KHOA HOC C O N G NGHl
/ THAIMH PHAIM LOAI VI KHUAIM TREIM MEHEU IVUDI [Meretrix lyratm] QUA CAC DOT D|CH CHET HAIVG LOAT TAI CAC TIIVH V E M BIEIV VIET IVAM
Bui Ngpc TTianh', NguySn Thi Hiinh', Pham Thi Y & ' vi Phan Thj Vta' T6MTAT
Hien nay, nghgu Ben Tre Meretrix lyrata la ddi tuong nuoi quan trong o vimg bai tri^u nhi^u tinh ven bi^n Viet Nam boi gia tn o ca thi truong n6i dia va xulit IdlSu. Tuy nhien, trong nhiing nam g ^ day Men tirong ngheu ch^t hang loat da xiiy ra lam suy giam nghiem trong san luong ngheu cua ca nuoc. Nghign ciiu duoc thuc hien nham xac dinh thanh phan loai va ty le nhilm vi khuan tren ngheu nuoi trong cac dot dich b^nh chet hang loat. Tdng sd 558 mau ngheu thu duoc qua 11 dot dich chet hang loat trong 2 nam tu thang 2/2012 den thang 6/2013 tai Hai Phdng, Nam Dmh, Thai Binh, Thanh Hoa, TP. Hd Chi Minh, Ben Tre va Bac Lieu.
Vi khuan duoc phan lap tir tim ngheu bang phuong phap nudi cay tren mdi truong tdng hop Nutrient Agar (thach dmh duong) cd bd sung 2% NaCl, mdi truong chon loc TCBS va Kit API 20E duoc six dung de dmh danh vi khuan. K^t quik nghien cuu cho thay ngheu cd hien tuong nhiem khuan cao vdi ty le nhidm chung la 68,78%, trong dd ngheu thu tai Hai Phdng cd ty 14 nhiSm 71,78%, Nam Dmh 54,00%, Thai Binh 80,65%, Thanh Hda 40,49%, TP. Hd Chi Mmh 94%, Ben Tre 80% v4 Bac Ueu 100%. Nghien cihl da xac dmh duoc tdng sd 18 loai VI khuan thudc 5 gidng khac nhau trong dd chu yeu la gidng Vibno, diic biet la mdi viing diu CO 1-2 loai VI khuan chiem uu the - cd ty le nhidm cao hon so vdi cac loai khac. Loin uu the tren ngheu thu duo^ tai Hai Phdng la V. aigmolyticus (29,44%); tai Nam Dinh la V. parahaemolyticus (54%); tai Thai Binh la V. Ssberi (43%) va V. vulniScus (39,7%); tai Thanh Hda la V. tubiasUi (12,4%) vk V. tapetis (11,5%); tai TP. Hd Chi Minh la V. ichfhyoenteri (94%); trong khi do tai Ben Tre 14 V. vulniicus (56,66%) va V. ichthyoenteri (40%); tai Bac Lieu la V. alginolyticus (80,95%). Hau het cac loai vi khuan uu the nay da timg duoc ghi nhan la tac nhan gay benh d ddng vat thiiy san. Ket qua nghien cuu nay buoc dau xac dmh duoc su cd mat va tan suat bat gap ciia mdt sd loai Vibrio cd kha nang gay benh tir ngheu nudi trong cac dot dich chet hang loat, tuy nhien, vai trd cua nhimg loai vi khuan nay ddi vol hien tuong ngheu chet hang loat gan day tai Viet Nam can phai duoc lam ro trong cac nghien cuu ti4p theo.
Til^6a:. Benh nhuyCn the, ch^t hang loat, Meretnx lyrata, ngheu, vildiuan, Vibno.
1- MViH luong dat 168.290 tan, dn€m ti trong 83% tong san NghA nuoi ngheu dang ngay m6t phat trien, san luong nhuySn the (Tong cue Thiiy san (TCTS), Immg hi nghe nuoi vuot troi so vdi tir khai thac hi 2011). Tuy nhiSn, h i t a t u m g nghSu chet hang loat nhifin. Theo thdng k6 cua FAO (2009), t6ng san xay ra frong may nam gan day da lam thiM hat Irai v4 luong ngheu tr6n toan the gioi nam 2009 dat kinht^ (CueThuy,2011).Nam2011, chitmhriengd 5.648.070 tin, tang gan 1 frifeu tan so vol nam 2000 3 tinh phia Nam la Bfa Tre, Tien Giang va Bac Utu, (4.941.572 tan) vm gia h i khoang 3,8 ty USD, trong tong dien tich thiet hai len toi 2.980 ha hrang ling vdi do san luong nghtu nuoi la 4.262.787 tan, chiem lucmg ngMu chet khoang 30.000 tan, uoe tinh gia hi 75,5%. Mdt sd loai ngh6u iiudi phd bidn va cd san thifit hai la 648 ty ddng (JtTTS, 2011).
