getpdf  NLM-PubMed-Logo  
doi: 10.17113/ftb.55.01.17.4693 

Three New Lactobacillus plantarum Strains in the Probiotic Toolbox against Gut Pathogen Salmonella enterica Serotype Typhimurium


Mia Potočnjak1, Petra Pušić1, Jadranka Frece2, Maja Abram1, Tamara Jankovićand Ivana Gobin1*
 

1University of Rijeka, Faculty of Medicine, Department of Microbiology and Parasitology, Braće Branchetta 20, HR-51000 Rijeka, Croatia
2University of Zagreb, Faculty of Food Technology and Biotechnology, Laboratory for General Microbiology and Food Microbiology, Pierottijeva 6, HR-10000 Zagreb, Croatia




Article history:
Received  March 9, 2016
Accepted  November 23, 2016
cc



Key words:
probiotic bacteria, antagonistic activity, Salmonella, mechanism of action



 

Summary:
The benefits of probiotic bacteria have been widely explored. However, fermented foods and digestive system of humans and animals are an inexhaustible source of new potentially probiotic microorganisms. In this study we present three new Lactobacillus plantarum strains isolated from different dairy products: cow′s cheese, sheep′s cheese and whey. In order to determine the antibacterial activity of yet unexplored L. plantarum strains against Salmonella enterica serotype Typhimurium, in vitro competition and co-culture tests were done. Furthermore, adhesion of these strains to Caco-2 cells and their influence on the adhesion of Salmonella were tested. Results showed the potential probiotic activity of isolated strains. L. plantarum strains survived in the presence of 1 % bile salts, they possessed acidification ability, antibacterial activity and significantly attenuated the growth of S. Typhimurium in brain heart infusion broth. All tested L. plantarum strains were able to adhere to Caco-2 cells and significantly impair the adhesion of S. Typhimurium. All three L. plantarum strains exhibited significant probiotic potential and anti-Salmonella activity; therefore, further testing on in vivo models should follow.






*Corresponding author:  email3  ivana.gobin@uniri.hr
                                      tel3  +385 51 651 265
                                      fax2  +385 51 651 177

 


getpdf  NLM-PubMed-Logo  
doi: 10.17113/ftb.55.01.17.4729 

Effect of Temperature-Shift and Temperature-Constant Cultivation on the Monacolin K Biosynthetic Gene Cluster Expression in Monascus sp.

 

Lin Lin, Changlu Wang*, Zhenjing Li, Huijia Wu and Mianhua Chen

 

Key Laboratory of Food Nutrition and Safety, College of Food Engineering and Biotechnology, Tianjin University of Science and Technology, No. 29, 13th Avenue, TEDA, Tianjin 300457, PR China





Article history:
Received   April 5, 2016
Accepted   October 12, 2016
cc 


Key words:
Monascus fuliginosus CG-6, monacolin K, temperature, protein analysis, gene analysis



 

Summary:
In this study, the effects of temperature-shift (from 30 to 25 °C) and temperature-constant (at 30 °C) cultivation on the mass of Monascus fuliginosus CG-6 mycelia and concentration of the produced monacolin K (MK) were monitored. The expression levels of the MK biosynthetic genes of M. fuliginosus CG-6 at constant and variable culture temperatures were analysed by real-time quantitative polymerase chain reaction (RT-qPCR). The total protein was collected and determined by liquid chromatography-electrospray ionisation with tandem mass spectrometry (LC-ESI-MS/MS). Results showed that the maximum mycelial mass in temperature-shift cultivation was only 0.477 g of dry cell mass per dish, which was lower than that in temperature-constant cultivation (0.581 g of dry cell mass per dish); however, the maximum concentration of MK in temperature-shift cultivation (34.5 μg/mL) was 16 times higher than that in temperature-constant cultivation at 30 °C (2.11 μg/mL). Gene expression analysis showed that the expression of the MK biosynthetic gene cluster at culture temperature of 25 °C was higher than that at 30 °C, which was similar to the trend of the MK concentration, except for individual MK B and MK C genes. Analysis of differential protein expression revealed that 2016 proteins were detected by LC-ESI-MS/MS. The expression level of efflux pump protein coded by the MK I gene exhibited the same upregulated trend as the expression of MK I in temperature-shift cultivation. Temperature-shift cultivation enhanced the expression of proteins in the secondary metabolite production pathway, but suppressed the expression of proteins involved in the mycelial growth.



 


*Corresponding author:  email3  clw123@tust.edu.cn
                                      tel3  +86 187 2232 9297

 


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doi: 10.17113/ftb.55.01.17.4520 

General Characteristics and Treatment Possibilities of Dairy Wastewater – A Review

 

Aleksandar Kolev Slavov
 

University of Food Technologies, Faculty of Economics, Department of Environmental Engineering, 26 Maritsa Blvd, BG-4002 Plovdiv, Bulgaria

 


Article history:
Received  November 11, 2015
Accepted  October 19, 2016
cc


Key words:
dairy wastewater, wastewater composition, whey, biological treatment


 

Summary:
The milk processing industry is one of the world’s staple industries, thus the treatment possibilities of dairy effluents have been attracting more and more attention. The purpose of the paper is to review contemporary research on dairy wastewater. The origin, categories, as well as liquid by-products and general indicators of real dairy wastewater are described. Different procedures applied for dairy wastewater management are summarised. Attention is focused on in-factory treatment technologies with the emphasis on biological processes. Aerobic and anaerobic methods with both their advantages and disadvantages are discussed in detail. Consecutive anaerobic and aerobic systems are analysed, too. Finally, future research niches are identified.


