Tgp chi i Khoa hgc Tnr&ng Dgi hgc Cdn Tha Plidn B Ndng ngbiip Thuy sdn va Cdng nghi Sinh hoc: 26 (2013). i
Tap Chl Khoa hpc Tri/cing Oai hoc Can Thd website: sj.ctu.edu.vn
PHAN LAP V A T U Y E N C H Q N M Q T SO D O N G VI K H U A N D A T V U N G R E LUA CO K H A NANG CO D I N H D A M VA T O N G HOfP l A A
Nguyen Thj Phuang Oanh', Trin Biru Minh' va Nguyin Thi Pha"
' Sinh vien khda 35. Viin Nghien ciru vd Phdt triin Cdng nghe Sinh hgc, Trudng Dai hgc Cdn Tlia
^ Vi^n Nghien cuu vd Phdt triin Cdng nghi Sinh hgc. Trudng Dai hgc Cdn Tha Thong tin chung:
Ngaynhdn 13/12/2012 Ngdy chdp nhdn. 20/06/2013 Title:
Isolation and selection several bacterial strains with the ability of fixing nitrogen and synthesizing Indole .Acetic acid (lAA)from rice rhizosphere soil
Tir klwa:
C6 djnh dam. tdng hap Indole acetic acid, vi khudn ddt vimg re liia. vi khudn sdng tudo Keywords:
Free-living bacteria, lndole-3- acelic acid, nitrogen-fixing, rice rhizosphere soil
ABSTRACT
Free-living bacteria colonizing the rhizosphere soil zone of rice possess many good capacities that should be exploited to support a sustainable agriculture In particular, nitrogen-fixing and lndole-3-acetic acid ilAA) biosynthesis abilities are IM'O features which have received the most interest in researches. In this research, 56 bacteria strains have been isolated from rhizosphere soil samples of 4 different rice varieties collected in Can Tho and Tra Vinh and screened for nitrogen-fixing ability. From which, 15 isolates with high nitrogen fixation capacity have been chosen lo continue examining the ability lo synthesize lAA.
Five bacterial isolates TV2C1, TV3A4, TV2B7, CTA3 and CTB3 perform both nitrogen fixation and lAA synthesis ability at high levels.
Tlie amount of synthesized lAA ranges from 28.6293/ug/ml (TV2C1) to 42.1351 p.g/m'l<TV2B7).
TOM TAT
Cdc lodi vi khudn sdng tif do irong vimg ddi re lua sa hiru nhieu ddc tinh tdt cdn dugc khai thdc diphuc vu cho nen ndng nghiip thdn thiin han vdi mdi trudng Trong do, khd ndng cd dinh dgm vd sinh tdng hgp Indole acetic acid (lAA) la 2 dgc tinh dugc quan tdm nghien ciru nhieu hon cd. Trong nghiin ciru ndy, td mdu ddt vimg ri lua cua 4 gidng liia khdc nliau thu tgi 2 tinh Cdn Tha vd Trd Vinh, cd 56 ddng vi khudn dd dugc phdn lap vd khdo sdt khd ndng cd dinh dgm Tit kit gud ihu dugc, 15 ddng cd khd ndng cd dinh dam cao dugc chgn di tiip tiic khdo sdt khd nang long hop lAA. Ndm dong vi khudn Ti^2Cl, TV3A4, TV2B7, CTA3 vd CTB3 vita co khd ndng cd dinh dgm d muc khd cao. vita cd khd ndng long hgp lAA tdt. Lucmg lAA long hgp dugc ciia 5 dong vi khudn ndy biin dgng tit 28,6293pg/ml (TV2C}) din 42.1351pg/ml (TV2B7).
1 DAT VAN DE
Liia gao dugc xem la loai cay lucmg thuc quan ugng khdng chi d Viet Nam ma cdn d nhieu qudc gia Chau A khac nhu: Trung Qudc.
