ANH HUdNG CUA NITROGEN - AMMONIUM LEN SV SINH TRU^dNG CUA VI TAG
CHAETOCEROS SUBTILIS VAR. ABNORMIS PROSCHKINA-LAVRENKO DUQfC PHAN LAP 6 CAN Gid, TP H 6 CHi MINH
VQ H Q N G T R U N G \ L^ THI TRUNG"
T 6 M TAT
f y * '
Nitrogen Id chdt dinh dudng quan trgng gdp phdn vdo su sdn xudt sinh khdi ciia vi lao vd nitrogen - ammonium dugc xem la ngudn nitrogen ua thich ddi vdi cdc vi sinh vdt.
Su sinh trudng vd ddp ieng sinh li cua le bdo Chaetoceros subtilis var. abnormis Proschkina-La\renko dugc nudi cay tren mdi trudng ESAW cd bd sung nitrogen - ammonium vdi cdc ndng dg khdc nhau dugc nghien cieu. Ket qud cho thdy, a mdi trudng ESA W cd bd sung nitrogen - ammonium vdi ndng dg 75pmol/L te bdo vi tdo dgt dugc su sinh trudng vd sinh li tdt nhdt.
Tu khda: Nitrogen, Chaetoceros, mdi trudmg ESAW ABSTRACT
Effect of ammonium nitrogen on the growth of microalgae Chaetoceros subtilis var.
abnormis Proschkina-Lavrenko/rom Can Gio, Ho Chi Minh Ciii isolated
Nitrogen is the important nutrient contributing to producing biomass of microalgae and ammonia nitrogen often regarded as favorite nitrogen-source for microorganisms.
Growth and physiological responses of Chaetoceros subtilis var abnormis Proschkina- Lavrenko cultured in the ESAW medium supplemented with the different ammonium nitrogen concentrations are studied. Results show that, in the ESAW medium supplemented with ammonium nitrogen at the concentration of75pmole/L,the growth and physiology of cells are the best.
Keywords: Nitrogen, Chaetoceros, The ESAW medium.
I. Mddau
Sau carbon, nitrogen (N) Id chat dinh dudmg quan trgng nhat gdp phan vdo sy sdn xudt sinh khoi eiia vi tdo. Nitrogen duge cung cap ehu ylu nhu nitrate (NO3"), nhung thudng ammonium (NH,*) vd ure eung dugc sir dyng. Mgt so hgp chdt nitrogen htm eo (hypoxanthine, lysine, guanine...) cung duge sir dyng bdi tdo
HVCH, Trudng Ogi hpc Khoa hpc Ty nhi6n, OHQG TPHCM
" T S , Trudng Ogi hpc Su pham TPHCM
(Richmond, 2004).
Nitrogen - ammonium (N - Ml/) thudmg Id nguon nitrogen ua thich ddi vdi vi sinh v?it vd su dong hda NO3 hodc NHj* deu lien quan den pH ciia mdi trudmg. Khi NH,"" dugc sir dung nhu la nguon nitrogen duy nhdt, pH cd thi gidm ddng ke trong giai doan tdng hirdng manh, do su gidi phdng cdc ion H*
Nguge lai, pH tdng khi NOa" dugc cung cdp nhu nguon nitrogen duy nhat (Richmond, 2004).
Tap chl KHOA HQC DHSP TPHCM Vd Hdng Trung vd tgk
Nitrogen la thdnh phan cua acid amin, nucleotide, hormone, coenzyme,...
Thilu nitrogen, sudn carbon khdng dugc dimg cho sy tdng hgp cdc hgp chdt nitrogen (ty If C/N cao) (Biii Trang Vift, 2000).
Budc ddu lien trong sy ddng hda ammonium ngoai bdo la sy van chuyin nhd cdc chdt van chuyen nam tren mang le bao, lyc lap vd ti the. Ammonium dugc cung cdp tir mdi trudmg hay ndi bdo (tir qua trinh quang hd hap, sy ddi mdi protein vd sy biln dudmg acid nucleic) duge ket hgp vdo sudn carbon qua chu trinh GS/GOGAT de tao ra L-glutamate (Stem, 2008).
