T R U O N G D A I H Q C D O N G THAP Tgp chi Khoa hpc s6 28 (10-2017) K H A O S A T A N H HlTCfiVG C U A N O N G D O C A R B O X Y M E T H Y L C E L L U L O S E
BtN K H A N A N G S I N H T R U ' D N G , T O N T ^ I v A K H A N G N A M C U A V I K H U A N LACTOBACILLUS T R E N C H U N G N A M M O C
LASIODIPLODIA PSEUDOTHEOBROMAE
• Nguygn Thi Ngoc True", D 5 Thj Hi§n", Nguyen Phan Thao'™) Tdm tat
CMC (Carboxymethyl cellulose) dugc sie dung tgo mdng bao gdi di bdo qudn trdi cdy, nhdm giie dugc do tuoi md khdng dnh hudng den chdt lugng cua thue phdm. Cdc chung vi khudn Lactobacillus spp. dge biet IdL.plantarum CC6, L.fermentum DC2 vd L.fermentum DG2 dugc chimg minh ed hogt tinh khdng ndm cao. Nghien cuu dd sie dung kit hgp CMC vd ba chung vi khudn Lactobacillus spp nhdm tdng hogt tinh khdng ndm Lasiodiplodiapseudotheobromae gdy benh tren trdi edy dgc biet chdm chdm sau thu hoach de keo ddi thdi gian bdo qudn. Kit qud khdo sdt eho thay ede ehung vi khudn Lactobacillus spp d 13°C phdt trien tdt han nhiit do phdng. Kit hgp vdi 1% CMC d nhiet do phdng vd 1,5% CMC d 13°C vi khudn L.fermenium DC2 vd Lplantarum CC6 cd khd ndng phdt triin vd khdng ndm benh tdt nhdt
Tie khoa: Trdi edy bihu hong, Lactobacillus plantarum, Lactobacillus fermentum, Carboxymethyl cellulose, Lasiodiplodia pseudotheobrvmae.
1. Bat van de
Nam Lasiodiplodia pseudotheobromae thudng gay ra su thoi rua, mat nude vd biln mdu cia vd cdc loai tidi cay ma nd cdmat Benh xdy ra tten mpt vung nhd vd qud, benh thudng xuat hien vao ngay thu 3, thu 4 ttong qua trinh bao quan.
Ban dau, ti'en vd qua chi xuat hien mpt vet man nau rat nhat, rdt md cd dudng kinh khodng 0,8 cm.
vlt benh tiep tuc phdt triln lan dan ra b l mat vd qud vdi tdc dp kha nhanh. Sau khi xuat hien 1 din 2 ngay vet benh chuyen sang mdu nau ddm, chay nude vd ttdi cay bdt dau hdng. Phan bi nhiem ndm cd mdu den vd xuat hien cac khuan
ty nam [7].
0 nhiet do cao vd am dd thap ttai cdy de bi hu hdng do su phdt trien cua nam benh. Do vay, ttdi cay cd thdi gian bao qudn ngdn.
Vi^c su dung thudng xiQ-en thuoc diet ndm de kilm sodt benh se anh hudng xau din mdi trudng vd it dupc ngudi tteu dung c h ^ nhdn [5] Ngoai ra, sau thu hoach, ttai
'•' ViSn CSy an qui MiSn Nam '•"' Tni6ng Dai hpc CSng nghidp Thvc phim Thanh ph6 H6 Chi Mmh
'"•' Sinh viSn, Truong Dgi hpc Cong nghidp Thvc pbkm Thanh phi H5 Chi Mmh
cay cdn dupc bdo qudn bang phuong phdp x i ly hda chat hogc kiem soat khi quyen nhimg kit qud thu dupc chua thuc su khd quan [10].
CMC (carboxymethyl cellulose) dupc i n g dung phi biln ttong tgo mang bao gdi de bdo qudn ttai cay, nham giu duoc dp tuoi Idu md khdng dnh hudng din chat lupng cua thuc pham. Trong [11], Tinzhe va cpng su da nghien cuu s i dung mdng bao CMC bdo quan qua ho ddo d nhiet dp thudng Kit qua vi§c s i dung cac mang CMC han che qua trinh oxy hda chat beo md khdng dnh hudng din cau trie cua qud. Kit qua nghien ciu bdo qudn cam mdt cho thay cd the lam gidm ton that khoi lupng cia cam mat vd keo dai thdi gian ton tru cam den 9 tuan bang bi?n phap xu ly ozone kit hpp voi bao mdng CMC (hogc mang pectin) vd bao qudn ttong bao bi PE (hodc PP) khdng due Id dnhiet ddl0"C [9]. Theo [11]
da nghien cin dnh hudng cia CMC va alginate kit hop vdi men bia vl bdo qudn nho sau thu hogch \^ec s i dyng 2%
cua alginate va 3% CMC kit hpp vdi nam men bia giip cho vi^c mat ttpng lupng va tong chat rdn hda tan han che.
