Characterization of a heterogeneous camel milk whey non-casein protein

A milk protein, occurring in the whey fraction, has been characterized from camel milk. Determination of the primary structure reveals the existence of two related types of chain with residue differences in at least the N-terminal region. A fragment representing an N-terminal part of the protein was also recovered (heterogeneous at the same positions). The absence of cysteine residues in the protein shows that no disulphide bridges are present. The pattern of fragments and a parent protein resembles that for casein and its fragments, showing that fragments and a multiplicity of forms may be typical for different milk proteins.     

Characterization of recombinant camel chymosin reveals superior properties for the coagulation of bovine and camel milk

Enzymatic milk coagulation for cheese manufacturing involves the cleavage of the scissile bond in kappa-casein by an aspartic acid protease. Bovine chymosin is the preferred enzyme, combining a strong clotting activity with a low general proteolytic activity. In the present study, we report expression and enzymatic properties of recombinant camel chymosin expressed in Aspergillus niger. Camel chymosin was shown to have different characteristics than bovine chymosin. Camel chymosin exhibits a 70% higher clotting activity for bovine milk and has only 20% of the unspecific protease activity for bovine chymosin. This results in a sevenfold higher ratio of clotting to general proteolytic activity. The enzyme is more thermostable than bovine chymosin. Kinetic analysis showed that half-saturation is achieved with less than 50% of the substrate required for bovine chymosin and turnover rates are lower. While raw camel milk cannot be clotted with bovine chymosin, a high clotting activity was found with camel chymosin.     

Characterization of dominant microbiota of a Ghanaian fermented milk product, nyarmie, by culture- and nonculture-based methods

AIMS: To characterize the predominant micro-organisms in a Ghanaian traditional fermented dairy product, nyarmie, made from cows' milk, using both culture- and nonculture-based methods. METHODS AND RESULTS: Samples of nyarmie were analysed from three production sites in Accra, by determining the counts on selective culture media. The microbial diversity occurring in nyarmie was also evaluated by 16S/18S ribosomal DNA PCR amplification and denaturing gradient gel electrophoresis. Results showed that nyarmie contained lactococci and lactobacilli in the range of 10(8) and 10(10) CFU ml(-1), respectively, and yeasts at around 10(7) CFU ml(-1). The pH ranged between 3.49 and 4.25. The predominant lactic acid bacteria (LAB) in nyarmie were Leuconostocmesenteroides ssp. mesenteroides, Streptococcus thermophilus, Lactobacillus delbrueckii ssp. bulgaricus, Lact.helveticus, Lact. delbrueckii ssp. lactis and Lactococcus lactis, while Saccharomyces cerevisiae was the predominant yeast species. Lactobacillus delbrueckii ssp. delbrueckii was not detected by cultivation but its predominance was revealed by PCR-DGGE analysis. CONCLUSIONS: The flora in products from different producers varied in the LAB composition present and may result in variations in product quality. SIGNIFICANCE AND IMPACT OF THE STUDY: Development and use of starter cultures for nyarmie may be beneficial in improving the consistency of product quality.     

