growth pattern cell division in neisseriadepartments ofmicrobiology,* bacteriology, andpathology,...

JOURNAL OF BACTERIOLOGY, Jan. 1977, p. 333-342Copyright ©) 1977 American Society for Microbiology

Vol. 29, No. 1Printed in U.S.A.

Growth Pattern and Cell Division in Neisseria gonorrhoeaeBRITTA WESTLING-HAGGSTROM,* THEODOR ELMROS, STAFFAN NORMARK, AND

BENGT WINBLADDepartments of Microbiology,* Bacteriology, and Pathology, University of Umed, S-901 87 Umed, Sweden

Received for publication 1 June 1976

The gram-negative coccus Neisseria gonorrhoeae was found to grow regularlyin at least two dimensions. Growth proceeded at a linear rate sequentially ineach dimension. Growth in the second dimension (former width) was initiatedslightly before the pole-division plane distance equalled the cell width. Penicil-lin treatment localized presumptive growth zones to the existing septum region.It was suggested that new growth zones were always formed perpendicular tothe longitudinal axis created in the incipient daughter cells of a dividing coccus.Neither penicillin nor nalidixic acid induced filaments ofN. gonorrhoeae. Suchstructures could nevertheless be formed in the rod-shaped species Neisseriaelongata. N. gonorrhoeae divides by septation; however, complete septal struc-tures with separated cytoplasms were rather infrequent. It is proposed that N.gonorrhoeae be regarded as a short rod which always extends parallel to theactual longitudinal axis and which never undergoes a rod-sphere-rod transition.

Studies on biogenesis of cell shape and onregulation of cell division in the gram-negativebacteria have mostly concerned the rods. Littleis therefore known about these processes in thegram-negative cocci, e.g., the species of Neis-seria (8, 21).

In a defined medium during steady-state con-ditions, the gram-negative rod Escherichia coliincreases its mass by elongation in one dimen-sion only, there being no changes in width. Inslow-growing E. coli cells, elongation appearsto proceed from the pole at which the septumwas formed during the last cell division (6).After cell division, the two daughter cells growin opposite directions. One explanation for thisgrowth pattern would be a synthesis of enve-lope material from a growth zone that wouldduplicate at the end of each cycle (6, 25). Pre-sumptive growth zones in E. coli have beenlocalized by autoradiography (22) and may alsobe revealed by their specific sensitivity to peni-cillins (6, 11, 25). An equatorial orientation ofsuch zones has been suggested (22).

Deviations from this growth pattern havebeen observed in E. coli. Certain E. coli mu-tants have lost their normal rod shape (15, 17).One such mutant containing the envB muta-tion changes growth direction upon cellular di-vision, thereby giving rise to irregular shapedcocci (1). Moreover, the penicillin derivativemecillinam inhibits cell elongation and in-creases the cell width, thereby inducing osmoti-cally stable cocci (12, 19). A shift from a poor toa rich medium also causes a considerable ex-

pansion of the cell width. Thus, the rod-shapedE. coli has the capacity to expand in bothlength and width. In this communication wedemonstrate that Neisseria gonorrhoeae, un-like E. coli and other enterobacteria, exhibits aregular bidimensional growth pattern. The re-lationship between orientation of presumptivegrowth zones and the coccal shape will be dis-cussed.

MATERIALS AND METHODSMicroorganisms used, growth conditions, and

materials. N. gonorrhoeae (82409/55), colony type 4,was obtained from Alice Reyn, Copenhagen, Den-mark. Neisseria elongata was kindly supplied byKjell Bovre, Tromso, Norway. The bacteria wasstored at -60°C in GC medium base (GCMB) (Difco)from which agar was omitted, plus supplement B(Difco) and 20% glycerol.

Cultivation on solid medium was performed onGCMB plus supplement B at 36°C in a CO2 incubator(6% C02). The liquid medium used was GCMB plussupplement B, except agar was omitted. Growth wasperformed in the presence of 10% CO2 in air or inmedium containing 10 mM bicarbonate (28). Growthwas followed in a Klett-Summerson photometer (redfilter) or in a Zeiss spectrophotometer at a wave-length of 450 nm.