Hi^n nay, vi?c nghien cuu, phdn liqi cdc chiing Hinh 1. Trieu chung bSnh thoi lan mif
do LasiotSphfdia pseudotheobromae gdy r a trSn chdm chdm
69
TOU(3NG DAI HOC DQNG THAP Tap chi Khoa hpc s6 28 (10-201 vi sinh vgt cd hogt tinh doi khdng chong lai mdt so
benh sau thu hoach tten ttdi cay tuoi ndi chung vd chdm chdm ndi rieng ciing dang dupc quan tam va ling dung vdo tiiuc t l [6], [4], [8]. Cd till ke din 3 chiing vi khuan Lactobacillus spp. (CC6, DC2 va DG2) dupc phdn 1 ^ va tuyin chpn t i 56 chung vi khuan Lactobacillus spp. cd hoat tinh doi khdng chong lgi nam Lasiodiplodia pseudotheobromae vd Phomopsis mali gay benh thoi tren chdm chdm, Nghien cuu nay kit hpp nhung dac tinh uu viet cua chat mang CMC vdi 3 chung vi khuan Lactobacillus spp nham tdng hogt tinh doi khdng chong lai nam Lasiodiplodia pseudotheobromae gdy benh tten ttdi cay dl cd thi keo dai thdi gian bdo qudn vd xuat khau.
2. Vat lieu va phuong phap nghien cuu 2.1. Vat lieu nghien cuu
Hai giong vi khuan Lplantarum CC6 (phan
\^ t i chdm chdm), Lfermentum DC2 (phdn lap t i dua cdi) va L.fermentum DG2 (phdn lap tu dua gang) duoc thuc hien bdi tdc gidNguyen Thi Ngpc Trie vd cdng tdc vien (2013) l^am Lasiodiplodia pseudotheobromae dupc phan lgp bdi tac giaTran Thuy Ai Tdm (Ludn van Thgc sy, ndm 2012) tai ViSn Nghien cuu vaPhat triln cdng nghe Sinh hoc, Dai hoc Can Tho. Mdi trudng MRS dl nudi cay, mdi ttudng PDA khdo sat hoat tinh khdng nam cia hai vi khuan ttSn. Chdt mang CMC mua tai Cdng ty Trach nhiem huu ban Phuong Duy (Suntze Chemical Co. Ltd). Dung dich doi khang la dung dich tang sinh vi khuan Lactobacillus spp. cd bo sung CMC vdi cdc nong dp khac nhau. Doi tuong doWhrngXauam Lasiodiplodia pseudotheobromae dupc phdn lap t i chdm chdm.
2.2. Phirong phap nghien cuu 2.2.1. Thi nghiem 1; khdo sdt khd ndng sinh trudng vd tdn tgi eua vi khudn Lactobacillus spp.
kit hgp CMC tren MRS
Thi nghiem dupc b l tti hodn toan ngau nhien gom 3 nhan to vdi 42 nghidm thuc, lap lai nglu nhien 3 Ian. Nhiet dd: nhi?t dp phdng (khodng 25±2''C) vd 13°C (nhiet dp bdo quan cdc logi ttdi cdy xuat khau). Nong do CMC: 0; 0,25; 0,5; 0,75;
1; 1,25; 1,5 (%). Ba chung vi khuan. Lplantarum CC6, L.fermentum - DG2, Lfermentum - DC2.
Phuong phdp thuc hiin: Hut 1 ml dung dich vi khi^ Lactobacillus spp, mdt dp 10^ CFU/ml,
tang sinh trong moi trudng MRS ldng trong;
gid. Sau dd, bo sung lan lupt cac dung dich CM cd nong dp 0; 0,25; 0,5; 0,75; 1; 1,25; 1,5 (%) vi dich tang sinh vi khuan; tiln hdnh pha loang ml t i nong dp 10' din 10"^ CFU/ml. Ding mi cropip hutO,01 ml t i mdi nong dp pha loang mau nhu tn vao dia mdi trudng MRS agar dd chuan bi true (moi nong dp 1 ^ lai 3 Ian). Dpi khd, dgy dia, ti ngupc Igi va u ky khi d nhiet dp phdng (khoar 25±2''C) va nhiet dp 13°C. Dim mat dp vi khua Lactobacillus spp. d 6 khodng thdi gian (1, 3,:
7, 14, 21 ngdy).
Cki tieu theo doi: So khuan Igc rdi hien die tten dia dem mdt dp ttong moi tnidng MRS agi t i nhimg nong do pha loang d cac nghiem thu khao sat
2.2 2. Thi nghiem 2: Khdo sdt dnh hudng nin do CMC den hogt tinh khdng ndm cdc chung i khudn Lactobacillus spp.
Thi nghi?m duoc bo tri hoan toan ngdu nhie gom 3 nhan to vdi 42 nghiem thuc, Ijqj lai nga nhien 3 lan Nhiet dp: nhiet dp phdng (khodn 25±2''C) vd 13°C. Nong dd CMC 0; 0,25; 0,'.
0,75; 1; 1,25, 1,5 (%). Sinh khoi cua cac gion vi khuan Lplantarum CC6, L.fermentum DG.
