肉制品中的绿色魏斯氏菌

尽管魏斯氏菌无处不在,不过魏斯菌属的细菌都没有受到足够的重视。该属的许多成员最初被归为明串珠菌或乳酸菌。随着分子生物学技术的发展,这些系统发育密切相关的细菌被归为一个单独的属,魏斯氏菌属。魏斯氏菌的异型新陈代谢给肉类工业造成相当大的损失。粘液形成和肉制品绿化被认为跟绿色魏斯氏菌密切相关。主要介绍了绿色魏斯氏菌对肉类加工的影响。     

魏斯氏菌在发酵食品中的应用

魏斯氏菌是一类存在于酱油、泡菜、豆豉、香肠等多种发酵食品的乳酸菌。它是参与食品发酵的重要微生物,在发酵食品中具有广泛应用价值。在食品发酵过程中,魏斯氏菌对食品中有机酸、酯类及短链脂肪酸等风味物质的合成具有重要作用。此外,魏斯氏菌属的有些菌株具有合成细菌素、低聚糖、胞外多糖和纤维素等特性,具有潜在的益生菌特性。该文主要对魏斯氏菌的分离鉴定、生理生化特性以及菌株在发酵食品中的应用特性等几方面的研究进展进行了综述。     

孝感米酒中乳酸菌的分离及其对黄酒品质的影响

目的:探明孝感米酒中乳酸菌的种类及其对黄酒品质的影响。方法:采用传统可培养方法使用MRS培养基、厌氧工作站,对孝感米酒中乳酸菌进行分离,并接入黄酒对黄酒发酵过程进行干预,进而通过分析黄酒有机酸与滋味等理化特征来评价乳酸菌的发酵特性。结果:从孝感米酒中分离到9株乳酸菌,基于16S rDNA基因对乳酸菌分离株进行了系统发育分析,结果显示它们属于魏斯氏菌属(Weissella)、片球菌属(Pediococcus),种水平上分为戊糖片球菌(Pediococcus pentosaceus)、融合魏斯氏菌(Weissella confusa)、食窦魏斯氏菌(Weissell acibaria)。将这9株菌应用于黄酒发酵制作,在菌株融合魏斯氏菌MJ3-1与MJ4-1、戊糖片球菌MJ6-1、食窦魏斯氏菌MJ8-1干预下,黄酒中乳酸含量显著增加(p<0.05),苹果酸含量显著减少(p<0.05);同时黄酒的滋味中咸味和丰度有显著增加(p<0.05)。总体上来说,乳酸菌对黄酒滋味的影响由酸味、鲜味与丰度引起。结论:融合魏斯氏菌MJ4-1能增加黄酒乳酸,并降低苹果酸含量作用最强,适用于黄酒复合型发酵剂的研发。     

麻竹笋腌制过程中细菌群落动态变化分析

为了解麻竹笋腌制发酵过程中细菌群落的微生态演变情况,采用细菌16S r DNA的V3可变区的PCRDGGE技术监测6%Na Cl腌制麻竹笋的细菌群落组成和优势菌群的动态变化。经发酵液中细菌基因组DNA提取、巢式PCR、二次DGGE、切胶回收、测序及序列比对,共得到10条明显条带,分别鉴定为绿色气球菌、乳球菌属、食窦魏斯氏菌、魏斯氏菌属、噬甲基菌属、嗜盐嗜碱菌属、未培养细菌、乳球菌属、乳酸乳球菌、厌氧芽孢杆菌属和芽孢杆菌属。其中,发酵前3 d优势菌为绿色气球菌,7 d后优势菌为食窦魏斯氏菌和乳酸乳球菌。     