基于16S rRNA基因序列分析法比较苏尼特双峰驼和阿拉善双峰驼自然发酵酸驼乳的微生物多样性

【目的】传统发酵乳制品是一类未经任何处理自然发酵而成的,其微生态环境未遭破坏,从而乳酸菌的生物学特性和基因多样性得到了很好的保留,具有开发和利用价值。自然发酵酸驼乳常用来治疗多种疾病且效果良好,与其中丰富的乳酸菌资源有着密不可分的联系。然而,目前有关自然发酵酸驼乳微生物菌群及多样性相关研究甚少。因此进一步挖掘内蒙古地区双峰驼自然发酵酸驼乳微生物群落结构和多样性是至关重要的。【方法】本研究采用IlluminaMiseq测序技术,测定了苏尼特和阿拉善双峰驼的自然发酵酸驼乳中微生物16S rRNA V3–V4区序列,并对群落结构和多样性进行了比较分析。【结果】多样性分析表明,苏尼特双峰驼酸驼乳中微生物群落丰富度和种群差异性比阿拉善双峰驼酸驼乳大,细菌多样性也高。在门水平上,苏尼特和阿拉善双峰驼酸驼乳中的菌群均以厚壁菌门(Firmicutes)和变形菌门(Proteobacteria)为主。在属水平上,苏尼特双峰驼酸驼乳主要以乳杆菌属(Lactobacillus)和乳球菌属(Lactococcus)为优势菌群,阿拉善双峰驼酸驼乳以乳杆菌属(Lactobacillus)和醋酸杆菌属(Acetobacter)为优势菌属。此外,肠杆菌属(Enterobacter)、拉乌尔菌属(Raoultella)和明串珠菌属(Leuconostoc)等的含有食源性致病菌和环境污染菌的菌属被检出。综上所述,不同地区不同品种酸驼乳的乳酸菌种类及优势菌群有较大差异,存在显著的地理差异。【结论】通过本研究,不仅对苏尼特和阿拉善双峰驼自然发酵酸驼乳乳酸菌的组成和种类有了明确的认知,为评估发酵酸驼乳微生物群落对消费者身体健康的影响提供了数据基础的同时为今后筛选优势菌群和挖掘新型益生菌奠定基础。     

Occurrence and dominance of yeast species in naturally fermented milk from the Tibetan Plateau of China

To determine which yeasts are present in the naturally fermented milks of China, 69 samples made by the nomads of Tibet were collected from the Tibetan Plateau in China. From these samples, 225 strains of yeast were isolated and identified using conventional microbiological analysis and gene sequencing analysis of the D1/D2 domain of the large subunit (26S) ribosomal DNA. The results showed that the total concentration of yeasts in these samples ranged from 5.01 to 8.97 log10 colony-forming units (CFU)/mL (6.91?± 1.02 log10 CFU/mL; mean?± SD). The number of cultivable yeasts was higher in the samples from Qinghai (7.55?± 0.75 log10 CFU/mL) than those from Tibet (6.21?± 0.79 log10 CFU/mL, P?< 0.05). Moreover, there were 15 phylotypes in these 69 samples. Among these phylotypes, Kluyveromyces marxianus (49.3%, frequency percentage), Saccharomyces cerevisiae (62.3%), and Pichia fermentans (46.4%) appeared frequently and can be considered the most common culturable species in naturally fermented milk products. Traditional fermented Mongolian cow milk featured a wide diversity of yeast species, including Issatchenkia orientalis, Kazachstania unisporus, Rhodotorula mucilaginosa, Candida pararugosa, Torulaspora delbrueckii, Geotrichum sp., Kazachstania unisporus, Geotrichum fragrans, Debaryomyces hansenii, Yarrowia lipolytica, Trichosporon gracile, and Pichia membranifaciens. This study provides new data on yeast composition in naturally fermented milk and shows the yeast biodiversity of fermented milk products from the Tibetan Plateau of China.     

Characterization of lactic acid bacteria isolated from the one humped camel milk produced in Morocco

One hundred and twenty (120) strains of lactic acid bacteria (LAB) were enumerated and isolated from raw dromedary milk in Morocco using various cultured media. Strains isolated were characterized by phenotypic, physiological and biochemical properties. Results showed that high counts of LAB were found. Presumptive lactobacilli counts ranged from 2.5x10(2) to 6x10(7)cfu/ml, presumptive lactococci levels varied from 5x10(2) to 6x10(7)cfu/ml, presumptive streptococci counts varied from 4.2x10(2) to 8x10(7)cfu/ml, presumptive leuconostoc levels ranged from 5.4x10(2) to 5.4x10(7)cfu/ml. Results showed also that Lactobacillus and Lactococcus were the predominant genera with 37.5% and 25.8%, respectively. The dominated species found were Lactococcus lactis subsp. lactis (17.5%), Lactobacillus helveticus (10%), Streptococcus salivarius subsp. thermophilus (9.20%), Lactobacillus casei subsp. casei (5.80%) and Lactobacillus plantarum (5%). This is the first report on the characterization of LAB strains isolated from the one humped camel milk produced in Morocco.     

