Effect of culturing conditions on the expression of key enzymes in the proteolytic system of Lactobacillus bulgaricus

Hou, Juncai; Liu, Fei; Ren, Dawei; Han, Weiwei; Du, Yueou

doi:10.1631/jzus.b1400230

Cited by 13 publications

(11 citation statements)

References 46 publications

(52 reference statements)

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“…The highest total amino acid concentration in the sample ( Figure 5A ) might be attributed to the strain hydrolyzed proteins forming the necessary amino acids required for growth ( Hou et al, 2015 ). Amino acids play a key role in enhancing the flavor and increasing the nutrition of the sausages.…”

Section: Discussionmentioning

confidence: 99%

Complete Replacement of Nitrite With a Lactobacillus fermentum on the Quality and Safety of Chinese Fermented Sausages

Zhu

2021

Front. Microbiol.

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This study investigated the positive effects of complete replacement of nitrite with a Lactobacillus fermentum on the quality and safety of Chinese fermented sausages, and evaluated the risk of this strain. The effects of the strain on pH, color, nitrite, thiobarbituric acid reactive substances (TBARS), total volatile basenitrogen (TVB-N), metmyoglobin (Met-Mb), biological amines, free amino acid content, and sensory index have been studied. The results revealed that the strain reduced the pH of the sausages, which reduced the risk of food-borne pathogens, and accelerated the acidification and gelation process. The inoculation of the strain produced pink color similar to 50 mg/kg nitrite, significantly reducing the residual risk of nitrite in the sausages. In addition, the strain effectively improved quality and nutrition of the sausages through preventing fat oxidation, protein decomposition, and myoglobin oxidation and increasing free amino acid content. The harmful biogenic amines species of the treated sample were reduced, although the tyramine contents were higher than the control, and the contents of the two groups were all far below the specified limit (800 mg/kg). The sensory analysis showed that the strain enhanced the taste, flavor, sourness, and overall acceptability of the sample sausages. Therefore, replacing nitrite completely with the strain L. fermentum could be a potential strategy to produce healthier and safer acceptable sausages through decreasing the risk of nitrite and improving nutrition and quality of the sausages.

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Section: Discussionmentioning

confidence: 99%

Complete Replacement of Nitrite With a Lactobacillus fermentum on the Quality and Safety of Chinese Fermented Sausages

Zhu

2021

Front. Microbiol.

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“…These results suggest that L. plantarum within its capacity may cause a nitrite response. In addition, Hou, Liu, Ren, Han, and Du () reported several similar observations. Real‐time PCR analysis indicated that the gene expression decreased significantly at the stationary phase compared with the exponential growth phase ( p < .05).…”

Section: Resultsmentioning

confidence: 64%

Morphological and genetic responses of lactobacillus plantarum FQR to nitrite and its practical applications

Tian

Lin

Zhigeng

et al. 2016

Journal of Food Safety

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In this article, the growth, morphological, and genetic responses of Lactobacillus plantarum FQR to nitrite were investigated. The growth and degrading ability of the strain to nitrite was delayed; slight changes were also observed on the cell surface. FQR exposed to 0.120% nitrite exhibited rough surfaces with folds, as shown by scanning electron microscopy. Transmission electron microscopy presented numerous white granules in the FQR incubated without nitrite, compared with FQR exposed to 0.045% and 0.120% nitrite. These granules are common energy storage molecules, which decrease with increasing nitrite concentration. In addition, nitrite reductase (nir) gene and membrane‐related genes were activated in varying degrees. A similar trend in relative gene expression indicated that the expression levels of membrane‐related genes (with the exception of lp_1403) in FQR increased significantly (p < .05) in the presence of 0.120% nitrite compared with 0.045% nitrite. However, a marked difference was shown for the nir gene in FQR; the nir gene exhibited a relatively low level of expression when exposed to 0.120% nitrite concentration. In summary, the cell morphology and genetic level of L. plantarum FQR were changed in varying degrees after treatment with different nitrite concentrations. Practical Applications Nitrite is an important food additive and nitrite pollution issues of fermented food have become an increasing concern given its potential hazards. L. plantarum has the function of degrading nitrite. However, the detailed mechanisms and pathways involved in the regulation of nitrite in L. plantarum were still unclear. In this article, the growth, morphological, and genetic responses of L. plantarum to nitrite were investigated. It serves as an important reference for future studies of the mechanism of signal transduction in L. plantarum and the mechanism of stress response, and to determine the possible regulating targets. In practice, it can serve as a reference for genetic engineering improvement of L. plantarum used in the fermented food industry reducing nitrite residue.