lutmg eao d khu vuc chau A nhu Meretrix merebix Sau khi khao sat tai cac viing nudi cd xay ra hito va M. lyrata Ou-Shey Ho va Zheng, 1994), M. lusoria tugng ngheu chdt hang loat, nh4n dinh btidc dau cho GengvaTyan, 1982). rang nang ndng keo d ^ dan tdi nhiet dd va do man
0 Viet Nam M. lyrata phan bd hi nhidn d cac tang eao duoc eho la mdt h-ong nhOng nguydn nhSn tmh phia Nam, chu yeu a Ben Tre nhung ddn nay quan h-ong lam ngheu chdt (T(jrS, 2011; Bill Dac loai nay dugc nudi phd bien o nhieu tmh/ thanh phia Thuydt va Tran Van Dung, 2013). Nghidn ciiu ve tic Bac nhu Hai Phdng, Nam Dmh, Thanh Hda, Thai nhan gay bdnh da phat hidn Ferklnsus sp nhidm vdi Binh. Dien hch nudi ngheu hidn nay la 17.730 ha, ty le cao (Ngo Thi Ngoc Thuy, 2011) va cd su hidn chidm 74,3% tong dien hch nudi nhuydn the, dat san dien mdt sd loai vi khuan, trong dd chu ydu la K alginolyticus vi V. vulnificus (Nguyen Thi Thu Hien va Tran Thi Nguydt Mmh, 2012). Mac du vay, v5n cdn nhidu quan didm khac nhau vd nguydn nhan va Vien Nghien ciiu Nudi trdng Thuy siin 1
KHOA HOC CONG N G H £
tac nhin gay b6nh lam nghfeu nu6i thuong pham ch^t hang loat. Trong nghifen cmi nay, tren quy mo Ion hon, chung t6i mu6n danh gia thanh phan loai vi khuan nhi^m tr^n ngh^u qua cac dgt ngheu nuoi thuong pham ch^t hang loat xay ra tai 7 tinh co di^n tich nuoi ngheu Ion nhat trong ca nuoc.
2 . PHUONG PHAP NGHDU CUU 2.1. Vkt li$u, thdi gian v^ dia di^m
Vat li6u nghidn cihi la 558 mku ngheu chu yeu \k kich CO thuong pham thu duoc tir 11 dot dich lam chet ngheu xay ra tai 7 tinh, thanh doc ven bien ca nu6c bao gom Hai Phong, Nam Dinh, Thai Binh, Thanh Hoa, thanh pho Ho Chi Minh, Ben Tre va Bac Lieu tit thang 2 nam 2012 den thang 6 nam 2013 (bang 1).
Miu ngheu duoc van chuyen song ve Phong Benh Thuy san - Trung tam Nghidn cuu Quan trdc, canh bao Moi truong va Phong ngira Dich benh thuy san Khu vuc mien Bac, thupc Vien Nghien cuu Nuoi trong Thuy san 1 tai Dinh Bang, Tu Son, Bdc Ninh.
Bang 1. vat lifeu nghifen cuu Dia diem
Cat Hai, Hai Phdng Giao Thdy, Nam Dmh Tien Hai, Thai Bmh Hau Ldc, Hoang Hda, Thanh Hda Can Gid, TPHCM Binh Dai, Ba Tn, Bdn Tre
Bac Lidu
Tyle Ngheu chet
7080
(%)
70-80 70 90 60-80 50-70 60 70 20-30 50-60 80
Thdi gian 3/2013 4/2013 4/2012 4/2013 2/2012 4/2013 6/2013 6/2012 3/2013 6/2013 10/2012
Sd mau thu (ca the) 163 50 45 48 41 80 50 50 5 5 21
trong ong eppendoft. Sir dung Kit API-20E d6 thu phan ling smh hoa bdng each lay dung dich vi khuan pha trong NaCl 2% nho len cac gi^ng phan ling cua tets API va xi trong tu am a nhiet do 29''C, sau 24 h doc k^t qua phan ling sinh hoa va tra cuu loai trfen website duoc cung cap boi nha san xuat https://apiweb.biomerieux.com/servlet/Authenticat e?action=prepareLogin.
