmotile: some motile. Oxidative, never ferrmentative. Catalasc-positive. Little or no gas produced from glucose or other sugars. Type species is Arthrobacter globiformix. For species differentiation see tables on pages 1294 and 1295.

Group V (Section 13. Vol. 2) This group. which has only one genus in it. is closely related to genus Bacillus.

Sporosarcina Cells arc spherical or oval when single. Cells may adhere to each other when dividing to produce tetrads or packets of eight or more. Endospores formed (see photomicrographs on page 1203). Strictly aerobic. Generally motile. Only two species: S. ureae and S. hatophila.

Group VI (Section 12. Vol. 2) This section contains two families and 15 genera. Our concern here is with only three genera in this group. Oxygen requirements and cellular arrangement are the principal factors in differentiating the genera. Most of these genera are not closely related.

Micrococcus Spheres, occurring as singles. Pairs, irregular clusters. tetrads, or cubical packets. Usually nonmotile. Strict aerobes (one species is facultative anaerobic). Catalase- and oxidase-positive. Most species produce carotenoid pigments. All species will grow in media containing 5% NaCI. For species differentiation see Table 12.4 on page1007.

Planococcus Spheres, occurring singly, in pairs. in groups of three cells, occasionally in tetrads. Although cells are generally gram-positive, they may he gram-variable. Motility is present. Catalase- and gelatinase.positive. carbohydrates not attacked. Do not hydrolyze each or reduce nitrate. Refer to Table 12.9 on page 1013 for species differentiation.

Siapirciococcuc Spheres. occurring as singles. pairs. and irregular dusters, Nonmotile, Facultative anaerobes. Usually catalase-posive. Most strains grow in media with 10% NaCl. Susceptible to lysis by lysostaphin. Glucose fermentation: acid, no gas. Coagulase production by some. Refer to Excercise 78 for species differeniation, or to Table 12.10 on pages 1016 and 1017.

(Group VII (Section 12. Vol. 2) Note that the single genus of this group is included in the same section of Bergey's Manual as the three genera in group VI. Members of the genus Streptococcus have spherical to ovoid cells that occur in pairs or chains when grown in liquid media. Some species, notably S. murtans, will develop short rods when grown under certain circumstances, Facultative anaerobes. Catalase-negative. Carbohydrates are fermented to produce lactic acid without gas production. Many species are commensals or parasites of humans or animals. Refer to Exercise 79 for species differentiation of pihogens. Several tthlcs in Bergey's Manual provide differention on characteristics of all the streptococci.


(Group VIII Section 4. Vol. I) Although there are many genera of gram-ncgative aerobic rod-shaped bacteria, only four genera are likely to be encountered here.

Pseudomonas Generally motile, Strict aerobes, Catalase-positive. Some species produce soluble f1uoresent pigments that diffuse into the agar of a slant. Many tables are available in Bergey's Manual for species differentiation.

Alcaligenes Rods, coccal rods, or cocci. Motile, Obligate aerobes with some strains capable of anaerobic respiration in presence of nitrate or nitrite.

Halobacterium Cells may be rod- or disk-shaped Cells dividc by constriction. Most are strict aerobics; a few are facultative anaerobcs, Catalase. and oxidase-positive. Colonies are pink, red, or red to orange. Gelatinase produced, Most species require high NaCI concentrations in media. Cell lysis occurs in hypotonic solutions.

Flavobacterium Gram-negative rods with parallel sides and rounded ends. Nonmotile. Oxidative. Catalase-, ozidase-, and phosphatase-positive. Growth on solid media is typically pigmented yellow or orange. Nonpigmentcd strains do exist. For differentiation see tables on pages 356 and 357.

Groups IX and X (Section 5. Vol. 1) Section 5 in Bergey's Manual lists three families and 34 genera: of these 34 only 10 genera of Family Enterobacteriaceae
have been included in these two groups. If your unknown appears to fall into one of these groups. use the seperation outline in figure 51.3 to determine the genus. Another useful separation outline is provided in figure 80.1 on page 270. Keep in mind. when using these separation ouitines. That there are somw minor exceptions in the oapplications of these texts. The diversity of species within a particular genus often presents some problematical exceptions to the rule.. Your final decision can be ma only after checking the species charactcnstics tables for each genus in the Bergey's Manual

(Group XI These gernera are morphologically quite simiar. yet physiologically quite different.

Neisseria (Section 4. Vol. 1) Cocci, occurring singly. but more often in pairs (diplococci) adjacent sides are flattened. One species (N. elongata) consists of short rods. Nonmotile. Except for N. elongata. all species are oxidase- and catalase-positive, Aerobic.

Veilllonella (Section 8. Vol. I ) Cocci, appearing as dplococci, masses. And short chains. Diplococci have flattening at adjacent surfaces. Nonmotile. All are oxidase- and catalase-negative. Nitrate is reduccd to nitrite. Anaerobic.