产壳聚糖酶微生物的筛选及产酶条件的优化

目的 从土壤中筛选能降解壳聚糖的微生物,并优化其产酶条件。方法利用平板筛选法对采集的土壤中的微生物进行富集培养、初筛和复筛,得到能降解壳聚糖的菌株,并对降解壳聚糖能力最强的菌株进行发酵培养,优化产酶条件。结果筛选出3株产壳聚糖酶菌株,编号为C-01、C-02和C-03,其中,C-01、C-02为细菌,C-03为霉菌。C-01菌株产酶能力最强,其最适产酶条件为:以1%粉末壳聚糖+0.1%葡萄糖为碳源,0.5%(NH4)2SO4+0.5%蛋白胨为氮源,培养基初始pH值8.0,培养温度30℃,菌株接种量2.0%,培养时间48 h。在最适条件下,壳聚糖酶活力可达7.78 U/ml。结论已筛选出1株高产壳聚糖酶的菌株,并优化了其产酶条件,为壳寡糖的生产及应用奠定了基础。     

甲壳低聚糖功能性质

对５种平均分子量（ＭＷ）分别为１５００，３０００，５０００，８０００，１３０００甲壳低聚糖的水溶性、保湿性、吸湿性以及抑菌作用进行了研究。结果表明：ＭＷ１５００和３０００的甲壳低聚糖具有优良的水溶性，其吸湿性和保湿性强于透明质酸、乳酸钠和甘油，并且也有显著的抑菌作用。甲壳低聚糖的分子量大小和游离氨基的存在是影响其功能性质的关键因素。     

耐高温抗H2S/CO2缓蚀剂的合成及评价

采用天然大分子壳寡糖、缩水甘油三甲基氯化铵、苯甲醛为原料,合成了绿色壳寡糖衍生物缓蚀剂(BHC)。通过红外光谱、核磁共振氢谱对缓蚀剂BHC结构进行了表征。采用失重法、电化学法、扫描电镜、原子力显微镜、接触角等对缓蚀剂BHC进行缓蚀性能评价和机理分析。得到的优化缓蚀剂BHC合成条件为m(HTCOS)∶m(苯甲醛)=1.0∶2.4,反应温度80℃,反应时间24 h。在总压为15 MPa(H2S、CO2、N2分压分别为1、5和9 MPa)条件下,缓蚀剂BHC质量浓度为100 mg/L时,P110钢片在140℃、含H2S/CO2腐蚀介质中的缓蚀率为85.62%,与市售缓蚀剂相比,BHC缓蚀率提高16.90%,可有效减缓高温高含H2S/CO2腐蚀环境下钢材的腐蚀速率。缓蚀剂BHC是一种偏阴极保护的混合型缓蚀剂,在金属表面的吸附行为符合Langmuir吸附等温式,与钢表面形成稳定共价键,能很好保护钢管。     

Anticoagulant activity of heterochitosans and their oligosaccharide sulfates

Three kinds of partially deacetylated heterochitosans, 90% deacetylated chitosan, 75% deacetylated chitosan and 50% deacetylated chitosan, were prepared from crab chitin by N-deacetylation with 40% sodium hydroxide solution for different durations. Nine kinds of heterochitooligosaccharides (hetero-COSs) with relatively high molecular weights (5,000–10,000 Da; 90-HMWCOSs, 75-HMWCOSs, and 50-HMWCOSs), medium molecular weights (1,000–5,000 Da; 90-MMWCOSs, 75-MMWCOSs, and 50-MMWCOSs), and low molecular weights (below 1,000 Da; 90-LMWCOSs, 75-LMWCOSs, and 50-LMWCOSs) were prepared using an ultrafiltration membrane reactor system, respectively. In addition, their sulfated derivatives were prepared by a method using a trimethylamine-sulfur trioxide, and the anticoagulant properties of the heterochitosans and their COS sulfates with different chain lengths and degrees of deacetylation were investigated. Clotting times in thrombin-time assay were prolonged in the presence of various concentrations of the heterochitosans and their COS sulfates using normal human plasma. The 90% deacetylated chitosan sulfate exhibited the highest anticoagulant activity among all the heterochitosans and their COS sulfates.     

Effect of chitooligosaccharide from squid pen on gel properties of sardine surimi gel and its stability during refrigerated storage

Effect of chitooligosaccharide from squid pen prepared using lipase (COS-L) at various concentrations (0–30 g kg⁻¹) on gel properties of sardine surimi gel was investigated. Breaking force (BF) and deformation (DF) of gel were increased, when COS-L level was increased up to 10 g kg⁻¹ (P < 0.05). Water holding capacity and whiteness of gel were improved with the addition of COS-L than those of control. Gel added with 10 g kg⁻¹ COS-L had denser network with higher likeness score for all sensory attributes, compared to control. When gel incorporated with 10 g kg⁻¹ COS-L was stored at 4 °C, BF, DF and whiteness were maintained during 10 days of storage. Textural properties of surimi gel added with COS-L were higher than those of control throughout storage. Thus, incorporation of 10 g kg⁻¹ COS-L could improve gel properties of sardine surimi gel and retarded the deterioration of gel properties during refrigerated storage.     