冬瓜腌制过程中微生物多样性的分析

采用分子生态检测方法研究传统腌冬瓜加工过程中微生物多样性及其变化情况,揭示传统腌制冬瓜品质形成规律及产品质量控制的微生物学本质。采用构建16S rDNA克隆文库法并结合传统的微生物培养方法解析冬瓜腌制过程中微生物种类组成及变化,对照理化品质的变化分析结果。试验结果表明,冬瓜腌制体系中,在腌制开始时的优势种群为不动杆菌属、魏斯氏菌属、芽孢杆菌属和肠杆菌属;第5天的优势种群为魏斯氏菌属、芽孢杆菌属和肠杆菌属;第10天的优势种群变成了乳杆菌属、魏斯氏菌属和芽孢杆菌属;腌制后期的优势种群为魏斯氏菌属、芽孢杆菌属和葡萄球菌属。与此同时,冬瓜腌制过程中腌制体系的pH值和亚硝酸含量下降较显著,最低值分别为3.33 mg/kg和3.55 mg/kg。乳酸菌总数增加,盐度和细菌总数相对稳定。本研究结果可促进冬瓜腌制的微生物生态研究,为生产上优化控制提供微生物学依据。     

自然发酵三樱椒中乳酸菌的分离及鉴定

为获得适用于三樱椒发酵的乳酸菌,该研究采用钙溶圈法从自然发酵三樱椒中分离乳酸菌,通过形态观察和分子生物学技术对其进行菌种鉴定,并对其生长、产酸、耐酸特性进行分析。结果表明,从自然发酵三樱椒中共分离纯化得到19株乳酸菌,经鉴定,16株为植物乳杆菌（Lactobacillus plantarum）,3株为赫轮魏斯氏菌（Weissella hellenica）。培养初期,赫轮魏斯氏菌生长比植物乳杆菌快,但培养12 h后植物乳杆菌比赫轮魏斯氏菌生长速度更快;植物乳杆菌产酸能力优于赫轮魏斯氏菌,培养21 h后,植物乳杆菌发酵液的pH值稳定在3.7,赫轮魏斯氏菌发酵液pH值稳定在4.3,其中植物乳杆菌PLP-1产酸能力最好;植物乳杆菌的耐酸性优于赫轮魏斯氏菌,在pH值＜4.0的培养条件下赫伦魏斯氏菌生长受到严重抑制,而植物乳杆菌可以在pH值为3.0的培养基中生长,其中植物乳杆菌PLP-1耐酸性最好。     

基于宏基因组分析四川泡菜母水作引子的泡菜发酵过程中细菌多样性变化

本文旨在研究以泡菜母水作引子的蔬菜发酵过程中细菌多样性变化,并对泡菜质量控制和泡菜中功能性细菌资源开发提供理论支持。采集发酵过程中不同发酵时间的样品,提取基因组,PCR扩增16S r RNA的V3+V4区并进行Illumina高通量测序,通过生物信息学分析比较发酵不同时间细菌多样性。结果表明:以老坛水作引子的发酵过程中发酵启动时魏斯氏菌属可达到74.5%,而之后则在10%左右,取而代之成为优势菌的是乳杆菌属,含量达到80%~85%。说明泡菜发酵中启动菌为魏斯氏菌属,发酵的关键菌为乳杆菌属,同时表明四川泡菜是优良的微生物资源,可用于魏斯氏菌属,乳杆菌属,乳球菌属,片球菌属和明串珠菌属等益生菌的分离和筛选。     