2.3. Phan tich s6 U^u
Nhap so li^u va ve bang bieu duoc thuc hi^n tren Excel Microsoft Office 2010. Ty le nhi&m vi khuan CTLN) dupe tinh theo cong thiic sau:
S6 miu nhiem
TLN(%)= xlOO Sd mau Idem tra
Ty le nhi^m cac loai vi khuan khac nhau trong cung mot viing nu6i duoc so sanh bang "Chi-square with Yates correction" sir khac biet co y nghia thdng ke duoc xac dinh khi P<0,05 dua tren phan m^m Graphpad.
s.XFrquAniGHBicuu
3.1. Ty te nhilm k h u ^ tr^n ngheu qua cAc d(pt dich chdt hang loat tai mpt sd tinh ven bi^n Viet Nam Bang 2. T^ 1^ nhiSm khuan trfin ngheu thu duoc qua cac dgt dich ch^t hang loat tai mpt sd tinh Ihanh ven
bi^n Viet Nam
2.2. Phan l|ip va dinh danh vl khuan
Ngheu duoc giai phlu bang each cat diit co khep vo, su dung que cay khu trimg tren ngpn liia den edn sau do l^y miu tir tim ngheu va eay len 2 mdi truong khac nhau; mdi truong tdng hop NA (Nutrient Agar) c6 bd sung 2% NaCl va mdi truong chon loc Vibrio TCBS (Jhiosulfete-citrate-bile salts-sucrose agar).
Tidn hanh ii miu nudi eay trong tu am o nhiet dd 29°C va kiem tra su phat trien cua khuan lac sau 24 h. Chpn mpt khuan lac dien hinh mpc rieng re tren dudng cay, cay chuyen sang lEa mdi trucmg moi NA bd sung 2% NaCl dd nudi c^y thuan, tiep tuc u trong tu am trong vong 24 h de vi khuan thuan phat trien.
Chpn 1 khuan lac tir dia mdi truong nudi eSy thuan pha loang thanh dich huydn phii bang NaCl 2%
Dia diem Hai Phdng Nam Dinh Thai Bmh Thanh Hda TP. Hd Chi Minh
BdnTre Bac lidu
Sd man nhidm khuan (ca thd)
117 27 75 49 47 48 21
Ty le nhidm khuan (%)
71,78' 54,00'' 80,65*
40,49'' g^OO' 80,00-
100' Ghi chu: tiong ciing 1 cdt, sdmti khac nhau gia tri ty 10 nhidm khic nhau cd y nghia v4 m$t thdng kd (P<0,05) va nguoc lai.
Nghien ciiu qua cae dot dich gay chet hang loat 6 ngheu, ehii yeu nghdu nuoi thuong phim tai 7 linh va thanh phd trong ea nuoc cho thay vai tro quan trong cua vi khuan, ehu yeu la vi khuan Vibrio. Ty Id nhiem khuan chung tren nghdu thu dupe tir cac vimg nuoi dang xay ra hidn tugng chet hang loat la 68,81%, dao ddng 40,49% -100% (bang 2). Cd su bien ddng ve ty le nhidm khuan trdn ngheu thu dugc tir cac viing nudi khac nhau. Ngheu thu duoc tir cac dpt dich b Bac Lidu va thanh phd Hd Chi Minh co ty le nhidm vi khuan cao nhat, tiep den 11 Thai Binh, Bdn Tre va NONG NGHIEP VA PHAT TRIEN NONG THON - KY 1 - THANG 11/2014 97
KHOA HOC C O N G N G H E
Hai Phdng. Ty Id nhiem khuan thap nh^t trdn nghdu thu dupe tai Thanh Hoa va Nam Dinh Ian lugt la 40,49% va 54%.
3.2. Thanh p h ^ loai va ty 1^ nhidm vi khuan nhidm trdn nghdu qua eae dgt dich chdt hang loat tai mdt sd tinh ven bidn Vidt Nam
Bang 3. Thanh phin loai va ^ 1^ nhidm vi khuan IrSn ngheu qua cac dot dich chdt hang loat tai mdt sd tinh
ven bidn Vidt Nam STT
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Thanh phan loii
V. vulnihcus V. alginolyticus V. ichthyoenteri V. parahaemolyticus V. lischeri V. splendidus V. tubiashii V. ordalii V. tapetis Pseudomonas sp.
Photobacterium damselae subsp. damselae Vibrio agarivorans V. anguillarum Vibrio sp.
Streptococcus sp.
