Tap chi Khoa hgc Tnr&ng Dgi hgc Cdn Tha Phdn B: Ndng nghiip. Thuy san vd Cong ngh? Sinh hgc 26 CO!3) 134-142
Tap chi Khoa hoc TrLTcJng Oai hpc Can Thd website: sj.ctu.edu.vn
K H A NANG SU^ DUNG B A M I A T R O N G S A N X U A T C H A T B E O T i r NAM M E N Y A R R O W I A L I P O L Y T I C A P o I G
Ho Qudc Phong', Huynh Lien Huang', Vd Trudng Giang" va Trucmg Thj Cam Tii^
' Khoa Cdng nghi, Tnrdng Dgi hge Cdn Tha
Sinh viin lap Cdng nghi boa hgc K35, Truang Dai hgc Cdn Iha
" Hgc vien cao hgc Cdng nghi hda hgc. Tnrdng Dgi hgc Bdch Khoa Thdnh phd Hd Chi Minh Thdng tin chung:
.Ngd}-nhgn. 03 01 2013 Ngdy chdp nhdn 20,062013 Title:
Study of using sugarcane bagasse for lipid produetion by the yeast Yarrowia lipolyiica Polg Tir khda:
Bd mia. chdt bio. diesel sinh hgc. nhien lieu sinh hgc.
Yarrowia lipolyiica Polg Keywords:
Biodiesel. biofuel lipid, sugarcane bagasse. Yarrowia lipolyiica Polg
ABSTRACT
This study is lo explore the use of sugarcane bagasse for culturing Yarrowia lipolyiica Polg in order to obtain lipid. After pretreatmeni, bagasse was converted into sugars by hydrolysis with dilute sulfuric acid at various concentrations (I - 4%). temperature (60 - 120''C), and reaction time (1-8 hours). The results showed that the concentration oj total sugar increased proportionally to the increase of applied acid concentration, time, and temperature. Tlie highest concentration of sugar obtained when bagasse was hydrolyzed with 3% H2SO4 al 90°C for 6 hours and the ratio between bagasse and acid solution was 1/25 g/mL.
The culturing process of Y. lipolyiica Polg showed that detoxified sugarcane bagasse hydrolysate gave the highest biomass of 12.07 g/L, compared to D-glucose (10.3 g/L), and D-xylose (8.45 g/L). The highest lipid obtained when yeast gran'n in detoxified sugarcane bagasse hydrolysate with total sugar concentration of 30 g L was 46.7%.
TOM TAT
Nghien ciru ndy nhdm khdo sdt khd ndng sit dung ba mia di nudi cdy ndm men Yarrowia lipolyiica Polg nham thu duac chdt beo. Sau khi dugc xir li sa bg, bd mia dugc chuyin bda thdnh duang bdng phuang phdp thity phdn vdi H2S0^ lodng & ndng do (1 - 4%), nhiet do (60 - I20°C), vd thdi gian (I- 8 gid). Kit qud cho thdy ndng do dudng long tang ti li thudn vdi ndng do acid, thoi gian. vd nhiet do thicy phdn.
Ndng do dudng tdng cao nhdl thu dugc khi bd mia dugc thuy phm bang HjSO_i 3% a 90"C trong 6 gia vd v&i li li bd mia vd dung dich
acid Id 1/25 g'mL. Qua tiinh nudi cdy ndm men Y. lipolytica Polg cho thdy sdn phdm thity phdn ba mia dd khir doc cho kit qud tdng tntang sinh klidi Id cao nhdt (12.07 g/L) so vdi D-glucose (10.3 g/L)yd D-xylose (8.45 gf). Hdm lugng chdt beo cao nhdt Ihu dugc khi ndm men dugc nuoi cdy trong bd mia thuy phdn cd ndng do duang tdng 30 gL Id 46.7%.
1 GIOI THIET
Naa> nay. dau sinh hgc hay biodiesel ngay cang dugc quan tam manh me nhu la nhien
lieu cd the phan huy sinh hgc. phat sinh it chat thdi, cd the hda Iron vdi peuodiesel va tucmg thich tdt vdi cac ddng ca hien tai (Knothe,
Tap chi Khoa hgc Tru&ng Dgi hgc Cdn Tha Phan B: Ndng nghiep. Thm san i a Cdng nghi Sinh hgc: 26 (2013). 134-142 2008). Tuy nhien, chi phf cao ciia nguyen lieu
thd. udc tinh chilm 70 - 88%, khiln biodiesel chua the canh tranh vdi peuodiesel (Chen et fl/., 2009; Haas e/a/., 2006).
