Preparation and Functionalities of Bacillus Agents Cultured on Soymilk Wastewater
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摘要:
目的 利用豆腐黄浆水为发酵原料制备芽孢杆菌制剂,降低芽孢杆菌制剂生产成本,提高菌制剂活菌数。 方法 利用豆腐黄浆水发酵制备枯草芽孢杆菌SB13和地衣芽孢杆菌BL14菌制剂,并以菌落数为指标,采用单因素试验进行制备工艺优化;通过体外模拟消化及DNS法分析其作为饲料添加剂的功效。 结果 菌株SB13和BL14在黄浆水基质中均能正常生长,其产孢最佳温度为35 ℃,最适培养时间分别为72 h和48 h,最佳保护剂分别为10%脱脂奶粉和4%蔗糖,最适载体分别为10%麦耚和10%淀粉,最适干燥工艺均为冷冻干燥。此工艺条件下, SB13和BL14菌制剂的活菌数分别为6.40×108和9.80×108 cfu·mL−1,菌存活率分别为97.71%和94.69%。两种菌制剂经过人工胃、胰液处理2 h后,菌存活数在2.55×107~13.10×107 cfu·mL−1,内切葡聚糖酶活保存率均大于39%(胃液)和72%(胰液),并对鸡、猪和牛饲料均有显著的糖化作用。其中,菌株BL14对金黄色葡萄球菌有显著抑制效果。 结论 实现了黄浆水在芽孢杆菌制剂生产中的创新应用,降低了生产成本;通过工艺优化提高了菌制剂中的单位活菌数;制备的芽孢杆菌制剂有助于促进畜禽对饲料的吸收利用,其中菌制剂BL14还可应用于金黄色葡萄球菌感染的畜禽治疗。 Abstract:Objective Fermentation processes utilizing soymilk processing wastewater to prepare feed additives with a high viable bacteria count and desirable functionalities were tested for applications. Method Bacillus subtilis SB13 and B. licheniformis BL14 were cultured in the wastewater. Medium formulation and process optimization were conducted with a single factor experiment determined by the count of viable bacteria in the resulting preparations. Functions as an additive for chicken, pig, and cattle feeds of the preparations was evaluated by an in vitro simulated digestion and a DNS method. Result Both SB13 and BL14 grew normally in the soymilk wastewater. The optimized culture processes for SB13 and BL14 included sporulation temperatures at 35 ℃ for 72 h and 48 h, respectively. To facilitate dehydrating the fermentation broths, a protective agent of 10% skim milk powder was added in the medium for SB13 and 4% sucrose for BL14, as well as a carrier of 10% wheat bran for SB13 and 10% starch for BL14. After completion of the fermentation, the broths were freeze-dried and kept in sealed containers prior to functionality tests. The dried SB13 agent showed a viable bacteria count of 6.40×108 cfu·mL−1 and a survival rate at 97.71%, while BL14 a count of 9.80×108 cfu·mL−1 and a survival rate at 94.69%. Upon the artificial gastric juice and pancreatic juice treatments for 2 h, the two preparations had survived counts ranged from 2.55×107 to 13.10×107 cfu·mL−1. The endoglucanase activity of the preparations was more than 39% retained after the gastric juice treatment and 72% after the pancreatic juice treatment. Both agents displayed significant glycation on feed, and BL14 exhibited a significant inhibitory effect on Staphylococcus aureus. Conclusion Utilizing the wastewater from soymilk processing to culture B. subtilis SB13 and B. licheniformis BL14 resulted in preparations that could become a functional additive to forages for livestock and poultry industry. The process was cost effective and environmentally friendly. -