V. harveyi V. logel Flavobacterium sp.
Sdmau nhidm (ca
thd) 91 88 70 69 38 37 14 13 10 9 6 4 3 3 2 2 1 1
Tyld nhidm
(%)
16,38"
15,69- 12,59*
12,41*
6,89' 6,72'' 2,59=
2,41' 172=J 1,55='' 1,03"' 0,69'' 0,52'' 0,52'' 0,34'' 0,34'' 0,17'' 0,17'' Ghi ehd- tiong ciing 1 cdt, sdmQ khac nhau gia tri ty Id nhidm khac nhau cd y nghia ve mat tiidng ke (P<0,05) va nguoc lai.
Nghien ciiu xac dinh dugc 18 loai vi khuan nhidm trdn ngheu thu dugc qua cac dpt dich chet hang loat tai 7 tinh nghien cmi. Cae loai vi khuan bao gdm Vibrio vulnihcus, V. alginolyticus, V.
icthyoenteri, V. parahaemolyticus, V. tisheri, V.
splendidus, V. tubiashii, V. ordalii, V. tapetis, V.
agarivorans, V. anguillarum, V. harveyi, Vibrio sp., Pseudomonas sp., Photobacterium damselae subsp.
damselae vk Stieptococcus sp (bang 3). Trong cac loai vi khuan phan lap va dinh danh dupe, 4 loai vi khuan la V. vuhihcus, V. aigmolyticus, V.
ichthyoenteri vk V. parahaemolyticus cd ty le nhidm cao nhat tuong ung la 16,73%, 15,86%, 12,59% va 12,41%. Vi khuan V. tischerivk V. splendidus ed ty le
nhidm chung th^p hon 4 loai vi khuan noi tren, tuong ling la 6,89% va 6,72%. Cac loai vi khuan cdn lai ty Id nhidm chung thap dao dong tir 2,59% 6- V. tubiasha den 0,17% d- Flavobacterium sp. (chi tidt o bang 3).
3.3. Thanh p h ^ loai va t^ Id nhi^m vi khudn tren nghdu t$i Hai Phdng
Nam loai vi khuan bao gdm V. alginolyticus, V.
splendidus, V. parahaemolyticus, V. tapetis va V.
damselae subsp. damselae dugc phat hidn nhidm trdn ngheu qua dgt dich lam chdt 7{>-80% Nghdu thuong pham nudi tai Cat Hai, Hai Phdng vao thang 3 nam 2013 (bang 1). Cd 2 loai chiem uu thd vdi ty le nhidm cao nhat bao gdm V. alginoyticus vk V.
splendidus tuong img la 29,47% va 23,31%. Vi khuan V. parahaemolyticus nhidm ven ty Id 13,49% cao hon so vdi V. tapetis va P. damselae subsp. damselae nhidm ty Id tuong ling la 3,06% va 2,45% (bang 4).
BSng 4. Thanh phdn loai va ty Id nhidm vi khuan tai Hai Phdng
STT
1 2 3 4 5
Thanh phan loai
V. alginolyticus V. splendidus V. parahaemolyticus V. tapetis
P. damselae suhsp. damselae Sdmiu
nhidm (cathe) 48 38 22 5 4
Tyle nhidm
(%)
29,44*
23,31*
13,49*
3,06' 2,45"
Ghi chu: trong cimg 1 cot, sdmu khac nhau gia tri ty li nUim khac nhau co y nghia vi mat thSng ki (P<0,05) va nguoc lai
3,4. Thinh phan loM v i ty Id nhidm vi khuan trdn nghdu tai Nam Dinh
<J Nam Dmh dieh chet xay ra tai Giao Thiiy, cac diem thu mSu cd ty le chdt len toi 70-80% vao thing 4 nam 2013 (bang 1). Nghidn ciiu chi phin lap duoc 2 loii vi khuan l i V. parahaemolyticus vi Streptococcus sp. Ty le nhidm V. parahaemolyticus la 54% cao hon so vcri vi khuan Streptococcus sp. 4%
(bangs).
Bing 5. Thinh pMn loai v i t^ 1^ nhidm vi khuin lai Nam Binh
STT 1 2
Loai VI khuan V. parahaemolyticus
Stieptococcus sp.
Sd miu nhidm (ca thd)
27 2
Ty Id nhilm
(%)
54*
4' Ghi chu: tiong ciing 1 cot, sd mu khac nhau gia tri ty Id nhidm khic nhau co y nghia ve mat thdng kd (P<0,05) va nguoc lai.