Han the nda, viec su dung cac loai diu thuc vat cho qua trinh sdn xuat biodiesel quy md cdng nghiep lam giam dien lich dit canh tac cua cac cay ndng nghiep truyen thdng, dnh hudng dang ke den van de an ninh luang thuc, gia thuc pham tang cao va nguy co thieu cac loai ddu an dugc. Vi vay, viec phdt frien cdng nghe khac de san xuat chat beo dung cho qua trinh sdn xuat biodiesel la rit quan frgng.
Trong dd, san xudt chat beo thdng qua qua frinh Ien men su dung cac vi sinh vat cho dau CO the la mgt each thay the cho cac loai dau thuc vat truyen thdng (Ralledge. 2008). Cac vi sinh vat cho dau dugc biet den vdi viec tich luy cac chat beo frong ndi bao tir su trao ddi chat dua tren cac nen carbon. Mdt vdi loai vi sinh vdt tich luy len den 87% khoi lugng te bdo khd (Papanikolaou et al, 2004). Chit beo tir vi sinh vat (microbial lipid) cdn dugc ggi la ddu dan bdo (single cell oil, SCO) dugc quan tam nhu la mdt ngudn nguyen lieu day hua hen cho viec sdn xuat ddu biodiesel bdi nhung tm diim nhu thdi gian san xuat ngan, cdng lao ddng it va de dang nhdn rgng.
Nim men )'. lipolytica Polg cd kha nang tich luy ham lugng chit beo cao. thudng dugc tim thay trong mdi trudng giau cac chat nen Vs.
nudc (hydrophobic subsuate, HS), Chiing phat trien nhiing ca che phuc lap cho viec su dung hieu qua nhirng chdt nen khac nhau nhu Id ngudn carbon cho qua frinh sinh trudng. Chat beo frung linh thu dugc tu )" lipolytica Polg la ngudn nguyen lieu tiem nang de chuyen hda thanh biodiesel vi chung chua mgt lugng Ion cdc acid beo tu do. Tuy nhien, chat beo tu nam men cho diu chi cd the canh franh vdi cdc ngudn chit beo thuang mai khac neu dugc san xuit tu nguyen lieu re ban ngudn truyen thdng.
Gin day, dang cd khuynh hudng tan dung cac ngudn phe pham ndng nghiep (ram. ra) nhu la nguon carbon frong qua trinh nudi ciy vi sinh de san xuit chit beo. mac dii \d> nhung cdng frinh nghien cuu vdn dang cdn rit ban che.
Ngudn phe lieu lignocellulose cd tiem nang rat quan frgng bdi nd dugc thai ra hang nam vdi sd iugng khdng Id, dac biet la cdc nudc cd nen ndng nghiep phat Uien. Trong do, ba mia - phu phdm ciia qua trinh san xudt dudng. Id ngudn nguyen Heu chua lignocellulose. cd mat d hau het cac nudc nhiet ddi, frong do cd Viet Nam. Tuy nhien frong thdi gian qua, cdc img dung cua ba mia chua dugc khai thac uiet de.
chi dimg Iai d viec dimg lam nhien lieu ddt Id hoac lam hot giay va van ep dung frong xay dung,... Trong khi ba mia la ngudn lignocellulose tiem nang cho qua frinh san xuat nhien lieu sinh hgc tir vi sinh vat do cd ham lugng carbonhydrate cao, ham lugng chat uc che thap va la phe phdm tai cdc nhd may dudng. Chinh vl va\. viec nghien cuu ung dung ba mia trong qua trinh nudi cay Y.
lipolytica Polg de san xuat chat beo phuc vu cho viec san xuat nhien li|u sinh hgc la rat can thiet. Muc freu cua nghien cihi nay nham tim ra dieu kien thich hgp cho phan iing thuy phan ba mia bang acid loang de thu dugc dung dich thiiy phdn cd hdm lugng ducmg cao. Ddng thdi, nghien cuu se tan dung cac thanh phan dinh dudng tu dung dich ba mia thiiy phan de nudi cay nam men Y. lipolytica Polg nham san xuat chat beo (ddu). Qua dd de xuat nguyen lieu thd re tien cho qua frinh san chat beo cd quy md cdng nghiep, ndng cao gid tri cua cay mia, ddng thdi gidi quyet mot phan d nhiem mdi trudng.