Thai Lan. Campuchia, ... Hien tai, san lugng
Ilia tren loan thi gidi ndi chung v i n tilp tuc tang bit chip cac thay ddi bit 6n dinh cua dilu kien khi hau. Theo td chuc Luang Ndng the gidi, san lugng lua thi gidi tinh din thang 2 nam 2012 dat 722 trieu tin (tucmg duang
Tgp chi Khoa hgc Ti-u&ng Dai hgc Cdn Tha Phdn B- Ndng nghiip. Tlmy san vd Cong nghe Smh hgc: 26 i20/3j '
481,2 trieu tin gao), tang 3% so vdi 700 trieu tin vao nam 2010 (Cue xuc tiln thuang mai, 2011). Cac nguyen nhan chinh lam tang san lugng Ida bao gdm viec md rgng dien tich canh tac khi gia liia tang, san xuit tang vu va su day manh iing dung khoa hgc ky thuat vao san xuat ndng nghiep. Tuy nhien, san lugng lua tang lai din den mdi quan ngai ve mdi trudng do su gia tang lugng phan bdn (chu yeu la phan dam de bii dap lai mdt phan lugng dam trong dat bj mat di hang nam) va cac loai ndng dugc dugc su dung dl kich Ihich sy phat triln cay Ilia, phdng tru, quan ly benh hai, dac biet d cac nudc dang phat trien, gay anh hudng nghiem trgng ddn chat lugng mdi trudng va he sinh thai ndng nghiep. Hien tai, de gdp phan giai quyet vdn de moi trudng hi gay ra bdi su lam dung phan hda hgc, cac ddng vi khuan cd kha nang co dinh dam cung nhu tdng hgp chat kich thich sinh trudng dien hinh nhu lAA dang dugc nghien ciru irng dung vao cac loai phan bon vi sinh ngay cang nhieu. U'u the cua cac loai phan bdn vi sinh nay la khdng gay d nhiem mdi trudng, phuc hdi dam trong dat thong qua qua trinh cd dinh dam sinh hgc, giup tiet kiem chi phi nhung van dam bao nang suat va chat lugng ndng san.
Vi khuan sdng tu do trong vimg re Itia rat da dang va phong phii ve chting loai, nhieu loai trong sd chiing co kha nang cd dinh dam va tdng hgp lAA rat tdt. Day la ngudn nguyen lieu tilm nang ldn cho viec san xuat phan sinh hgc tir ngudn vi khuan san cd nay. Tu sau khi nghiSn ciiu ciia Gillis va cdng su (1995) phat hien loai Burkholderia vietnamiensis cd kha nang co dinh dam phan lap tir vting re lua tai Binh Thanh, Viet Nam. cac nghien cuu ve vi khuan dit vimg re liia trong nudc da phat trien kha manh. Them nhieu chung vi khuan viing re chu yeu thupc cac chi Pseudomonas, Burkholderia va Agrococcus,... da dugc phan lap tir cac loai dat khac nhau va dugc xac dinh cd kha nang co dinh dam tdt dat yeu cau de san xuit phan bdn vi sinh. Viec nghien ciiu khao sat cac ddng vi khuan phan lap tu vimg rl lua trong nghien cuu nay nhim chgn lgc them cac chung vi sinh vat cd uien vgng hudng tdi san xuit cac chl pham sinh hgc cho cay liia.
2 DOI TUgfNG VA MUC TIEU NGHIEN ClTU
Muc tieu cua nghien ciiu la phan lap va tuyen chgn cac ddng vi khuan cd kha nang cd dinh dam va sinh tdng hgp lAA tu vung dat re lua, hudng tdi cac nghien cuu ve su lac ddng cua cac ddng vi khuan nay len su sinh trudng va phat trien cay Iua cung nhu chgn lgc cac ddng cd tiem nang ung dung vao san xuat che pham vi sinh.