Lfermentum DC2.
Phuong phdp thuc hien: Tang smh vi Idiua Lactobacillus spp. trong mdi trudng MRS 16n ttong 24 gid. Sau dd, bo sung lan luot CMC vdi cl nong do 0; 0,25; 0,5,0,75; 1; 1,25; 1,5 (%)vao die tang sinh vi khuan (dung dich doi khang) Hut 1 n dung dich doi khang phi Ien moi trudng PDA Tie hdnh cay ndm Lasiodiplodia pseudotheobroma Ien mdi trudng PDA phu dich doi khang da due dl khd, kich thude nam d cac nghiSm thic kha sat nhu nhau. Dgy kin vd up ngupc dia u ky kl d 13°C va nhi§t dp phdng. Theo ddi hogt tinh di khang cua dung dich kit hpp d nhi?t dp phdng sa 40 gid va 13 ngdy d nhiet dp 13°C.
Chi tieu theo dot: Do dudng kinh nam phi triln tten be mgt i£a thgch PDA Dudng kinh nai cua vi khuan dupc tinh tu ^ I m to nam hi ?n tt&i d do doi xung qua tam la tiigch nam Laswdiplod pseudotheobromae cay tten mdi tnrdng PDA. K qua do dudng kinh la trung binh cia 3 lan lgp 1^
Khd nang uc chl cia vi khuan doi vdi nam dm;
xac dinh nhu sau:
rRn(3NG DAI HOC DONG THAP Tap chl Khoa hpc s d 28 (10-2017) Khd nang khang nam (%) = [(A - a)/ A]x 100.
Trong do: A: dudng kinh trung binh ba Ian sp lgi cua dia nam doi chung; a: dudng kinh trung linh ba Ian lap Igi cia cdc nghiem tiiuc khdo sat.
2 2.3.Xulysdlieu
Cdc tiii nghiem dupc ldp lai 3 Ian, kit qud luoc ghi nhan va xu ly thong ke bdng phin mem Statgraphic Centurion XVI, Excel 2013 vdi muc id tin cdy 95%.
3. Ket qua va thao l u ^
3.1. Khao sat anh huvng nong do CMC din kha nang sinh truong, ton tai va ho^t tinh khang nam cua cac chung vi khuan Lactobacillus spp.
s nhiet do phong
3.1.1. Anh hudng eiia ndng dd CMC din khd mng sinh trudng vd ton tgi cua cdc chung vi khudn Lactobacillus spp. a nhiet do phong
Ket qud khdo sdt dnh hudng CMC den khd ldng sinh trudng va ton tgi c i a cdc chung vi khuan, cho thay: thdi gian ton tai cia cdc chiing vi khuan L.fermentum DC2, L.fermentum DG2 vd Lplantarum CC6 ttong mdi trudng MRS den ngay 21 cdn ton tai. Cac ching vi khuan Lactobacillus 3pp. mat dp tucmg doi cao khi kit hpp vdi CMC d ihung nong dp khdc nhau. Giiia cdc nghidm thuc khdng cd sir chenh I^ch Idn ve mat dp. Dieu nay the hien cu tiie d ting ching vi khuan Lactobacillus 5pp. (Hinh 2)
6 nhiet dp phdng, su phdt triln cua vi khuan
r:
*^^ ^ i _ ^Hlnb 2. Khd nang sinh tnr&ng vd tin tai cua vi khuan DC2, DG2 va CC6 kit hgrp CMC d nhi$t do ph&ng
Jhichu DC = dSi chiing. 0.25 = DC2 + 0.25% CMC. 0.5 = DC2 + 0.5% CMC. 0,75 = DC2 + 0,75%
CMC. 1.0 = 1X2+ 1.0%CMC. 1.25 -DC2 + 1.25%CMC,1,5 -DC2 + I.5%CMC
Lfermentum DC2 keo ddi den hon 21 ngdy. Khi kit hpp vdi CMC ttong cdc nghiem thuc khao sat nong dp tu 0,25% den 1,5%, vi khudn Lfermentum DC2 vdn phdt triln tdt vdi dudng sinh trudng tucmg duong vdi nghiem thuc doi ching (Hinh 2a). Trong so cac nghiem thuc ket hpp CMC, nghiem thic vdi nong dp 0,75% CMC cd mat dd vi khuan cao nhat la 10^ CFU/ml sau 5 ngay, ttong khi cdc nghiem thic khdc hau nhu giam. Ondngdd 1%, l,25%val,5%
CMC, vi khuan Lfermentum DC2 cd dudng sinh trudng tuong dong, mat dp cao nhat sau 1 ngdy Id 10* CFU/ml, ttong khi nghiem thuc doi ching chi dgt khodng 10^ CFU/ml.
Vl khuan L.fermentum DG2 chi ton tai duoc khodng 14 ngay trong mdi trudng MRS. Khi kit hop vdi CMC, vi khuan Lfermentum DG2 cd thi keo ddi thdi gian ton tgi hon 21 ngdy d cdc nghiem thuc cd nong do t i 0,25% din 1,5% (Hinh 2b). Ket qua thu dupc d Hinh 2b cho thay khd nang ton tai cia VI khuan Lfermentum DG2 d cac nghiem thuc tuong duong nhau, gan nhu khdng cd sir khac bi?t.