K H O A HOC C O N G NGHfi
3.5. Thanh phin loai va ty le nhidm vi khuin trdn nghdu tgiTliai Binh
Tai Tien Hai, Thai Binh, nghidn euu da thu dupe miu ngheu tir ca 2 lan dieh chdt hang loat khae nhau xay ra vao eiing 1 thdi didm thang 4 nhimg nam la 2012 va 2013 (bang 1). Kdt qua phan lap vi khuin phat hidn dupe 5 loai Vibrio khdc nhau, trong dd c6 2 loai uu the la V. hscheri vk V. vulnihcus ed ty le nhidm tuong img 43,01% va 39,78%. Cac b a i V.
alginolyticus, V. parahaemolyticus vk V agarvivorans cd ty le nhidm thap hon lan lugt la 18,27%, 15,05% va 4,30% (bang 6).
Bang 6. Thanh p h ^ loai va ty Id nhidm vi khudn trdn ngheu tai Thai Binh
STT
1 2 3 4 5
Loii vi khuin
V. Sscheri V. vulnificus V. aigmolyticus V. parahaemoylicus V. agarivorans
S d m l u nhidm (ci
the) 40 37 17 14 4
Tyle nhidm
(«)
43,01"
39,78*
18,28'' 15,05' 4,30'^
Ghi chu: tiong ciing 1 cdt, sd ma khac nhau gia tii ty le nhidm khic nhau co y nghia ve mat thdng kd (P<0,05) vangiroclai.
3.6. Thanh phin loed va t^ 1$ nhidm vi k h u & frdn nghdu tai Thanh Hda
Bang 7. Thanh p h ^ b a i va ty Id nhidm vi khu&i tren ngheu tai Tiianh Hoa
STT 1 2 3 4 5 6 7 8 9
Loii VI khuan V. tubiashii V. ordalii V. alginolyticus V. tapetis V. parahaemolyticus V. ichthyoenteri V. splendidus V. logel Flavobacterium sp.
Sd mau nhidm (cathe)
15 14 6 5 3 2 1 1 1
Tyld nhidm (%)
12,40' 11,57"-'' 4,96'*
4,13'=
2,48'' 1,65=
0,82'^
0,82' 0,82"
tapetis, V. parahaemolyticus, V. ichthyoenteri, V.
splendidus, V. logei vk Flavobaterium sp. Mac dii vay, ty Id nhidm cac loai vi khuan tren ngheu tai Thanh Hda kha thap. C6 4 loai vi khuan uu thd hon ea la K tubiashu, V ordalii, V. alginolyticus va V.
tapetis, mac dii v^y ty le nhidm chi lan lugt la 12,40%, 11,57%, 4,96% va 4,13% (bang 7).
3.7. Tiianh p h ^ b a i va ty Id nhidm vi khuin tren ngheu tai thanh phd Hd Chi Minh
Nghidn ciiu chi phat hien 2 b a i la V.
ichthyoenteri vk V. vulnihcus tren ngheu thu dugc qua dgt dich tai huydn Can Gio, TP. Ho Chi Minh vao thang 3 nam 2013. Trong do, V. ichthyoenteri co ty le nhidm len tdi 94% cao hon so vdi V. vulnihcus la 38% (bang 8).
Bang 8. Thanh phdn bat va ty le nhidm vi khudn trdn nghdu tai TP. Hd Chi Minh
Ghi chii: trong ciing 1 cot, sd mu khac nhau gia tri ty Id nhidm khac nhau cd y nghia vS mat thdng kd (P<0,05) va nguoc lai.
Qua 2 dgt dieh xay ra vao thang 2 nam 2012 va thang 4 nam 2013 tai Hau Ldc va Hoang Hda, Thanh Hoa vdi t^ le chet dao ddng 50-80% (bang 1) nghien cuu da phan lap va dinh danh dugc 9 b a i vi khuan bao gdm V. fischeri, V. vulnihcus, V. alginolyticus, V.
STT 1 2
Loai vi khuan V. ichthyoenten V. vulnificus
Sd mau nhidm (cathe)
47 19
Tyld nhidm (%)
94"
38' Ghi chu: tiong cimg 1 cdt, sd mQ khac nhau gia tri ty Id nhiim khac nhau cd y nghia ve mat thdng ke (P<0,05) va nguoc lai
3.8. Thanh phan b a i va ly le nhidm vi khudn tren nghdu tai Bdn Tre
Tai Ben Tre, ehiing tdi da xac dinh duoc 7 loai vi khudn trdn ngheu thu dupe qua 3 dpt ngheu chdt xay ra vao thang 6/2012, 3/2013 va 6/2013 vdi ty le chet 20-70% (bang 1). Trong sd 7 loai phan lap duoc, cd 2 loai uu the bao gdm V. vulniticus vk V. ichthyoenteri vdi ty le nhidm vugt trpi (55,66% va 40%) so vdi cae b a i cdn lai (bang 9).