O thye vdt phii du nude man, sy dap img dien hinh nhdt ddi vdi su giai han nitrogen la sy thay ddi mdu sdc eua te bdo (gidm lugng difp lyc td vd tdng lugng earotenoid), tich liiy ede hgp chdt carbon hihi ea nhu polysaccharide vd mgt sd loai ddu (PUFAs). Dong thdi N eiing anh hudmg len quang hgp vi gidm hifu qud thu nhdn ndng lugng do mat difp luc td a. N ciing dnh hudmg true tiep den sy bien ddi ndng lugng quang hda vi su gidm sinh tdng hgp protein. Dieu ndy ed the anh hudmg len ede protein eua lye lap (nhu ede protein eiia trung tdm phdn iing
^ PSI vd PSII) hom Id cdc protein tl bdo chdt (Berges e/a/., 1996).
Dinh dudmg nitrogen ddng vai trd ' quyet dinh trong vife xdc dinh hifu sudt
• quang hgp. Cdc thdnh phdn eiia hf thdng ' thu nhdn dnh sdng va chudi van chuyin
difn hi thudmg eho thdy sy dap ting i tuang ling vdi dinh dudmg nitrogen. Tuy
nhien, d hdu hit ede nghien curu da eho
d enzyme Rubisco de dap iing vdi sy bd sung nitrogen. Cac lhanh phdn ehiia nitrogen cd nhifm vy quang hgp la: phiic hgp Chl-protein thu nhan dnh sang, phiie hgp mdng van chuyen difn tir va phosphoryl hda, ede enzyme cua con dudmg RPP (Reductive Pentose Phosphate) vd sinh tdng hgp carbohydrate, enzyme Rubisco (Foyer and Noctor, 2002).
2. Vat lifu - phuomg phdp 2.L Vgtli^u
Mdu nude bien duge thu d viing ven bd biln Can Gid. Sy phdn lap vi tdo Chaetoceros subtilis var. abnormis Proschkina-Lavrenko dugc thuc hifn thea Andersen va Kawachi (2005), Guillard (2005) va luu giiitai Phdng thi nghifm Sinh li Thye vdt Trudmg Dai hgc Su pham TP Hd Chi Minh.
2.2. Phuang phdp
2.2.1. Chudn bi mdi trudng
Cdc thi nghifm duge thye hifn tren mdi trudmg ESAW (Harrison et al, 1980, Berges et al., 2001). Cdc dung dich gde vd vitamin duge giii d 4 °C trong tdi. Mdi trudmg dugc dieu ehinh pH = 8,2 ± 0,2 vd sir dyng trong vdng 24 gid sau khi pha.
2.2.2. Dieu kien nudi cdy
Mdu dugc nudi theo phuomg phdp nudi cdy md bdn lien tyc (Wood et al, 2005). Binh tam gidc 250ml duge sii dyng vdi 125ml mdi trudmg. Dilu kifn nudi cdy ldng ldc vdi cudng do 60vdng/phut. Cudmg do anh sdng 60
±5pmol/m^/s, ehu ki sdng: tdi 12:12, nhift do 26 ± 2 °C.
Chaetoceros subtilis var. abnormis Proschkina-Lavrenko dugc nudi thich
hoan loan nitrogen lir 2 - 3 ngay Irudc khi lien hanh eae thi nghifm.
2.2.3. Quan sdt hinh thdi le bdo
Chaetoceros subtilis var. abnormis Proschkina-Lavrenko dugc quan sal mdi ngay dudi kinh hien vi quang hgc.
2.2.4. Mat dg le bdo vd dieang cong tdni^
truang
Vi lao Chaetoceros subtilis var.
abnormis dugc nudi tren mdi Irudng ESAW ddi chirng (lo^i bd hoan loan nitrogen) vd mdi Irudng ESAW cd bd sung N - N H / (NH4CI) d eac nong dg 75pmol/l.. 250pmol/L, 500pmol/L, 750pmol/L va lOOOpmol/L.