 


*Corresponding author:  email3  alexander_slavov@abv.bg
                                      tel3  +359 887 132 540


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doi: 10.17113/ftb.55.01.17.4858

Developing a Molecular Identification Assay of Old Landraces for the Genetic Authentication of Typical Agro-Food Products: The Case Study of the Barley ‘Agordino’

 

Fabio Palumbo, Giulio Galla and Gianni Barcaccia*
 
 

University of Padova, Department of Agronomy, Food, Natural Resources, Animals and Environment, Viale dell’Università 16, IT-35020 Legnaro (Padova), Italy




Article history:
Received  June 29, 2016
Accepted  November 23, 2016
cc 


Key words:
microsatellites, genotyping, landraces, traceability, barley, food authentication


 

Summary:
The orzo Agordino is a very old local variety of domesticated barley (Hordeum vulgare ssp. distichum L.) that is native to the Agordo District, Province of Belluno, and is widespread in the Veneto Region, Italy. Seeds of this landrace are widely used for the preparation of very famous dishes of the dolomitic culinary tradition such as barley soup, bakery products and local beer. Understanding the genetic diversity and identity of the Agordino barley landrace is a key step to establish conservation and valorisation strategies of this local variety and also to provide molecular traceability tools useful to ascertain the authenticity of its derivatives. The gene pool of the Agordino barley landrace was reconstructed using 60 phenotypically representative individual plants and its genotypic relationships with commercial varieties were investigated using 21 pure lines widely cultivated in the Veneto Region. For genomic DNA analysis, following an initial screening of 14 mapped microsatellite (SSR) loci, seven discriminant markers were selected on the basis of their genomic position across linkage groups and polymorphic marker alleles per locus. The genetic identity of the local barley landrace was determined by analysing all SSR markers in a single multi-locus PCR assay. Extent of genotypic variation within the Agordino barley landrace and the genotypic differentiation between the landrace individuals and the commercial varieties was determined. Then, as few as four highly informative SSR loci were selected and used to develop a molecular traceability system exploitable to verify the genetic authenticity of food products deriving from the Agordino landrace. This genetic authentication assay was validated using both DNA pools from individual Agordino barley plants and DNA samples from Agordino barley food products. On the whole, our data support the usefulness and robustness of this DNA-based diagnostic tool for the orzo Agordino identification, which could be rapidly and efficiently exploited to guarantee the authenticity of local varieties and the typicality of food products.






*Corresponding author:  email3  gianni.barcaccia@unipd.it
                                      tel3  +39 049 827 2814

 


getpdf  NLM-PubMed-Logo  doi: 10.17113/ftb.55.01.17.4617 

Biosynthesis of Oxytetracycline by Streptomyces rimosus: Past, Present and Future Directions in the Development of Tetracycline Antibiotics

 

Hrvoje Petković1*, Tadeja Lukežič2 and Jagoda Šušković3
 

1Department of Food Science and Technology, University of Ljubljana, Biotechnical Faculty, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia
2Department of Microbial Natural Products, Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI) and Pharmaceutical Biotechnology, Saarland University, Campus E 8.1, DE-66123 Saarbrücken, Germany
3Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, HR-10000 Zagreb, Croatia




Article history:
Received January 21, 2016
Accepted October 12, 2016
cc
 


Key words:
antibiotics, biosynthesis, polyketides, polyketide synthase, tetracyclines, oxytetracycline, chlortetracycline, Streptomyces, Streptomyces rimosus, Streptomyces aureofaciens


 

Summary:
Natural tetracycline (TC) antibiotics were the first major class of therapeutics to earn the distinction of ‘broad-spectrum antibiotics’ and they have been used since the 1940s against a wide range of both Gram-positive and Gram-negative pathogens, mycoplasmas, intracellular chlamydiae, rickettsiae and protozoan parasites. The second generation of semisynthetic tetracyclines, such as minocycline and doxycycline, with improved antimicrobial potency, were introduced during the 1960s. Despite emerging resistance to TCs erupting during the 1980s, it was not until 2006, more than four decades later, that a third-generation TC, named tigecycline, was launched. In addition, two TC analogues, omadacycline and eravacycline, developed via (semi)synthetic and fully synthetic routes, respectively, are at present under clinical evaluation. Interestingly, despite very productive early work on the isolation of a Streptomyces aureofaciens mutant strain that produced 6-demethyl-7-chlortetracycline, the key intermediate in the production of second- and third-generation TCs, biosynthetic approaches in TC development have not been productive for more than 50 years. Relatively slow and tedious molecular biology approaches for the genetic manipulation of TC-producing actinobacteria, as well as an insufficient understanding of the enzymatic mechanisms involved in TC biosynthesis have significantly contributed to the low success of such biosynthetic engineering efforts. However, new opportunities in TC drug development have arisen thanks to a significant progress in the development of affordable and versatile biosynthetic engineering and synthetic biology approaches, and, importantly, to a much deeper understanding of TC biosynthesis, mostly gained over the last two decades.






*Corresponding author:  email3  hrvoje.petkovic@bf.uni-lj.si
                                      tel3   +386 1 320 3779
                                      fax2   +386 1 256 5782

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