Penicillin G was purchased from AB Kabi, Stock-holm, Sweden. Nalidixic acid was from WinthropLaboratories, Newcastle upon Tyne, England. Me-cillinam was a gift from AB Lovens, Ballerup, Den-mark. [3H]adenine (22 Ci/mmol) was purchasedfrom The Radiochemical Centre, Amersham, Eng-land.

Phase-contrast microscopy. GCMB was dissolved333

on June 3, 2020 by guesthttp://jb.asm

.org/D

ownloaded from

http://jb.asm.org/

334 WESTLING-HAGGSTROM ET AL.

during shaking and heating to about 80°C. At 50°Csupplement B was added, and the melted agar solu-tion was gassed for 1 min with 10% CO2 in air. Onemilliliter was poured onto a glass slide and allowedto harden for about 5 min in a petri dish. Smallholes, arranged in a circle, were made in the agar,and 25 ul of a suspension of bacteria (about 106) inthe logarithmic growth phase was placed within thiscircle on the agar surface. The small holes werefilled with C02, and the inoculated area and thecircle of holes were immediately covered with acover slip. Agar pieces outside the cover slip werecut away, and it was sealed with vaseline. Themicroculture was kept at 37°C by use of a heatedstage (Zeiss), and the growth of individual cells wasfollowed in a Zeiss phase-contrast microscope withcamera equipment. The film negatives were pro-jected on a screen at a fixed distance, and cell di-mensions were determined by direct measurements.

Scanning electron microscopy. An 0. 1-ml amount(about 107 bacteria) of a cell suspension in the loga-rithmic growth phase was spread on GCMB plateswith or without the addition of drugs. The plateswere incubated for various times. The processing forscanning electron microscopy was performed accord-ing to Elmros et al. (7).

Transmission electron microscopy. The cells tobe studied were harvested by centrifugation (2,000x g) for 10 min at 4°C. Fixation and preparation forelectron microscopy was carried out as previouslydescribed (18).

Determination of DNA and RNA synthesis. Cells

.2

0O

90

were pregrown in GCMB containing 0.01 MNaHCO3 for several generations. Incorporation of[3H]adenine (15 ,uCi/ml) was followed. Incorporationinto ribonucleic acid (RNA) and deoxyribonucleicacid (DNA) was followed in samples (200 ul) precipi-tated in 5 ml of ice-cold 10% trichloroacetic acidwhich were allowed to precipitate at 0°C for at least30 min (trichloroacetic acid-precipitable material).Samples for DNA determination were hydrolyzedovernight in 0.5 ml of 0.5 M NaOH and afterwardsprecipitated with trichloroacetic acid as describedabove (alkali-stable material). Each sample wasthen filtered through a Whatman glass filter (25mm) and washed five times with ice-cold 5% trichlo-roacetic acid containing adenine (10 ug/ml), oncewith hoiling water, and once with acetone. The fil-ters were dried and counted in a liquid scintillationcounter (Nuclear-Chicago Mark II).

RESULTSGrowth pattern of N. gonorrhoeae type 4.

Growth of individual cells was followed duringincubation on agar slides. The cell shown inFig. 1 expands perpendicular to the divisionplane. However, growth in this dimensionceased, and the developing daughter cells initi-ate growth parallel to the existing septum. As aconsequence, consecutive division planes willbe formed at right angles to each other, givingrise to tetrads of cells. This bidimensional

60'

120'FIG. 1. Growth of "type 4 gonococcal cells." Note the perpendicular orientation oftwo consecutive division

planes. x6,550.

J. BACTERIOL.


.org/D

ownloaded from

http://jb.asm.org/

GROWTH PAITERN AND DIVISION IN N. GONORRHOEAE 335

growth pattern was observed in all gonococcal cocci was followed on agar slides (Fig. 2). Thecells examined. It was also found in other Neis- following observations were made. (i) Expan-seria species such as N. meningitidis and N. sion of individual gonococci proceeded in onlypharyngitis. one dimension throughout virtually the entireThe growth in two dimensions of six gono- cell cycle. However, expansion in two dimen-

TII I

a AAA

II

GZO.6:00-- A

GD 00o

50 100 0

9 1.A 1 1 1 AA

*---I9 I I I itLr82- - - - - - - - - - - - - - - -

0

0~~~~00b0 _

IIII1 3I

woa a a a

0

50 100Time (minutes)

FIG. 2. Bidimensional growth of six independent type 4 gonococci. The development of the respectivegonococcal cell is drawn above each diagram. The vertical (squares) and horizontal extension (circles) was

followed. The two gonococci at the bottom of the figure were initially in a late stage of septation. The verticalextension of each of the developing daughter cells was therefore followed (closed and open squares).