Mgt dp VI khuan giam dan theo thdi gian. Tvy nhien, den ngdy thu 21 van duy tri dupc d muc khd cao khoang 10" CFU/ml Cd till tiiay, nong dd CMC tuy cd anh hudng den su phdt tnen cia vi khuan Lfermentum DG2 nhung khdng Idn.
Tuong ttr nhu vi khuan L.fermentum DG2, d nhiing dp CMC khdc nhau vi khuan Lplantarum CC6 khdng cd su khdc biet nhieu (Hinh 2c). Ket
qua thu duoc d Hinh 2c cho thay vi khuan L.plantarum CC6 cd the tdn tai trong mdi trudng MRS cd bo sung CMC vdi ndng dp khdo sat tti 0,25% den 1,5%, tiidi gian ton tai keo ddi den ngdy thu 21. Songd nghiem thuc DC, thdi gian tin tgi cia vi khuan Lplcmianim CC6 ngdn hon, khoang 14 ngdy. Nghiem thuc vdi nong dp 1,5% cd mat dp 10'' CFU/ml gan nhu khdng biln ddng sau 3 ngay dau tten. Trong khi dd cdc ngbem thuc kit hpp khac diu gidm mgnh sau 1 ngdy (trung binh khoang 10^ CFU/ml). Nong
7 1
T R U d N G DAI HOC D O N G T H A P Tap chl Khoa hpc so 28 (10-201 dp 0,5%. vi khuan phdt tiien on dinh nhat vd dat
mgt do cao nhat so vdi cac nghi?m thuc cdn ton tai Vl khuan. Trong dd, nong dp 0,75% vi khuan Lplantarum CC6 dgt mdt dp cao nhdt (10^ CFU/
ml) sau 7 ngay, gap 103 Ian so vdi nghiem thuc doi chung cing thdi dilm.
Nhu vgy, d nhiet dp phdng chung DC2 cd kha nang tdng trudng vd phat tnen on dinh nhat d nong dp CMC 0,75%. Chung DG2 vd CC6 cd muc tdng trudng tuong duong nhau.
3.1.2. Anh hudng eua ndng do CMC din hogt tinh khdng ndm cdc ddng vi khudn Lactobacillus spp. d nhiet do phong
Nam Lasiodiplodia pseudotheobromae dupc ciy len mdi trudng PDA phi dich doi khang theo ddi ttong 40 gid. Ket qud khdng nam dupc the hien d Bdng 1 vd Hinh 3
Bang 1. Ket qua doi k h i n g nam Lasiodiplodia pseudotheobromae cua cac chung vi khuan Lactobacillus spp. kit hop v ^ CMC il nbi£t do phong
Nghi£m thux:
NT13 NTM NTS NT12 NTH NT7 NT9 NT16 NT6 NT21 NT18 CV(%)
Kha nang khang nam giira cac nghiem thuc
31,25-
(%)
33,85"
36,08«
44,63' 47,23' 60,98- 63,21'' 66,93*
71,01"
76,59"
77,33"
= 0,57; LSD Nghiem
thuc
NT17 NT20 NTIO NT15 NT5 NT4 NT19 NT3 NT2 NTl
Kha nang khang nam giira cdc nghiem thitc
80,68'
(%)
84,02' 92,57- 100- 100- 100- 100- 100- 100- 100' (5%) = 2,82
* Ghi chU: Cdc gid tri a bdng Id trung binh ciia ba ldn lgp lai; trong cung mot c6t. cdc chir cdi biSu thf sw khdc biet l(h6ng cd ;^ nghta vi thdng ki& miic 5% qua phep ihieDuncan: NTl = DC2DC(+): NT2 = DC2 + 0,25% ClidC. Nr3=DC2^ 0.5%
CMC:NT4=DC2 + 0.75%CMC;NT5=DC2 + ]%CMC:NT6
= DC2 + 1.25% CMC: NT? = DC2 + 1.5% CMC; NTS = DG2 DC(+J: NT9 ^DG2 + 0.23%CMC; NT}0=DG2 + 0,5%CMC;
NTll =DG2 + 0.75% CMC; NTH ^DG2 + i% CMC; NTJ3
= DG2 + 1,25% CMC; NT14 = DG2 + 1,5% CMC; NT15 = CC6DC(+);NT16 = CC6 + 0.25% CMC; NT17= CC6 + Q.5%
CMC: NT 18 = CC6 + 0.75% CMC; NTl 9 =CC6 + 1% CMC.
NT20^ CC6 + 1.25% CMC; NT2I = CCiS + 1.5% CMC; CV (Coefficient of variation - he sdbien thien): LSD (Least significant difference - sai khdc bi$tnh6 nhdtcd;^ nghta).
