Lactococcus Lactis Strains Research Articles

Restructured Lactococcus lactis strains with emergent properties constructed by a novel highly efficient screening system

BackgroundAfter 2.83% genome reduction in Lactococcus lactis NZ9000, a good candidate host for proteins production was obtained in our previous work. However, the gene deletion process was time consuming and laborious. Here, we proposed a convenient gene deletion method suitable for large-scale genome reduction in L. lactis NZ9000.ResultsPlasmid pNZ5417 containing a visually selectable marker PnisZ-lacZ was constructed, which allowed more efficient and convenient screening of gene deletion mutants. Using this plasmid, two large nonessential DNA regions, L-4A and L-5A, accounting for 1.25% of the chromosome were deleted stepwise in L. lactis 9k-3. When compared with the parent strain, the mutant L. lactis 9k-5A showed better growth characteristics, transformability, carbon metabolic capacity, and amino acids biosynthesis.ConclusionsThus, this study provides a convenient and efficient system for large-scale genome deletion in L. lactis through application of visually selectable marker, which could be helpful for rapid genome streamlining and generation of restructured L. lactis strains that can be used as cell factories.

Volatile and sensory evaluation of Mexican Fresco cheese as affected by specific wild Lactococcus lactis strains

Lactococcus lactis is the lactic acid bacteria most frequently used for the production of cheese starter cultures, mainly because of their efficient production of aroma compounds. However, commercial cultures do not always produce the typical aroma notes of artisanal raw-milk cheeses. Thus, the objective of this study was to characterize the volatile compounds generated by wild L. lactis strains in Mexican Fresco cheese made with pasteurized milk. Four strains of wild L. lactis were evaluated for their aroma production in Mexican Fresco cheese using sensory and instrumental analysis. The aroma profiles were evaluated by descriptive sensory analysis. Volatiles were determined by solid-phase microextraction and gas chromatography-mass spectrometry. Principal component analysis was applied to interpret analytical and sensory data. Mexican Fresco cheese aroma was described as milkfat, yogurt, yeasty, barny, dirty socks, and Fresco cheese. Cheese with L. lactis strains R7 or B7 were most similar to commercial raw milk Fresco cheese in all aroma descriptors. Volatiles identified in all cheeses were esters, acids, alcohols, ketones, and aldehydes, but the main differences were found for total volatile relative abundance. Also, volatile concentrations (µg/g) in commercial raw milk Fresco cheese and cheeses made with L. lactis R7 or B7 were 4 methyl esters [C4 (4.15 vs. 5.47-13.74), C6 (0.12 vs. 1.53-15.34), C8 (1.06 vs. 0.32-6.65), and C10 (0.62 vs. 0.41-3.74)], 7 acids [C4 (1.92 vs. 0.30-9.29), C6-C10 (0.05-4.48 vs. 0.11-30.45), and C12 (0.13 vs. 0.28-0.30)], 2 alcohols [(3-methyl-1-butanol (3.48 vs. 3.4-13.13) and phenylethyl alcohol (0.10 vs. 0.63-2.04)], and 1 ketone (acetoin; 1.22 vs. 0.28-0.99). The first 3 principal components explained 78.2% of the total variation and clearly distinguished 3 main groups. Cheese made with L. lactis R7 was classified in the same group as key compounds associated with Fresco cheese aroma and show potential as a starter in Mexican Fresco cheese manufacture.

Plasmacytoid dendritic cell dysfunction caused by heat stress is improved by administration of Lactococcus lactis strain plasma in mice.

Plasmacytoid dendritic cells (pDCs) are crucial in anti-viral immunity, acting as regulators in both adaptive and innate immunity. In this study, brief heat stress caused a decrease in splenic pDC activity in mice. Administration of Lactococcus lactis strain Plasma (LC-Plasma) significantly suppressed the decrease in pDC activity and IFN-α production. Abbreviations: LC-Plasma: Lactococcus lactis strain Plasma; LAB: lactic acid bacteria; pDC: plasmacytoid dendritic cell; IFN: interferons; mDC: myeloid dendritic cells.

Systemic understanding of Lactococcus lactis response to acid stress using transcriptomics approaches.