怀集黄菜发酵微生物群落与理化品质相关性分析

怀集黄菜是肇庆怀集的一种特色发酵萝卜叶菜,仍采用步骤繁琐、耗时长的传统发酵工艺。为改进怀集黄菜传统工艺和提高产品质量,揭示自然发酵黄菜的微生物群落结构以挖掘其菌种资源,论文选取了当地四种具有代表性的自然发酵黄菜,采用扩增子测序分析其微生物多样性,并通过冗余分析、Spearman相关性分析确定影响黄菜品质的关键微生物,为黄菜的产业化提供理论指导。结果表明,自然发酵黄菜具有丰富的微生物多样性,主要细菌属包括乳杆菌属、魏斯氏菌属、片球菌属、甲基杆菌属、假单胞菌属、鞘氨醇单胞菌属和Allorthizobium-Neorhizobium-Pararhizobium-Rhizobiu,丰度最高的主要菌种为植物乳杆菌植物亚种（Lactobacillus plantarum subsp. plantarum）、消化乳杆菌（Lactobacillus alimentarius）、食窦魏斯氏菌（Weissellacibaria）、乳酸片球菌（Pediococcusacidilactic）、莫氏土壤杆菌（Agrobacterium larrymoorei）、人参皂苷乳杆菌（Lactobacillus ginsenosidimutans）和偶氮假单胞菌（Pseudomonas azotoformans）。盐度、pH值、水分活度、总酸是影响黄菜细菌群落组成的主要因素,乳杆菌属、片球菌属、魏斯氏菌属为促进黄菜品质的关键菌属,种水平则体现在植物乳杆菌植物亚种、乳酸片球菌、食窦魏斯氏菌对促进黄菜酸味、色泽和质构的保持作用。研究结果表征了自然发酵黄菜的微生物群落结构和主导菌属与品质之间的关系,有助于实现黄菜发酵过程的品质控制。     

山西老陈醋和怀仁醋酒精发酵阶段细菌菌群多样性分析

为了探明山西老陈醋酿造工艺和怀仁醋酿造工艺对细菌菌群的影响,该研究利用高通量测序技术对两种工艺酒精发酵阶段样品（分别编号为S和X）的细菌菌群多样性进行分析。结果表明,S样品的细菌菌群多样性更高。两种工艺酒精发酵阶段样品的细菌菌群组成差别较大,与S样品相比,X样品中相对丰度较高的乳杆菌属（Lactobacillus）、魏斯氏菌属（Weissella）、乳球菌属（Lactococcus）均增多,片球菌属（Pediococcus）、明串珠菌属（Leuconostoc）、泛菌属（Pantoea）、链霉菌属（Streptomyces）、短状杆菌属（Brachybacterium）、肠杆菌属（Enterobacter）和非培养细菌（uncultured bacterium）均减少。导致两种工艺酒精发酵阶段样品有显著差异的细菌在S样品中为片球菌属、明串珠菌属、链霉菌属和泛菌属,在X样品中则为乳杆菌属、魏斯氏菌属和乳球菌属。相关性分析结果表明,乳杆菌属、泛菌属、魏斯氏菌属和片球菌属与其他物种联系紧密。     

绿色魏斯氏菌发酵液对单核细胞增生李斯特菌的抑制及其在冷却猪肉保鲜中的应用

采用微量肉汤稀释法测定绿色魏斯氏菌（Weissella viridescens）发酵液对单核细胞增生李斯特菌（Listeria monocytogenes,Lm）的最小抑菌浓度,微孔板法结合显微镜观察检测绿色魏斯氏菌发酵液对Lm生物被膜形成的影响,最后通过测定冷藏过程中冷却猪肉的菌落总数、Lm总数、感官指标和理化指标评估绿色魏斯氏菌发酵液对冷却猪肉产品特性的影响。结果表明：绿色魏斯氏菌发酵液可抑制Lm的生长,亚抑菌浓度的发酵液能有效抑制Lm生物被膜的形成;绿色魏斯氏菌发酵液能够抑制冷藏期间冷却猪肉中细菌和Lm的生长,延缓冷却猪肉因腐败导致的感官品质下降,同时对贮藏过程中冷却猪肉pH值升高和挥发性盐基氮含量的增加也具有抑制作用,使冷却猪肉的货架期明显延长。     