Mat dg te bdo dugc xdc djnh thdng qua vifc dem sd lugng le bdo. Mau duge Idy vd cd djnh bang lugol moi ngdy vdi 3ml vd bd sung vdi lugng mdi trudng ESAW tuomg duong da ldy. Sd lugng ll bdo dugc dem bdng budng dim hdng cdu cd do sdu 0,1mm vd difn lieh d vudng
Imm" Mat do t l bdo dugc tinh todn theo cdng thue Guillard vd Sieraeki (2005).
Dudng cong tdng trudmg dugc xdc dinh thdng qua mat do t l bdo dim hdng ngay.
2.2.5. Cudmg do quang hgp vd cudmg do hd hdp
Cudng dg quang hgp vd hd hdp ciia vi tdo Chaetoceros subtilis var. abnormis Proschkina-Lavrenko duge do bdng may Hansateeh tir ngdy thir 3 den ngdy thir 6.
Mau duge lay tir ngdy thir 3 din ngdy thir 6 vdi 3ml moi ngdy va sir dyng 1,5ml cho mdi Idn do.
3. Ket qua - thao luan 3.1. Kit qud
3.1.1. Hinh thdi ti bdo
Moi trudmg ESAW doi chirng Chudi te bao ddi khoang 3 - 8 16 bao/chudi (tb/ehudi) tir ngdy thii 2 din ngay thir 5. The sdc id nhal trong sudt qud trinh khao sdt, sy hinh thanh bdo tir nghi bdl ddu tir ngdy thir 2 (dnh 3.1).
i
rv23*
.m Mm
^ 40 nni
•" 1 ^ ' 30 ^m
{
N5 3^ji«;
Anh 3.1. Sic thay ddi hinh dgng te bdo Chaetoceros subtilis \ar. abnormis tie ngdy fX) thic 2 den ngdy thie 5 tren mdi Irudng ESA W ddi chirng
Moi tru-oTig ESAW bo sung 75jimol/L N - N H /
Chuoi te bdo ddi khodng 3 - 8tb/ehudi tir nga\ thii 3 den ngdy thii 6.
The sdc td nhat \ a chiem khodng 1/2 the lich te bdo tir ngdy thii 3 den ngdy thiir 4, the sdc Id dam ddc vd chiem todn bd the lich le bao tir ngd> thiir 5 din ngdy thu 6 (anh 3.2).
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N6^ 30jini
Anh 3.2. Su thay ddi hinh dgng ti bai) Chaetoceros subtilis var. abnormis tic ngay thu 3 din ngdy thii 6 tren mdi trudng ESA^
bd sung 75pmol/L N-NHf
Tap chl KHOA HQC DHSP TPHCM Vd Hdng Trung vd tgk
Moi tru'omg ESAW bd sung 250pmol/L N - N H /
Chudi te bao dai khoang 3 - 8tb/chudi lir ngay thir 3 den ngd)' thir 6.
The sac td nhal \ a chiem 1/2 the tich te bao tir ngay thir 3 den ngd}' thir 6 (anh 3.3).
,€••'w'*" ^jfz. jfo - ^ ^ ^ e t o « ^ 4 : :
f^3 35 ^m N4 30 mn
•-m ^ . f t .
NS" 40 mn ' N6e * 30 urn
Anh 3.3. Su thay ddi hmh dgng le bdo Chaetoceros subtilis var abnormis lir ngdy ihic 3 din ngdy thu 6 tren mdi trirdng ESA W bd sung 250pmolL N - NH4
Moi tru-dmg ESAW bd sung 500
^mol/L N - N H /
Chuoi t l bao ddi khoang 3 - 8lb/chuoi tir ngdy thir 3 din ngdy thir 4, tir ngdy thir 5 din ngdy thir 6 chudi t l bao ngdn vd rdi rac vd bdt ddu cd su hinh thanh bdo tir tir ngdy thir 3. The sdc td nhat vd chilm 1/2 thi tich t l bdo tir ngd}
thir 3 din ngdy thir 4 (dnh 3.4).