1.20.6

04

1.4

1.0

(16

021.2

04

.1

a

1,

1.

aa0

;. 1.4C

o 1.0

c

E0= a20

(12t1u0400

DaDL

A4

1.0

LS04

.4

.0

l.2

14

10

(12

0

I1.4

1.0

061

(2

0

a s a a . . . . . . . . . . .

I IA .I aI

9 I 9 I - I I

. a . . . ..

I

a. a 0 v r-T-T- v v I 0 9 9 I I I I IJ,w . V . F I t 0 1 - I I v v W V's v I

b

L.

4

I

0

0

lik-O--o-

if

VOL. 129, 1977

i

lsl..--O--10

I I I I a I I I

--A- a a a s A . . A a

I v I I

I a i I 1-

I v v p I v

a a j A . 2 a a


.org/D

ownloaded from

http://jb.asm.org/


sions was observed in some cells at the end ofthe division period. (ii) The rate of extension ineach dimension appeared to be linear. (iii)Growth in the second dimension (former width)was initiated slightly before the distance from

one pole to the division plane equalled the cellwidth.Presumptive growth zones in N. gonor-

rhoeae. At present there are no direct methodsfor visualization of envelope growth zones in N.

FIG. 3. Scanning electron micrographs of type 4 gonococcal cells incubated on GMCB agar for 60 min (Aand B, controls) and incubated on GCMB agar supplemented with 1 ug ofpenicillin Gper ml ofagar mediumfor 60 (C), 90 (D), 120 (E), and 240 min (F). Note the occurrence of a protruding area in the invaginationregion of the penicillin-treated gonococci (C-F). In both controls and penicillin-treated gonococci sphericalbodies of unknown nature are seen on the surface. x24,000.

J. BACTERIOL.


.org/D

ownloaded from

http://jb.asm.org/

GROWTH PAITERN AND DIVISION IN N. GONORRHOEAE

gonorrhoeae. We have chosen to study the mor-phological effect on N. gonorrhoeae of penicillinG. A series of scanning electron microscopicobservations were made on N. gonorrhoeaetype 4 cells growing on solid medium in thepresence of penicillin G (1 ,ug/ml). The effect of1 to 2 h of penicillin treatment was restricted tothe septal region, which showed a protrudingarea (Fig. 3C, D, and E). Even after 4 h ofpenicillin exposure, the polar caps appearedconserved, whereas the septal region was heav-ily distorted (Fig. 3F). Blebs of an unknownnature were observed both in the control and inthe drug-exposed cells (Fig. 3). In 33 cells bothseptum region and poles were visible. In allthese cells penicillin-induced weakeningsshowed an equatorial orientation. In the trans-mission electron microscope similar weaken-ings of the septal region were observed afterpenicillin treatment. In rare cases, cells werefound that contained two protrusions perpen-dicular to each other (Fig. 4). Bulges with clearconnection to the cell were not found outsidethe existing septum region.

Septal structures in N. gonorrhoeae type 4.N. gonorrhoeae divides by septation and not byconstriction (Fig. 5). Cell division is initiated byan ingrowth of cytoplasmic membrane enclos-ing a fold of peptidoglycan (Fig. 6A). This givesrise to partial or complete septal structures.

The septal peptidoglycan was often visualizedas two distinct layers (Fig. 6A and B). In a fewcells (3 out of 25 with complete septa; Fig. 6C),the cytoplasmic membrane together with onefold of peptidoglycan formed an ingrowth per-pendicular to the septum.