Microbial communities and malt quality of durum wheat used in brewing

Durum wheat (Triticum durum Desf.) has potential as an adjunct in brewing given its agronomic, chemical and technological properties. The aim of this work were to identify the cultivable microflora and evaluate the technological quality of the durum wheat variety ‘Senatore Cappelli’ grown and used by a craft brewery in Sardinia, Italy. The isolated bacterial strains were mainly rhizospheric (Kocuria rizophila, Microbacterium aerolatum and Bacillus pumilus) and associated with the microbiota of wheat (Staphylococcus spp.). None have been reported previously as spoilage species in brewing. The dominant yeast genera were Cryptococcus spp. and Rhodotorula spp., followed by Saccharomyces cerevisiae. The dominant filamentous fungus genera were Alternaria and Rhizopus. Low levels of mycotoxigenic Fusarium spp., Aspergillus spp. and Penicillium spp. were isolated. However, the levels of deoxynivalenol, T2‐HT2, fumonisin, aflatoxin and ochratoxin detected in the malt and grain were below the thresholds defined by European law. Malt obtained from raw grain showed interesting technological properties, but required specific malting parameters different from those of common wheat and barley. These data suggest that the use of locally grown durum wheat in brewing can increase sustainability and reduce costs, while reinforcing the link with the terroir and promoting reduced mycotoxin levels. © 2019 The Institute of Brewing & Distilling     

Microbiology and foodborne pathogens in honey

Honey has been considered a relatively safe foodstuff due to its compositional properties, with infant botulism caused by Clostridium botulinum being the most prominent health risk associated with it. Our review is focused on the honey microflora along the food chain and evaluates the pathogenic potential of those microorganisms found in honey. This product may contain a great variety of bacteria and, particularly, fungi that eventually entered the food chain at an early stage (e.g., via pollen). For many of these microorganisms, opportunistic infections in humans have been recorded (e.g., infections by Staphylococcus spp., Citrobacter spp., Escherichia coli, Hafnia alvei, Aspergillus spp., Fusarium spp., Trichoderma spp., Chaetomium spp.), although direct infections via honey were not registered.     

Probiotic Bacillus spp. in Soy‐Curd: Nutritional,Rheological, Sensory,and Antioxidant Properties

The focus of this study was to coculture probiotic Bacillus spp. with dairy starter cultures namely, Streptococcus thermophilus and Lactobacillus bulgaricus for enhanced nutritional properties of soy‐curd. Subsequently, rheological, sensory, and antioxidant properties of soy‐curd along with mineral as well as fatty acid composition were analyzed. Data revealed an increase in the cell viability of probiotic Bacillus spp. on coculturing rather than as mono‐culture. Proximate analysis showed higher nutritional value along with increased trace elements. UFA/SFA ratio, rheology, and sensory properties of probiotic soy‐curd were in the acceptable range. Probiotic soy‐curd showed higher antioxidant activity as measured by the ability to scavenge free radicals. No significant difference in the overall quality within the probiotic products was observed. However, B. flexus MCC2427 cocultured product displayed slightly better attributes than other samples. In general, the results suggest that soy‐curd can be a suitable carrier for probiotic Bacillus spp. and the enhanced nutritional and antioxidant properties could be of additional advantage to combat malnutrition problem.     

Microbiological and physicochemical properties of farm bulk tank milk and antimicrobial resistance of its dominant bacteria

This study determined the antibiotic resistance of the dominant bacteria in the 85 farm BTMs according to the guidelines recommended by the epidemiological cutoff values in the EUCAST. In addition, some physicochemical and microbiological properties of farm BTMs were investigated. The milk samples were divided into two groups according to their SCC values. The milk samples with higher SCC than 400,000 cells mL⁻¹ were further examined bacteriologically, and the antibiotic resistance of isolates was determined. The average TAMB value was 6.34 log CFU/mL in farm BTM. It was found that high-SCC values did not affect other physicochemical properties of BTM samples, such as fat, protein and total solids, except for lactose content. Seventy-two strains were isolated from 45 bulk milk samples. The most prevalent bacteria were Enterococcus spp. (23.61%). The other isolates were Citrobacter spp. (12.5%), Staphylococcus spp. (12.51%), Serratia spp. (11.12%), Klebsiella spp. (9.72%), Bacillus spp. (9.72%), and Enterobacter spp. (8.33%). In antibiotic resistance analysis, 52.6% of Enterobacterales isolates showed cefoxitin resistance, and nine Enterobacterales isolates were determined as the presumptive ESBL producers. None of them was confirmed as ESBL producers. Moreover, MDR was detected in 83.3% of Enterobacter spp. isolates and all Bacillus spp. isolates. The over and inappropriate use of antibiotics in mastitis treatment may cause antibiotic-resistant microorganisms in milk. It was found that 52.7% of the isolated bacteria were MDR, which could pose a risk to public health and food safety, with the consumer's increasing interest in consuming raw milk.     