. ^
-fl N: 20 iim N4
N5 25 Jim -Ne - - . ^ I g g t
Anh 3.4. Hinh dgng ti bdo Chaetoceros subtilis var. abnormis Proschkina- Lavrenko tren mdi trudng ESA W bd sung
Mdi trudmg ESAW bd sung 750pmol/L va lOOOpmol/L N - N H /
0 hai mdi trudng ESAW cd bd sung 750^mol/L va lOOOpmol/L N - NH4^ su hinh thanh bao lir lir ngay thir 2, mat do le bao gan nhu bang 0 tir ngay thir 4 va ehi cdn lai la cac bao tir hinh cau cd kich Ihudc ldn (anh 3.5, 3.6).
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N2 40 ^m
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N3
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30 fim
^
N4 OTjun N5 07 Jim
Anh 3.5. Su Ihay ddi hinh dgng le hao Chaetoceros subtilis var. abnormis tir ngdy thir 2 din ngdy thir 5 tren mdi Inrdng ESA W bd sung 750pmol/L N - NHj
^ ' ^ ^ ^ l . ' . ^ ^ ^ X
>t.
OTjm >aN5
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07 ^m
Anh 3.6. Sic thay ddi hinh dgng ti bdo Chaetoceros subtilis var. abnormis lie ngdy Ihic 2 din ngdy thie 5 Iren mdi Inedng ESAW bd sung lOOOpmol/L N-NHf
3.1.2. Diedng cong tdng tnrdng
Dudng cong tang trudmg cua Chaetoceros subtilis var. abnormis Prosehkina - Lavrenko tren mdi trudng ESAW bd sung 75pmol/L N - N H / ed dang hinh chu S diln hinh, trong khi dd,
bd sung 250pmol/L, 500pmo!/L, 750pmol/L va lOOOpmol/L N - NHj^ ed dang dudmg ihdng. 6 hai mdi Irudng ESAW cd bd sung 750pmol/L vd
lOOOpmol/L N - N H / tl bdo gan nhu suy hoan loan lir ngay ihir 5 (hinh 3.1).
Tren mdi trudmg ESAW cd bd sung 75pmol/L N - N H / cd pha thich nghi la 1 ngay lir ngay thir 0 den ngdy thir 1 vd pha tdng irudng kdo dai 4 ngdy lir ngdy
thir 1 den ngdy thir 5, sau dd vdo pha suy vong d ede ngdy tiep sau (hinh 3.1).
M$t dg tl bdo tren ede mdi trudng ESAW doi chimg vd cd bd sung 250pmol/L, 500pmol/L, 750pmol/L va
lOOOpmol/L N - N H / khdng ed sy khdc bift, nguge lai, tren mdi trudmg ESAW ed bd sung 75pmol/L N - NH4* dat mat
f y
dq le bdo cao vd born nhieu so vdi cac mdi trudng ESAW cdn lai (hinh 3.1).
• 1 2 :
- 1
11
Nn N; N^ M-l N> NV«
E)>'1 cluiiii:
5' "1 iimol L
Thdi gian (ngiy)
- • - " 5 fiuK'l L
— "5i'}iuiol L
—*—25i'nnK'l L - • - 1 0 " < t M'uol L
Hinh 3.1. Dudng cong tdng trudng cua Chaetoceros subtilis var. abnormis Proschkina- Lavrenko tren mdi trudng ESA W bd sung N - NHf a cdc ndng dg khdc nhau
3.1.3. Cuang dg quang hgp
Cudmg dg quang hgp ciia te bdo Chaetoceros subtilis var. abnormis Prosehkina - Lavrenko tren mdi trudng
f y
ESAW ddi chimg vd cd bd sung 250pmol/L N - NH4'' tdng nh? tir ngdy thir 3 den ngdy thii 5 vd tir ngdy thiir 3 den ngdy thir 4 ddi vdi mdi trudng ESAW cd bd sung 500pmol/L N - NH4*, sau dd gidm ddn d ngdy tilp sau (hinh 3.2).
