KHOA H p c CONG NGHfi
PHAIM L A P V A TUYEIV CHOIXI CAC DOIXIG l^ctabacillus s p p . c d K H A IXIAIMG KHAIMG IXIAIVI G A Y T H O I Q U A C H O M
C H O M {IMepitetium lappaceurrii S A U T H U H O A C H
Th^ch Thi Ngpc YdnS Nguydn Van Th4nh^
Nguyin Thi NgQC Tnic^, Nguyfin Van Phong^
T6MTAT
Dd tai nghien ctru gdm noi dung phan lap vi khuan Lactobacillus spp. tir cac ngudo trai cay tuoi va cac san pham rau qua len men tmyen thdng s&i c6 b ddng biing s6ng Cuu Long v^ ladm tra kha nSng khang nam cua cac dong vi khuan Lactobacillus spp. ddi voi cac tac nhan gay b6nh sau thu hoach phd bidn tren qua chflm chom (cu the do la Lasiodiplodia pseudothobromae va Pbomopsis mali) da duoc thirc hi^n. Ket qua cho thay trong 56 dong Lactobacillus spp. duoe danh gia, co khoang 98% so lupng cac d6ng the hien boat tinh khang nam cho ca lasiodiplodia pseudothobromae va Phomopsis mah. Tuy nbien sd luong cac d6ng nam co boat tinh khang nam manh (+++) tuong ling vdi duong kinh vong iJrc che > 75 mm khi duoc danh gia tren in-vitro bang phirong phap do tran, thi chiem sd luong rat nho (chi co ba dong ttr 56 dong khao sat kd trSn). Cac dong do la CC6 co ngudn gdc phan lap tir dich trich chom chom l6n men, DC2 tir san pham dua cai chua va DG2 tir san pham dira gang mudi. Ket qua dinh danh bilng phuong phap giai trinh tu gen 16S rRNA va so sanh voi ngan hang gen da xac dmh duoc CC6 la Lactobacillus plantarum vi DC2, DG2 la Lactobacillus fermentum.
Til kh6a: Lactobacillus plantarum, Lactobacillus fermentum, Lasiodiplodia pseudothobromae. Phomopsis mali, khang n^, chdm chdm.
I.BATVANDE
Chdm chdm la mdt loai cay an qua tra thich va dugc trdng phd bien d cac tinh phia Nam Vidt Nam (Cue Trdng trpt, 2013). Qua sau khi thu hoach dd nhidm nam bdnh, trong dd nam Lasiodiplodia pseudothobromae va PhomopslsmaU la mot trong cac nam gay bdnh thdi qua chii ydu sau thu hoach trfen qua chom chdm (Tran Thuy Ai Tam, 2012).
Hien nay, phuong phap bao quan rau qua sau thu hoach bang hoa chat dd diet trir nam da bi han che va cam sir dung b nhieu quoc gia, thay vao dd la nhiing bien phap xu ly sinh hgc. Trong sd dd, Lactobacillus la mdt trong nhiing nhdm Igi khuan cd thd tiet ra chat khang khuan, khang nam, (reuterin, acid lactic, acid caproic, reutericyclm...) (Owen et al., 2004) dugc dimg nhu tac nhan Idem soat sinh hpc, ban che su tan cdng ciia nam benh, nam gay thdi tren rau qua, duy tri chat lupng san pham va than thien vdi con nguoi (Rosalia etal, 2008). Vi vay, nghi&n ciiu 'Than lap va tuyen chon cac dong vi khuan Lactobacillus spp. co kha nang khang nam
' NCS Vi?n NC va PT CNSH. Truang Dai hpc C^n Tho - Vi?n NC vj PT CNSH, Truong Dai hpc Cdn Tho
"' Viijn NC vS PT Cay an qua mien Nam
gay thdi qua chom chom {Nephehum lappaceun})' dupe thuc hidn vdi muc ti^u tuydn chpn dugc dx ddng vi khuan cd kha nang ddi khang cac ddng nam bdnh tren trai chdm chdm.
2. VAT U£U VA PHUDNG PHAP NGHra CUU 2.1. V4t Udu, hda ch^t, phuong tidn V^t lieu: san pham I6n men chua (dua cai mudi chua, mang chua, nem chua,...); mdt sd trai cay c6 tren thi trudng d DBSCL (chom chom, so- ri, cam, nho, di, cam).