S n h 3. Hoat tinh khang nam cua vi k h u ^ Lactobacillus k i t hop CMC a n h i ^ do phdng
Ghi chu: So lieu ghi a cot Id gid tn trung binh c\
3 ldn lap lai; Cdc sd cd cUng mdu tif khdc biet khdng cl nghta vi thong ke & mifc 5% qua phep thir Duncan: BC (+) dung dich tang sinh vi khudn Lactobacillus trong moi inm MRS khdng bd sung CMC: 0.25 = Lactobacillus + 0.25% CM 0,5 = Lactobacillus + 0.5% CMC; 0.75 = Laclobacitlus + 0,7i CMC. 1 = Lactobacillus + 1% CMC; 1.25 = Lactobacillus 1.25% CMC: 1.5 = Lactobacillus + 1.5% CMC.
d nhiet do phdng, vi khuan Lactobacilli kit hpp vdi CMC the hien hogt tinh khang na cao. Trong do, 2 chung vi khuan Lactobacillx fermentum DC2, Lactobacillus plantarum CC6 tl hien hogt tinh khdng nam manh nhat va gan nl tuong duong nhau.
So sanh boat tinh khang ndm cua vi khui L.fermentum DC2 d cac nong dp CMC khac nha ket qua khao sat cho thay cdc nghiem thic DC2 B (+), DC2+0,25% CMC, DC2+0,5% CMC, DC2 0,75% CMC va DC2 + 1% CMC khang nam hoi toan (nam khdng phat tnen d <£a khao sat). C;
nong dp khdo sdt cao hon, vi khuan Lfermentu DC2 cd the hi|n hogt tinh khang nam nhung fha su khdc biet khdng cd y nghTa vl mat thong ke, Ket qud phdn tich thong ke cho thay, vi khui Lfermentum DG2 d nhiet dp phdng nhin chung i hoat tinh khang nam tuong doi thap. Nghiem thi DG2 + 0,5% CMC vi k h u k Lfermentum DG2 ti hien hogt tinh khang nam cao nhat (80,86%) so v cdc nghiem thuc cdn lgi, ke cd nghiem thic D(
DC (+) (36,08%) vd cd su khac biet khdng co nghTa ve mat thong ke d mic 5%. Trong khi c mdt dp vi khuan Lfermentum DG2 d cac nghi(
thuc nay khdng cd khdc biet nhieu, vdi gia tri tru binh khoang 10^ CFU/ml. Do do, su khac biet tr khdng do dnh hudng cua mgt do vi khuan DC
rRUeiNG DAI H O C D O N G T H A P Tap chl Khoa hoc sd 28 (10-2017) nd cd till do Vl khudn Lfermentum DG2 chi phdt
11^ khd nang khang nam cao nhit khi kit hpp vdi ldng dp CMC thich hpp, d nhung nong dp cao ion vupt qua nguong toi uu se Idm gidm boat tinh diang nam cua L.fermentum DG2.
Vi khudn Lplantarum CC6 khdng nam hodn :oan d nghiem thuc CC6 DC (+) vd CC6 + 1%
CMC Nghiem tiiuc CC6 + 0,5% vd CC + 1,25%
khong khang nam hodn todn nhung cd hoat tinh khang nam cao vd su khdc bi?t cd y nghia vl mat [hong ke d muc 5% vdi cdc nghiem thic cdn lai Hoat tinh doi khang giua cdc nghiem thuc cd su tang gidm khdng on dinh. Trong khi dd, kit qud khao sat su sinh trudng cua vi khuan L.plantarum CC6, mgt dp vi khuan khdng cd su khac biet nhilu
^ua cdc nghiem thuc khdo sdt. Tu kit qud khdo sat, cd the thay nong dp CMC khdng dnh hudng len hogt tinh khdng nam cua dung dich doi khang.
Mot so hinh anh khang nam dien hinh thu nhan duo'c:
cao khoang 10^ CFU/ml. Su sinh trudng cua timg chimg vi khudn Lactobacillus spp. d cac nghiem thic thi hien cu the o Hinh 5.
Xet khd nang sinh trudng c i a vi khuan Lfermentum DC2 ket hpp vdi CMC d nhiing nong dp khac nhau, nhdn thay khdng cd su khac biet Idn giua cac nghiem tiiuc khao sat (Hinh 5a). Ket qud sat cho thay, vi khuan Lfermentum DC2 ton tgi duoc ttong mdi trudng cd bo sung CMC nong do thi nghiem t i 0,25% din 1,5% vdi dudng tdng trudng kha on dinh. Dac biet, nghiem thuc kit hpp 1,25% CMC cd mat dp cao nhdt Id 10« CFU/
ml ttong khoang ngay thu 5 din ngdy thu 7. Nong dp CMC hau nhu khdng anh hudng den vi khuan Lfermentum DC2, su chenh lech mat do cd thi xdy ra do Idi thao tdc ttong qua trinh tiiuc hien tiii n ^ e m
0 nhimg nghiem thic ket hop CMC, vi khuan Lfermentum DG2 cd dudng tang trudng tuong dong giua cac nghiem thic (Hinh 5b). Dua vdo do thi sinh trudng vi khuan Lfermentum DG2 (Hinh 5b), cd the thay tiong mdi trudng cd bo sung CMC ndng do thi nghiem t i 0,25% din 1,5% thdi gian dl ton keo dai hem 21 ngay vdi mgt dp kha cao khoang 10^
CFU/ml. Sau 1 ngay, mat dp vi khuan Lfermentum DG2 d cdc nghiem thic kit hpp deu dgt t i 10' den 10^ (CFU/ml), cao hon khoang 100 Ian so vdi ae cua dong DG2-K)^% nghiem tiiic doi chung. Cac nghiem tiiic kit hpp CMC, DC2+1.5% CMC, CC6 + 0,75% CMC so sdnh T * - ™ , ^ - ' I.L • ^-^ u^ -
' ,. T^ " > : " , ' , w,'^'-ov.i.v,»u>«u nong do CMC CO anh huong den su smh truong cua VOI nam doi chung or nhiet do phong - ,T i r r TX*^-. L I U - L>.