During fermentation, acid stress caused by the accumulation of acidic metabolites seriously affects the metabolic activity and production capacity of microbial cells. To elucidate the acid stress-tolerance mechanisms of microbial cells, we performed genome mutagenesis combined with high-throughput technologies to screen acid stress-tolerant strains. Mutant strain Lactococcus lactis WH101 showed a 16,000-fold higher survival rate than that of the parent strain after 5h of acid shock at pH 4.0 and maintained higher ATP, NH4+, and intracellular pH (pHi) levels during acid stress. Additionally, comparative transcriptomics analysis revealed enhanced regulation of carbohydrate metabolism and sugar transport to provide additional energy, amino acid metabolism and transport to maintain pHi homeostasis and ATP generation, and fatty acid metabolism to enhance cellular acid tolerance. Moreover, overexpression of identified components resulted in 12.6- and 12.9-fold higher survival rates after acid shock for 3h at pH 4.0 in L. lactis (ArcB) and L. lactis (MalQ) compared to the control strain, respectively. These findings provide valuable insight into the acid stress-response mechanisms of L. lactis and promote the further development of robust industrial strains.

A food-grade engineered Lactococcus lactis strain delivering Helicobacter pylori Lpp20 alleviates bacterial infection in H. pylori-challenged mice.

To construct a food-grade bacterium producing and delivering H. pylori Lpp20 antigen and evaluate its immune efficacy against H. pylori challenges with aim to develop anti-H. pylori oral vaccines and functional foods. Lpp20 was expressed as a 22kDa protein in Lactococcus lactis, constituting 11.2% of the cell lysate proteins, and recognized by mouse antisera. Mice orally gavaged with the engineered bacterium had elevated serum IgG levels and lowered urease activity of stomach following H. pylori challenges. This study firstly reports a food-grade L. lactis strain delivering Lpp20 to mucosal immunization sites, demonstrating a novel efficient production and safe utilization mode of Lpp20, offering a promising vaccine candidate and health food sources.

Autochthonous and Probiotic Lactic Acid Bacteria Employed for Production of "Advanced Traditional Cheeses".

Microbial characterization of two Italian traditional cheeses, Giuncata and Caciotta Leccese, was carried out, with the aim to isolate autochthonous bacterial strains to be used as starters to improve and standardize the quality of these cheeses. More than 400 bacterial isolates were found, using PCR-based identification, to belong to 12 species of the Streptococcus, Lactococcus, Lactobacillus, and Leuconostoc genera. The dominant strains were screened for antagonistic activity against pathogenic and spoilage bacteria and exopolysaccharide production, acidification, and proteolytic activity. Since Streptococcus macedonicus was found to be the most prevalent lactic acid bacteria species present in milk and in both types of cheese, the best performing strain of this species was successfully used, alone or in combination with a selected autochthonous Lactococcus lactis strain, in pilot-scale productions of Giuncata and Caciotta Leccese cheeses, respectively. The combined inoculums of selected autochthonous strains positively influenced the sensory characteristics of both Giuncata and Caciotta cheeses. Finally, the selected autochthonous cultures were enriched with a potentially probiotic Lactobacillus rhamnosus strain and successfully used in pilot-scale productions of these traditional cheeses. To the best of our knowledge, this is the first study reporting the use of an autochthonous S. macedonicus strain as a starter for the production of cheeses with added probiotics. In addition, the identification of the probiotic strain in the feces of healthy volunteers fed with the advanced traditional cheese proved its effectiveness as a carrier for the delivery of probiotics to the human body.

Oral delivery of pancreatitis-associated protein by Lactococcus lactis displays protective effects in dinitro-benzenesulfonic-acid-induced colitis model and is able to modulate the composition of the microbiota.

SummaryAntimicrobial peptides secreted by intestinal immune and epithelial cells are important effectors of innate immunity. They play an essential role in the maintenance of intestinal homeostasis by limiting microbial epithelium interactions and preventing unnecessary microbe‐driven inflammation. Pancreatitis‐associated protein (PAP) belongs to Regenerating islet‐derived III proteins family and is a C‐type (Ca+2 dependent) lectin. PAP protein plays a protective effect presenting anti‐inflammatory properties able to reduce the severity of colitis, preserving gut barrier and epithelial inflammation. Here, we sought to determine whether PAP delivered at intestinal lumen by recombinant Lactococcus lactis strain (LL‐PAP) before and after chemically induced colitis is able to reduce the severity in two models of colitis. After construction and characterization of our recombinant strains, we tested their effects in dinitro‐benzenesulfonic‐acid (DNBS) and Dextran sulfate sodium (DSS) colitis model. After the DNBS challenge, mice treated with LL‐PAP presented less severe colitis compared with PBS and LL‐empty‐treated mice groups. After the DSS challenge, no protective effects of LL‐PAP could be detected. We determined that after 5 days administration, LL‐PAP increase butyrate producer's bacteria, especially Eubacterium plexicaudatum. Based on our findings, we hypothesize that a treatment with LL‐PAP shifts the microbiota preventing the severity of colon inflammation in DNBS colitis model. These protective roles of LL‐PAP in DNBS colitis model might be through intestinal microbiota modulation.