Hda chat: Moi trudng MRS_ deMan Rofosa Sharpe, CaCOg, thudc thu Catalase, dung dich iod, crystal violet, fuschine kidm loang, methyl red...
Phuong tien thi nghiem phdng vi smh v|it' Ngudn n ^ benh sau thu hoach tren chdm chdm: tir phdng thi nghiem vi sinh vat hgc thudc Phdng Sau thu hoach, Vi0n Nghien ciiu Cay an qua mien Nam.
(Thach Thi Nggc Ydn cvt, 2017).
2.2. Phuong p h ^ thi nghidm
2.2.1. Phan lap vi khuan Lactobacillus spp.
Cac mau trai cay (cam, so n, chom chom, dua gang, di...) va cac thuc pham len men chua sau khi thu, xu ly va cay tren moi tnrong MRS agar va u ff 37''C ti-ong 48 gid. Sau khi u. duiu- dich man dupe 48 NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG 3/2020
KHOA HOC C 6 N G NGHE
cay chuydn qua mdi trudng MRS agar. Qua trinh cay chuydn ti-fin ffla mdi trudng thach dugc lap lai nhieu lan cho den dp thuan vi khuan dugc xac dinh. (Ngo Thi Phuong Dung va ctv, 2011). Vi khuan Lactobacillus dupe xac dinh khi nhung ddng phan lap cd hinh que, khong sinh bao tu, Gram duong, catalase am tinh, oxydase am tinh va phan giai duoc CaCOa (Vemoux etal, 2003).
2.2.2. XAc dinh kha nang khang nam cua cac dong vi khuan Lactobacillus spp. phan lap dupe trong dieu ki$n in-vitro
Lay 1 khuIn lac don, thuan cua cac ddng vi khuan Lactobacillus spp. cay Ihanh mot dudng dai khoang 2 cm, lap lai m6t Idn niia dd tao thanh 2 dirdng song song tr6n dia MRS agar. Sau do gdi dia, lat ngugc dia va it ky khi 37°C trong 48 gid nham tao didu kien thiic day su phat tridn cua vi khuan. Sau thdi gian ii 48 gid, iKa dugc dd tran vdi 5 ml m6i tnrdng malt extract soft agar (0,05% malt extract va 1% agar) chiia 1 x 10^ bao tu moi chung nam gay bdnh trSn chom chdm/ml cd nhiet dp khoang 35 - 40°C (rieng dia ddi chiing khong cd khuan lac vi khu£n) va li hidu khi d 30°C trong 48 gid (Magnusson va Schnurer, 2001; Kun, 2005). Thi nghidm dupe bd tri theo kieu hoan toan nglu nhien, I9.P lai 3 lan vdi mdi chung nam. Ndu thuc hifen trong thdi gian qua lau, moi trudng thu kha nang khang nam dupe giii trong bd didu nhiet 0 35°C. Ket qua do dudng kinh la tnmg binh ciia 3 lan lap lai. Kha nang lie chd cua vi khuan ddi vdi nam dugc xac dinh theo:
- lie che khong nhin thjly, + dudng kinh vong lie che tir 0,1 - 30 mm, ++ dudng kinh vong lic chd tir 30 - 75 mm, +++ dudng kinh vong uc che >75 mm (Kim, 2005).
. , , , Hinh 1. Dac tinh khuIn lac va hinh dang td bao ddng 2.2.3 Binh danh Uctobacmus spp bangphuong cC6tr6nm6i truong MRS agar v4diupdir6i kinh
Phap giai trmhttrgenlOS rRNA hi&vifltatu Cac ddng vi khuIn Lactobacillus spp. cd dudng
Bang 1. Kdt qua dgc tinh hfaugn Ijic c ^ ddng vi khu&i phan lap tren m6i trudng MRS agar sau 48 gid nuoi c^y kinh vdng khang nam Idn tren 75 mm ddi vdi ca 2 loai n ^ dupe chpn va gui dinh danh tai Cdng ty Nam Khoa (Phdng xet nghiem NK_Biotek 793/58 Tran Xuan Soan, phuong Tan Hung, quan 7, TP. Hd Chi Minh). Su dinh danh dupe tien hanh thong qua phuong phap PCR va giai trinh ti doan gen 16S rRNA Ket qua dupe phan tich bang phan mdm sequecing analysis 5.3 va so vdi ngan hang gen.