Identification and characterization of the dominant lactic acid bacteria isolated from traditional fermented milk in Mongolia

Five samples of Airag and 20 of Tarag (both in Mongolia) were collected from scattered households. One hundred strains of lactic acid bacteria (LAB) were isolated and identified from these samples according to phenotypic characterization and 16S rRNA gene sequence analysis. Eighty-five isolates belonged to the genus Lactobacillus, 15 being classified as coccoid LAB. All isolates belonged to 5 genera and 11 to different species and subspecies. Lactobacillus (Lb.) helveticus was predominant population in Airag samples, Lb. fermentum and Lb. helveticus were the major LAB microflora in Tarag.     

Characterization of a camel milk protein rich in proline identifies a new beta-casein fragment

A camel milk whey protein has been isolated by reverse-phase high performance liquid chromatography. The protein is, like caseins, rich in proline (25% of the whole protein). The N-terminal amino acid sequence shows that the protein is homologous with a C-terminal region of beta-caseins analyzed from other species. The protein is concluded to be a fragment of beta-casein, derived from a non-tryptic type of cleavage of the parent molecule, and increasing the multiplicity of known casein products.     

驼乳源益生菌对db/db鼠肠道菌群的调节作用

目的 探究驼乳来源复合益生菌对db/db鼠血糖及肠道菌群的调节作用。方法 将60只db/db鼠随机分为5组,每组12只,分别为模型组、二甲双胍组、利拉鲁肽组、低剂量复合益生菌组和高剂量复合益生菌组,12只C57BL/Ks小鼠为正常对照组。阳性药组分别灌胃0.3 mg/g二甲双胍及皮下注射0.2 μg/g利拉鲁肽,低剂量复合益生菌组灌胃乳酸菌1.0×108 CFU/d和酵母菌1.0×106 CFU/d,高剂量复合益生菌组灌胃乳酸菌1.0×1010 CFU/d和酵母菌1.0×108 CFU/d,其他组灌胃生理盐水。血糖仪检测空腹血糖（FBG）及不同时间段血糖水平。ELISA法检测糖化血红蛋白（HbA1c）含量。实时荧光定量PCR检测粪便菌群含量。结果 与模型组相比,低、高剂量复合益生菌组FBG水平明显减少,改善葡萄糖耐受（OGTT）能力,降低HbA1c含量。与模型组相比,低、高剂量复合益生菌组显著降低厚壁菌门、放线菌门和大肠埃希菌属水平,增加拟杆菌门、乳杆菌属和双歧杆菌属水平,但对总菌与梭杆菌属无影响。结论 驼乳来源复合益生菌可通过调节肠道菌群降低db/db鼠血糖含量。     

Characterization of starter lactic acid bacteria from the Finnish fermented milk product viili

Aims: Phenotypic and molecular methods were used to identify and compare the strain composition of three industrial dairy starters used for the manufacture of viili. Methods and Results: Preliminary differentiation was made by phenotypic methods. Genotypic differentiation was carried out using polymerase chain reaction (PCR) and further characterization at strain level by pulsed‐field gel electrophoresis (PFGE). The isolates could be assigned as acid‐producing Lactococcus lactis strains of both lactis and cremoris subspecies, and aroma producers, identified as L. lactis subsp. lactis biovar diacetylactis and Leuconostoc mesenteroides. PCR analysis discriminated between the lactococcal subspecies, and cluster analysis of the digestion patterns of PFGE analysis revealed different genotypes in each subspecies. Each Leuconostoc‐genotype seemed to be specific to only a single starter mix. Conclusions: The work proved that in addition to L. lactis subsp. lactis biovar diacetylactis and Leuc. mesenteroides subsp. cremoris, commercial viili starters of traditional origin may contain (i) only L. lactis subsp. cremoris, (ii) both L. lactis subsp. cremoris and L. lactis subsp. lactis as a minority, and – as a new discovery – (iii) only L. lactis subsp. lactis. Significance and Impact of the Study: The results obtained give an overview of the microbial population of viili starters and can be exploited in the development of optimized starter cultures for industrial‐scale manufacture of viili.     