3 PHU'ONG PHAP NGHIEN CUtl Miu dat vung rl liia dugc thu tu cac rugng lua trdng 4 gidng liia khac nhau (OM545I, IR504 04, OM4900, OM3536), tai Tra Vinh va Can Tha. Mau dat dugc lay tu 3 dia diem khac nhau Uen cung 1 rudng bang each thu lay phan dat nam tren be mat re lua khi nhd. Cac mau dat dugc ghi nhan pH va gidng liia canh tac tai rudng, tru mat va mang v8 phdng thi nghiem.
Thao tac phan lap dugc thuc hien bang ky thuat pha loang (serial dilution) va trai mlu tren mdi trudng Burk's khdng bd sung dam, Cac chung vi khuan ttr dat viing rl thu d Tra Vinh dugc ky hieu lan lugt la TV I. TV2 va TV3, miu vi khuan tu dat vimg re thu d Can Tha dugc ky hieu la CT. Cac ddng vi khuan sau khi phan lap rdng dugc nuoi Uong mdi trudng Burk's khdng dam Idng tren may lie de xac dinh kha nang cd dinh dam va mdi trudng Burk's khdng dam cd bd sung L-Tryptophan (100 mg/l) de khao sat kha nang tdng hgp lAA. Trong ca 2 trudng hgp, cac dng nghiem nudi vi khuan dugc nudi trong dieu kien tdi, thi nghiem dugc lap lai 3 lan cho mdi ddng vi khuan.
3.1 Dinh lugng dam bang phuomg phap Indophenol blue (Page et al., 1982) Phuang phap Indophenol blue cho phep xac dinh ham lugng NH/ tu 0,2 den 12,5 ppm nhd phan ung giua NH3 vdi phenol va Naui hypoclorite vdi su xiic tac cua niuoprusside tao thanli hgp chat Indolphenol cd mau xanh d dieu kien pH kiem. ham lugng NR]' cang cao thi mau xanh cang dam. Lugng dam do vi khuan co dinh dugc xac dinh vao ngay thu 2, 4. 6 sau khi chiing. Hut can than 0,5 ml phin
Tgp chi Khoa hoc Tnmng Dgi hgc Cdn Thcr PMn B: Song nghiep. Thin- son vg Cong nghe Sinh hgc: 26 (2013}. 82-88 djch trong sau khi ly tam dich nuoi vi khuan
cho vao cac ong nghiem da chira sin 2 ml nuac cat khir trung cong voi 0,5 ml EDTA.
Them 1 ml dung dich Phenol nitroprusside va 2 ml dung dich Sodium hypocloride vao moi ong, trgn deu dung dich bang may Vortex. De on dinh a nhiet dp phong khoang 30 phiit. Sau do tien hanh do OD a birdc song 636 nm (OD636nm). Kct qua do OD cua cac dong vi khuan dirge thay vao phuong trinh do thi dirong chuan, tir do su\ ra dugc ham lugng ammonium sinh ra trong dung dich.
3.2 Djnh Ivgng lAA bang phirong phap Salkowski (Glickmann va Dessaux, 1995)
Lugng lAA sinh ra dugc xac dinh vao thai diem ngay 2. 4, 6 va 8 sau khi chiing vi khuan. Hut can than 1 ml phan dich trong sau khi ly tam lanh (4°C) djch nuoi vi khujn cho
vao cac dng nghiem chiia sin 2 ml thu6c thil Salkowski R2 (HiSOj 10,8M va FeClj), trgn deu bang may vortex. U hon hgp tren trong t6i 10-15 phiit de phan img xay ra hoan toan. Ti^n hanh do OD 6 birdc song 530 nm (ODssom).
Ket qua do OD ciia cac dong vi khuan dtrgc thay vao phuong trinh do thj dudng chuSn lAA, tir do suy ra dtrgc ham lugng lAA sinh ra trong dung dich. Ham lugng lAA cang cao thi mau hong sinh ra do phan img cua lAA vdi thuoc thir cang dam.