2.2.4. Phuong phap xii lysd heu
Cac sd lieu dem mat sd va dudng kinh vdng khang nam ciia cac ddng vi khuan Lactobacillus spp.
dupe xu ly bang phan mem Microsoft Office Excel 2007.
3. KFT QUA VA THAO LUAN
3.1. Kdt qua phan lap vi khudn Lactobacillus spp.
Dac tinh hinh thai khuan lac quan sat dupe trfin 56 ddng Lactobacillus spp. phan lap tir trai cay tuoi va thuc pham len men, cho th^y cac ddng ddu cd hinh dang khudn lac trdn, khong deu, bia nguyen, bia ggn sdng va bia rang cua, Idi, hoi Idi, mau trang due, trdng siia, trang xam va vang nhat tren moi tnrdng MRS agar Qrlinh 1), dupe thd hidn chi tidt trong bang 1.
Ngudn phan lap Trai
cay tuoi Chom chdm Nho S o n Cam
Sd ddng
11 5 2 2
Hinh dang khuan lac
Trdn, bia nguy&n, Idi, hoi Idi Trdn, bia nguydn, Idi, hoi Idi
Trdn, bia nguydn, Idi Trdn, bia nguyen, Idi, hoi Idi
Mau sac khuan lac Trang sua, trang due,
trang xam Trang sira, trSng due
Trang siia Trang siia, trang due
11 1
0 , 1 - 2
KHOA HQC CdNO NGHt
Thuc p h ^ Ign men
Oi Dua bdn bdn
Comnrou Dua cai Dua gang mudi
chua Mang chua Nude tau hu Nem chua tir
birdi 6 2 2 14 4 2 4 2
Tron, bia nguyen, hoi Idi Trdn, bia nguydn, hoi Idi Trdn, bia nguydn, hoi Idi Trdn, khong ddu, bia nguydn, bia ggn sdng, bia rang cua, Idi, hoi Idi Trdn, bia nguydn, Idi, hoi Idi
Trdn, bia nguyen, Idi Trdn, bia nguydn, Idi, hoi Idi Trdn, bia nguydn, Idi, hoi Idi
Trang due . _ Trang due Trdng siia, ti-dng due Trang siia, ti^ng due, vang
nhat Trdng sira Trans siia Trdng sua, trdng due Trdng due, vang nhat T^t ca cac ddng vi khuan phan lap dupe deu De danh gia kha nang khang nam Lasiodiplodia thudc Gram duong va Catalase am tinh, rieng ddng vi pseudotheobromae va Phomopsis mall gay hai ti-fin khuan P18 cd catalase duong tinh va khdng sinh acid chdm chdm eua cac ddng vi khuan Lactobacillus ^'p^.
trong kiem tra vdi CaCOj va Methyl red. phan lap dugc, da thu khang nam ti-en hai loai nam nay. Sau khi do tran vdi 5 ml mdi trudng 0,05% malt extract va 1% agar cd chiia 1 x 10^ bao hi nin {Lasiodiplodia pseudotheobromae va Phomopsis mali)/m] 48 gid, dudng kinh vdng khang nam eiia 56 ddng vi khuan dupe do va kha nang tie che ciia cic ddng vi k h u & ciing duoc xac dinh (Hinh 3 va Bang 3).
Hinh 2. Kha ndng phdn giai CaCOj (a) va kdt qua methyl red duong tinh ctia cic ddng vi khudn (CC7,
MCI, CC3, DC2) so vdi ddi chiing ff)C) (b) Mdt sd thu nghidm khac nhu kiem tra kha nSng hinh thanh indole, kha nang sinh H2S, dich hda gelatin, methyl red, VP, kha nang phan giai CaCOg cung dupe hdn hanh kidm tra. Tdng 56 ddng vi khuan thuan phan lap dupe deu khdng co kha nang dich hda gelatin, khong sinh indole, khdng cd kha nang sinh HgS. Ben eanh dd, 56 ddng vi khuan thuan ddu cho kdt qua methyl red duong tinh (Hirib 2) va VP (Voges-Proskauer) am tinh.