2 PHL/ONG PHAP NGHIEN CL L 2.1 Nguyen lieu va fada chat
Ba mia dugc cung cap tu cac nha may che bien dudng. sau dd dugc rua sach bang nudc.
say khd d 50°C frong khodng thai gian 24 gid.
Sau khi sdy. ba mia dugc xay nhd dat kich thudc khoang 0.71 mm va dugc bdo quan d 4°C de su dung.
Nam men Y. lipolytica Polg tir cdng ty
•^EASTERN Biotech Co. Ltd., dugc cung cap bdi phdng thi nghiem KJ thuat Sinh hgc. Dai hgc Khoa hpc Cdng nghe Qudc gia Dai Loan.
Hda chat diing Uong qud trinh nudi cay nam men dugc cung cap bdi cac cdng t\ khac
Tap chi Khoa boc Tnr&ng Dgi hgc Cdn Tha Phan B: Ndng nghiep. Thuy san vd Cdng nghe Sinh hgc 26 12013): 134-142 nhau nhu yeast exfract, peptone (Bacto. Phap),
D-glucose (Merck, Dire) va agar, urea (Acros Organics, USA). Cac dung mdi su dung cho uong trich ly, H2SO4, Ca(0H)2 va thudc thu phan tich 3.5-dinifrosalicy!ic acid (DNS) dugc cung cap bdi cdng t\ Meek (Due).
2.2 Thiiy phan ba mia
Ba nua dugc thuy phan theo phucmg phap ciia (Chandel et ah, 2007) vdi mgt sd dieu chinh nhd ve nhiet do, thdi gian va ti le ba mia/dung dich acid. Ba mi'a da xu ly sa bd dugc trgn vdi H2SO4 de thuc hien phan ung ihuy phan vdi dieu kien nhiet do vd thdi gian nhat djnh. Sau khi phdn iing hon hgp dugc de ngudi den nhiet do phdng (30 °C), phan chat Idng (dung djch ba mia thuy phan, DDBMTP) dugc tach bang each lgc chan khong va bdo qudn d 4 °C Sa dd 1 md ta viec chuan hi DDBMTP cung nhu qua Uinh nudi cdy Y.
lipolyiica Polg.
13 Qua trinh khir dgc san pham thuy phan ba mia
De gidm su anh hudng ciia cac chat uc che nhu HMF va furfural, DDBMTP dugc khu ddc bang phuang phap vdi hda (overliming).
Ca(OH): dugc them vao DDBMTP d l tang pH len den khoang 9 - 10 va giii d dieu kien ndy tu 30 phiit, sau dd dieu chinh den pH 6,5 bang H2SO4, pH dtmg djch dugc xac dinh bang may do pH (Meller Toledo. My). Sau khi khir ddc, dung djch dugc Igc chan khdng 2 lan nhdm loai bo kel tiia CaS04 va dung djch sau dd giu d 4°C cho den khi dugc su dung.
2.4 Nudi cay nam men
Nam men }". lipolytica Polg dugc tdn tru Iren mdi trudng "VTOA d 4°C. Sau dd nim men tu mdi trudng YPDA dugc nudi ciy so bg trong mdi trudng YPD gom D-glucose (20 g/L), peptone (10 g/L), yeast exfract (10 g/L) d nhiet dp 26°C, trong hi nuoi ciy vi sinh JSSI lOOC (JSR. M\) vdi tdc dp lie 160 vong/phiit, frong 24 gid. Ndm men dugc nudi ca\ sa bd tiep tuc dugc nhan rdng frong
mdi trudng ba mia thiiy phan vdi t> le the tich 1:10, su dung binh tam giac 500 mL vdi Ihl tich mdi trudng nudi cay la 250 mL, frong tii nudi cay vdi nhiet do la 26°C va ldc do lac 160 vdng/phut. Mdi trudng nudi cay bao gdm:
san pham thuy phan ba mia (da khu ddc vd chua khd ddc). peptone (5 2/L). \ east extract (5 g/L).
