scholarly journals Newly isolated lactic acid bacteria from silage targeting biofilms of foodborne pathogens during milk fermentation

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Elizaveta Gavrilova ◽  
Elizaveta Anisimova ◽  
Alsu Gabdelkhadieva ◽  
Elena Nikitina ◽  
Adel Vafina ◽  
...  

Abstract Background Raw milk, meat and plant materials are subjected to high risks of contamination by various pathogenic bacteria and thus their growth prevention is a great challenge in the food industry. Food fermentation by lactic acid bacteria (LAB) besides changing its organoleptic characteristics also helps to eliminate unfavorable microflora and represses growth of pathogens. To the date only few LABs has been reported to exhibit activity against bacteria embedded in the biofilms characterized by extreme resistance to antimicrobials, high exchange rate with resistance genes and represent high risk factor for foodborne disease development. Results Six novel LAB strains isolated from the clover silage exhibited pronounced antibacterial activity against biofilm embedded pathogens. We show explicitly that these strains demonstrate high acidification rate, completely repress the growth of E. coli, S. aureus and to a lesser extent P. aeruginosa as well as exhibit appropriate probiotic and milk-fermenting properties. Moreover, in contrast to the approved probiotic strain Lactobacillus plantarum 8PA3, the new isolates were able to efficiently eradicate preformed biofilms of these pathogens and prevent bacterial spreading originating from the biofilm. We suggest these strains as potential additives to the pre-cultures of conventional LAB strains as efficient tools targeting foodborne pathogens in order to prevent food contamination from either seeded raw material or biofilm-fouled equipment. Conclusions The AG10 strain identified as L. plantarum demonstrate attractive probiotic and milk fermentation properties as well as high resistance to simulated gastric conditions thus appearing perspective as a starter culture for the prevention of bacterial contamination originating from fouled equipment during milk fermentation.

1995 ◽  
Vol 58 (9) ◽  
pp. 998-1006 ◽  
Author(s):  
MARIA L. RODRIGUEZ MEDINA ◽  
MARIA E. TORNADIJO ◽  
JAVIER CARBALLO ◽  
ROBERTO MARTIN SARMIENTO

The levels of several microbial groups (aerobic mesophilic flora, aerobic psychrotrophic flora, lactic acid bacteria, Micrococcaceae, enterococci, Enterobacteriaceae, and molds and yeasts), and some biochemical parameters were investigated during the manufacture and ripening of four batches of León cow cheese produced from raw milk without the addition of starter cultures. The study of the microbial characteristics of this cheese constitutes the first step towards the establishment of a starter culture which would allow the making of a product both more uniform and safer from the point of view of health. The total microbial counts were high throughout the elaboration and ripening. Almost all the microbial groups reached their maximum counts in curd and afterwards dropped throughout the ripening process. The greatest drop was shown by Enterobacteriaceae, which had disappeared after 3 months of ripening. Lactic acid bacteria were the major microbial group, reaching counts similar to the total aerobic mesophilic flora at all sampling points. Lactococcus lactis subsp. lactis dominated in milk (62.5% of the isolates obtained in de Man-Rogosa-Sharpe (MRS) agar at this sampling point), curd (82.5% of the isolates obtained at this sampling point) and one-week-old cheese (85% of isolates obtained at this sampling point), while Lactobacillus casei subsp. casei was the most predominant species in eight-week-old cheese (55% of isolates obtained at this sampling point) and twelve-week-old cheese (47.5% of isolates obtained at this sampling point). According to our data, a starter suitable for the production of León cow cheese would be made up of these two species. Some species of Leuconostoc or enterococci could also be added to this starter with the aim of improving the organoleptic characteristics of the final product or to emphasize the characteristics of this variety.


2019 ◽  
Vol 366 (Supplement_1) ◽  
pp. i60-i67
Author(s):  
Mette Lübeck ◽  
Peter Stephensen Lübeck

ABSTRACT Lactic acid bacteria (LAB) have extensive industrial applications as producers of lactic acid, as probiotics, as biocontrol agents and as biopreservatives. LAB play a large role in food fermentation and in silage processes, where crops such as grass, legumes, cereals or corn are fermented into high-moisture feed that is storable and can be used to feed cattle, sheep or other ruminants. LAB also have great applications within green biorefineries, with simultaneous production of protein-rich feed for monogastric animals, silage or feed pellets for ruminants and production of lactic acid or specific amino acids. In green biorefineries, fresh or ensiled wet biomass is mechanically fractionated into green juice and solid residues (press cake), where the plant juice, for example, can be used for production of lactic acid using LAB. In a process named ‘ENLAC’, recovery of protein and chlorophyll from silage by simultaneous lactic acid fermentation and enzyme hydrolysis has been developed. Furthermore, a process for protein recovery was recently developed by applying a specific LAB starter culture to green juice from freshly harvested crops. This paper focuses on reviewing LAB for their applications within biorefining of ‘green’ crops such as clover, alfalfa, grasses and other green plant materials.


