Probiotic Potential and Functional Properties of Lactobacillus Reuteri, Lactobacillus Rhamnosus and Lactobacillus Helveticus: A Comparative Study

This study was conducted to evaluate and comparethe probiotic propertiesofLactobacillus helveticusNK1, Lactobacillus rhamnosusF and Lactobacillus reuteriLR1lactobacilli strains.Changes in pH, cell growth, proteolytic activity, antioxidantactivity, and angiotensin-converting enzyme(ACE)inhibitoryactivity were monitored during fermentation ofreconstituted skim milk (RSM) by pure cultures of lactobacilli.Among the tested strains, L. helveticusNK1 showed the highest proteolytic, ACE inhibitoryand antioxidantactivitiesduring milk fermentation,followed by L. rhamnosus F and L. reuteriLR1.The promising capability of all of the lactobacilli strains to release bioactivepeptides from the milk proteins was demonstrated. Keywords: Lactobacillus, probiotic, milk fermentation, bioactive peptides

Identification of Putative β-Galactosidase Genes in the Genome of Lactobacillus helveticus OSU-PECh-4A

The Lactobacillus helveticus OSU-PECh-4A strain, from the Ohio State University Parker Chair collection, produces exceptional β-galactosidase activity using acid whey as a culture medium, compared with a commercial broth. The strain has a genome sequence of 1,834,843 bp, and its GC content is 36.69%. Using InterProScan v5.50-84.0 software, four genes with putative β-galactosidase function were found.

Caracterização físico-química do leite fermentado por Lactobacillus helveticus adicionado de extrato de hibisco durante a estocagem

Este trabalho propôs desenvolver um leite fermentado por Lactobacillus helveticus (LH) ou associada com cultura de Streptococcus thermophilus (LHST) adicionado de extrato de hibisco e avaliar a atividade antioxidante e evolução do crescimento das culturas láticas durante a estocagem sob refrigeração a 4 ± 1ºC. O leite fermentado recebeu extrato de hibisco na forma livre (LHExL e LHSTExL) ou encapsulado com PVP e Tween 80 (LHExE e LHSTExE). Avaliou-se a atividade antioxidante (DPPH e FRAP) nos tempos de 1, 15 e 30 dias. Os resultados demonstraram que o teor de acidez titulável foi inferior após a fermentação. A viabilidade das bactérias láticas foi satisfatória, as quais atenderam os requisitos legais e mantiveram estáveis até 30 dias de estocagem para ambas as caldas do leite fermentado (LH e LHST). A atividade antioxidante frente ao radical DPPH foi superior a 80%, porém não apresentou resultados conclusivos relativos à interação das culturas láticas e das diferentes formas de aplicação do extrato de hibisco. Porém, o LH apresentou maior atividade antioxidante pelo método FRAP quando associado ao extrato de hibisco encapsulado no tempo inicial. Esta análise permitiu observar que a associação do extrato de hibisco independente da forma veiculada ao leite fermentado aumentou a atividade antioxidante pelo método de FRAP e este manteve estável ao longo do tempo de estocagem. Portanto, o estudo permitiu concluir que o leite fermentado associado ao extrato de hibisco contribuiu com o aumento da atividade antioxidante e manteve estável ao longo do tempo de estocagem.

Caseinolytic proteases of Lactobacillus and Lactococcus strains isolated from fermented dairy products

Proteases of Lactobacillus and Lactococcus strains catalyze casein degradation in fermented dairy products, which can result in the production of bioactive peptides. Proteolytic properties of a selection of lactic acid bacteria (LAB) strains previously isolated in Croatia, including Lactococcus lactis and Lactobacillus strains, are described. All strains of Lactobacillus and Lactococcus showed an Fmc+ phenotype that can be associated with efficient growth in milk. The significant caseinolytic effect, after incubation of culture supernatant or concentrated cell biomass, was observed for Levilactobacillus brevis D6 and Lactiplantilactobacillus plantarum D13 after growth in the optimal growth medium, while for Lactoccocus lactis ZGBP5-32 and Levilactobacillus brevis SF9B strains after growth in skimmed milk. To assess the LAB growth in skimmed milk, the acidification rate was monitored. Statistically, significant acidification capacity was determined for L. plantarum D13 in the optimal medium and by the proteolytic strain Lactobacillus helveticus M92 in skimmed milk. After extraction of proteinases from the strains with caseinolytic activity, protein samples were analysed by the SDS-PAGE. The protein extract of the Lc. lactis ZGBP5-32 and ZGZA7-10, retained proteolytic activity even at very low concentrations. The ultrafiltration improved protein extraction. The crude extract possibly contained putative protease, as a decrease in contaminating proteins was confirmed by SDS-PAGE in samples of L. brevis D6 and SF9B, L. fermentum D12 and L. plantarum D13.