It has been suggested that residual activity ofautolysins may derange native septal struc-tures (2, 3). One argument for the presence ofboth partial and complete septa in vivo was theobservation that mecillinam added to dividinggonococci either induced one spheroplast (Fig.7A) or caused the formation of two individualspheroplasts, one lysing before the other (Fig.7B and C). In the former case a communicatingcytoplasm is likely present, whereas a completeseptum must exist in the latter cells examined.Comparative effects of nalidixic acid and

penicillin G on N. gonorrhoeae and N. elon-gata. At present no gonococcal mutants areavailable showing a unidimensional growthpattern. However, a rod-forming species ofNeisseriaceae has been isolated, N. elongata (4,5). On agar slides this species grows in onedimension only. Moreover, unlike N. gonor-rhoeae, N. elongata maintains the same ori-entation of the longitudinal axis throughoutseveral generations.

Nalidixic acid and penicillin G are drugsknown to induce filamentous growth of gram-

FIG. 4. Transmission electron micrograph ofgonococcal cells grown for2 h in liquid medium (GCMB withagar omitted) supplemented with penicillin G (1 jg/ml). Note the cell with two protrusions located perpendic-ular to each other (arrows). xl 7,400.

VOL. 129, 1977 337


.org/D

ownloaded from

http://jb.asm.org/

:'S~~~~~~~~~~~~i,,''$4/r <

.._... ".'.>gs,,A, iv

FIG. 5. Survey transmission electron micrograph of type 4 gonococcal cells. Note that most cells duringdivision exhibit only partially developed septa. x27,1 00.

'A ~~~~~~~~~~~~~~~~~~~~~~. ..._7_._.--I, ..v _

FIG. 6. Different stages in septum development. Two separate septal peptidoglycan layers may be discov-ered (arrows, A and B). Note in (C) that the cytoplasmic membrane together with the peptidoglycan layer forman ingrowth perpendicular to the complete septum. (A and C) x79,000; (B) x118,000.

338

10.-..A.aI-1,."-MM


.org/D

ownloaded from

http://jb.asm.org/

GROWTH PA1YrERN AND DIVISION IN N. GONORRHOEAE

.., .t Ab. s

A as :LI * :t W

.,

B *

C ..f

:J,- s.s.t>r.M d M *!AE#, 'Yr C aiiiilW!li r .

t S 2F>liltel aj irstMA#go .s is, * !-_ 6 X . W L P_E .,. _L_l {R;1 _ , fS Zf

. >.i. _w.i , | i;.t > s | t.. , w M . !s I w . . B; . s' ,%t . v | I s

t.U .> *,>;.SF*'

e t_ t.'. _l

_F..;

.'t'' '_ il X,#

* - " - .;!rst

o ol*t, *it

FIG. 7. Mecillinam-induced changes of three dividing type 4 gonococcal cells grown on GCMB supple-mented with mecillinam (1 pg/ml). Photographs in each series were taken at intervals within a time span of2h. Note the induction of either one (A) or two (B and C) spheroplasts. x6,900.

negative rods (9, 25). When N. elongata wastreated with nalidixic acid (5 ,g/ml), DNA syn-thesis was inhibited, whereas RNA synthesiscontinued (Fig. 8). Due to agglutination, themass increase was difficult to follow. However,on agar slides, short, nonseptated filamentscould be visualized after nalidixic acid treat-ment. In contrast, in N. gonorrhoeae, nalidixicacid (5 ,g/ml) caused an almost instantaneousinhibition of mass increase and ofRNA as wellas DNA synthesis (Fig. 9). The drug also in-hibited completion of cell separation. Likewise,penicillin G (1 ,g/ml) induced filaments of N.elongata and round, large cells of N. gonor-rhoeae.

DISCUSSIONThe shape and dimension of a bacterium re-

flect the processes by which the cell envelope orshape determining structures grow. In rod-shaped bacteria evidence has been provided forboth a dispersed and a localized synthesis of cellenvelope (6, 11, 13, 16, 22-24, 26). In E. coli, atleast certain envelope components, notably thepeptidoglycan layer, seem to be layed down inannular zones (22, 26). In the gram-positivecoccus Streptococcus faecalis, it seems convinc-ing that peripheral wall extension proceedsfrom specific growth zones. After cessation inlength extension from a particular growth site

it continues to develop a septum. The growthzone is thereafter inactivated, and new zonesare formed de novo at the junction of old andnew walls (10, 27). In N. gonorrhoeae, penicil-lin-induced bulges of the envelope are re-stricted to the septal region. This may indicatethat this region represents the region of activegrowth.