3.2. Kha nang khang n ^ cua die ddng vi k h u &
Lactobacillus spp. phan % dupe trong didu kidn in- VJttV
Bkag 2. I^t qua kha nftng lic chd Lasiodiplodiapseudotbeobromaewk Pbomopsis maHciia cic ddng vi khuin Hinh 3. Phd khing n ^ I^siod^Iodia pseudotheobromae ctia ddng CC6 v i MC2 so vdi (lA
chiing khdng c6 vi khudn ff)C)
Trii cay tuoi
Ngudn phan lap Chdm chom
Nho
Sd ddng 1 9 1 5
Lasiodiplodia
pseudotheobromae Sddong
-
++
+++
++
2 9 1 4
Phomopsismal i
++
+++
L_ -H-+
50 NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG 3/2O20
KHOA HOC C 6 N G NGHl
Thuc phdm len men
Sari Cam
6i
Dua bdn bdn Comnrou
Dua cai
Dua gang mudi chua
Mang chua Nude tau hu Nem chua tir budi
2 2 2 4 2
2 13
1 3 1 2
4 2
++
++
+ ++
++
++
-M- +++
++
+++
++
-H- ++
2 2 1 5 1 1 2
14
4 1 1 4 2
+++
+++
++
-H-+
++
+++
-H-+
•H-+
+++
++
+++
+++
+++
Ghi chii: - tic che khdng nhin thiy, + duong kinh vong IK chS tit 0,1 - 30 mm, ++ dimngkinh vong uc chStfi30- 75mm, +-H- duangkinh vong uc chi>75mm
Qua kdt qua kidm tra kha nang uc che nam Lasiodiplodia pseudotheobromae bang phuong phap Ao tran (Bang 2), nhin chung 55 ddng vi khuan Lactobacillus spp. deu cd kha nSng lie che nam nay va chi cd 1 ddng CC5 dugc phan lap tir chdm chdm khdng cd kha nang ire che trong sd 56 ddng vi khuan Lactobacillus spp. phan lap dupe. Trong dd, chi cd 3 ddng ta CC6, DC2, DGMC2 cd kha nang lie che nam Idn nhat vdi dudng kinh vdng lie che >75 mm. Chiing dugc phan l|p lan lugt tir chdm chdm, dua cai va dua gang mudi chua. Bdn canh dd, 50 ddng cd kha nang lie che n ^ vdi muc do trung binh (dudng kinh vdng lie chd 30 - 75 mm) ciing dugc phan lap tir chdm chdm, nho, so ri, cam, di, bdn bdn, com rupu, dua cai, dua gang mudi chua, mang chua, nude tau hu, nem chua tir budi. Ddng thdi, kha nang lic chd nam vdi miic dp ydu (dudng kinh vdng lic che 0,1 - 30 mm) thudc vd 2 ddng dupe phan lap tir 6i.
pi^MM
^^^^^^^^^^^^1
Hinh 4. Phd khing n & i Phomopsis mah'cCia ddng DC2 v i MCI so vdi ddi chiing (^Q Theo bang 2, kha nang lic chd nam Phomopsis mah, nhin chung tdng 56 ddng vi khuan Lactobacillus spp. phan lap ddu cd kha nang lie che n ^ Phomopsis mali (Hmh 4). Trong dd 50 ddng vi
khuan cd kha nang lic che Idn nhat vdi dudng kinh vdng lie che >75 mm dupe phan lap tir trai cay tuoi, thuc pham len men va 6 ddng vi khuan cd kha nang tre che nam vdi miic dp trung binh (dirdng kinh vdng ue chd 30 - 75 mm) dupe phan lap tir chdm chdm, nho, di, dua bdn bdn, mang chua.