Phenotypic variations in blood and milk of the Somali camel

132 blood samples and 54 milk samples obtained from Somali camel were analysed for red blood cell antigens with the cattle reagents and for Hb, Ca, X proteins, Tf, Alb, Am, SOD, alpha-La, beta-Lg and casein systems respectively. Positive lytic reactions were obtained with the anti-B, -Q, -Q', -W, -F1 and -J reagents. No biochemical polymorphism was observed except for Hb, X protein and beta-Lg systems.     

Antibiotic resistance and probiotic properties of dominant lactic microflora from Tungrymbai, an ethnic fermented soybean food of India

The present investigation was conducted to assess lactic acid bacteria present in traditionally fermented food of ethnic tribes in India for probiotic properties, antibacterial activity, and antibiotic tolerance behavior. Enterococcus sp., Lactobacillus sp., and Lactococcus sp. showed antibacterial activity against Bacillus cereus MTCC 430, Staphylococcus aureus subsp. aureus MTCC 740, and Salmonella enterica ser. paratyphi A MTCC 735. Lactococcus sp. and Lactobacillus sp. could tolerate acidic conditions (pH 2) and high bile salt concentration (4000 ppm). The lactic microflora were found to be sensitive to most common antibiotics, except for cloxacillin (5 μg), cephalexin (30 μg), and cephalothin (30 μg).     

Phenotypic variations in blood and milk of the Somali camel*

132 blood samples and 54 milk samples obtained from Somali camel were analysed for red blood cell antigens with the cattle reagents and for Hb, Ca, X proteins, Tf, Alb, Am, SOD, α-La, β-Lg and casein systems respectively. Positive lytic reactions were obtained with the anti-B, -Q, -Q, -W, -F₁ and -J reagents. No biochemical polymorphism was observed except for Hb, X protein and β-Lg systems.     

Biotherapeutic role of fermented milk

Fermented milk was used as therapy in infantile diarrhoea due to post-gastroenteritis syndrome. This treatment eliminated the disease in 4.0 days (mean value, SD=2.8; n=13) and allowed patients to return to free feeding according to their age. The weight percentile variation during treatment with fermented milk (15 days) was higher in the patients showing 3^rd degree malnutrition than in other children. Bacteriotherapy can restore faecal flora which has been lowered by diarrhoea. Our results showed that levels higher than 10⁶ UFC lactobacilli/g of faeces correlated with a healthy status of the children. Clinical applications of fermented milk with a mixture ofLactobacillus casei andLactobacillus acidophilus in the prevention of gastrointestinal disorders are possible.     

The primary structure of alpha-lactalbumin from camel milk

The primary structure of camel alpha-lactalbumin was determined by analysis of the intact protein, and of CNBr fragments and enzymatic peptides from the carboxymethylated protein chain. Results show that camel alpha-lactalbumin has 123 residues and a molecular mass of 14.6 kDa. The amino acid sequence is strictly homologous to alpha-lactalbumins characterized, but also exhibits extensive differences: 39 residues differ in relation to the bovine protein and only 35 residues are conserved among hitherto known alpha-lactalbumins with characterized structures. All residues ascribed critical structural or functional roles are strictly invariant in the camel protein.     