In Vitro Antithrombotic and Hypocholesterolemic Activities of Milk Fermented with Specific Strains of Lactococcus lactis.

Milk fermented with specific lactic acid bacteria (LAB) was reported to be a rich source of metabolites, such as peptides with different biological activities that may have a positive effect on cardiovascular health. Thus, in this study, the antithrombotic and hypocholesterolemic activities of fermented milk with specific strains of Lactococcus lactis were investigated before and after exposure to a simulated gastrointestinal digestion (SGD) model. The inhibition of thrombin-induced fibrin polymerization (IC50 peptide concentration necessary to inhibit thrombin activity by 50%), anticoagulant activity, inhibition of micellar solubility of cholesterol and bile acid binding capacity of water soluble fractions (WSF) <3 kDa from fermented milk were evaluated. Results indicated that the WSF from fermented milk with Lc-572 showed antithrombotic (IC50 = 0.049 mg/mL) and hypocholesterolemic (55% inhibition of micellar solubility of cholesterol and 27% bile acid binding capacity) activities. Meanwhile, fermented milk with Lc-571 showed mainly antithrombotic activity (IC50 = 0.045 mg/mL). On the other hand, fermented milk with Lc-600 presented mainly hypocholesterolemic activity (31.4% inhibition of micellar solubility of and 70% bile acid binding capacity). Moreover, biological activities were not lost after simulated gastrointestinal digestion conditions. Thus, fermented milk with these specific L. lactis strains show potential for the development of functional foods.

Draft Genome Sequences of Four Lactococcus lactis Strains Isolated from Diverse Niches, Including Dairy Products, Grass, and Green Peas.

Lactococcus lactis has been used for millennia as a starter organism in the production of many fermented dairy products. This announcement includes the draft genome sequences of four strains of Lactococcus lactis, two of dairy origin and two from nondairy sources.

Surface display of hirame novirhabdovirus (HIRRV) G protein in Lactococcus lactis and its immune protection in flounder (Paralichthys olivaceus)

BackgroundHirame novirhabdovirus (HIRRV) can infect a wide range of marine and freshwater fish, causing huge economic losses to aquaculture industry. Vaccine development, especially oral vaccine, has become an effective and convenient way to control aquatic infectious diseases. HIRRV glycoprotein (G), an immunogenic viral protein is a potential vaccine candidate for prevention of the disease. Here, we aimed to construct a recombinant Lactococcus lactis strain expressing HIRRV-G on the cell surface as an oral vaccine to prevent HIRRV.ResultsGlycoprotein gene of HIRRV was successfully cloned and expressed in L. lactis NZ9000 in a surface-displayed form, yielding Ll:pSLC-G. An approximately 81 kDa recombinant G protein (containing LysM anchoring motif) was confirmed by SDS-PAGE, western blotting and mass spectrometry analysis. The surface-displayed G protein was also verified by immunofluorescence and flow cytometry assays. Furthermore, to evaluate the potential of Ll:pSLC-G as oral vaccine candidate, flounders were continuously fed with commercial diet pellets coated with 1.0 × 109 cfu/g of induced Ll:pSLC-G for 1 week. Four weeks later, booster vaccination was performed with the same procedure. Compared with the controls, Ll:pSLC-G elicited significantly higher levels of specific IgM against HIRRV in flounder gut mucus at the second week and in serum at the fourth week (p < 0.05). Meanwhile, oral immunization with Ll:pSLC-G could provide 60.7% protection against HIRRV infection and a significantly lower virus load was detected than the controls on the third day post-challenge (p < 0.01). Moreover, on the first day post 1-week feeding, approximately 104–105 recombinant L. lactis cells were detected in every gram of foregut, midgut and hindgut of flounder, which were mainly localized at the bottom of gut mucus layer; and on day 21, 102–103L. lactis cells could still be recovered.ConclusionsHIRRV-G protein was successfully expressed on the surface of L. lactis cells, which could trigger mucosal and humoral immune response of flounder and provide considerable immune protection against HIRRV. It suggests that genetically engineered L. lactis expressing G protein can be employed as a promising oral vaccine against HIRRV infection.