VI khuan L.fermentum DG2 nhung khong nhieu.
3.2. Khao sat anh huvng long do CMC den kha nang iinh tnrdtig va ton tai, ho^t tinh k h a n g n a m cAa cac :hung vi khuan Lactobacillus ipp. 6* nhiet do IS'C
3 2. J. Anh hudng cua ndng id CMC din khd sinh trudng vd on tai cua ede chung vi khudn Mctobacillus spp. d 13°C (S d i l u kipn nhiet dd 3"C, kha nang sinh trudng
;ua vi khuan L.fermentum )C2, L.fermentum DG2 va
..plantarum CC6 phat ttien j ^ ^ ^ ^ ^
aanh hon nhieu so vdi nhiet i j t ,. , , ~- . . • uA**^i« Hinh 5. Kha nang sinh tnromg va ton cua vi khuan DC2, DG2 va CC6 ket
lp phong.-nio. g.an phat tnen hyp CMC ft nhiet <to 13-C
eo dai h o n 2 I n g a y v o l m a t d o Ghichu:DC=d6icbimg:0.25=DC2 + 0.25%CM:;'o^=DC2+0.5%CM::Q.75^DC2
* OJS'ACM:: I.O-1X2+l.mCUC: 1.25-DC2 + I,25%CM0:U-DC2 + 1J%CM:
73
IRUONG BAI HOC D6NG THAP Tap chi Khoa hpc sd 28 (10-2017)
Tuong tu nhu 2 ddng vi khuan Lfermentum, sv sinh trudng cia vi khuan Lplantarum CC6 giua cac nghiem thuc ciing khdng cd su khdc bi?t ldn Dudng tang trudng cia vi khuan Lplantarum CC6 kit hop vdi cdc nong do CMC khac nhau till hi?n cu thi d bilu do sinh tnidng (Hinh 5c).
VI khuan Lplantarum CC6 cd till ton tai ttong mdi trudng MRS bo sung CMC o nong dp khdo sdt t i 0,25% den 1,5%. Sau 1 ngdy, d cdc nghiem thio kit hpp, mat dd vi khuan Lplantarum CC6 cd giatn trung binh khodng 10' CFU/ml, cao hon nghiem tiiic doi chung khoang 100 Ian. Trong dd, nong dp 1,5% vi khuan Lplantarum CC6 cd dudng sinh trudng cao nhat ttong cac nghi?m thic khdo sat. Tu ngdy t h i nhat din hon ngay t h i 7, radt dp cao (10^ CFU/ml). Cd till tiiay, d D^C vi khuan Lplantarum CC6 phdt triln vd tot hon khi cd su kit hpp vdi chat mang CMC.
3.2.2. Anh hudng cua nong do CMC den hogt tinh khdng ndm cua cdc chung vi khudn Lactobacillus spp. d 13°C
Hoat tinh khang nam c i a ching vi khuan Lactobacillus spp. kit hpp vdi cac nong dp CMC khac nhau dupc khao sat d dieu kien nhi§t dd 13°C. Sau 13 ngdy, do dudng kinh vdng ndm Lasiodiplodia pseudotheobromae tten mdi trudng PDA da dupc phi dung dich doi khang. Kha nang khang nam cua cdc nghiem thic duoc xdc dmh bang phuong phdp xu ly thong ke (Bang 2) va duoc bieu dien bang do thi Excel (Hinh 6).