Bang 9. Tiianh phdn b a i va ty Id nhiSm vi khudn trdn nghdu tai Bdn Tre STT
1 2 3 4 5 6 7
Loai VI khuan
V. vulnificus V. Ichthyoenteri V. alginolyticus V. parahaemolyticus V. anguillarum Pseudomonas sp.
V. harveyi
S d m i u nhidm (ca thd)
34 24 3 3 2 2 1
Tyld nhidm (%)
56,67"
40,00"
5,00' 5,00' 3,33' 3,33' 1,67' Ghi chii: tiong cimg 1 cdt, sd mU khac nhau gii tii ty Id nhidm khac nhau co y nghia ve mat thdng ke (P<0,05) va nguoc lai.
NONG NGHIEP VA PHATTRIEN NONG THON - KY 1 -THANG 11/2014 99
KHOA HOC CONG N G H l
3.9. Tiianh phan b a i va ^ le nhiSm vi khudn tren ngheu tai Bac lieu
Co 8 loai vi khuin (bang 10) dupe xac dinh nhidm tren nghdu thu dugc qua dgt dieh chet xay ra tai Bac Lidu vao thang 10 nam 2012 voi ^ Id chet len tdi 80%.
Ty Id nhidm khudn trdn nghdu thu duoc tai Bac lieu la 100%, trong do V. alginolyticus cd ty le nhidm len tdi 80,95%, vugt trpi so voi Pseudomonas sp. 33,33% va V.
vulniticus 23,81%. Cac bdi V. parahaemolyticus, Vibrio sp. V. damselae subsp. damselae, V.
anguillarum va V. harveyi co ty le nhiem thap lan lugt la 14,28%, 14,28%, 9,52% va 4,78% (bang 10).
Bang 10. Thanh phin b a i va ^ Id nhidm vi khudn tgi Bac lidu
STT 1 2 3 4 5 6 7 8
Loai vi khu£n V. alginolyticus Pseudomonas sp.
V. vulnificus V. parahaemolyticus Vibrio sp.
P. damselae subsp.
damselae V. anguillarum V. harveyi
Miu nhidm
17 7 5 3 3 2 1 1
Tyle nhidm (%)
80,95"
33,33' 23,81'' 14,28"
14,28'' 9.52"
4.76=
4.76=
Ghi chu: tiong cung 1 cdt, sdmu khic nhau gia tri ty Id nhidm khic nhau co y nghia ve mat thdng ke (P<0,05) vangiroclai.
4 . THAO LUAN
Ket qua nghien ciiu eho thay co su sai khae dang kd vd thdnh phan b a i vi khudn va muc do nhidm ddi vdi nghdu thuong pham bi bdnh d cac tinh, Ihanh eua 2 mien (midn Bac: Hai Phong, Thai Binh, Nam Dinh, Thanh Hda; midn Nam: Tp Hd Chi Minh, Bdn Tre, Bac Lieu). 6 mien Bdc: phat hidn dugc 13 loai {V.
alginolyticus, V. parahaemolyticus, V. vulnihcus, V.
ichthyoenteri, V. splendidus, V. tapetis, Stieptococcus sp., V. hsheri, V. agarivorans, V.
tubiashh, V.ordalu, V. logei, P. damselae subsp.
damselaei. 6 mien Nam: phat hien dugc 8 loai {V.
alginolyticus, V. parahaemolyticus, V vuhihcus, V.
ichtiiyoenteri, V. anguillarum, V. harveyi, Pseudomonas sp.. Vibrio sp.). Trong dd cd 4 b a i deu gap chung b ca hai midn la: V. ichthyoenteri, V.
aigmolyticus, V. vulnificus, V. parahaemolyticus vbi ty Id nhidm tuong ddi cao, tuong ling la 94%, 80,95%, 56,67%, 54%. Ty le nhidm cua cac loai vi khudn b nghdu cung rdt khac nhau giiia cac tinh (Bang 4, 5, 6, 7, 8, 9, 10). Sd" di c6 su khac nhau dang ke vira neu
trdn, theo ehiing tdi, cd thd do dieu kidn tu nhidn mdi trudng khac nhau b cac vimg mien; do thoi gian thu mdu va sd lugng mdu thu dd nghien ciiu cung r^it khac nhau (d midn Bac thu 427 mdu, d- mien Nam thu 131 mdu; b linh it nhat la 21 mdu nhu Bac Lidu, o thanh phd nhieu nhat la 163 mdu nhu Hai Phdng).