Physiological and biochemical characteristics of the &lt;i&gt;Lactococcus lactis&lt;/i&gt; strains isolated from natural sources

The data have been presented on physiological and biochemical properties (growth, acidogenic, proteolytic and antagonistic аctivity, resistance to NaCl) of lactic acid bacterial strains of Lactococcus lactis isolated from Belarus natural sources. These strains are promising for use as starter cultures for fermented dairy products, cheese.

Long-chain vitamin K2 production in Lactococcus lactis is influenced by temperature, carbon source, aeration and mode of energy metabolism

BackgroundVitamin K2 (menaquinone, MK-n) is a lipid-soluble vitamin that functions as a carboxylase co-factor for maturation of proteins involved in many vital physiological processes in humans. Notably, long-chain vitamin K2 is produced by bacteria, including some species and strains belonging to the group of lactic acid bacteria (LAB) that play important roles in food fermentation processes. This study was performed to gain insights into the natural long-chain vitamin K2 production capacity of LAB and the factors influencing vitamin K2 production during cultivation, providing a basis for biotechnological production of vitamin K2 and in situ fortification of this vitamin in food products.ResultsWe observed that six selected Lactococcus lactis strains produced MK-5 to MK-10, with MK-8 and MK-9 as the major MK variant. Significant diversities between strains were observed in terms of specific concentrations and titres of vitamin K2. L. lactis ssp. cremoris MG1363 was selected for more detailed studies of the impact of selected carbon sources tested under different growth conditions [i.e. static fermentation (oxygen absent, heme absent); aerobic fermentation (oxygen present, heme absent) and aerobic respiration (oxygen present, heme present)] on vitamin K2 production in M17 media. Aerobic fermentation with fructose as a carbon source resulted in the highest specific concentration of vitamin K2: 3.7-fold increase compared to static fermentation with glucose, whereas aerobic respiration with trehalose resulted in the highest titre: 5.2-fold increase compared to static fermentation with glucose. When the same strain was applied to quark fermentation, we consistently observed that altered carbon source (fructose) and aerobic cultivation of the pre-culture resulted in efficient vitamin K2 fortification in the quark product.ConclusionsWith this study we demonstrate that certain LAB strains can be employed for efficient production of long-chain vitamin K2. Strain selection and optimisation of growth conditions offer a viable strategy towards natural vitamin K2 enrichment of fermented foods, and to improved biotechnological vitamin K2 production processes.

Diversity and functional characteristics of lactic acid bacteria from traditional kefir grains

Traditional kefir grains were collected from distinct parts of Turkey, and their microbial profile was determined. A wide bacterial biota was observed formed by distinct lactic acid bacteria (LAB) in which Lactococcus lactis strains appeared to be dominant. Yeast species were also identified in kefir grains. Significant levels of antifungal and antibacterial activities were monitored in kefir isolates. All tested LAB produced an exopolysaccharide (EPS) containing glucose and galactose, and some strains formed a fructan‐type EPS. Importantly, low levels of antibiotic resistance were observed among the kefir isolates.

Exploiting the diversity of streptococcal hyaluronan synthases for the production of molecular weight–tailored hyaluronan

The molecular weight (Mw) of hyaluronic acid (HA) determines its suitability for medical and cosmetic applications. Here, we characterize in vitro and in vivo HA synthesis of streptococcal HA synthases (HASs) with a special focus on HA Mw. To date, four streptococcal HA producers are described (Streptococcus equi subsp. equi, S. equi subsp. zooepidemicus, S. pyogenes, and S. uberis). We identified two more potential HA producers in this study: S. iniae and S. parauberis. Indeed, the HA Mw produced by the different streptococcal HASs differs in vitro. To exploit these different HA Mw synthesis capacities, Lactococcus lactis strains expressing the streptococcal HASs were constructed. HA of different Mw was also produced in vivo by these engineered strains, strongly suggesting that the protein sequences of the HASs influence HA Mw. Since the HA Mw in vivo is also influenced by metabolic factors like specific growth rate and HA precursor availability, these were also determined. In summary, the maximal Mw of HA synthesized is specific for the individual synthase, while any decrease from the maximal HA Mw is influenced by physiological and metabolic factors. The results open new avenues for Mw-tailored HA synthesis.

Shear and extensional rheology of acid milk gel suspensions with varying ropiness.