Tren hai mdi trudmg ESAW cd bd sung 750pmol/L vd lOOOpmol/L N - NRj* cudng dg quang hgp rat thdp tir ngdy thiir 3 din ngdy thii 4 vd gdn nhu bdng 0 d ngdy thii 5 vd thur 6 (hinh 3.2).
Trong khi do, tren mdi trudng ESAW cd bd sung 75pmol/L N - NH4' cudmg dg quang hgp tdng manh tir ngdy thur 3 vd d^t cudmg dg cyc d^i o ngdy thii 5, sau do gidm 6 ngdy tilp sau, (hinh 3.2).
Tap chi KHOA HQC DHSP TPHCM Vd Hdng Trung vd tgk
^ 5 0 0015
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0
~^ Doi cluhijj
»?l)0 fimol L
NM N5
1 h i / i j;i:in ( n j ; i i y )
- ''f uinol l
~ 750 fmiol I.
NY.
)IM)() u n i o l L
Hinh 3.2. Cudng do quang hop cua Chaetoceros suhiilis \ar. ahnormi.s Proschkina- La\ renko tren moi trudng ESA W hd .sung N - A7/v (/ cdc nong do khdc nhau
3.1.4. Cirdyig do ho hdp
Cudng do ho hap ciia te bao Chaetoceros subtilis \ar. abnormis Prosehkina - Lavrenko 6 nga>' thir 3 tren cac mdi trudng ESAW doi chimg va co bd sung N - NHj^ vdi cac ndng do khac nhau d mirc thap va khdng cd su khac biet. Cudng do hd hap ciia te bao tren hai mdi Irudng ESAW cd bd sung 750pmol/L va 1000[imoLT. N - NH4^ d mure thap tir ngay thir 3 den ngay thir 4 va
gan nhu bang 0 d ngay thir 5 va thir 6 (hinh 3.3).
Tren mdi Irudng ESAW cd bd sung 75)imol/L N - NH4'' cudng do ho hdp tang manh vd dn dinh tir ngay Ihii 4 den ngay thir 6. Trong khi dd, tren hai mdi trudng ESAW co bo sung 250pmol/L va 500|imoI/L N - NH4 cudng do hd hdp CLia te bao tang manh d ngay thir 4 va giam nhe d cac ngay tiep sau (hinh 3.3).
"'•= -I '2 ^
5 "c
^ Doi chirng
» 500 MHiol/l.
\ 4 N5 Thoi gian (ngay)
rl; 75 ^inioll.
= 750 \imo\il.
N6
III 250 nmol/1.
S5l000jimol'L
3.2. Thdo lugn
Hinh thai le bao Chaetoceros subtilis \ar. abnormis Proschkina-
l.a\renko Iren eae mdi Irudng ESAW cd bd sung SOOpmol/1,. 750pmol/L va
lOOOpmol/L N - NII4* ed sy hinh thanh bao tir lir rat sdm \ a mat do te bao giam theo lhdi gian thi nghiem (anh 3.4, 3.5, 3.6; hinh 3.1). dac biet vdi mdi Irudng ESAW cd hd sung 750pmol/L va
lOOOpmol/L N - NII4' thi so lugng tl bao gan nhu da su\ Ihoai hoan loan tir ngay thir 4 (anh 3.5. 3.6). Theo Biii Trang viet (2000). NII4' ddi khang vdi K^ Ca'^
hay Mg" Do dd, sir dung NH4'' qua lieu se gdy thilu K" Ca'"*" hay Mg^* NH4"' edn trd NO3 nhung giup cac ion phosphor vdo te bdo. Sy thira NH4" thudng rat dgc so vdi NO3, \i gay nhieu xdo iron lrong tinh thdm ciia le bao.