A facile construction method for pH and oxidation dual-responsive assembly based on ferrocene-modified chitooligosaccharide

Here, we present a novel and facile method for constructing “snowflake-like” assemblies that respond to external stimuli, similar to snowflakes in nature, via the self-organization of ferrocene-modified chitooligosaccharide (FcCOS) in an acid aqueous solution. Interestingly, the snowflakes were sensitive to pH and redox stimuli. They not only formed irregular network-like aggregates when the pH was adjusted to 7.0, they also gradually transformed into loose snowflakes with holes after exposure to air for 5 d and totally collapsed after treatment with hydrogen peroxide. Due to their interesting responses to pH and oxidation, these assemblies are a very interesting and promising system for biomaterial applications.     

大豆几丁质酶应用的研究

研究了大豆种子几丁质酶对壳聚糖的降解作用,采用测定壳聚糖溶液黏度降低和还原糖增加的方法。结果表明,大豆种子经甲壳低聚糖诱导后发芽的提取物作用于DD值为71.1%的壳聚糖15min,可使其乙酸盐溶液的VDP值达60%以上。初步纯化的大豆几丁质酶可降解壳聚糖释放还原糖,且较适合降解DD值低的壳聚糖,其作用于DD值71.1%的壳聚糖37.5h可得到平均聚合度为4￣5的水溶性甲壳低聚糖,得率为40%左右。大豆种子几丁质酶对壳聚糖有降解作用。     

壳寡糖佐剂对甲型肝炎病毒疫苗诱导小鼠体液免疫应答的影响

目的探讨壳寡糖(chitooligosaccharide,COS)佐剂对甲型肝炎病毒(hapatitis A virus,HAV)疫苗诱导小鼠体液免疫应答的影响。方法将ICR小鼠随机分成9组:甲型肝炎减毒活疫苗Hep A-l 18 EU+不同剂量COS(100μg、500μg、1 mg、2.5 mg、5 mg、10 mg)组、阴性对照组(生理盐水)、抗原对照组(Hep A-l 18 EU)和铝佐剂对照组[Hep A-l18 EU+Al(OH)3200μg],每组6只,各组均经皮下注射ICR小鼠,200μl/只。于免疫后的第4、8、12和16周,采用间接ELISA法检测小鼠血清中抗-HAV特异性Ig G抗体水平。在实验期间,观察小鼠的健康状况,并于免疫16周后,取COS最佳剂量组及阴性对照组小鼠肾脏、脾脏、肝脏、肺脏、心脏组织,制备病理切片,进行对比观察。结果除阴性对照组外,各组小鼠免疫4周后均产生抗-HAV Ig G抗体,并随着时间的延长呈上升趋势,在第8周时均达峰值,随后逐渐下降;COS 2.5 mg、5 mg和10 mg组小鼠血清在各时期的抗体水平均显著高于抗原对照组和铝佐剂对照组(P0.05),且能维持较长时间,至16周抗体水平仍与铝佐剂对照组相当,差异无统计学意义(P0.05),其中COS5 mg组在整个试验过程中产生的抗体水平均最高,且与2.5 mg组峰值水平差异有统计学意义(P0.05),与10 mg组水平相当,至免疫后16周,COS 5 mg组与10 mg组抗体水平差异有统计学意义(P0.05)。COS最佳剂量为5 mg/只。试验期内,观察小鼠各项生理指标未见异常,COS 5 mg组小鼠心脏、肝脏、脾脏、肺脏、肾脏组织均未观察到病变。结论 COS可显著增强HAV疫苗诱导小鼠的体液免疫应答,有望开发为一种可替代铝佐剂的新型佐剂。     

Radical scavenging activity of chitooligosaccharide with different molecular weights

Two chitooligosaccharides, Ch1100 (average molecule weight: 1,100; average degree of polymer: 7) and Ch500 (average molecule weight: 500; average degree of polymer: 3), were obtained by partial hydrolysis of chitosan. Their antioxidant activities were investigated with scavenging activity of chitooligosaccharide against superoxide radical using phenazin methosulphate (PMS)–β-nicotinamide adenine dinucleotide (NADH)–nitroblue tetrazolium (NBT) system, scavenging activity of chitooligosaccharide against carcinogen-induced active oxygen species and scavenging activity of chitooligosaccharide against hydrogen peroxide released from polymorphonuclear leukocytes stimulated by phorbol-12-myristate-13-acetate (PMA). By the aforementioned three measurements, the radical scavenging activity (Inhibition%) of Ch1100 was determined to 54.8, 35.3 and 38.9%, respectively, at the concentration of 100 μmol/L, while that of Ch500 was 40.1, 13.9 and 18.2%, respectively, at the same concentration. These results clearly suggest that Ch1100 is a potent radical scavenger, which has the high radical scavenging activity.     

Industrial applications of crustacean by-products (chitin,chitosan, and chitooligosaccharides): A review

BackgroundFood processing produces large quantities of by-products. Disposal of waste can lead to environmental and human health problems, yet often they can be turned into high value, useful products. For example, crustacean shell wastes from shrimp, crab, lobster, and krill contain large amounts of chitin, a polysaccharide that may be extracted after deproteinisation and demineralization of the exoskeletons.Scope and approachThis review summarizes the current state of knowledge of these crustacean shellfish wastes and the various ways to use chitin. This biopolymer and its derivatives, such as chitosan, have many biological activities (e.g., anti-cancer, antioxidant, and immune-enhancing) and can be used in various applications (e.g., medical, cosmetic, food, and textile).Key findings and conclusionsDue to the huge waste produced each year by the shellfish processing industry and the absence of waste management which represent an environmental hazard, the extraction of chitin from crustaceans’ shells may be a solution to minimize the waste and to produce valuable compound which possess biological properties with application in many fields. As a food waste, it is important to also be aware of the non-food uses of these wastes.