Mdt sd tdc gia trong va ngoai nuoc da cdng bo nhung cdng trinh nghidn a i u xac dmh mdt sd loai vi khudn nhu V. alginolyticus la tac nhan gay benh lam chet hang loat ngheu Meretrix sp. (Nguydn Thi Hidn va Trin Thi Nguydt Minh, 2012); V. parahaemolyticus lam chdt hang loat ngheu M. meretrix (U Guo va ctv, 2008; Yue Xin va etv, 2010; Yue Xin, 2011). Nghien ciiu cua chung tdi, b cac dgt dich bdnh Idm chet rat nhidu ngheu ]^. lyrata, da phat hidn dugc 18 loai vi khuIn, dac bidt cd mdt sd loai co ty Id nhidm kha cao nhu V.
ichthyoenteri, V. alginolyticus, V. vulniticus, V.
parahaemolyticus Mdt hoac nhidu loai vi khuan nay Cling da dupe xac dinh la tac nhan gay benh trdn cac lodi nhuydn thd khdc nhu so R decussatus (Monia El Bour va ctv., 2013; Gomez-Leon va ctv., 2005).), Hau C gigas (Gamier va ctv., 2007 ) va Trai Tapes philippinarumvk T. decussatus (Paillard va ctv., 1989).
Tuy nhidn, de xac dinh ro loai vi khudn nao la tac nhan gay bdnh cho ngheu M. lyrata Ihi cdn phai tiep tuc cd nhiing nghidn ciiu sau hon, ddy du hon dd co nhung bidn phap phdng hi, gdp phan phat tridn nghe nudi nghdu thuong phdm o'Vidt Nam.
5.KFrLUAN
Ket qua nghidn cuu da phat hien dupe 18 lodi vi khuan thudc 5 gidng (ehu ydu Id Vibrio), frong do a eac tinh phia Bac cd 13 lodi, o' cac tinh phia Nam cd 8 loai. Ty le nhidm chung cae loai vi khudn ddi voi ngheu M. lyrata thu diKxc qua cac dpt dich chdt hang loat la 68,81%. Ddi vdi timg loai vi khudn bat gap b cac tinh khac nhau thi ty le nhidm cung rdt khae nhau.
TAI LIB! THAM KHAO
1. Bui Ddc Thuyet vd Tran Van Dung, 2013. Hidn trang nghe nudi ngao 6 mdt so tinh ven bien midn Bac va Bac Trung bo, Vidt Nam. Tap ehi Khoa hoc va Phat tridn 11, 972-980.
2. Cue Thii y 2011. Bao cao tinh hmh dich bdnh trdn Ngao b ddng bdng sdng Cmi Long. Td cdng tac phdng chdng dieh benh Ngao (Cue Thii y).
3. Gamier, M., Labreuche, Y, Garcia, C , Robert, M., Nicolas, J. L., 2007. Evidence for the involvement of pathogenic bacteria in summer mortalities of the Pacific oyster Crassostrea gigas. Microb. Ecol. 53, 187-196.
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4. Gomez-Leon, J., Villamil, L , Lemos, M. L , cuu cac benh hen mdt sd ddi hiong nhuydn the nudi Novoa, B., Figueras, A., 2005. Isolahon of Vibrio tai vimg ven hidn Vidt Nam. Bio cio kdt qua chuong alginolyticus and Vibrio splendidus from hinh khoa hpc cdng nghe. Bd Khoa hgc vi Cdng aquacutored caipet sheU clam (Rudltapes nghe. Co quan chu hi dd tai: Vien Nghien cuu Nudi decussatus) larvae associated with mass mortahhes. trdng Thuy san 2.