It has been suggested that bacteria showing aunidimensional growth pattern extend lin-early, with doublings in rate in relation to theformation of new growth zones (14, 29). How-ever, experimentally it has been very difficultto distinguish this growth pattern from that ofa cell extending exponentially from a largenumber of sites. In N. gonorrhoeae exhibiting abidimensional growth pattern, growth in eachdimension apparently proceeds linearly. Thisagain suggests a localized formation of shape-determining structures.N. gonorrhoeae, like most gram-negative

bacteria, divide by septation. The constrictionsobserved may, as pointed out by Burdett andMurray (2, 3), be artifacts due to partial autoly-sis during the preparation procedure. Completesepta were visualized rather infrequently. Theyconsisted of two, often separate layers of pepti-doglycan and were delimited by the cytoplas-mic membrane of each incipient daughter cell.At times cytoplasmic ingrowths perpendicular

339VOL. 129, 1977


.org/D

ownloaded from

http://jb.asm.org/


of mass increase is lower than the rate of enve-105 . . lope growth. However, the rate of mass in-

crease augments and the hydrostatic pressureis increased within the cell. This increase in

* internal pressure is relieved by the formation ofa new growth zone. The pressure rapidly fallsand excess envelope material goes into the sep-

* / tum. The oscillation in the volume-to-mass ra-

a04., ^ tio is finely regulated by changes in width. In| £o N. gonorrhoeae, septation is initiated before

the pole-division plane distance has reached theAw&same value as the cell width. A new longitudi-

nal axis is thereby generated in the incipientdaughter cells. It is suggested that the changein growth direction observed in N. gonorrhoeae