4 K E T QUA VA T H A O LUAN 4.1 Ket qua dinh lirgng Dam
Ket qua cho thay 56 dong vi khuan phan lap dugc deu cd kha nang c6 djnh dam, hi|u qua c6 djnh dam bien dgng kha nhieu giira cac dong vi khuan va giira sd ngay nuoi khac nhau.
Dudng chuan dam cd gia tri tir 0 den 2.5 mg/l (Hinh I).
UA'- n-l
I
0.3 Hinh 1: Bir&ngchuSo NH/tirOd4n -^ ^ --^2,5 mg/l £ 0 2
= 0.15
~ u l (iO>
0 • - ' 0 Sau 2 ngay chung \i khuSn. ham lugng ammonium sinh ra ciia da so cac ddng vi khuan cdn thap, hoat dgng co dinh dam tang len va dat ham lugng cao nhSt vao ngaj thir 4 sau khi chung, den ngay thii 6 sau khi chung, ham lugng ammonium giam di. Mgt sd ft ddng vi khuan lai cd hoat dgng cd dinh dam r^t cham, phai den ngay 6 ham lugng ammonium mdi tang len nhung lai dat ham lugng rSt th^p.
Dua tren dudng chuan duoc xay dung
>'=0.1581x-0.0009 (Hinh I), hiiu qua c6 dinh dam cua 15 ddng vi khuan cd klia nang co dinh dam cao nhat sau khi nudi c^> 2. 4 \ a 6 ngay
y = 0 I 5 S 1 X - 0 11(1110
R-=0.'»9S
I : 3 H a m l i r a n g NH4" (mg/l)
dugc trinh bay d Bang 1, kit qua dugc phan tich thdng ke bjng phin mem SPSS 20.
Nhu vay, ddng TV2C2 cd kha nang cd djnh dam cao nhat d ngay thii 4 (dat 4,6720 mg/l), khac biet cd y nghia so vdi cac ddng cdn Iai d mirc 5% qua kilm djnh. Khi so sanh vdi ket qua cd djnh dam ciia ddng 0 M 4 a l la 2.0640 mg/l (Duong Thj Kim Loan, 2009) thi ket qua nay kha quan hon. Tuy nhien, kit qua cua nghien cim nay lai thip han so vdi bao cao ciia Ngd Thanh Phong va cgng su (2011). dat 13.56 mg/l.
Tgp chi Khoa hgc Tnr&ng Dgi hgc Cdn Tba PhdnB .\ dng ngliiep. Thuy san vd Cdng nghi Sinh ligc: 2612013j: ' 6 ngay thti 4 sau chung, ham lugng
ammonium dugc tdng hgp tang dang ke so vdi ngay 2 va cd su khac biet kha ro giua cac ddng vi khuan. Den ngay thu 6 sau chung, hieu qua cd dinh dam cd khuynh hudng giam ro ret.
ham lugng ammonium trong dich nudi vi khuan rat thap. E)ieu nay cd the la so lugng dinh dudng cd trong mdi trudng giam di Uong
qua uinh sinh trudng cua vi khuan hoac do boat tinh cua enzyme xiic tac qua uinh cd dinh dam hi uc che bdi ham lugng ammonium cao.
Chinh vi vay, ngay thu 4 sau khi chung dugc chgn la thdi diem tdt nhat de so sanh hieu qua CO dinh dam giua cac ddng vi khuan ciing nhu la can cu de tuyen chgn 15 ddng vi khuan cho thf nghiem khao sat kha nang tdng hgp \.\A.