Bdng 2. Ket qua doi kh j n g nam Lasiodiplodia pseudotheobromae cua cdc chung vi khuan Lactobacillus spp. k i t h<^ voi CMC & IS^C
Ghi chu: Cdc gid trj & bdng Id trung binh ciia baldnl^p lai; trong cimg mgl c^t. cdc cha cdi biiu thi sir khdc biet khong c6 y nghTa vi thong I^&muc 5% qua phdp thvDuncan.NT22 = DC2 DC(+J: NT23 = DC2 + 0.25% CMC. NT24=DC2 + 0,5%
CMC: NT25 =DC2 + 0,75% CMC; NT26 = DC2 + 1% CM:- NT27=DC2 +1.25% CMC; NT28 =DC2 +1,5% CMC. NT29 = DG2DC(^).NT30=DG2 + 0.25%CMC:NT31=DG2^0.5%
CMC: NT32 = DG2 + 0.75% CMC: NT33 = DG2 + 1% citC;
NT34 =DG2 + 1.25%CMC;NT35 =DG2^-1.5%CMC;mu
= CC6DC(+).NT37 = CC6+O.25%CMC:NT38=CC6+0.5%
CMC; NT39 = CC6 + 0,75% CMC; NT40 = CC6 + }%0^- NT41=CC6 + 1.25% CMC; NT42 = CC6 + 1.5% CMC;"^
(Coefficient of variation- M sd biin thiSn), LSD (Least signijii^t difference - sai khdc biet nho nhdt cd ^ nghia).
Nghiem thiic
NT36 NT26 NT34 NT4I NT27 NT37 NT22 NT31 NT25 NT29 NT24
C \ i ^ a nSng Idling n ^ nghidm thiic
69,03'
(%)
74,77"
7 6 , 6 3 "
78,1'-' 80,47»"
8 3 , 3 3 "
84,27-"' 85,23'"' 86,67-"
86,67'"
88,07-"
(%) - 1,07; I Nghigm
tbiic
N n 2 NT33 NT30 NT23 NT3S NT40 NT39 NT3S NT42 NT28 SD (5%) = 5
Kha nang khang nam nghiem thirc
{%) 88,57-"
89,03-"
89,07-"
89,53-"
90'"
92,37-' 92,37"
100' 100- 100- 77
U(175 1 « S
CV 1 0 % HoflClUkUagiiD(H)aCCE >DC2 IDQ
Hinh 6. Hoait tmh khang nim cua vi khu^
Lactobacillus ket hgrp CMC d nhiet do 13°C Ghi chii: Xem Hinh 3.
Tu kit qua phan tich thong ke va Hinh 6 co the thay boat tinh khdng ndm cia 3 chiing vi khuan Lactobacillus d nhiet dp 13°C, the hi§n manh nhat d nghiem thic Lactobacillus DC (+). Cac nghi?m thic cdn lai hogt tinh khdng nam tucmg doi cao, tuy nhien cd su khdc bi?t khong cd y nghia ve mat thong ke d muc 5%.
6 cing nong dp CMC kit hop, hogt tinh khdng nam cia cdc ching hau nhu tucmg duong nhau Tuy nhien, nong dp 0,5% CMC, vi khuin L.fermentum DC2 thi hien hogt tinh doi khang thdp nhat trong 3 chimg Lactobacillus spp. Nong dp 1,5% CMC, vi khuan L.fermentum DG2 co hogt tinh khdng nam t h ^ nhat so vdi cdc nghi?m thuc d cd 3 chiing Lactobacillus khdo sat. Thi nghi?m khdo sdt kha nang sinh trudng va ton W cua ching Lactobacillus, mat dp vi khuan gjiia cac ching Lactobacillus spp. d cac ndng dp khac biel khdng cd y nghia ve mdt tiiong ke d mic 5%. Nhir chung, d dilu kien 13°C, vi khuan Lplantartm CC6 thi hi?n boat tinh khdng nam mgnh nhat s{
74
KUCfNG DAI H O C DONG THAP Tap Chf Khoa hpc so 28 (10-2017) dl 2 ddng L.fermentum DC2 vd L.fermentum
)G2, kit qua nay p h i hpp vdi kit qud khdo sat igt dp vi khuan, ttong dilu kien nhi?t dp WC, i khuan CC6 phdt triln mgnh nhat so vdi 2 ddng i khuan cdn lai
M^t sdMnh dnh khdng ndm diin hinh:
Hinh 7. Ket qud khang n ^ cua nghiem thic DC2 +1,25% CMC; CC6 DC (+) so v «
doi chung 3. Ket l u ^ va kien nghi
Kit qud khdo sat kha nang sinh trudng va su m tai cia vi khuan Lactobacillus cho tiiay dieu ien nhiet dp 13°C, vi khudn Lactobacillus phat ien tot hon nhiet do phdng. 0 nhiet do phdng.
ching L.fermentum DC2 phat trien tot nhat. (!) nhiet do 13''C, ching Lplantarum CC6 phat tnin tot nhat. Trong mdi trudng MRS mat dp vi khuan ti le nghich vdi nlng dp CMC.
Kit qud khdng nam cho thdy, cd 3 ching vi khuan Lactobacillus diu cd hogt tinh doi khdng d dilu kien nhiet dp phdng (khoang 25±2''C) va 13"C. Dac bipt, chung vi khuan Z,.^mien/Hm DC2 vkL.plantarum CC6 cd boat tinh khang nam manh d cd 2 nhiet dp Kit hpp vdi 1% vd 1,5% CMC d cd hai dllu ki^n nhi§t dp, vi khuan Lactobacillus till hien boat tinh doi khdng chong lai nam benh Lasiodiplodia pseudotheo bromae tot nhit.