Appl. Environ. Microhiol. 71, 98-104. 10. Nguydn Thi Thu Hidn, Trin Thi Nguydt 5. Jeng, S. S., Tyan, Y. M., 1982. Growth of the hard Mmh, 2012. Kdt qua nghien ciiu mdt sd tac nhan giy clam Meretrix lusoria m Taiwan. Aquaculhu-e 27,9. henh thuong gap frtn ngao Merebix sp. tai vimg ven
6.Ju-SheyHo,Zheng, G.-X., 1994. Ostancolakoe hien Hii Phdng. Bin tin (Vien Nghidn cim Nudi (Copepoda, Myicolidae) and mass mortality of frdngThuy san l ) , h a n g 2 .
culhired hard clam (Meretilx meretrbi) in Chma. 11. Paillard, C. L., Percelay, M., Le Pennec, D. L Hydrobiogia 284, 4. Picard, 1989. Origine pathogene de l"'anneau brun"
7. Li Guo, Yan Maocang, Chang Weishan, Liu chez Tapes philippinarum (Mollusque, bi-valve). C.
Liansheng, M. A Ahnin, Zhihua, L , 2008. Shidy on R Acad. Sci 309, 6.
indirect ELBA method for detecting Vibrio 12. TUTS, 2011. Bao cao hidn hang nghd nudi parahaemolyticus m hard clam Meretrix meretiix Ngao tai VietNam (Bd Ndng nghiep va PTNT).
Linnaeus. Marine Science Bulletin. 13. Yue Xin, 2011. Vibrio Disease, Anti-vibrio 8. Monia El Bour, Fatma Lakhal, Radhia Immuiuty and Vibrio resistance selective Breeding of Mraouna, Annick Jacq, Christine Paillard, Klena, J., Clam Meretrix meretrix. Instihite of Oceanography.
2013. Characterization of Vibrio Isolates from Carpet 14. Yue Xin, Liu Bao, Xiang J., Jia J., 2010.
Shell Clam {Ruditrtpes descussatusi Suffering from Identification and characterization of the pathogenic Brown Ring Disease (BRD) on Tunisian Coasts, effect of a Vibrio related bacterium Isolated from Journal of Microbiology Research 3,8. clam Meretiix meretrix with mass mortahty. J.
9. Ngd Thi Ngoc Thuy, 2011. Didu ha nghidn Invertebr. PathoL 103, 6.
BACTERIA SPECIES ON CULTURED HARD CLAM ( M r e S i f .Jrate^FROM MASSIVE MORTALmES IN COASTAL PROVINCES OF VIETNAM
Bui Ngoc Thanh', Nguyen Thi Hanh', Pham Thi Yen' and Phan Thi Van'
^ Research Institute for Aquaculture Noi Summary
Currently, hard clam Meretnx lyrata is a major cultured mollusc species m coastal provinces of Vietnam due to its high value both m domestic and exported markets as well. However, massive mortalities have occurred recentiy descreasing seriously the hard clam production. This study onducted aims to determine the component and infection of bacteria on cultured hard clam collected from the mortalities. Total 558 hard clams were collected from 11 mortalities during 2 years from 4/2012 to 6/2013 in 7 provinces/city kities of Hai Phong, Nam Dinh, Thai Binh, Thanh Hoa, Ho Chi Minh, Ben Tre and Bac Lieu. Bactena were isolated from heart by culture method using the medium of nuMent agar plus 2% NaCl and TCBS, tiien species were identified by using API 20E KIT. Results showed that high infection of bacteria in hard clam from mortahties is 68.78% in which Hai Phong is 71.78%, Nam Dmh 54.00%, Thai Binh 80.65%, Thanh Hoa 40.49%, Ho Chi Minh 94%, Ben Tre 80% and Bac Lieu 100%. The study has identified 18 bacterial sepcies belongmg to 5 geneus mamly of Vibno, especially there are about 1-2 prominent bacterial species in each province. Those species are V. aigmolyticus m Hai Phong (29.44%) and Bac Lieu (80.95%), V. parabaemoIyticusinNam Dinh (54%), V.Bsherim Thai Binh (43%), V. raimfcosin Thai Binh (39.7%) and Ben Tre (56.66%), V. tubiashii(,12.4%) and V. tapetis (11.5%) m Thanh Hoa, V. ichthyoenteri in Ho Chi Mudi (94%) and Ben Tre (40%). Most of these species have been previously reported as pathogenic agents in aquatic animals. Therefore, this study reports the pnmaiy findings of the present and infection of major bactena that could be pathogens m hard clam. However, it is needed to clarify the role of tiiese bacteria in relation to the occurrence of masive mortahties in hard clam by further studies.
Key words: Bateria, hard clam, massive mortality, meretrix lyrata, mollusc diseases. Vibrio.
Ngudi phan bidn: TS. H i KJi NgaynhSn bit: 28/7/2014 Ngay ttidng qua phan bidn: 29/8/2014 Ngay duy^t dang: 5/9/2014
NONG NGHIEP VA PHAT TRIEN NONG THON - KY 1 - THANG 11/2014 101