Theo Becker (1994). sy ddng hda nitrate vd ammonia cd lien quan chat che vdi pH ciia mdi trudmg, sy hap thu nitrogen lam thay ddi pH. Khi ammonia duge sir dung nhu mdt ngudn nitrogen duy nhdt, pH eiia mdi Irudng cd the giam nhanh den miic thdp pH = 3 do su giai phdng H"*" ra mdi Irudng, gay ra nhumg tdc dyng phu cd hai cho le bdo. Mgt sd tdo nhay cam voi ndng dg ammonium cao vd sy sinh irudng cua ehiing bi Ore chl d ndng do ammonium khoang ImM. Sy thay ddi pH ndy ed the Id nguyen nhdn lie ehe su sinh trudmg dugc quan sdt d mgt sd tdo gay ra do ndng do ammonium cao trong mdi trudmg nhu sy ldng pH ndi bdo do sy thdm nhdp eua ede phdn tir NH3. CJ ndng do ammonium eao, NH3 khuleh tdn mdt each ty do qua pha lipid cua mdng (Caneja and Brezo, 2007). Vi thi, vdi mdi trudng ESAW bd sung N - NH4* vdi
nong dg cao (500pmol/L, 750pmol/L va lOOOpmol/L) da gay ddc eho tl bdo dan den sy hinh lhanh bao lir tir ngdy thir 2 va mat do te bao giam ddn trong qud trinh khao sal (anh 3.4, 3.5, 3.6; hinh 3.1).
Sy ha thap pH kich thich sy hdp thu va dong hda nitrate, lrong khi sy tdng pH kich thich su hdp tbu vd ddng hda ammonium. I uy nhien, khi pH ben ngoai cao, ammonia (base yeu) khuech tdn nhanh vao le bao chdt (acid hom). Do do, ammonia, thill ylu d pH trung tinh, trd lhanh dgc trong mdi trudmg kiem (Biii Trang Vift. 2000).
Vdi dieu kifn loai bd hodn toan nitrogen trong mdi trudmg ESAW ddi chimg thi the sdc td eiia te bdo nhat, ed su hinh lhanh bdo tir nghi tir ngdy thiir 2 (dnh 3.1) vd mat do te bdo van duy tri d mirc thdp nhung eao hom so vdri ede mdi trudmg ESAW ed sy du thira N - NH4"' (750pmol/L \a lOOOpmolT) trong sudt qua trinh khao sdt (hinh 3.1). Smith et al.
(1992) vd Parkhill et al. (2001) dd nhdn thdy, dnh hudmg eiia sy thieu hut nitrogen len \ i tdo silic nude mdn thi chdm ban so vdi cdc nudi cdy du thira nitrogen khi so sdnh giiira cdc dieu kifn nudi cdy gidi ban nitrogen. Sy thieu hyt nitrogen va phosphor trong mdi trudng ddn den su .(
hinh thdnh bdo tir nghi (Kuwata et ai, 1 1993). Cudmg dg quang hgp eiia tl bao ^ trong mdi trudng ESAW ddi ehiing duy <
tri d mire thap (hinh 3.2). Sir thilu hut .-.
nitrogen dnh hudmg manh len PSII, nhung khdng dnh hudmg len PSI, do sir mdt cdc protein ciia trung tdm phdn iing ;- trong dilu kifn gidi ban nitrogen keo dai :j vd sy suy thodi chgn lgc cua eac phyeobilisome gdn vdi PSII d cdc lodi vi - khudn lam, tuy nhien khong thay ed su ,
Tap chi KHOA HQC DHSP TPHCM Vd Hdng Trung vd tgk
Ihay ddi d cdc protein lien kit voi PSI trong cac te bao Chlamydomonas sp. bj gidi han nitrogen. Nguyen nhan ciia su anh hudng manh \ a chgn loc ciia su ihieu hut nitrogen len PSII cd ihl lien quan din sy ddi mdi nhanh cua cac protein Dl va D2 so vdi cac protein ciia Irung lam phan ling PSI dn dinh ban (Berges et al..