Exopolysaccharides (EPS) synthesized by lactic acid bacteria during fermentation significantly affect the rheology of set-style acid milk gels and that of acid gel suspensions, produced from the gels by stirring. In this study, shear and uniaxial extensional flow of acid gel suspensions made with seven single strains of Streptococcus thermophilus or Lactococcus lactis was investigated. Six strains produced ropy EPS, and maximum filament length determined by using a continuous stretching method was up to four times higher than filament length of an EPS-negative control strain. The systems containing ropy EPS showed a different response to shear and extensional deformation. In shear rheology, higher apparent viscosities and an enhanced structural breakdown was observed for acid gel suspensions with more pronounced ropiness. Breakup time and extensional viscosity, determined by using a Capillary Breakup Extensional Rheometer (CaBER™), significantly increased with increasing ropiness. The increase of extensional viscosity with increasing ropiness was, however, much higher than the effects of ropiness on shear viscosity. As relaxation times also depended on ropiness, it is concluded that ropiness is caused by EPS-EPS interactions that can be better discriminated in extensional rheology. PRACTICAL APPLICATIONS: To improve the texture of fermented milk, lactic acid bacteria that are able to produce ropy exopolysaccharides (EPS) are increasingly used in the dairy industry. The EPS exhibit a significant influence on processing properties and sensory characteristics of the resulting products, which can be estimated by means of shear and extensional rheology. The current work provides information on these respective properties of acid gel suspensions, which facilitate product design by supporting the selection of appropriate starter cultures.

Effects of dietary supplementation of three strains of Lactococcus lactis on HIFs genes family expression of the common carp following Aeromonas hydrophila infection

HIFs (Hypoxia inducible factors) are the main regulators of the expression change of oxygen-dependent genes, in addition, they also play important roles in immune regulation. HIFs participate in infectious diseases and inflammatory responses, providing us a new therapeutic target for the treatment of diseases. In this study, 16 HIFs were identified in common carp genome database. Comparative genomics analysis showed large expansion of HIF gene family and approved the four round whole genome duplication (WGD) event in common carp. To further understand the function of HIFs, the domain architectures were predicted. All HIF proteins had the conserved HLH-PAS domain, which were essential for them to form dimer and bind to the downstream targets. The differences in domain of HIFα and HIFβ might result in their different functions. Phylogenetic analysis revealed that all HIFs were divided into two subfamilies and the HIFs in common carp were clustered with their teleost counterparts indicating they are highly conservative during evolution. In addition, the tissue distribution was examined by RT-PCR showed that most of HIF genes had a wide range of tissue distribution but exhibited tissue-specific expression patterns. The expression divergences were observed between the copy genes, for example, HIF1A-1, HIF2A-1, ARNT-2 had wide tissue distribution while their copies had limited tissue distribution, proving the function divergence of copies post the WGD event. In order to find an effective activation of HIFs and apply to treatment of aquatic diseases, we investigate the dietary supplementation effects of different strains of Lactococcus lactis on the expression of HIFα subfamily members in kidney of common carp infected with A. hydrophila. In addition, all of the HIF genes have a high expression in the early stages of infection, and decreased in the treatment time point of 48 h in common carp. This phenomenon confirms that as a switch, the main function of HIFs is to regulate the production of immune response factors in early infection. So activation of the switch may be an effective method for infectious disease treatment. As expected, the treatment groups improved the expression of HIFs compared with the control group, and the effects of the three strains are different. The strain1 of L. lactis had a stronger induction on HIF genes than strain2 and strain3, and it might be applied as a potential activation of HIF genes for disease treatment. So, adding befitting L. lactis maybe a well method to activate the HIF genes to protect them from mycobacterial infection.

The Effects of Plasmacytoid Dendritic Cell-Stimulative Lactic Acid Bacteria, Lactococcus lactis Strain Plasma, on Exercise-Induced Fatigue and Recovery via Immunomodulatory Action.

The unique lactic acid bacteria, Lactococcus lactis strain plasma (LC-Plasma), stimulates plasmacytoid dendritic cells, which play an important role in viral infection. The authors previously reported that LC-Plasma reduced the number of days athletes experienced cold-like symptoms and fatigue feelings after high-intensity exercise training; however, the mechanism was unclear. In this study, the authors investigated the effect of LC-Plasma on recovery from physical damage after single exercise on a treadmill in BALB/c mice model. Oral administration of LC-Plasma (AIN-93G + 0.029% LC-Plasma) for 4 weeks significantly improved the locomotor reduction after treadmill exercise. This effect was not detected in mice receiving Lactobacillus rhamnosus GG, representative probiotics strain. LC-Plasma also improved voluntary locomotor activity after exercise. Blood and muscle sample analysis indicated that LC-Plasma affects plasmacytoid dendritic cell activation, which, in turn, attenuates muscle degenerative genes and the concentration of fatigue-controlled cytokine transforming growth factor-β.