Dieu kien 13°C Id nhiet dp tot uu cho su phdt trien cia vi khuan L.plantarum CC6. Dong thdi d nhiet dp nay, vi khudn L.plantarum CC6 the hien hogt tinh doi khdng tot nhat. Vi khuan Lfermentum DG2 cd kha nang sinh trudng vd boat tinh khang nam thap nhat trong 3 ching Lactobacillus khdo sdt /.
Tai lieu tham khao
[1]. AIam,KM,Ahmed,M,Akter,S.,Islam,NandEun, J. (2009),"Effectofcarbo^qmietfiylcellulose nd starch as thicketung agents on the quality of tomato ketchup", Pakistan Joumal of Nutrition, (8), .1144-1149.
[2]. Ngi^en Thi Diem Huong, Dd Thi Bich Thiy (2012), "Xac dinh vd khdo sat mdt so tinh chat 6 Ipi cia ching Lactobacillus fermentum DC 1 phan \^ t i san pham dua cdi Hue", Tgp chi Khoa hgc iaihocHui, 71 (2), tt. 177-187.
[3]. Jarvenpaa, S., Tahvonen, R. L., Ouwehand, A. C , Sandell, M., Jarvenpaa, E and Salminen, S 2007), "AProbiotic, Lactobacillus fermentum ME-3, has antioxidative edacity in soft cheese spreads /ith different fats", Joumal of Dairy Science, 7 (90), p. 3171-3177.
[4]. Kasra - Kermanshahi, R,, Fooladi, J., Peymanfar, S. (2010), "Isolation and microenc^sulation
? Lactobacillus spp from com silage for probiotic application", Iranian Joumal of Microbiology, 2 l), p. 98-102.
[5]. Tran Dinh Manh (2013), Phdn lap, tuyin chgn cdc dong vi khudn Lactobacillus spp. ed tdc ung uc chi in-vitro mdt sd ndm benh sau thu hogch tren chdm chdm, Ludn vdn Thac sT nganh Cdng ghe thuc pham, Trudng Dai hoc Ndng Lam, thdnh pho Ho Chi Minh, tt. 1-51
[6]. Martinez-Castellanos, G., Shirai, K , Pelayo-Zaldivar, C , J. Perez-Flores, L, D. Sepulveda- anchez, D. (2009), "Effect oi Lactobacillus plantarum and chitosan in the reduction of browning of
;ricarp Rambutan (Nephelium lappaceum)". Food Microbiology, 4 (26), p. 444-449
[7]. Tran Thuy Ai Tdm (2012), Nghien cieu benh do ndm tren chdm chdm sau thu hogch tie hinh ue canh tde theo mo hinh VietGap vd md hinh tu do, Ludn vdn Thgc sT ngdnh Cdng nghe sinh hpc, rudng Dai hpc Can Tho, Can Tho, tt. 12, 32-53.
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TRUONG DAI HOC DONG THAP Tgp chi Khoa hoc sd 28 (10-2(
[9j. Nguyen Minh Thuy vd Nguyln Thi My Ti^ln (2011), Bdo qudn Cam mat bdng phuang ( Map (Modified Atmosphere Packaging), Tap chi Khoa hgc Dgi hoc Can Tha, 17(a), tt, 229-238.
[10] Wdjcik, W, Ztotek, U. (2008), "Use of chitosan film coatings in the storage of carrots (Dai carota)". Department of Food Biochemistry and Chemistry, University of Life Sciences, p. 141-14(
[11]. Ymzhe, R and Shaoymg, Z (2013), "Effect of carboxymethyl cellulose and alginate coa combined with brewer yeast on postharvest grape preservation", ISRNAgronomy, 871396 (2013), ]
INVESTIGATING THE EFFECT OF CARBOXYMETHYL CELLULOSE CONCENTRATIONS ON THE GROWTH, SURVIVAL AND ANTIFUNGAL ACTIVm
OF LACTOBACILLUS ON POSTHARVESTEVG ON FUNGI OF LASIODIPLODIA PSEUDOTHEOBROMAE
Summary
CMC (Carboxymethyl cellulose) is used to make food covering for freshment and nutn quality preserved. Some Lactobacillus spp. sttams, especially L.plantarum CC6, Lfermentum DC2 L.fermentum DG2, have been proved to have high antifungal ability. The study combined CMC 3 Lactobacillus spp. sttains to increase the antifugal ability against Lasiodiplodia pseudotheohro\
w^ich causes disease on fruits, especially rambutan, for longer time preservation after harvest, obtained results show that Lactobacillus spp. at 13''C develop better than the room temperature. \ CMC combined 1% at room temperature and 1.5% at 13°C, Lfermentum DC2 and Lplantarum ( have the best quality of development and anttfugal ability.
Keywords: Damaged fruit, Lactobacillus plantarum, Lactobacillus fermentum, Carboxyme cellulose, Lasiodiplodia pseudotheobromae.
Ngdy nhdn bar 19/3/2017; Ngdy nhdn lgi: 20/7/2017; Ngdy duyet ddng: 29/9/2017.