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“…Considerable differences exist in the activity of proteolytic enzymes among different L. bulgaricus. Hou et al (2015) studied the expression of the PepD, PepB, PepC, PepF, PepQ, PepX, and PepT genes in 3 strains of L. bulgaricus under different conditions. The results showed that the protein supply had the least effect on the PepX gene and the strongest effect on OppD (Hou et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

“…Hou et al (2015) studied the expression of the PepD, PepB, PepC, PepF, PepQ, PepX, and PepT genes in 3 strains of L. bulgaricus under different conditions. The results showed that the protein supply had the least effect on the PepX gene and the strongest effect on OppD (Hou et al, 2015). In our study, the sequences of the genes prtB, oppD, pepC, pepF, pepQ, pepX, and pepT, which are key in the proteolysis system, were compared between L. bulgaricus KLDS1.1011 and KLDS1.0207.…”

Section: Discussionmentioning

confidence: 99%

Analysis of the complete genome sequence of Lactobacillus delbrueckii ssp. bulgaricus with post-acidification capacity and its influence on yogurt in storage

Yue

Wang

et al. 2022

Journal of Dairy Science

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In recent years, yogurt has been one of the most popular fermented dairy products and is sold worldwide. In this study, pH and titrated acid changes of 4 strains of Lactobacillus delbrueckii ssp. bulgaricus fermented milk during storage were detected. The difference between L. bulgaricus KLDS1.1011 and KLDS1.0207 was significant, with the latter exhibiting reduced acidity levels. Therefore, we determined the complete genome sequence of the 2 strains. Then the expression of specific genes and common genes related to glucose metabolism and proteolysis of L. bulgaricus KLDS1.1011 and KLDS1.0207 were detected by quantitative real-time reverse-transcription PCR. Analysis indicated that the key enzymes in glycometabolism and proteolysis of L. bulgaricus KLDS1.1011 were significantly different than those of L. bulgaricus KLDS1.0207. The contents of lactose and glucose decreased during storage of L. bulgaricus fermented milk, as determined by HPLC, and the contents of lactic acid and galactose increased, with L. bulgaricus KLDS1.1011 increasing less. With skim milk as a raw material, L. bulgaricus KLDS1.1011, KLDS1.0207, and Streptococcus thermophilus S1 were used as fermentation strains to yield yogurt at 42°C, and sensory evaluation was compared with yogurt fermented by commercial starter cultures. Yogurt from L. bulgaricus KLDS1.1011 was the highest-rated. Therefore, the study may provide guidelines for the development of yogurt starters.

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Effect of culturing conditions on the expression of key enzymes in the proteolytic system of Lactobacillus bulgaricus

Cited by 13 publications

References 46 publications

Complete Replacement of Nitrite With a Lactobacillus fermentum on the Quality and Safety of Chinese Fermented Sausages

Complete Replacement of Nitrite With a Lactobacillus fermentum on the Quality and Safety of Chinese Fermented Sausages

Morphological and genetic responses of lactobacillus plantarum FQR to nitrite and its practical applications

Analysis of the complete genome sequence of Lactobacillus delbrueckii ssp. bulgaricus with post-acidification capacity and its influence on yogurt in storage

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