2.5 P h u a n g phap danh gia 2.5.1 Xdc dinh hdm lirang ndm men
Su phat trien cua te bao Y. lipolytica Polg dugc xdc djnh bing phep do mat dd quang ciia cac miu pha loang d budc sdng 600 nm bdi may quang phd hdng ngoai UV/VIS Cary 50 (Varian, My) va ddi chieu ket qua vdi dudng cong chuan dugc xay dung tu sinh khdi cua t l bao. Trong dd sinh khdi dugc thu hoach bing phucmg phdp ly tam va khdi lugng ciia no dugc xac dinh bang each do frgng lugng sau khi say khd den khdi lugng khdng ddi.
2.5.2 Xdc dinh nong dp du&ng long Ndng dp dudng tdng Uong sdn pham thiiy phan dugc xdc djnh theo phuang phdp DNS (Marsden et ai, 1982; Miller, 1959) dua fren phan ling lao mau giua DNS va dudng khu 3 mL thudc thu DNS dugc them vao 1 mL mdu thuy phan da pha loang Uong dng nghiem dugc bgc giay nhdm de tranh DNS phan buy bdi anh sang. Hon hgp dugc nung ndng den 90°C frong 15 phut frong be dilu nhiet. Sau do dugc lam ngudi frong mdt chau nudc mat den nhiet dp phdng, mat dp quang cua mau dugc ghi nhan bang may quang phd UV-VIS d budc sdng 575 nm. Ket qua dugc tinh loan dua Uen dudng cong chuan cua D-glucose.
2.5.3 Xdc dinh hdm lucmg chdt beo Chat beo dugc frich ly bang phuang p h ^ Soxhiet vdi hdn hgp hexane : methanol ti Ie 2:
1 (v/v) trong 6 gid, Hdn hgp dugc cd quay trong thilt hi cd quay Model R205 (Buchi, Thuy sT) de loai bd dimg mdi. Ham lugng chat beo dugc phdn tich bang each can khoi lugng.
Tap chl Khoa bgc Tru&ng Dgi hgc Cdn Tha Ph&n B. Ndng nghiip. Thuy san vd Cdng nghe Sinh hgc. 26 (2013)
I Ba mia I Te bao Yarrowia lipolyiica P o l g
^
Ca\ vdo moi trudng YPDA
Te bao da sinh trudng Uong YPDA 24h
Chuan bl moi truang ^ ; .; ; -•. . .. ; * .. Cay giong nam men \'ao moi truong
nuoi cav < ' " ° - rl
"TT
Nuoi ciy J^ Xac dinh su sinh truong
^ sinh khoi va chat beo Hinh 1: So* dd qua trinh thuy pfaan t
2.5 4 Phucmg phap phdn tich thong ke Tat ca cdc thi nghiem dugc lap Iai 3 Idn va ghi nhan gia fri frung binh. Cdc sd lieu thuc nghiem dugc xu ly bing phan mem Excel (Microsoft Excel 2010, Microsoft, My) d l xac dinh gia frj trung binh, sai sd ngdu nhien.
3 KET QUA VA THAO LUAN
Trong qua trinh thiiy phan lignocellulose ndi chung hay ba mia ndi rieng cac thdng sd nhu nhiet dp, thdi gian va ndng do acid ddng vai frd quan trgng de thu dugc lugng dudng loi uu va sinh ra chat uc chl tdi thieu. Them vao dd. mdt sd tac gia cung quan lam den su anh hudng cua kich thudc nguyen lieu va ti le giiia nguyen lieu/dung djch acid (Chandel et ai, 2012; Taherzadeh & Karimi, 2007a). Chinh vi thi frong nghien cuu nay. cac thdng sd Uen se dugc khao sat.
3.1 Khao sat anh hudng ciia nong do acid len ndng do d u d n g tdng
Bk khao sat dnh hudng ciia ndng dp acid
a mia ^ a nudi cay Y. lipolytica P o l g
den qua frinh thuy phan, ba mia dugc thiiy phan tuang ung vdi nhirng ndng do H2SO4 khac nhau, thay doi tu I - 4% (v/v), d nhiet do 90''C trong I gid vdi ti le ba mia/dung dicli acid (BM/DDA) la 1/20 g/mL. Kit qua thiiy phdn dugc the hien trong Hinh 2.