2015 ◽  
Vol 1 (1) ◽  
pp. 26-33
Author(s):  
IRA ERDIANDINI ◽  
TITI CANDRA SUNARTI ◽  
ANJA MERYANDINI

The development of industrial fermentation food could not separate with the availability of culture starter that suffice to support its production. Dried starter can be an option to use in fermentation industry because it can be stored for longer time without rejuvenation. However, in the process of production of dried starter needs the matrix to maintain cell viability, economically and availability of raw material. This research was conducted to use selected dried starter of indigenous lactic acid bacteria by using sour cassava starch matrix. Eleven local isolates lactic acid bacteria isolates from spontaneous fermentation of carbohydrates commodity were selected based on their acid production capabilities and antibiotics susceptibilities. Isolate of E 1222 showed the best result and was identified as Pediococcus pentosaceus. The isolate was encapsulated with sour cassava starch matrix for making dried starter by using freeze dryer and spray dryer. Freeze dried starter culture could maintained the cell viability higher than spray dried starter culture i.e 10.34 log CFU/g and 8.91 log CFU/g, respectively. Finally, freeze dried starter culture could maintain the percentage of cell viability until 89.38% during four-weeks storage at 4 oC. 


1993 ◽  
Vol 56 (11) ◽  
pp. 972-976 ◽  
Author(s):  
O. M. ABDALLA ◽  
P. M. DAVIDSON ◽  
G. L. CHRISTEN

Effect of lactic acid bacteria starter culture, nisin, hydrogen peroxide, or potassium sorbate on Listeria monocytogenes, Staphylococcus aureus, and Salmonella typhimurium in white pickled cheese made from pasteurized milk with 4% salt and preserved in 4% brine solution at 4°C for 60 d was studied. The starter culture inhibited all three pathogens while antimicrobials did not. Beyond day 50 in curd and day 30 in brine solution, L. monocytogenes was not detected by direct plating in cheese with added starter culture. S. aureus was not detected after day 30 in curd and day 20 in brine solution in the same cheese. S. typhimurium was not detected after day 30 in cheese curd and was not detected in brine solution at any time with lactic acid bacteria starter culture added. The pH of brine solution of starter treatment dropped below 4.7 in all experiments, while antimicrobial treatments all had a pH >5.5.


2017 ◽  
Vol 25 (4) ◽  
pp. 231-241 ◽  
Author(s):  
Cecile Levasseur-Garcia ◽  
Christel Couderc ◽  
Helene Tormo

Raw milk is often described as a major source of lactic acid bacteria for indigenous lactic starter. These indigenous starters contribute to the sensorial quality of cheese. Raw milk, rich in Lactoccocus lactis may therefore be very interesting for the cheese making. Currently, the most commonly used methods to differentiate lactic acid bacteria, and particularly the closely related phenotypes Lactococcus and Enterococcus, are based on DNA sequencing, but the cost and time required for these analytical methods hinder their use for rapid screening of raw material. The present study therefore proposes a simple alternative method to identify and discriminate against Lactococcus and Enterococcus, at the genus, but also at the species level, that is based on collecting near infrared spectra directly from bacterial colonies in Petri dishes. The infrared spectra of 280 strains of Lactococcus and Enterococcus cultured on solid media were collected by using a spectrometer with a wavelength range of 908 to 1684 nm and a remote probe. The best Classification And Regression Trees models for genus and species discrimination gave an excellent classification rate of 87% on an external validation set (30 strains). Loading line plots, with prominent bands at 900–960 and 1270–1390 nm, confirmed that the source of variation was due to changes in the polysaccharides.


Foods ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 17 ◽  
Author(s):  
Dimitrios A. Anagnostopoulos ◽  
Vlasios Goulas ◽  
Eleni Xenofontos ◽  
Christos Vouras ◽  
Nikolaos Nikoloudakis ◽  
...  

Table olives are one of the most established Mediterranean vegetables, having an exponential increase consumption year by year. In the natural-style processing, olives are produced by spontaneous fermentation, without any chemical debittering. This natural fermentation process remains empirical and variable since it is strongly influenced by physicochemical parameters and microorganism presence in olive drupes. In the present work, Cypriot green cracked table olives were processed directly in brine (natural olives), using three distinct methods: spontaneous fermentation, inoculation with lactic acid bacteria at a 7% or a 10% NaCl concentration. Sensory, physicochemical, and microbiological alterations were monitored at intervals, and major differences were detected across treatments. Results indicated that the predominant microorganisms in the inoculated treatments were lactic acid bacteria, while yeasts predominated in control. As a consequence, starter culture contributed to a crucial effect on olives fermentation, leading to faster acidification and lower pH. This was attributed to a successful lactic acid fermentation, contrasting the acetic and alcoholic fermentation observed in control. Furthermore, it was established that inhibition of enterobacteria growth was achieved in a shorter period and at a significantly lower salt concentration, compared to the spontaneous fermentation. Even though no significant variances were detected in terms of the total phenolic content and antioxidant capacity, the degradation of oleuropein was achieved faster in inoculated treatments, thus, producing higher levels of hydroxytyrosol. Notably, the reduction of salt concentration, in combination with the use of starter, accented novel organoleptic characteristics in the final product, as confirmed from a sensory panel; hence, it becomes obvious that the production of Cypriot table olives at reduced NaCl levels is feasible.