Bang 1: Ham luong N H / (mg/l) ciia IS dong vi khuan co kha nang co dinh dam cao nhat STT
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
%CV F Sis. (P-value)
Dong VI khuan —
. ,
TV2C2 TV1A4 TV3A4 TV2B3 TV3B4a TV2B7 TV2Ala TV3C1 TV3C4 TV2C1 CTA3 CTBSa CTC4 CTB3 CTA4
Neayl 0,1539"
0,3025*
0,0888' 0,1348"
0,1214"
0,3607"
0,1808"""
0,1960=*' 0,9267' 0,1310"
0,1214"
0,1922°""
0,1233°'"
0.1597°'"
0,2631"
33.2 6,141 0,000
Ham Iinrng N H / (mg/l) Ngav 4 4,6720"
4,1762' 4,1380"
3,7948' 3.7948' 2.9748' 2,8413°"
2.6125°"=
2,4981''=
2,4600"
2,4027*
2.3837"
2,3646*
2,3074"
2.2883"
15.2 51.335 0,000
Ngay 6 0,1257°""
0,0227"
0.0707"
0,0227' 0,0662' 0,1234°'"
0.0776""
0,0776""
0.0730' O.lOSl"'*' 0.0616"
0.0686*
0,1165°""' 0,0227' 0,2035"
12.4 80,145 0.000 Cdc gid iri irong ciing mpl cot ciing mdu tu (a. b. c, d e ..) khdc biel khong cd y nghfa thdng ke (p>0.05) 4.2 Ket qua dinh lugng lAA
K^t qua khao sat kha nang long hgp lAA uong mdi trudng cd bd sung L-Tryptophan (lOOmg/1) cua 15 ddng vi khuan cd kha nang cd dinh dam cao nhat cho thay ca 15 dong vi khuan nay deu co kha nang tdng hgp lAA (Bang 2). Trong sd do. 4 ddng vi khuin TV3C4, CTC4, CTA4, TV2B3 va ddng TV2C2 dat ham lugng lAA cao nhit lin lugt chi sau 2 va 4 ngay nudi. Tuy nhien, tru ddng TV3C4 va CTC4 co ham lugng lAA kha cao va tuang ddi dn djnh Uong cac ngay cdn lai ciia thi nghiem, 3 dong cdn lai lai cd ham lugng lAA sinh ra rat thip (dudi 8 ^ig/ml).
Mudi ddng vi khuan cdn lai dugc chia thanh 2 nhdm: nhdm thu nhat bao gdm cac ddng yi khuin cd ham lugng lAA tao thanh cao nhat vao ngay thu 6 sau khi chiing bao gdm ddng
CTA3, TV3B4a, TV3A4, TV2Ala va TV2B7 trong khi nhom thu hai la tap hgp cac ddng vi khuan dat ham lugng lAA cao nhat sau 8 ngay nudi (CTB3, CTB5a, TV2C1- TV3C1 va T V l A l ) . Dudng chuan lAA dugc su dung cd ham lugng tu 0 den 80 |ig/ml (Hinh 2). ket qua dugc phan tich thdng ke bang phan mem SPSS 20.
Trong so 8 ddng vi khuan cd kha nang tong hgp lAA cao nhat vao ngay thu 6 sau khi chung, ddng TV2B7 cd ham lugng lAA cao nhat dat 42,14 pg/ml, dung sau dd la cac ddng CTA3. TV3B4a va TV3A4 vdi ham Iugng L\A lin lugt la 39,61 pg/ml, 33,60 pg/ml \ a 31,39 pg/ml. Trong nhom vi khuan tdng hgp ham lugng lAA cao nhat sau 8 ngay nudi cay.
ddng CTB3 cd kha nang tdng hgp lAA tdt nhat dat 41,38)ig/mK ham lugng lAA ciia
Tgp chi Khog ligc Tnrong Dgi hoc Cdn Tha Phdn B: Kong nghiep. Thuy son vd Cdng ngiii Sinh tigc: 2612013) 82-8S
ddng vi khuan nay tai thdi diim 2. 4 va 6 ngay sau khi chiing cung rat cao, lan lugt dat 24,96 ng/ml, 31,91 pg/ml va 39.26 ng/ml.
