Biology Reference
In-Depth Information
The sudden disappearance of this bloom was attributed to the presence of virus-like particles akin
to cyanosiphoviruses. Electron microscopy revealed the existence of these particles inside the cells
of
L
.
majuscula
and caused a decrease in photosynthetic effi ciency and electron transport (Hewson
et al.,
2001). A cyanomyovirus S-KM1 infecting
Synechococcus
sp. (PE-rich strain KFM001) with a
capsid diameter of 83 nm and a contractile tail of 166 nm long has been isolated from Kagoshima
Bay by Okunishi
et al
. (2002). Phage titers of S-KM1, at the Kagoshima Bay, have been found to be
almost undetectable but a corresponding increase in its titer (7.5 x 10
3
ml
-1
) occurred about one
week after the onset of the bloom of the PE-rich strain of
Synechococcus
. They provided estimates
of host population lysed per day from 0.0055% to 2.1% suggesting that the lytic phages control the
populations of their respective hosts.
Cyanophages infecting
Prochlorococcus
and
Synechococcus
(44 of them) have been characterized
with reference to morphology and host-range (20 different host strains belonging to both of the
genera; Tables 6 and 7). Of these, 31 cyanophages have been isolated from Red Sea, Gulf Stream and
BATS by Sullivan
et al
. (2003) and these workers included in their study two cyanophages reported
earlier by Wilson
et al
. (1993) from English Channel and Woods Hole and 11 cyanophages isolated
by Waterbury and Valois (1993) from different locations such as Sargasso Sea, Woods Hole, Gulf
Stream and English Channel. This report constitutes the fi rst comprehensive account of the marine
Table 7:
Marine cyanophages isolated on
Prochlorococcus.
Location
Family
Cyanophage(s)
Head Dia. (nm)
Tail L x W (nm)
Authors
BATS
P
P-SSP1
45
-
Sullivan
et al
. (2003)
BATS
P
P-SSP2
55
-
Sullivan
et al
. (2003)
BATS
P
P-SSP3
P-SSP4
P-SSP7
P-SSP8
50
-
Sullivan
et al
. (2003)
BATS
P
P-SSP5
P-SSP6
55
6 x 10
Sullivan
et al
. (2003)
Gulf Stream
P
P-GSP1
Syn12
45
45
-
8 x 10
Sullivan
et al
. (2003)
Red Sea
P
P
P-RSP1
P-RSP2
P-RSP3
55
40
50
6 x 10
-
-
Sullivan
et al
. (2003)
Sargasso Sea
P
Syn-5
-
-
Waterbury and Valois (1993)
Slope
S
P-SS1
P-SS2
P-SP1
45 x 90
50 x 100
60
280 x 15
260 x 12
8 x 12
Sullivan
et al
. (2003)
P
BATS
M
P-SSM1
P-SSM2
P-SSM3
P-SSM4
P-SSM5
P-SSM6
60
85
95
80
60
90
160 x 20
110 x 25
105 x 25
160 x 20
20 x 80
150 x 28
Sullivan
et al
. (2003)
Red Sea
M
P-RSM1
P-RSM2
P-RSM3
80
75
80
110 x 27
170 x 23
175 x 23
Sullivan
et al
. (2003)
Shelf
M
P-ShM1
P-ShM2
75
-
120 x 18
-
Sullivan
et al
. (2003)
Note: M = Myoviridae; P = Podoviridae; S = Siphoviridae