Key words:
- Bacillus preparation /
- carrier /
- protective agent /
- endoglucanase /
- soymilk processing wastewater
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表 1 不同培养时间的芽孢形成率
Table 1. Bacillus sporulation under varied culture durations
(单位:%) 发酵时间 Fermentation time 12 h 24 h 36 h 48 h 72 h 96 h SB13 — 3.85±1.24 d 25.35±2.42 c 49.36±6.12 b 78.80±3.92 a 76.78±1.56 a BL14 — 3.34±0.62 d 40.02±2.49 c 70.99±2.45 a 64.73±1.31 b 36.18±1.30 c 注:同行数据后不同小写字母表示差异显著(P<0.05)。表2~9同。
Note: Data with different lowercase letters on same row represent significant difference at 0.05 level. Same for Tables 2–9.表 2 不同培养温度条件下的芽孢形成率
Table 2. Bacillus sporulation under varied culture temperatures
(单位:%) 温度 Temperature 20 ℃ 25 ℃ 30 ℃ 35 ℃ 40 ℃ SB13 12.97±1.53 d 52.12±1.16 c 75.58±0.37 b 92.48±1.51 a 9.15±1.62 e BL14 3.00±0.50 e 17.46±1.57 d 62.47±3.31 b 82.01±3.17 a 36.56±2.44 c 表 3 不同保护剂对菌存活率的影响
Table 3. Survival rates of bacteria cultured in media containing varied protective agents
(单位:%) 保护剂
Protective agent10%甘油
10% glycerin10%脱脂奶粉
10% skimmed milk powder10%海藻糖
10% trehalose10%麦芽糊精
10% maltodextrin10%蔗糖
10% sucrose0.5%海藻酸钠
0.5% sodium alginateBL14 84.43±1.61 b 61.05±3.75 c 85.09±0.96 b 63.18±2.02 c 91.10±2.53 a 64.00±1.65 c SB13 72.09±3.78 b 94.24±2.07 a 52.60±2.66 d 72.09±5.79 b 62.00±2.66 c 78.59±1.12 b 表 4 最佳保护剂加入量筛选
Table 4. Optimal addition of protective agent
单位:lg(cfu·mL−1) 加入量 Add amount (m/v) 2% 4% 6% 8% 10% 12% SB13/脱脂奶粉 Skimmed milk powder 9.15±0.04 d 9.22±0.06 cd 9.28±0.03 bc 9.32±0.06 ab 9.41±0.02 a 9.32±0.01 abc BL14/蔗糖 Sucrose 9.13±0.07 d 9.73±0.02 a 9.52±0.01 b 9.39±0.04 c 9.33±0.04 c 9.16±0.02 d 表 5 不同载体对菌存活率的影响
Table 5. Survival rates of bacteria cultured in media containing different carriers
(单位:%) 保护剂
Carrier10%麦麸
10% wheat bran10%米糠
10% rice bran10%豆粕
10% soybean meal10%稻壳
10% rice husk10%淀粉
10% starchBL14 83.36±3.57 b 87.35±1.04 ab 66.18±4.07 c 87.48±2.75 ab 92.44±0.87 a SB13 90.25±1.07 a 43.49±2.05 c 85.28±2.36 a 89.56±3.04 a 63.56±2.19 b 表 6 最佳载体加入量筛选
Table 6. Optimal addition of carrier
单位:lg(cfu·mL−1) 加入量 Add amount(m/v) 2% 4% 6% 8% 10% SB13/麦麸 Wheat bran 9.35±0.01 d 9.45±0.05 c 9.51±0.11 b 9.54±0.02 b 9.60±0.02 a BL14/淀粉 starch 9.45±0.02 c 9.49±0.04 bc 9.52±0.03 b 9.56±0.03 ab 9.61±0.00 a 表 7 不同干燥条件对菌存活率的影响
Table 7. Bacteria survival rates under varied drying conditions
(单位:%) 干燥工艺
Drying process常温烘干
Room temperature drying喷雾干燥
Spray drying冷冻干燥
Freeze drying60 ℃热泵干燥