Ngoai CTB3, ddng CTBSa cung la ddng vi khujn cd kha nang tong hgp lAA rat tdt vao ngay thi 8 sau khi chung (37.16 ng/ml). Dieu
dang liru y la 3 ddng vi khuan CTB3, TV2C1 va TV1A4 diu co ham lugng lAA ting lien tuc trong khoang thdi gian khao sat ciia tht nghiem, cho thSy kha nSng tdng hgp lAA cua cac ddng nay cdn dugc khao sat trong thdi gian thi nghiem dai han.
Hinh 2: Ducmg chuan lAA tir 0
den 80 ^ u i l
12 I OS 0 6 0 4
= 0,0I1()X+0 11.^49 R-=ii')S(il ^
Ham luong I.A.\ (fig/ml) 100
Bang 2: H^m lu^ng lAA (|lg/nil) cua 15 dong \i khuSn co kha nang co dinh dam cao nhat STT
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
%CV F Sig. (P-value)
Dong vi khuan — TV2B7 CTA3 CTB3 TV3B4a TV3A4 CTB5a TV2C1 TV2Ala TV3C4 CTC4 TV3C1 TV1A4 CTA4 TV2C2 TV2B3
Ham Nsay2
31,06"
17,53"
24,96' 6.46*
20.10°"
18.75'""
13.12' 13,01' 24,62' 20.92"
18.58'"
2.11' 7,16*
5.50*
5.50"^
6.6 246,765 0,000
lirong lAA (ug/ml) Ngav 4
26,75' 19,10°"
31,91"
16,20°"
20,70' 17,75°"
18.87°"
16.82"' 15.33' 17,41°"
17,62"' 3,26"
4,85"
5.61"
1.20"
17.2 30,818 0,000
Ngav 6 42,14"
39.61"' 39.26"' 33.60'"
31.39'"
21,30°"
28.63'°"
22.77"' 22,22"' 19,03'""
17.97'"
9,92"' 5,81' 3.74' 0.44' 26,5 15,074 0,000
Ngay 8 25,64°"
31,13'"
41,38"
19,34'"
26,45°"
37,16"' 30,02"
9,76*
19,52'"
13,88"
22,39°""
22,49°""
5,18*
2,93*
0,00' 23,7 19,219 0,000 Cdc gid tri irong citng mdt cot Cling mdu tu (a. b. c. d. e.. ) khdc biel khdng co y nghTa ihdng ki (p>0.05J
Tu ket qua thi nghiem cd the ket luan 6 la hai ddng vi khuin cd kha nang co dinh dam ddng vi khuan cd kha nang tdng hgp lAA cao tdt (TV3A4 cd ham lugng ammonium tong khac biet vdi cac ddng vi khuan khac xet ca tai hgp vao ngay 4 sau chung dung thu 3 uong sd thdi di^m ngay 6 va 8 sau khi chiing la: 15 ddng vi khuin da khao sat kha nang cd dinh TV2B7. CTA3. CTB3. TV3B4a. CTB5a va dam, dat 4,1380 mg/l, TV3B4a dung thu 5 vdi TV3A4. Ben canh kha nang tdng hgp lAA vdi 3,7948 mg/l).
ham lugng cao, ddng TV3A4 va TV3B4a cdn
Tgp chi Khoa hgc Tru&ng Dgi hgc Cdn Thcr Phdn B: Ndng nghiep. Thuy san vd Cdng nghe Sinh hoc: 26 (2013/: 82-88 Kat qua khao sat kha nang tdng hgp lAA
ciia cac ddng vi khuan phan lap dugc tu vung dat re liia su dung trong nghien cuu phu hgp vdi nghien cuu ciia Manivannan et al. (2012) va Shailesh et ai (2011), ca 2 nghien cuu nay deu cho thay cac ddng vi khuan cd ngudn phan lap tuang tu deu bieu hien kha nang ^ n g hgp lAA tdt khi nudi Uong mdi trudng cd bd sung L-Tryptophan. Ngoai ra, khi so sanh vdi lugng
lAA cao nhat tdng hgp bdi ddng vi khuan ndi sinh N7 phan ISp tu cay khdm tai tinh Hau Giang (Cao Nggc Diep va Phan Thi Nha.