Khi so sanh kha nang lie che nam Lasiodiplodia pseudotheobromae va Phomopsis mah ciia cac ddng Lactobacillus spp. phan lap dupe, cho thay kha nang lie che nam Lasiodiplodia pseudotheobromae cua cac ddng Lactobacillus spp. ydu hon so vdi Phomopsis mali Theo Tran Thuy Ai Tam (2012), ca Lasiodiplodia pseudotheobromae va Phomopsis mah la hai loai nam gay thdi trai chu yeu tren chdm chdm sau thu hoach, tuy nhien Lasiodiplodia pseudotheobromae ludn the hien su phat trien manh hon so vdi Phomopsis mah tren tat ca eac dieu ki&n dugc danh gia tren mdi trudng PDA hay tren sir lay nhidm nhan tao tren trai chom chdm. Tdc dp phat trien cua Lasiodiplodia pseudotheobromae nhanh hon the hien qua hinh dang va kich thudc vet benh chi sau 48 gid lay nhidm, trong khi dd ddi vdi Phomopsis mali la 120 gid. Ngoai ra, cd thd nam Lasiodiplodia pseudotheobromae phat trien tren mdi trudng PDA nhanh hon ndn tao bao tu nhidu va nhanh hon so vdi PhomopslsmaU va day cd thd la ly do tai sao hau het cac ddng vi khuan Lactobacillus spp. da cho kha nang uc che manh (+++) ddi vdi Phomopsis mah, trong khi dd nam Lasiodiplodia pseudotheobromae, phan Idn cho kha nang uc che d miic dd tnmg binh (++).
51
KHOA HOC CONG NGHt Vl khuan LAB da dupe chung minh nhu bien
phap bao quan sinh hgc (Milani etal, 1998), chu ydu ngan ngira hu hdng, keo dai thdi gian su dung cua san pham thuc pham va dam bao an toan cho ngudi sir dung (Lowe va Arendt, 2004). Thdng qua vide su dung vi khuan acid lactic hoae san pham trao ddi chat ciia chimg (Ross et al, 2002) nhu cay LAB chgn Ipe vao san pham thuc phim cd the lie chd su phat trien cua vi sinh vat khdng mong mudn. Vi vay, LAB dugc coi la an toan GR/^ (Generally regarded as safe) va ddng vai trd chat bao quan thuc pham (Stiles, 1996). Hau het cae ddng vi khuan Lactobacillus spp. phan lap duoc deu the hien hoat tinh lie che chdng lai nam Lasiodiplodia pseudotheobromae va PhomopslsmaU trong didu kien in-vitro, tuy nhien kha nang lie che khac nhau.
Kha nang khang n ^ cua cac ddng vi khuan Lactobacillus spp. thi phu thudc vao ngudn gdc ma chiing dugc phan lap vi ddi tugng loai chung nam ma chiing cd kha nang lie che. Trong nghidn ciiu cua Magnusson et al (2003), khi danh gia tren mdt sd lupng Idn 1200 ddng vi khuan Lactobacillus spp. ddi vdi loai nam A Aimigates bang phuong phap dd tran, nhung chi tim ra khoang 10% ddng phan lap cho hoat tinh khang nam va chi ed 4 - 5% cho hoat tinh khang nam manh. Kdt qua nghien ciiu ciia Magnusson etal .(2003) khac voi ket qua kha nang khang nam cua chiing tdi, trong 56 ddng vi khuan Lactobacillus spp.
dupe danh gia da cho thay tren 98% cd hoat tinh khang nam ddi vdi ca hai loai Lasiodiplodia pseudotheobromae va Phomopsis mah va trong eac sd nay thi cd tdi ba ddng CC6, DC2 va DGMC2 cho hoat tinh khang nam manh.
Kha nang ire che nam Lasiodiplodia pseudotheobromae va Phomopsis mah cua cac dong vi khuan Lactobacillus spp. cd the dupe giai thich theo nhieu tac gia da nghien ctru. Theo Magnusson e^ a/ (2003), cd nhidu miic do tic chd nam do sinh ra nhidu hgp chat khang nam khac nhau. Dien hinh nhu acid hiru co, acid lactic, acetic (Batish et al., 1997), acid caproic (Corsetti etal, 1998), acid formic, propionic va diacetyl (Lindgren va Dobrogosz, 1990).