Co thS thay rang ndng do acid anh hudng rat quan Ugng den qua trinh thiiy phdn, uong dd ndng do dudng long (NDDT) tang tucmg ung vdi tang ndng dp acid. Khi tang ndng dd H2SO4 tir 1% din 3% lam tang NDDT tu 10.32 den 17.86 g/L. Dieu nay chung td acid ndng do cao cd the pha vd cau triic polymer cua lignocellulose hieu qud ban. Tuy nhien, khi su dung acid 4%, NDDT gidm con 16.41 g/L.
Dieu ndy dugc giai thich la do su gidm cip ciia cdc loai dudng pentose va hexose thanh 5- HMF va furfural. Ddy la sdn phim phu khdng mong muln va la thanh phin uc che trong qua trinh nudi ciy nam men. H2SO4 d ndng dp 3 % la hieu qua nhit cho su thuy phan ba mia, tuang ung vdi NDDT Id 17.86 g/L.
Tap chi Khoa hgc Tnr&ng Dgi hgc Cdn Tha PhdnB: Nong nghiep. Thuy san vd Cdng nghi Smh hgc. 26(2013): 134-142
Hinb 2: Anb hirdng ciia nong dp acid den ndng dp dudng long
20
? 16
SE
ec
•2 12 an s b 8
BC 1
-•o c 4
0
0 1 2 3
Nong dg acid (% v/v) 4
3.2 Khao sat anh hud^g thdi gian thuy phan den nong do dudng tong Qua trinh thuy phan dugc khao sat d cac khoang thai gian khac nhau tir I - 8 gid, nhiet dp 90°C. ndng do acid da tdi uu la 3%. ti le BM/DDA la 1/20. Kit qud chi ra iing NDDT tang theo thai gian thuy phan, vdi thdi gian thuy phdn tdi uu la 6 gid. Khi tang thdi gian thiiy phan ttr 2 den 4 gid, NDDT tang tucmg ting tu 19.91 den 21.13 g/L va dat cue dai (23.69 g/L) tuang ung vdi 6 gid thuy phan.
Hinb 3: Anh hudng ciia thdi gian tfauy pfadn den nong do dudng tong
Tuy nhien, NDDT bat dau gidm cdn 21.69 g/L khi thdi gian thiiy phan tang len 8 gid (Hinh 3), Cac cdng frinh nghien ciiu tuang ttr cung cho thay NDDT lang khi tang thdi gian thiiy phan va ndng do acid su dung va cho den khi dat dugc gid trj cue dai thi NDDT bit ddu gidm dan sau dd (Tsigie et al, 2012; Wang, 2011). Nguyen nhdn chu yeu la do su chuyen hda cua phdn tu dudng thanh cdc hop chat khdng mong mudn khac d dieu kien ndng dp acid cao vd thdi gian phdn ung ddi.
3 3 Khao sat anh hudng ciia ti le ba mia/dung dich acid den ndng do dudng t6ng Tl le BM/DDA dugc tiln hanh khao sal vdi cdc ti le khdc nhau thay ddi tu 1/20 din 1/40 g/mL. tuang ung vdi dieu kien nong dp axit 3%. nhiet dp 90°C vd thdi gian la 6 gid. Kit qud khao sdt cho thay ring ndng dp dudng
tdng gdn nhu gidm tuyen tinh khi tang ti le giira ba mi'a va dung djch acid su dung trong qud trinh thuy phan (Hinh 4). NDDT thu dugc la 23.69, 19.94, 16.72, va 12.96 g/L tuang ung vdi ti Ie BM/DDA la 1/20, 1/25, 1/30, va 1/40 g/mL. Tuy nhien, lugng dudng thuc te thu dugc tinh fren khdi lugng bd mia su
r<9? chi Khoa hgc Tnr&ng Dgi hgc Cdn Tha Phdn B: Ndng nghiip. Thin- san vd Cdng nghe Smh hgc. 26 P013): 134-142 dung thi tang manh khi thay ddi fr le BM/DDA
thay ddi tu 1/20 din 1/25 g/mL va gia frj nay thay ddi khdng dang k l khi ti le rin Idng su dgng Idn ban 1/25 g/mL (Hinh 4). Nhu v a \ . neu ba mia dugc su dung la I g thi lugng dudng thu dugc lin lugt Id 0.27. 0.43. 0.46. va
0,47 g, tuang ung vdi ti le BM DD.A la I 20.
1/25, 1/30, va 1/40 g/mL. Td kit qua cho thay viec chgn khao sat u le BM/DDA la quan trpng. frong ti le 1/25 g/mL dugc xem la kit qua tdi tm cho qua trinh thiiy phan.