1996).
0 mdi Irudng ESAW cd bd sung N - NH4^ vdi ndng do thap 75pmol/L Id lot nhal vdi the sac td dam dac \ a chiem loan bd the lich te bao tir nga\ ihir 5 den ngay Ihli 6, mat do le bdo cao \a khac biel hodn toan so vdi cdc mdi trudng cdn lai (anh 3.2. hinh 3.1). Cudng do quang hgp lang ddn vd cao nhdt d ngay thir 5 so vdi cac mdi trudng cdn lai. tuomg iing \di thdi diem te bdo dang trong pha tdng trudng manh va dat mat do te bao cue dai d ngdy thii 5 (hinh 3.1. 3.2). Cudng do hd hdp cung dat miie cao d ngdy tir ngdy thir 4 den ngay thir 6, day ciing chinh la giai doan md te bdo dang trong pha tang Irudng (lir ngdy thir 4 den ngdy thir 5) vd bat ddu suy vong d ngdy thir 6 (anh 3.2;
hinh 3.1.3.3).
0 cdc mdi trudng ESAW bd sung 250pmol/L vd 500pmol/L N - N H / tl bdo cd the sdc id nhat vd chiem khodng
1/2 thi tich (anh 3.3, 3.4), cudng do quang hgp dat d miie thdp vd khdng cd su khdc bift so vdi doi chiing (hinh 3.2).
Cudng do hd hdp dat miie cao d ngay thir 4 vd ngdy thir 5, sau dd gidm ddn (hinh 3.3). Theo Haehiya and Noguchi (2011), khd ndng sir dung nitrogen la yeu td quylt djnh len su sinh trudmg vd cudmg do hd hdp eua thyc vat. Khi ammonium la ngudn nitrogen duy nhat d ndng do
so vdi dang nitrogen - nitrate (goi la tinh ddc ciia ammonium). Ngoai ra. ndng do ammonium cao lam tang sy hap thu oxi trong re, than va toan bo cay. lam tang qua trinh hd hap va su tang hd hap nay dugc ggi la "su tang hd hap phu thudc ammonium" (ARl). Vi the ARl dudng nhu lien quan den linh dgc ciia ammonium. Khi ammonium la dang nitrogen chiem uu the. sy can bang giiia NH^ va NH4* cd the lam phd va gradient proton qua mang Ihylakoid. mang lrong ti the hay mang khdng bao.
Trong khi dd, d mdi Irudng ESAW cd bd sung 750pmol/L va lOOOpmol/L N - NH4"' thi cudng do quang hgp ciing nhu hd hap d mirc thdp vd gan nhu bang 0 tir ngdy thir 5 den thir 6, day ciing la giai doan trong mdi trudng chi cdn lai Id cac bao lir vd mat do le bao gan nhu bang 0 (anh 3.5, 3.6; hinh 3.1, 3.2. 3.3). Trong cac mdi trudng cd bd sung N - NH4* cao (750pmol,/L vd lOOOpmol/L) lam giam pH mdi trudng do su gidi phdng H" vd lam tdng pH ndi bao do sy khuech tan tu do ciia NH3 vao te bao va lam mat cdn bang ion nen da gdy ddc va lam pha va cdc cdu true cua le bao.
4. Ket luan
Chaetoceros subtilis \ar. abnormis Proschkina-Lavrenko ldng trudmg tdt tren mdi trudng ESAW cd bd sung N - NHj"""
d nong do 75pmol/ L vdi mat do te bdo vd cudmg do quang hgp cao horn so vdi cdc nong do N - NH4'' khac.
0 cdc mdi trudmg ESAW cd bd sung N - NH4"'" d ndng do eao 500pmol/L, 750pmol/L vd lOOOpmol/L da gdy ddc va anh hudng manh len cdc qua trinh quang hgp vd hd hap cua te bao.
TAI LI$U THAM KHAO
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(Ngiy Ida scan nhin dwgc bii: 10-5-2011; ngiy chip nh$n ding: 02-6-2011)