Bdn eanh dd, LactobaciUus spp. cung smh ra hydrogen peroxide (Batish et al, 1997), cyclo (L-Phe- L-Pro), cyclo (l^Phe-tt3ns-4-OH-L-Pro) va acid phenylaeetic (Magnusson et al, 2003), acid 4- hydroxy-phenyllactic. acid beo 3-hydroxy (Sjogren et al, 2003). Ngoai ra, hgp chat ed chiia protein
(Lavermicocca etal, 2003), dipeptide vong (Rouse va van Sinderen, 2008) va bacteriocin cung dugc sinh (Bamidele etal, 2011). Hoac cd tiid do chinh bdi kha nang sinh acid lam giam pH cua mdi trudng. nguydn nhin true tidp lic chd su phat tndn cua nam. Theo T r ^ Thuy Ai Tam (2012), d pH thip 4 hay 4,5, Lasiodiplodia pseudotheobromae va Phomopsis mali phat tridn r^t ydu va hau nhu khdng phit trien khi duoe eay liy nhidm nhan tao tren trai chom chdm.
Tuy nhien kha nang lie che eua cic ddng LactobaciUus spp. ddi vdi nam Lasiodiplodia pseudotheobromae va Phomopsis mah \a mdt nghidn ciiu tuong ddi mdi vi chua tim thay nghidn ciiu nao trong va ngoai nude dupe thuc hien ddi vdi 2 loai nam nay.
Thu nghiem ddi khang ctia 56 ddng vi khuan Lactobacillus spp. tren 2 loii nam Lasiodiplodia pseudotheobromae va Phomopsis mah deu cho kdt qua kha tdt. Dac biet 2 ddng CC6, DC2 cd kha nSng lie che Idn nhat ddi vdi 2 loai n ^ so vdi eac dong cdn lai, do do dugc chgn lira de xac dinh den tdn loai.
3.3. Kdt qui dinh danh Lactobadttus spp. b ^ phuong phip giii hinh tu gen 16S rRNA
Ba ddng CC6, DC2 va DG2 cd kha nang khing nam Idn ddi vdi c i hai loii nam gay benh thdi qua Lasiodiplodia pseudotheobromae va Phomopsis mali dupe chpn de xac dinh ddn tSn loai bang ky thu^t PCR, giai trinh tu doan gen 16S rRNA va so txtVL ngan hang Gen NCBI
Ddng CC6, DC2 cd tdng sd nucleotide dupe giai Idn lugt la 531 va 498 nucleotide va cho kdt qua dong hinh 10096 vdi loai Lactobacillus plantarum BH1541 va Lactobacillus fermentum ND04 va dupe gpi la Lactobacillus plantarum CC6 va Lactobacillus fermentum DC2.
Ket qua so sanh tren ngan hang gen NCBI cho tiiay ddng DG2 cd trinh tu gen tuong ddng 100% vdi ddng vi khuan LactobaciUus fementum F-6 ndn dugc gpi la ddng LactobacUlus fementum DG2.
Ket qua nghien cuu cung phii hop voi ket luin ciia Magnusson va ctv, 2003 eho rdng cac chting vi khuan Lactobacillus spp. cd k h i nang lic chd nam benh bdi kha nang sinh hop chat khang nam cua chiing nhu: acid huu co, acid lactic, acetic, acid caproic, acid formic, propionic va diacetyl, hydrogen peroxide, cyclo (L-Phe-L-Pro), cycU. (L-Phe-ti-an&4- OH-L-Pro) va acid phenylaeetic,...
NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG 3/2020
KHOA HOC C 6 N G N G H £
4.KETLUANVJIIIENGH 4.LKdtlu$n
Dua vio d§c tinh hinh thii khuan lac, hinh thai td bio v i thu nghidm smh hda da phan lap duoe 56 ddng vi khuan LactobaciUus spp. tir ti-ai eay tuoi va thuc pham len men, trong dd chu ydu tir chdm chdm va dua cai.
Tat ca eac ddng vi khuan phan lap dupe deu cd kha nang uc che nam Lasiodiplodia pseudotheobromae - gay bdnh thdi den va thdi lan md trdn qui chdm chdm trong didu kien in-vitro theo phuong phap dd trin trir CC5. Trong dd kha nang lic che nam vdi mirc do trung binh l i chu yeu (dudng kinh 30 - 75 mm). Dac bidt. 3 ddng CC6, DC2 va DG2 cd kha ning lie chd Idn nhat vdi dudng kinh tren 75 mm. Hau hdt cac ddng vi khuan nay ddu cd kha nang lie che cao ddi vdi nam Phomopsis mah.- la mdt trong cac vi sinh vat gay bdnh thdi qua chdm chdm va ciy khac.