Hinfa 4: Anh fairdng ciia ti le mia/dun^ dfcfa acid d£n nong dg dudng tdng
30 - 3 •& 25
T , — 1 ^ - ^ — '
"-' I / "
ac
"5 20
«c e is 15
"a M 10 -<o s
Z
5 ~ • ~ Ham lugng duong Ihu ducrc
—•— Ham lui?iig ducmg Ihu dupe linh Uen gram mia
1/20 1'25 1/30 1/35 T i le B M / D D A ( g / m L )
-
~-
0,5 c-
•Z
s
en 0.4 3B
0.3 ^
^
b0.2
1fin
0.1 -^
u.u 1/40
3.4 Anh hudng cda nhiet dp den ndng do dutmg long
Anh hudng ciia nhiet do den qua trinh ihiiy phan dugc khao sat tu 60 - 120°C- trong dd ndng do axit 3 % , ti le BM/DDA 1/25 g/mL va thdi gian 6 gid la dieu kien cd dinh. Ket qua thi nghiem cho thay ndng do dudng long tang nhanh khi tang nhiet do thuy phan (Hinh 5).
NDDT thu duac lin luot la 7.36. 11.89. 16.25.
Hinfa 5: Anh faudng ciia nfaiet dp din ndng dp dudng tdng
vd 23.69 g/L tuang ung vdi nhiet do su dung Id 60, 70, 80, \ a 90°C. Tuy nhien, neu tang nhiet do len cao Uen 90°C thi ham lugng dudng giam do xa> ra qud trinh caramen hda dudng d nhiet dd cao va thdi gian dai. Han the nira, khi thuc hien phan iing thuy phdn d 120°C Uong 6 gid. dudng hi phan buy hodn toan thdnh carbon. Vi vdy. nhiet do thich hgp cho qua frinh thuy phan frong nghien cuu nay la 90°C.
70 80 Nhiet dp C O
Tap chi Khoa hgc Tnt&ng Dgt hgc Cdn Tha Phdn B Nong ngbiip Thm' san va Cdng ngbe Smh hgc. 26 (2013): 134-142 3.5 Anh hudng cua nguon cung cap carbon
den bam lugng sinh khoi
Anh hudng cua nguon cung cap carbon ten qua trinh phat trien ciia Y. lipolytica Po I g dugc khdo sdt vdi 4 ngudn cung cap carbon khac nhau nhu sau: (i) dung dich ba mia thuy^phdn 14"
^ 1 2
,no
H i n h 6: A n b b u d n g cua n g u d n c a r b o n -^
d e n s u sinh I r u d n g cua K/ipo/v'fica P o l g e« 6
I
Ket qua cho thdy nam men phat trien tdt nhat trong dung dich ba mia thuy phan da qua khir ddc vd ham lugng sinh khdi dat gia fri toi da la 12.07 g/L. Trong khi dd gid fri cue dai ciia sinh khdi thu dugc uong cdc mdi trudng chua D-glucose, D-xylose, dung djch ba mia thiiy phdn khong khu dgc ldn lugt la 10.3, 8.45, va 2.11 g/L. Quan sat su sinh trudng va phat trien ciia nam men theo thdi gian nhdn thdy rdng vao ngay thu 4 sinh khoi phdt frien manh nhat luy nhien sau do tdc dp nay gidm dan (Hinh 6). Nguyen nhan la do su can kiet ngudn cung cdp dam va carbon. Viec nuoi cay trong dung djch ba mia thuy phdn chua qua khu ddc cho ket qud thap nhat bdi vi cd su hien dien cua cdc chat uc che nhu ftirfiiral, HMF va ddc biel la pH moi trudng qua thap.
Sau khi frung hda vdi Ca(0H)2, ham lugng cac chdt uc che se gidm di va do dd khdng anh hudng xau dang ke len su phdt friln cua ndm men. Han the niia sau 6 ngay nuoi cay, sinh khdi cd xu hudng tang len. Dilu nay cd thi giai thich Id do vi sinh vat su dung lai chat beo nhu la ngudn cung cdp carbon cho su sinh trudng (Huang el al, 2009).
khdng khu ddc (DDBMTPKKD) (20 gA.); (ii) dung djch ba mia thuy phan da qua khu dpe (DDBMTPKD) (20 g/L); (iii) dung dich D- glucose tinh khiet (20 g/L) vd (iv) D-xylose tinh khiet (20 g/L).