Effects of Natural Antimicrobials on Xanthomonas Strains Growth

The aim of this work was to investigate the most promising natural antimicrobials effective for the growth suppression of Xanthomonas spp. bacteria. The research objects were Xanthomonas spp. strains isolated from tubers and stem of plants growing in Lithuania: Xanthomonas translucens NRCIB X6, X. arboricola NRCIB X7, NRCIB X8, NRCIB X9, and NRCIB X10; the supernatants of lactic acid bacteria Lactococcus lactis strains 140/2, 57, and 768/5, Lactobacillus helveticus strains 14, 148/3, R, and 3, Lb. reuteri 3 and 7, Streptococcus thermophilus 43, Enterococcus faecium 59-30 and 41-2; endophytic bacterial strains Bacillus, Pseudomonas, and Paenibacillus spp.; and essential oils of lavender (Lavandula angustifolia), grapefruit (Citrus paradisi), pine (Pinus sylvestris), thyme (Thymus vulgaris), rosemary (Rosmarinus officinalis), peppermint (Mentha piperita), lemon (Citrus limetta), aqueous extracts of blueberries (Vaccinium myrtillus), and cranberries (Vaccinium vitis-idaea). The antimicrobial activity of tested substances was determined by agar diffusion method. Supernatants of Lb. reuteri strain 7 and Lb. helveticus strains 14, R, 3, and 148/3 were found to have a high antimicrobial activity against Xanthomonas spp. bacteria strains when compared to the positive control—1.0% copper sulfate (diameter of inhibition zones was 28.8 ± 0.7 mm). The diameter of inhibition zones of supernatants ranged from 23.3 ± 0.6 mm to 32.0 ± 0.1 mm. Thyme (2.0%) and lavender (2.0%) essential oils inhibited the growth of Xanthomonas spp. strains. The diameter of the inhibition zones was from 14.7 ± 0.8 mm to 22.8 ± 0.9 mm. The aqueous extracts of blueberries had a weak antimicrobial activity. The diameter of inhibition zones ranged from 11.0 ± 0.2 mm to 13.0 ± 0.2 mm.

Phenolics Profile, Antioxidant Activity and Flavor Volatiles of Pear Juice: Influence of Lactic Acid Fermentation Using Three Lactobacillus Strains in Monoculture and Binary Mixture

The aim of this study was to evaluate the effects of lactic acid fermentation using three Lactobacillus strains (Lactiplantibacillus plantarum 90, Lactobacillus helveticus 76, and Lacticaseibacillus casei 37) in monoculture and binary mixture on phenolics profile, antioxidant activity and flavor volatiles in pear juice. Results showed that the colony counts of binary mixture were higher than monoculture in fermented pear juice. The total content of phenols was increased, while that of flavonoids was decreased significantly during fermentation (p < 0.05). Antioxidant activities in fermented peer juice including DPPH and ABTS radical scavenging abilities and ferric reducing antioxidant power (FRAP) were significantly improved (p < 0.05). Binary mixture of Lactiplantibacillus plantarum 90 and Lacticaseibacillus casei 37 fermentation exhibited strong DPPH radical scavenging ability, due to the increase in vanillic acid and arbutin contents. Furthermore, lactic acid fermentation improved the formation of alcohols, esters, acids and terpenoids, and reduced the contents of aldehydes and ketones. Thirty new compounds including 15 alcohols, seven esters, five acids, and three terpenoids were observed in fermented pear juice. Hierarchical cluster revealed that flavor volatiles in pear juice were improved dramatically by Lactobacillus strains fermentation, and there were dramatic differences between monoculture and binary mixture.