Dua vao ket qui giai trinh tu gen IBS rRNA va so sanh vdi ngan bing gen da xac dinh ddng vi khuan CC6 dupe phan lap tir -chdm chdm thudc vd loai LactobaciUus plantarum. Ddng vi khuan DC2 va DG2 dupe phan lap lan lugt tir dua cai va dua gang mudi chua thudc ve loii LactobaciUus fermentum. Hai loii vi khuan cd ich nay ciing da dugc cdng bd bdi cic cdng trinh nghidn ciiu khic vd kha ning khang n ^ gay bdnh thdi qui chdm chdm va mdt sd ciy khic (Magnusson, 2003; Gustavo, 2009).
4.2. Dd nghi
Danh gii them boat tinh khing nam eua L plantarum va L fermentum ddi vdi mot sd loai nam gay hu hdng khic ti-dn chdm chdm.
iChao sit thdm kha ning chdng chiu cua 2 loai L.
plantarum va L. fermentum dudi dieu kidn khac nghiet (nhidt do mdi trudng d vuon chdm chdm) ngoii thue dia v i dinh gii hidu qua cua 2 loai vi khudn niy bang cich phun tnrde thu hoach de lam giam benh trdn chdm chdm sau thu hoach dua theo khao sat cua Gustavo, 2009).
TAIUEUTHAMKHAO
1. Cue Trdng trpt, 2011. Hien trang va0ai phap phM tnen san xuat, ti&u thu ciy an trai Nam bp trong thoi 0an toi. Hdi nghi Ian thii hai. Hien trang sin xuat va tieu thu ciy an ti-ai d- Nam bd va giai phap phit trien cac viing cay in trii tip trung theo
VietGAP tai Tien Giang 24/5/2011. NXB Ndng nghiep. Trang 91-108.
2. Tran Thuy Ai Tam, 2012. Nghi€n cuu benh do nam tren chom chom sau thu hoach tu hmh thiic canh tac theo mo hinh VietGAP va mo hmh tu do.
Luan van thac sy nganh Cdng nghe sinh hpc, Trudng Dai hgc Can Tho, Viet Nam, pp. 12,32-53.
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khudn lactic cd kha nang sinh ch^t khang khuan.
ISOLATES AND SCREENING OF lACTOBACIUMSSYMSiiS FOR THEIR ANTIFUNGAL A C n v m E S AGAINST SOME FUNGI CAUSING POSTHARVEST DISEASES ON RAMBUTAN
FRUITS {Nephehum I^paceuni)
Thach Thi Ngoc Yen^ Nguyen Van Thanh^, Nguyen Thi Ngoc Truc^, Nguyen Van Phong' 'PhD student, Mekong delta Development Research, Can Tho University
^Mekong delta Development Research, Can Tho University
^Southern Horticultural Research Institute Summary
This research included the isolation of lactobacillus spp. from fresh fruits and the tiaditional fermented produces available in the Mekong nver delta region, the examination on antifungal activity of Lactobacillus spp. against Lasiodiplodia pseudothobromae and Phomopsis mali, which have been considered as main agents causing postharvest disease on rambutan fruit, was conducted. Results indicated that approximately 98% out of the screened 56 isolates showed inhibitory activity to both Lasiodiplodia pseudothobromae and Phomopsis mali. However, amount of Lactobacillus spp. which had sti-ong activity (+++) with a relative inhibitory cycling diameter (>75mm) as tested under w-vitro by using overlaid method was very less (only three isolates). Those three isolates are CC6 (isolated from rambutan); DC2 (from dua cai pickle) and DG2 (dua gang muoi pickle) respectively. Result of name identification by using PCR and a ADN sequence, it indicated tiiat CC6 was identified as Lactobacillus plantarum and DC2 and DG2 isolates as Lactobacillus fermentum.
Keywords: Lactobacillus plantarum, Lactobacillus fermentum, Lasiodiplodia pseudothobromae, Phomopsis mali, antifungal, rambutan.
Ngudi phin bidn: GS.TS. Nguydn Vin Tu^t Ngiy nh4n bii: 13/01/2020
Ngiy thdng qua phin bidn: 14/02/2020 Ngiy duydt dftng: 21/02/2020
54 NONG NGHIEP VA PHAT TRIEN NONG T H 6 N - KY 2 - TH, • 3/202O