i1ii II I I 0 °'f L 1.0

~~~~~10'~~~~~~~~~~~0I 0~~~~~~~

-20 0 20 U0 60 so0Time (min) E-..104

FIG. 8. Effect of nalidixic acid (NAL) on the in- ,. /corporation of [3H]adenine into trichloroacetic acid- /precipitable (DNA and RNA) and alkali-stable 0

(mostly DNA) material in N. elongata. [3H]adenine Z

(15 uCi/ml) was added to growing cells of N. elon- -ogata at -20 min. At zero time the culture was dividedinto two parts; NAL acid (5 pg/ml) was added to one ,4part and the other served as a control. Due to cellaggregation growth measured as absorbance at 450nm was not possible to follow. Each value given wasthe mean offour different samples. Symbols: A, con-trol, trichloroacetic acid-precipitable material; A,+NAL, trichloroacetic acid-precipitable material; *,control, alkali-stable material; 0, +NAL, alkali-sta-ble material. ._._ ._ . _ _

to the septum were observed, suggesting that -20 0 20 40 60 80new divisions may be initiated before the outer Time (min)membrane has completed the previous one. FIG. 9. Effect of nalidixic acid (NAL) on the in-Similar structures have been observed in a corporation of[3H]adenine into trichloroacetic acid-sphere-like mutant of E. coli containing the precipitable (DNA and RNA) and alkali-stableenvB mutation (1). (mostly DNA) material in N. gonorrhoeae (type 4).

Pritchard (20) has presented a simple model The experimental conditions were as in Fig. 8. Sym-Poritcllshardp(2)has pesent a simple mdelf bols: 0, control, optical density; 0, +NAL, opticalforellhapanddiviionwhic invlve a slf- density; A, control, trichloroacetic acid-precipitable

regulating system in which a linearly extend- material; A, +NAL, trichloroacetic acid-precipitableing surface area encloses an exponentially ex- material; *, control, alkali-stable material; 0,panding cell mass. In the newborn cell the rate +NAL, alkali-stable material.

J. BACTERIOL.


.org/D

ownloaded from

http://jb.asm.org/

GROWTH PATTERN AND DIVISION IN N. GONORRHOEAE

reflects a way to avoid a rod-sphere-rod transi-tion, which would occur if growth was unidi-mensional. Such a transition should causelarge oscillations in the volume-to-mass ratioand perhaps too large variations in the internalhydrostatic pressure. If as suggested by Prit-chard (20) resistance to extend in length islower than resistance to expand in width, thenbidimensional growth should exist in short rodswhere longitudinal axes of parent and incipientdaughter cells are perpendicular to each other.

Penicillin G and nalidixic acid are known toinduce filaments of rod-shaped bacteria (9, 25).This was also true for the rod-shaped N. elon-gata. In contrast, filaments of N. gonorrhoeaecould not be induced with either of theseagents. Penicillin induced large spheres,whereas nalidixic acid rapidly inhibited gono-coccal growth together with RNA and DNAsynthesis. The latter drug, at the same concen-tration, induced short filaments and selectivelyinhibited DNA synthesis in N. elongata. Nali-dixic acid has been suggested to affect cell divi-sion by inhibiting formation of new growthzones (30). In E. coli this leads to a constantrate of envelope extension and filamentation. Itseems likely that in N. gonorrhoeae growth inthe presence of nalidixic acid is inhibited whenthe pole-division plane distance has reachedthe same value as the cell width; i.e., a sphere-rod transition is not possible. The loss of alongitudinal axis may be a relevant factor forthis inhibition (1).

ACKNOWLEDGMENTSWe wish to express our gratitude to Gunnar D. Bloom for

preparing the transmission electron micrographs and toLena Norlander and Hans Wolf-Watz for stimulating dis-cussions. We also thank Marianne Borg, Per Horstedt, andGunnar Sandstrom for skillful technical assistance.

This work was supported by grants from the SwedishNatural Science Research Council (Dnr B3373-003), theSwedish Medical Research Council (Dnr 4769), and E. We-lander's Foundation.

LITERATURE CITED

1. Bloom, G. D., J. Gumpert, S. Normark, E.Schuhmann, U. Taubeneck, and B. Westling. 1974.Morphology and growth pattern of a rod-negativeenvB mutant ofEscherichia coli K12. Z. Allg. Mikro-biol. 14:465-477.

2. Burdett, I. D. J., and R. G. E. Murray. 1974. Electronmicroscope study of septum formation in Escherichiacoli strains B and B/r during synchronous growth. J.Bacteriol. 119:1039-1056.

3. Burdett, I. D. J., and R. G. E. Murray. 1974. Septumformation in Escherichia coli: characterization of sep-tal structure and the effect of antibiotics on cell divi-sion. J. Bacteriol. 119:303-324.