2 3 4 5 6 7 Tbdi gian len m e n (ngay)
3.6 Anh hudng nSng do dudng tong den ham lugng sinh khoi va chat beo Ham lugng sinh khdi cung nhu ham lugng chat beo thu dugc chju su anh hudng cua ndng do dudng long trong dung djch ba mia thiiy phan. Anh hudng nay dugc thuc hien bang viec nudi cay Y. lipolytica Polg trong moi trudng ba mia thuy phdn da dugc khu dpe tuang iing vdi NDDT khdc nhau tu 10 - 40 g/L, vdi thdi gian len men la 4 ngay. Ket qua thi nghiem chi ra rang ham lugng sinh khdi ciing nhu chdt beo tang khi tang NDDT tu 1 0 - 3 0 g/L va giam neu tiep tuc tang NDDT (40 g/L) (Bang 1). Khi NDDT sir dung la 10 g/L thi sinh khoi thu dugc la thap nhat 4.12 g/L, tuang tmg vdi lugng chit beo sinh ra chi 1.1 g/L, (chilm 26.7% sinh khdi). Sau do lugng sinh khoi tang len 12.07 g/L (lugng chat beo lich luy la 3.87 g/L, chiem 32.1%) khi NDDT frong ba mi'a Ihiiy phan la 20 g/L.
Lugng sinh khoi thu dugc cao nhat la 13.25 g/L (chit beo la 6.19 gA., chilm 46.7%), tuang iing vdi dung dich thuy phan co NDDT la 30 g/L. Tuy nhien khi NDDT tang len 40 g/L thi lugng sinh khdi thu dugc hi giam xudng 8.33 g/L va chat beo sinh ra 2,96 g/L
Tgp chi Khoa hgc Tru&ng Dgi hoc Cdn Thtr Phdn B: .Xdng nghiip. Thuy san vd Cdng nghe Smb hoc: 26 (2013/: 134-142 (chiem 35.5*>o). Dilu nay cd thi giai thich ring
ngoai chit ire chl nhu HMF va fiufiiral, ham lugng dudng cao cung se uc che su sinh trudng cua nam men cung nhu ham lugng chat beo sinh ra (Zhu et al, 2008). Mdt kit qud tuang tu cung dugc quan sat frong nghien ciru
Bang 1: Anh budng cua nong dp dutmg tdng len bam lugng sinb kfadi va cfaat beo sinb ra
san xuat ethanol bdi vi sinh vat Saccharomyces cerevisiae su dung mdi trudng lignocellulose thuy phan. Khi dung dich thuy phan cd NDDT cao se gay ra tdc dung uc che su sinh trudng cua vi sinh vat (Zhao & Xia, 2010).
Nong dp dirdng tdng.
(art.) 10 20 30 40
Ham lirong sinb klidi.
ie/U 4.12 ±0.11 12.07±0.15 13.25 ±0.34 8.33 ± 0.21
Ham lirong chat beo, 26.7 ±1.2
(%)
32.1 ±1.5 46.7 ±2.6 35.5 ±2.1
Ham lirgrng chat beo, (Brt.) 1.10 ±0.03 3.87 ± 0.05 6.19±0.16 2.96 ± 0.07 4 KET LUAN
Ket qua nghien cuu da chiing minh khd nang su dung ba mia cho qua trinh thuy phan dudng la rat kha quan. Cdc yeu td anh hudng den qud Irinh thuy phdn nhu ndng do acid, thdi gian. nhiet do. ti le ba mia / dung dich acid da dirge khdo sat va xac dinh dugc dieu kien tdi uu cho qua trinh thuy phan ba mia (H2SO4 5%.
90°C. 6 gid, ti le I ;25 g/mL). Dong thdi, qua trinh nudi cdy nam men Ylipolytica Polg cho thay san pham thuy phan ba mia da khu ddc cd the dugc su dung nhu mdt ngudn carbon thay the hieu qua cho qua frinh nudi cdy nham san xuit chit beo do hdm lugng sinh khdi vd chit beo thu dugc kha cao. Chinh vi the ba mia thu\- phdn cd the xem nhu la nguyen lieu liem nang diing de nudi cay nam men cho dau.
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