2001 ◽  
Vol 68 (1) ◽  
pp. 131-137 ◽  
Author(s):  
EVA RODRÍGUEZ ◽  
JUAN LUIS ARQUÉS ◽  
PILAR GAYA ◽  
MANUEL NUÑEZ ◽  
MARGARITA MEDINA

The ability of Listeria monocytogenes to grow at low temperatures and increase to hazardous levels during storage of dairy products is of great concern to the dairy industry. List. monocytogenes was detected in 3·6% of 774 cows' milk samples from 114 farms in Central Spain (Gaya et al. 1998). Ewes' and goats' milks produced in Spain had contamination levels of 2·2 and 2·6% respectively (Rodríguez et al. 1994; Gaya et al. 1996). List. monocytogenes may survive during the manufacture and ripening of most cheese varieties, with higher risk in soft surface-ripened cheeses owing to the rise in pH during ripening (Maisnier-Patin et al. 1992; Giraffa & Carminati, 1997).The efficacy with which actively growing bacteriocin-producing cultures inhibit List. monocytogenes in some cheese varieties has been demonstrated. Nisin-producing starters inhibited List. monocytogenes V7 in Camembert cheese (Maisnier-Patin et al. 1992) and List. innocua BL86/26 in raw ewes' milk Manchego cheese (Rodríguez et al. 1998). A lacticin 3147-producing starter culture (McAuliffe et al. 1999) reduced List. monocytogenes Scott A levels in cottage cheese. Inoculation of milk with enterocin AS-48-producing Enterococcus faecalis INIA 4 inhibited List. monocytogenes strains Ohio and Scott A during the manufacture and ripening of Manchego cheese (Nuñez et al. 1997).Semi-hard cheese varieties from raw or pasteurized cows' milk mixed with different proportions of ewes' and/or goats' milk represent ∼ 50% of Spanish cheese production. The objective of the present work was to evaluate the antilisterial activity of three bacteriocin-producing lactic acid bacteria strains isolated from milk (Rodríguez et al. 2000) during the manufacture and ripening of a semi-hard cheese manufactured from raw milk.


1996 ◽  
Vol 59 (13) ◽  
pp. 64-71 ◽  
Author(s):  
LYNN M. McMULLEN ◽  
MICHAEL E. STILES

ABSTRACT Bacterial spoilage and safety are major concerns in the marketing of raw and processed meats. When meat is packaged under modified atmosphere with elevated levels of carbon dioxide (including vacuum packaging), the prevailing microflora of meat is changed from aerobic, putrefactive bacteria to lactic acid bacteria. Some “new generation” convenience foods rely almost entirely on refrigeration for assurance of safety against growth of pathogenic bacteria. With the emergence of cold-tolerant foodborne pathogens it is desirable to increase the “hurdles” to pathogen growth. Lactic acid bacteria preserve meats by competitive exclusion of other microorganisms but they also produce inhibitory substances, including lactic and acetic acids and bacteriocins. Bacteriocins are naturally produced peptides that are antagonistic to other closely related bacteria. Although bacteriocins are expected to have a narrow range of antibacterial activity, nisin is a bacteriocin that is active against a relatively broad spectrum of gram-positive bacteria, including inhibition of the outgrowth of Clostridium botulinum spores. Nisin is not effective in meat systems; as a result, research on the lactic acid bacteria of meat is focused on the selection of lactic acid bacteria that do not cause meat spoilage and that enhance product safety.


2014 ◽  
Vol 32 (No. 2) ◽  
pp. 145-151 ◽  
Author(s):  
I. Složilová ◽  
S. Purkrtová ◽  
M. Kosová ◽  
M. Mihulová ◽  
E. Šviráková ◽  
...  

Eight individual bacteriocin-producing lactic acid bacteria (LAB) strains and three bacteriocin-non-producing cheese starter cultures were evaluated for their ability to inhibit the growth of six Listeria monocytogenes strains, originating from the guinea-pig lymph nodes, raw cow milk, and manufacturing dairy equipment. Results showed that either live cells or cell-free neutralised supernatant (CFNS) and/or heated CFNS of six individual LAB strains (Lcc. lactis subsp. lactis CCDM 416 and NIZO R5, Lbc. plantarum HV 11 and DC 1246, P. acidilactici HV 12, and Ent. mundtii CCM 1282) and one starter culture (DELVO-ADD<sup>&reg;</sup> 100-X DSF) were effective in the suppression of at least one listeria strain. Neither any individual LAB strain nor starter culture was antagonistic toward all studied L. monocytogenes strains, indicating diverse sensitivity/resistance among L. monocytogenes strains to antimicrobial compounds of LAB. The significant susceptibility of listerias isolated from raw milk and dairy equipment together with the strong antilisterial activity of DELVO-ADD<sup>&reg; </sup>100-X DSF could be applied in dairy technology, where commonly used starter cultures could play both the biopreservative and fermentation role. &nbsp;


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