Isolation, identification and biochemical characterization of lactic acid bacteria from selected yogurt samples

This research was conducted to study the types of lactic acid bacteria (LAB) present in selected yogurts available in the local market of Bangladesh. For this purpose, nine different yogurt samples were collected (viz. MV, Mw, Pst, Psr, Bik, Bog, WF, Kw and Nab) and cultured in the selective MRS agar media for enumerating LAB colony. Out of 9 samples, colony forming LAB were found in 6 samples and the population ranged from 1.0×104 to 9.5×105 cfu/ml. Catalase negative and Gram’s positive colonies were initially identified as LAB. Then the isolates were purified by subsequent culturing in MRS broth and MRS agar media. Biochemical properties of selected colonies were evaluated by performing gas production from glucose, growth at different temperatures (10ºC, 15ºC and 45ºC), growth at different NaCl concentrations (2, 4 and 6.5% NaCl) and sugar fermentation tests (lactose, sorbitol, salicin, trehalose, melibiose, sucrose, mannitol, melezitose, maltose, galactose, glucose, arabinose, raffinose and ribose). According to the tests stated above, a total of five different species of LAB were identified from 6 samples. The isolate Lactobacillus lactis was identified in MV, PSr and Bog yogurt, while Lactobacillus bulgaricus was found in MV and Bik yogurt. The species Leuconostoc cremoris, a avor producing bacteria, was found in six yogurt samples. On the other hand, Lactobacillus acidophilus and Lactobacillus helveticus was found only in Pst and Psr samples, respectively. Bang. J. Livs. Res. Vol. 27 (1&2), 2020: P. 64-72

Antihypertensive Peptides from Ultrafiltration and Fermentation of the Ricotta Cheese Exhausted Whey: Design and Characterization of a Functional Ricotta Cheese

Aiming at valorizing the ricotta cheese exhausted whey (RCEW), one of the most abundant by-products from the dairy industry, a biotechnological protocol to obtain bioactive peptides with angiotensin-I-converting enzyme (ACE)--inhibitory activity was set up. The approach was based on the combination of membrane filtration and fermentation. A Lactobacillus helveticus strain selected to be used as starter for the fermentation of the ultrafiltration protein-rich retentate (R-UF) obtained from RCEW. The fermented R-UF was characterized by a high anti-ACE activity. Peptides responsible for the bioactivity were purified and identified through nano-LC–ESI–MS/MS. The sequences identified in the purified active fractions of the fermented R-UF showed partial or complete overlapping with previously reported κ-casein antihypertensive fragments. The fermented R-UF was spray-dried and used to enrich ricotta cheese at different fortification level (1 and 5% w/w). An integrated approach including the assessment of the microbiological, chemical, functional, textural, and sensory properties was used to characterize the fortified products. A significantly higher anti-ACE activity was found in the ricotta cheese fortified with fermented R-UF as compared to the control and to the samples obtained with the unfermented R-UF fraction at the same levels of fortification. In particular, a 100 g portion of the ricotta cheese produced at 5% fortification level contained circa 30 mg of bioactive peptides. The fortification led to a moderate acidification, increased hardness and chewiness, and decreased the milk odor and taste of the ricotta cheese as compared to the control, while flavor persistence and sapidity improved.

Attempts to Improve Antimicrobial Efficiency by Mixed-Lactobacillus Extracts as Crude or Nano-formulated Against Pathogenic and Food Spoilage Bacteria, Molds and Yeasts

Over the world, there are millions of disease cases, in addition to thousands of deaths due to food-based outbreaks every year. In order to diminish the risk of foodborne infection and intoxications and control microbial food spoilage, there is a great need to improve modes of food preservation. As well-known, nature-dependent preservation enables consumers to keep their safety while eating highly qualified food. This work aims to enhance the safety and quality of common popular food products by introducing new preservative applications suggestions. The idea is to use different lactobacilli-based fermentations; in single or mixed-status and study the obtained extracts to evaluate their influence to manage microbial contamination of food. A set of five Lactobacillus strains was utilized by this study, methanol extract of cold acetone precipitate, Diethyl ether extract, and both were tested as crude or Nano-formulated against common microbial pathogens and food spoilers. Methanol extract of all lactobacillus strains shows antibacterial-specific activity with inhibition zone ranging from 7 mm in the case of Lactobacillus rhamnosus against Salmonella enterica, to 24 mm in the case of Lactobacillus helveticus against Escherichia coli. Diethyl ether extracts based on Lactobacillus helveticus and Lactobacillus plantarum show a considerable inhibition to all utilized microbial concerns, including Saccharomyces cerviceae. Upon estimating three forms of mixed-Lactobacillus that are based on Lactobacillus helveticus (h), Lactobacillus plantarum (p), and Lactobacillus rhamnosus GG (G), the ph-dependant combination showed uprising inhibition that reached maximally 58% over that of single Lactobacilli. Nano formulation of mixed-based total extracts maximally upraised the inhibition to 39%, 32%, and 100% against gram-positive, gram-negative, and the fungus; Penicillium chrysogenum, respectively.