60 ℃ heat pump dryingSB13 93.59±0.12 a 65.72±3.56 c 95.00±0.49 a 77.76±5.39 b BL14 91.01±1.69 a 63.56±1.59 c 94.52±5.18 a 74.59±0.95 b 表 8 几种保护剂在冷冻干燥条件下SB13存活情况
Table 8. Bacteria survival rates of freeze-dried SB13 preparation with various protective agents
项目
Item原液
Stock solution10%脱脂奶粉
10% skimmed milk powder10%麦麸
10% wheat bran10%脱脂奶粉+10%麦麸
10% skimmed milk powder + 10% wheat branSB13存活率
Survival rate of strain SB13/%37.50±1.36 b 92.59±2.62 a 91.13±3.42 a 97.71±4.32 a 菌落数
Number of colonies/(×108 cfu·mL−1)1.95±0.07 c 5.00±0.14 b 5.65±0.21 ab 6.41±0.28 a 表 9 几种保护剂在冷冻干燥条件下菌BL14存活情况
Table 9. Bacteria survival rates of freeze-dried BL14 preparation with various protective agents
项目
Item原液
Stock solution4%蔗糖
4% sucrose10%淀粉
10% starch4%蔗糖+10%淀粉
4% sucrose + 10% starch菌BL14存活率 Survival rate of strain BL14/% 36.11±1.96 b 90.20±4.16 a 92.75±4.1 a 94.69±1.37 a 菌落数 Number of colonies/(×108 cfu·mL−1) 2.59±0.14 c 9.24±0.42 b 9.58±0.43 a 9.89±0.14 a 表 10 酶菌制剂处理对饲料总糖含量的影响
Table 10. Effect of preparation addition on total sugar content of feed
(单位:mg·mL−1) 饲料种类
Feed species发酵时间
Fermentation time/hSB13 BL14 基础培养基
Basic medium黄浆水培养基
Soybean wastewater medium基础培养基
Basic medium黄浆水培养基
Soybean wastewater medium猪饲料 Pig feed 0 1.09±0.02 d 1.12±0.08 cd 1.10±0.07 c 1.09±0.05 c 2 1.21±0.02 b 1.27±0.05 a 1.21±0.02 ab 1.19±0.01 ab 9 1.15±0.03 bcd 1.19±0.07 bc 1.19±0.03 b 1.15±0.03 bc 12 1.13±0.01 cd 1.10±0.02 d 1.26±0.09 a 1.10±0.00 c 24 1.16±0.02 bcd 1.16±0.01 bcd 1.15±0.01 bc 1.16±0.04 bc 鸡饲料 Chicken feed 0 0.79±0.01 d 0.79±0.03 d 0.81±0.00 cd 0.81±0.04 cd 2 1.29±0.03 a 1.26±0.00 abc 1.27±0.01 b 1.26±0.00 b 9 1.28±0.00 ab 1.31±0.00 a 1.34±0.00 a 1.30±0.00 ab 12 1.22±0.00 c 1.23±0.04 bc 1.27±0.00 b 1.29±0.06 ab 24 0.76±0.03 d 0.79±0.04 d 0.85±0.02 c 0.78±0.03 d 牛饲料 Cattle feed 0 0.77±0.02 f 0.78±0.01 ef 0.78±0.00 e 0.77±0.02 e 2 0.82±0.01 e 0.91±0.01 d 0.85±0.00 d 0.87±0.03 d 9 0.97±0.03 c 0.90±0.01 d 0.99±0.05 bc 1.00±0.05 bc 12 1.18±0.05 b 1.18±0.03 b 0.98±0.00 bc 0.96±0.03 c 24 1.16±0.04 b 1.26±0.02 a 1.11±0.02 a 1.03±0.05 b 注:不同字母表示不同发酵时间和不同培养基之间差异显著(P<0.05)。
Note:Different lowercase represent significant difference at 5% level between different fermentation times and different media (P<0.05).表 11 菌BL14对病原菌的抑制作用
Table 11. Inhibitory effect of BL14 on pathogens
病原菌
Pathogen抑菌圈直径
Zone of inhibition病原菌
Pathogen抑菌圈直径
Zone of inhibition金黄色葡萄球菌 Staphylococcus aureus 14 mm 大肠杆菌 Escherichia coli — 单核细胞增生李斯特菌 Listeria monocytogenes — 宋内氏志贺细菌 Shiga sonnei — 奇异变形杆菌 Proteus mirabilis — 鼠伤寒沙门氏菌 Salmonella typhimurium — 注:“—”表示没有抑菌效果。
Note: "—" means no antibacterial effect. -
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