Oral delivery of a Lactococcus lactis strain secreting bovine lactoferricin-lactoferrampin alleviates the development of acute colitis in mice.

Ulcerative colitis (UC) is a chronic relapsing disease. Treatment of UC would benefit from specific targeting of therapeutics to the intestine. Previous studies have demonstrated that bovine lactoferricin and lactoferrampin have bactericidal, anti-inflammatory, and immunomodulatory effects. Here, we investigated whether oral administration of a bovine lactoferricin-lactoferrampin (LFCA)-encoding Lactococcus lactis (LL-LFCA) strain could alleviate experimental colitis. LFCA derived from LL-LFCA inhibited the growth of Escherichia coli and Staphylococcus aureus in vitro. In mice, administration of LL-LFCA decreased the disease activity index and attenuated dextran sulfate sodium (DSS)-induced body weight loss and colon shortening. LL-LFCA treatment also ameliorated DSS-induced colon damage, inhibited inflammatory cell infiltration, significantly decreased myeloperoxidase activity, and ameliorated DSS-induced disruption of intestinal permeability and tight junctions. In addition, 16S rDNA sequencing showed that LL-LFCA reversed DSS-induced gut dysbiosis. The production of proinflammatory mediators in serum and the colon was also reduced by administration of LL-LFCA. In vitro, LFCA derived from LL-LFCA decreased the messenger RNA expression of proinflammatory factors. The underlying mechanisms may involve inhibition of the nuclear factor kappa B (NF-κB) pathway. The results demonstrate that LL-LFCA ameliorates DSS-induced intestinal injury in mice, suggesting that LL-LFCA might be an effective drug for the treatment of inflammatory bowel diseases.

Hyaluronic acid: biosynthesis and application

Topicality. Hyaluronic acid with its antimicrobial and antiviral properties has found applications in medicine and cosmetics. Due to the high molecular weight, it prolongs the action of the active pharmaceutical components. The application spectrum of hyaluronic acid and hyaluronic acid-based products is increasing permanently. Therefore, new microbial producers of hyaluronic acid and new technologies for its biosynthesis are intensively developed. Aim. To compile integration of the advances in producers selection, and advances in the development of technologies and the hyaluronic acid applications.Results and discussion. The strains from the genera Streptococcus and Pasteurella are the main bacterial producers of hyaluronic acid. However, they are able to synthesize hyaluronic acid in concentrations lower than 7 g/l after 120 hours of cultivation and their use limited by potential pathogenic properties. To improve technological parameters of biosynthesis, new genetically modified strains of Lactococcus lactis, Corynebacterium glutamicum, Escherichia coli, and Pichia pastoris were constructed. The highest yield of hyaluronic acid, 8.3 g/l , is observed during the cultivation of C. glutamicum for 48 hours.Conclusions. Searching and construction of new hyaluronic acid producers and biotechnological improving when cultivated are the major points in the development of hyaluronic acid production for pharmaceuticals and cosmetic applications.

Short communication: Enzymatic perspective of galactosidases reveals variations in lactose metabolism among Lactococcus lactis strains

To date, most studies of lactose utilization have focused on the genetic diversity of lactic acid bacteria or its influence on product quality, but phenotypic evaluation has rarely been based on metabolic characteristics. In the present study, we investigated the growth, acid production, β-galactosidase, and 6-phospho-β-galactosidase activities of 16 Lactococcus lactis strains obtained from various habitats with lactose as the sole carbon source. The 15 L. lactis strains obtained from various habitats exhibited significant differences in growth and acid production characteristics in the de Man, Rogosa, and Sharpe-lactose broth, and 4 strains consumed more lactose when cultured in skim milk than the type strain ATCC 19435. Among these strains, DQHXNQ38-12 mainly produced acetoin and diacetyl when cultured in skim milk, whereas the strains 15M2 and 5G2 produced high levels of acid and formed curd rapidly. We concluded that the use of lactose is necessary for strain adaptation to the dairy niche. Comprehensive studies of lactose use and the fermentation characteristics of L. lactis are of significant importance.