Recent research on bioactive compounds of Scomber spp. and their health effects

Scomber spp. are fast-moving migratory fish found in the Pacific, Indian and Atlantic Oceans. Scomber spp. contain proteins, lipids, minerals and vitamins. However, recent studies on Scomber spp. have focused on improving the quality of products (S. colias), describing their morphology (S. indicus), as well as the exploration and application of their enzymes (S. australasicus) and bioactive compounds for health benefits (S. japonicus and S. scombrus). Bioactive compounds from Scomber spp. have been reported to exhibit antibacterial, antioxidant and antiproliferative activities, but there has been no review of this topic to date. Totally, 36 articles were reviewed after the duplicates were removed. Muscle protein hydrolysates, peptides, lipids, collagen, amino acids, lecithin and glycolipids are known as bioactive compounds from Scomber spp. that exhibit beneficial health effects, including antioxidant, antibacterial, antiproliferative, tyrosinase inhibition, hypoglycaemic and anti-lipoxygenase properties. However, these have been tested only in vitro, and there is still a lack of studies on bioactive compounds from S. australasicus, S. colias and S. indicus. Therefore, further studies are needed to test bioactive compounds from Scomber spp. at the in vivo and clinical stages, as well as to explore the presence of bioactive compounds from S. australasicus, S. colias and S. indicus.     

Determination of the botanical origin of honey by Fourier-transformed infrared spectroscopy: an approach for routine analysis

Fourier-transformed infrared spectroscopy has been established for analysing most of the physical–chemical parameters of honey. Additionally this technique can be used for determination of the botanical origin of a honey sample by comparison of the mid-infrared spectra. In this study calibrations for authentification of the main regional honey types should be developed to be able to measure simultaneously physical–chemical properties and the botanical origin at a minimum of time and at low costs. Honey samples from local beekeepers were collected and characterized by standard methods. The most common honey types were used for calibration. We recorded the mid infrared spectrum from each honey sample. Classification models were achieved by PCA-calibration and validated with samples from various botanical origins. Honey of Brassica spp., Robinia pseudoacacia, Calluna vulgaris, Trifolium spp., Tilia spp., Helianthus annuus, Centaurea cyanus and honeydew honey was used for calibration. Afterwards the calibration models were improved during routine analysis. Most of the honey samples from rape, false acacia, heather and honeydew can be classified correctly by the FTIR in consideration of the physical–chemical and sensorial properties.     

The influence of thiamine and riboflavin on various spoilage microorganisms commonly found in beer

Beer is generally considered a stable product owing to its intrinsic ‘unfavourable’ conditions (hops, alcohol, low oxygen, etc.) that inhibit the growth of pathogenic microorganisms. However spoilage microorganism such as Lactobacillus brevis , Pediococcus damnosus , Acetobacter aceti , Zymomonas mobilis and various wild yeasts (e.g. Brettanomcyes spp.) can have significant detrimental effects on the organoleptic properties of the final product. The presence of essential vitamins, such as thiamine and riboflavin, can help to enhance the growth of these microorganisms, accelerating the rate of spoilage. The presence of thiamine had a noticeable effect on the lactic acid productivity of L. brevis and P. damnosus , acetaldehyde productivity of Z. mobilis and acetic acid production of Brettanomyces spp., while riboflavin enhanced 2,3‐pentanedione production by P. damnosus and Brettanomyces spp. Copyright © 2017 The Institute of Brewing & Distilling     