2011) la 1,03 pg/ml va bdi chung BK-5 thudc chi Azotobacter phan lap tii dat canh tac tai Da Ning (Nguyin Kim Anh et al., 2008) la 4,313 (ig/ml thi ket qua thu dugc trong nghien cuu nay tdt han ban.
Hiub 3: Dirdng chuan lAA (0 den 80 pg/ml) va phan ung mau cua mQt so dong vi khuan voi thuoc thir Salkowski vao thoi diem ngay thir 6 sau khi chung, trong do, dong TV2B7 la dong co ham lirong lAA
duyc tong hgfp cao nhat (42,1350 p^/ml) 5 KET LUAN VA DE XUAT
5.1 Ket luan
Da sd cac ddng vi khuan vting re phan lap dugc deu cd kha nang co dinh dam va tat ca cac ddng vi khuan dugc chgn khao sat kha nang tdng hgp lAA deu co kha nang tdng hgp lAA. Ham lugng ammonium dugc cd dinh cao nhit vao ngay thu 4 sau khi chung trong khi ham lugng lAA lai dat gia tri cao nhat vao ngay thu 6 hoac 8 ddi vdi da sd cac ddng vi khuan. Trong cac ddng vi khuan da khao sat, ddng vi khuan tdng hgp ammonium tdt nhat la ddng TV2C2. dat 4,6720 mg/l, tigp theo la 4 ddng vi khuin f v i A 4 (4.1762 mg/l), TV3A4 (4,1380 mg/l). TV2B3 (3,7948 mg/l) va TV3B4a (3.7498 mg/l). Hai ddng vi khuin tdng hgp lAA cao dang chii y la ddng TV2B7 vdi ham lugng lAA cao nhat vao ngay thu 6 sau chiing (dat 42.14 pg/mi) va ddng CTB3 vdi ham lugng lAA cao nhat vao ngay thu 8 sau khi chung (dat 41,38 pg/ml).
5.2 De xuat
Tien hanh khao sat mdt sd dac tinh khac dac tnmg cho vi khuan vung re cho cac ddng vi khuan da dugc khao sat. Tien hanh dinh danh cac ddng cd bieu hien noi trdi va dang gia hieu qua ung dung bang thi nghiem tai nha ludi.
LOtI CAM TA
Tac gia xin chan thanh gui ldi cam an den tap the can bd phdng thi nghiem Vi sinh vat da hd \xg va tao dieu kien tdt nhat cho chung tdi thyc hien nghien cuu nay. Xin cam on cac tac gia ciia cac cdng Uinh dugc su dung nhu tai lieu tham khao uong nghien cuu,
TAI LIEU THAM KHAO
1. Cao Ngoc Diep va Phan Thi Nha. 2011. Phan lap va xac dinh dac tinh vi khuan noi sinh Uong cay khom {Ananas comosus L ) trong Uen dat phen thj xa Vi Thanh, tinh Hau Giang.
Tap chi Cdng nghe Sinh hgc. 9(2):243-250.
Tgp chi Khoa hgc Tnr&ng Dgi hgc Cdn Tha Phdn B: Nong ngbiip. Tlmy si a Cdng nghe Sinb hgc. 26 (2013j. 82-88 2. Gillis. M.. Tran Van Van, R, Bardin, M. Goor,
P. Hebbar, A. William. P. Segers, K. Kersters, T. Heulin and M.P. Fernandez. 1995.
Polyphasic taxonomy in the genus Burkholderia leading to an emened description ofthe genus and proposition of Burkholderia viemamiensis sp. Nov. for Ni - fixing isolates from rice in Viemam. IntemationalJoumal of Systematic Bacteriology, -/5(2):274-289.
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