4. Bovre, K., J. E. Fuglesang, and S. D. Henriksen. 1972.Neisseria elongata presentation of new isolates. ActaPathol. Microbiol. Scand. Sect. B. 80:919-922.

5. Bovre, K., and E. Holten. 1970. Neisseria elongatasp.nov., a rod-shaped member of the genus Neisseria.

Re-evaluation of cell shape as a criterion in classifica-tion. J. Gen. Microbiol. 60:67-75.

6. Donachie, W. D., and K. J. Begg. 1970. Growth of thebacterial cell. Nature (London) 227:1220-1224.

7. Elmros, T., P. Horstedt, and B. Winblad. 1975. Scan-ning electron microscopic study of virulent and aviru-lent colonies of Neisseria gonorrhoeae. Infect. Im-mun. 12:630-637.

8. Fitz-James, P. 1964. Thin sections of dividing Neisseriagonorrhoeae. J. Bacteriol. 87:1477-1482.

9. Goss, W. A., W. H. Deitz, and T. M. Cook. 1964. Mecha-nism of action of nalidixic acid on Escherichia coli. J.Bacteriol. 88:1112-1118.

10. Higgins, M. L., and G. D. Shockman. 1970. Model forcell wall growth of Streptococcus faecalis. J. Bacte-riol. 101:643-648.

11. Hoffman, B., W. Messer, and U. Schwarz. 1972. Regu-lation of polar cap formation in the life cycle ofEsche-richia coli. J. Supramol. Struct. 1:29-37.

12. James, R., J. Y. Haga, and A. B. Pardee. 1975. Inhibi-tion of an early event in the cell division cycle ofEscherichia coli by FL1060 an amidinopenicillanicacid. J. Bacteriol. 122:1283-1292.

13. Kepes, A., and F. Autissier. 1972. Topology of mem-brane growth in bacteria. Biochim. Biophys. Acta265:443-469.

14. Kubitschek, H. E. 1970. Evidence for the generality oflinear cell growth. J. Theor. Biol. 28:15-29.

15. Matsuzawa, H., K. Hayakawa, T. Sato, and K. Ima-hori. 1973. Characterization and genetic analysis of amutant of Escherichia coli K-12 with rounded mor-phology. J. Bacteriol. 115:436-442.

16. Mauck, J., L. Chan, and L. Glaser. 1972. Model of cellwall growth of Bacillus megaterium. J. Bacteriol.109:373-378.

17. Normark, S. 1969. Mutation in Escherichia coli K-12mediating spherelike envelopes and changed toler-ance to ultraviolet irradiation and some antibiotics.J. Bacteriol. 98:1274-1277.

18. Normark, S., H. G. Boman, and G. D. Bloom. 1971.Cell division in a chain forming envA mdtant ofEsch-erichia coli K-12. Fine structure of division sites andeffects of EDTA, lysozyme and ampicillin. Acta Pa-thol. Microbiol. Scand. Sect. B 79:651-664.

19. Park, J. T., and L. Burman. 1973. FL-1060: a newpenicillin with a unique mode of action. Biochem.Biophys. Res. Commun. 51:863-868.

20. Pritchard, R. H. 1974. On the growth and form of abacterial cell. Philos. Trans. R. Soc. London 267:303-336.

21. Reyn, A., A. Birch-Anderssen, and U. Berger. 1970.Fine structure and taxonomic position of NeisseriaHaemolysans (Thjotta and Boe 1938) or Gemella Hae-molysans (Berger 1960). Acta Pathol. Microbiol.Scand. Sect. B 78:375-389.

22. Ryter, A., Y. Hirota, and U. Schwarz. 1973. Process ofcellular division in Escherichia coli. Growth patternof E. coli murein. J. Mol. Biol. 78:185-195.

23. Ryter, A., H. Shuman, and M. Schwartz. 1975. Integra-tion of the receptor for bacteriophage lambda in theouter membrane of Escherichia coli: coupling withcell division. J. Bacteriol. 122:295-301.

24. Sargent, M. G. 1975. Control of cell length in Bacillussubtilis. J. Bacteriol. 123:7-19.

25. Schwarz, U., A. Asmus, and H. Frank. 1969. Autolyticenzymes and cell division of Escherichia coli. J. Mol.Biol. 41:419-429.

26. Schwarz, U., A. Ryter, A. Rambach, R. Hellio, and Y.Hirota. 1975. Process of cellular division in Esche-richia coli: differentiation of growth zones in the sac-culus. J. Mol. Biol. 98:749-759.

27. Shockman, G. D., L. Daneo-Moore, and M. L. Higgins.1974. Problems of cell wall and membrane growth,

341VOL. 129, 1977


.org/D

ownloaded from

http://jb.asm.org/


enlargement, and division. Ann. N. Y. Acad. Sci.235:161-197.

28. Talley, R. S., and C. L. Baugh. 1975. Effects of bicar-bonate on growth of Neisseria gonorrhoeae: replace-ment of gaseous CO2 atmosphere. Appl. Microbiol.29:469-471.

29. Ward, C. B., and D. A. Glaser. 1971. Correlation be-

tween rate of cell growth and rate of DNA synthesisin Escherichia coli B/r. Proc. Natl. Acad. Sci. U.S.A.68:1061-1064.

30. Zaritsky, A., and R. H. Pritchard. 1973. Changes in cellsize and shape associated with changes in the replica-tion time of the chromosome of Escherichia coli. J.Bacteriol. 114:824-837.

J. BACTERIOL.


.org/D

ownloaded from

http://jb.asm.org/

growth pattern cell division in neisseriadepartments ofmicrobiology,* bacteriology, andpathology,...

Documents