Isolation and molecular identification of yeasts in Greek kefir

The aim of this study was to enumerate and identify yeasts present in Greek kefir. Total yeast counts in kefir grains were 7.7 ± 0.5 log cfu/g, whereas in kefir drinks counts ranged from <0.4 to 6.7 log cfu/mL. Molecular identification tests revealed 14 different yeast species belonging to 10 genera (Candida spp., Debaryomyces spp., Galactomyces spp., Issatchenkia spp., Kazachstania spp., Kluyveromyces spp., Pichia spp., Saccharomyces spp., Wickerhamomyces spp., Yarrowia spp.). This study is the first to identify yeast species present in Greek kefirs and to isolate Pichia membranifaciens and Candida zeylanoides as part of the kefir microbiota.     

Radiation sensitivity of planktonic and biofilm‐associated Shigella spp. and Aeromonas spp. on food and food‐contact surfaces

Although ionising radiation has been shown to kill human pathogens Shigella spp. and Aeromonas spp. on various food products, there is lack of information regarding the relative efficacy of gamma radiation against their free‐living planktonic and biofilm‐associated cells. The radiation sensitivity (D₁₀ values) of planktonic, glass‐ and carrot‐associated biofilm cells of Shigella spp. and Aeromonas spp. was determined by forming biofilms on sterile glass and carrot surfaces, incubated at 37 °C (Shigella spp.) and 30 °C (Aeromonas spp.) for 48 h. No significant difference in the D₁₀ values of planktonic and glass‐associated biofilm cells of Shigella spp. and Aeromonas spp. was observed. However, significant increase in the D₁₀ values of carrot‐associated biofilm cells as compared to planktonic and glass‐associated biofilm cells of Shigella spp. and A. hydrophila A331 was observed, whereas A. salmonicida Y567 showed insignificant difference. SEM analysis further validated the formation of biofilm on the carrot and glass surfaces. The antimicrobial effectiveness of ionising radiation against both Shigella spp. and Aeromonas spp. is affected by growth form, strain and nature of attachment surface.     

Influence of Fermentation Time and an ‘Indigenous Tenderiser’ (Kanwa) on the Microbial Profile,Chemical Attributes and Shelf-Life of Rice Masa (a Nigerian Fermented Product)

Investigations on the influence of fermentation time, ‘Kanwa’ (an indigenous tenderiser and a flavouring agent) and potassium sorbate (0·5, 1·0 or 1·5 g kg⁻¹) were conducted by examining the microbial profile, chemical attributes and shelf-life of rice ‘Masa’ (a Nigerian fermented product). Various types of microorganisms occurred at the initial stages of rice slurry fermentation and these included fungi (Aspergillus spp, Penicillium spp, Saccharomyces spp, Rhizopus spp) and bacteria (Lactic acid bacteria, Bacillus spp, Enterobacter spp and Acetobacter spp). But beyond 8 h fermentation time, fewer types of micro-organisms (Lactobacillus spp, Saccharomyces spp and Rhizopus spp) were isolated.Total aerobic counts increased significantly (P=0·05) as fermentation progressed (0, 6 or 12 h), with lactic acid bacteria (LAB) and yeasts dominating and probably contributed to the sour–sweet spongy characteristic of the rice Masa. But after fermentation and baking process, the rice Masa became dominatedand spoilt by Bacillus spp, Lactobacillus spp and Saccharomyces spp withstorage time. Longer fermentation time resulted in a less acceptable product,being more acidic. Rice Masa produced from a 6 h fermentation showedbetter sensory qualities (aroma and visual appearance). Use of Kanwa(Na₂CO₃.NaHCO₃.2H₂O) improved aroma but was detrimental to visualappearance and spoilage was accelerated, probably due to higher pH. Potassium sorbate at higher concentrations (1·0 and 1·5 g kg⁻¹) induced beneficial antimicrobial effects and reduced the microbial load thereby prolonging the shelf life of the rice Masa (treated with 1·5 g kg⁻¹) by about 3 days.