乳杆菌在发酵乳饮料中的应用

为了制备更优质的乳酸菌饮料,本论文主要以鼠李糖乳杆菌、瑞士乳杆菌、副干酪乳杆菌、嗜酸乳杆菌四种典型的乳酸杆菌为研究菌种,详细分析它们在乳品发酵过程中pH、酸度变化,货架期内的活菌数变化以及代谢产生的有机酸种类和耐胃酸的能力,以确定乳杆菌在乳饮料中应用的最优条件,分析其应用于乳饮料中的可行性。本文为乳杆菌在乳饮料中的应用提供了参考依据。     

Nutritional aspects of fermented milk products

Abstract Fermented milk products are a palatable and economical source of a wide range of nutrients. The nutrient composition is similar to that in milk, but concentrations of vitamins are in general a little lower, with the possible exception of folic acid. Concentrations of lactic acid, galactose, free amino acids and fatty acids are increased as a result of the fermentation. Lactose-intolerant individuals tolerate lactose when it is consumed in yoghurt better than when it is taken in the equivalent quantity of milk. The mechanism of this effect has not been clearly established. By far the greatest proportion of published material freely available in the West concerns yoghurt; reference is made to other cultured products where results are available to indicate interesting differences.     

Purification and partial characterisation of camel milk xanthine oxidoreductase

Xanthine oxidoreductase (XOR) was purified in the presence of dithiothrietol from camel milk with yields of up to 22.2mg/l that were comparable to those obtained from bovine and human milk sources. On SDS-PAGE, the freshly purified camel milk XOR had a protein flavin (A280/A450) ratio of 5.3 +/- 0.4 and appeared homogenous with a single major band of approximately Mr 145.3 KDa. Surprisingly, in all the batches (n = 8) purified camel milk XOR showed no detectable activity towards xanthine or NADH. The molybdenum content of camel XOR was comparable to human and goat milk enzymes. After resulphuration, camel milk XOR gave a specific activity of 1.1 nmol/min/mg and 13.0 nmol/min/mg enzyme towards pterin (fluorimetric assay) and xanthine (spectrophotometric assay) respectively. This activity was markedly lower than that of human, bovine and goat enzymes obtained under the same conditions. These findings suggest that the molybdo-form of camel enzyme is totally under desulpho inactive form. It is possible that camel neonates are equipped with an enzymic system that reactivates XOR in their gut and consequently generates antibacterial reactive oxygen species.     

Amino acids content and electrophoretic profile of camel milk casein from different camel breeds in Saudi Arabia

This study aimed to evaluate amino acids content and the electrophoretic profile of camel milk casein from different camel breeds. Milk from three different camel breeds (Majaheim, Wadah and Safrah) as well as cow milk were used in this study.Results showed that ash and moisture contents were significantly higher in camel milk casein of all breeds compared to that of cow milk. On the other hand, casein protein of cow milk was significantly higher compared to that of all camel milk breeds. Molecular weights of casein patterns of camel milk breeds were higher compared to that of cow milk.Essential (Phe, Lys and His) and non-essential amino acids content was significantly higher in cow milk casein compared to the casein of all camel milk breeds. However, there was no significant difference for the other essential amino acids between cow casein and the casein of Safrah breed and their quantities in cow and Safrah casein were significantly higher compared to the other two breeds. Non-essential amino acids except Arg and the essential amino acids (Met, Ile, Lue and Phe) were also significantly higher in cow milk α-casein compared to α-casein from all camel breeds. Moreover, essential amino acids (Val, Phe and His) and the non-essential amino acids (Gly and Ser) content was significantly higher in cow milk β-casein compared to the β-casein of all camel milk breeds and the opposite was true for Lys, Thr, Met and Ile. However, Met, Ile, Phe and His were significantly higher for β-casein of Majaheim compared to the other two milk breeds. The non-essential amino acids (Gly, Tyr, Ala and Asp) and the essential amino acids (Thr, Val and Ile) were significantly higher in cow milk κ-casein compared to that for all camel milk breeds. There was no significant difference among all camel milk breeds in their κ-casein content of most essential amino acids.Relative migration of casein bands of camel milk casein was not identical. The relative migration of α_s-, β- and κ-casein of camel casein was slower than those of cow casein. The molecular weights of α_s-, β- and κ-casein of camel caseins were 27.6, 23.8 and 22.4 KDa, respectively. More studies are needed to elucidate the structure of camel milk.