Effect of incubation conditions and possible intestinal nutrients on cis-9, trans-11 conjugated linoleic acid production by Lactobacillus acidophilus F0221

Factors influencing conjugated linoleic acid content of dairy products: challenges and strategies

Conjugated linoleic acid (CLA), a bioactive fatty acid that provides various physiological benefits, has gained increasing attention in the food industry, and various studies have focused on enhancing its content in dairy products. The factors influencing CLA content in dairy products vary significantly, including lactation stage, breed type, seasonality, feed, management methods of the animals, the manufacturing processes, storage, and ripening periods of the product. Additionally, the incorporation of CLA-producing probiotic bacteria, such as Lactobacillus, Lactococcus, Bifidobacterium, and Propionibacterium, is an emerging study in this field. Studies have revealed that factors affecting the CLA content in milk affect that in dairy products as well. Furthermore, the species and strains of CLA-producing bacteria, fermentation conditions, ripening period, and type of dairy product are also contributing factors. However, production of CLA-enhanced dairy products using CLA-producing bacteria while maintaining their optimal viability and maximizing exposure to free linoleic acid remains limited. The current review emphasized the factors affecting the CLA content and related mechanisms, challenges in the application of CLA-producing probiotic bacteria, and strategies to address these challenges and enhance CLA production in dairy products. Therefore, the development of functional dairy products with enhanced CLA levels is expected to be possible.

Production of conjugated linoleic acid by lactic acid bacteria; important factors and optimum conditions

Conjugated linoleic acid (CLA) has recently attracted significant attention as a health-promoting compound. CLA is a group of positional isomers of linoleic acid (LA) with a conjugated double bond naturally occurring in dairy and ruminant meat products. Microbial biosynthesis of CLA is a practical approach for commercial production due to its high safety and purity. There are some factors for the microbial CLA production such as strain type, microbial growth phase, pH, temperature and incubation time, based on which the amount and type of CLA can be controlled. Understanding the interplay of these factors is essential in optimizing the quantity and composition of microbial CLA, as discussed in the current study. Further exploration of CLA and its influences on human health remains a dynamic and evolving area of study.

Small molecule linoleic acid inhibiting whey syneresis via interact with milk proteins in the fermentation of set yogurt fortified with c9,t11-conjugated linoleic acid

The study aimed to investigate the impact of fermentation conditions on c9,t11-conjugated linoleic acid (CLA) synthesis by Lactobacillus casei, as well as its effects on whey syneresis, water holding capacity (WHC), and texture characteristics of set yogurt. The amount of whey syneresis decreased about 30% with the adding of 0.1% linoleic acid (LA). The interaction between LA and casein (CS), β-lactoglobulin (β-Lg) and bovine serum albumin (BSA) was observed by UV-Vis absorption spectroscopy, 3D fluorescence spectroscopy and CD spectroscopy. It found that LA changed the microenvironment and polarity around amino acids, as well as the conformation of the three milk proteins. Scanning electron microscope (SEM) analysis revealed that the addition of LA resulted in a more uniform and compact microstructure of the set yogurt. It indicates that LA can promote the crosslink of milk proteins, which may be the reason for the reduction of whey syneresis in set yogurt.

Effects of different feeding patterns on the rumen bacterial community of tan lambs, based on high-throughput sequencing of 16S rRNA amplicons

Introduction

The mutton quality of Chinese Tan lambs (Ovis aries) has declined as feeding patterns have shifted from pasturing to pen rationing. While pen-fed can enhance the growth performance of sheep, it falls short in terms of meat quality attributes such as meat color and tenderness. Furthermore, compared to pen-fed, pasture-fed husbandry increases the proportion of oxidative muscle fibers, decreases the proportion of glycolytic muscle fibers, and reduces LDH (lactate dehydrogenase) activity. Mutton quality is affected by fatty acids, and rumen microorganisms play a role in the synthesis of short-chain fatty acids, long-chain fatty acids, and conjugated linoleic acids.

Methods

We used 16S rRNA sequencing to analyze the effects of two feeding patterns on the rumen bacteria of Tan lambs. In a randomized block design with 24 newborn Tan lambs, 12 lambs were fed by ewes in pasture and 12 were fed by pen-fed ewes. At 2 months, the biceps femoris and the longissimus dorsi were analyzed by gas chromatography for intramuscular fat content and fatty acids composition, and DNA in the rumen contents was extracted and used to analyze the structure of the bacterial community.

Results

Different feeding patterns had no significant effect on the intramuscular fat content of the biceps femoris and longissimus dorsi of the lambs, but there was a significant effect on fatty acids composition. The fatty acids c18:3n3 and c20:5n3 were significantly higher in the biceps femoris and longissimus dorsi of the pasture group than the pen-ration group. The alpha diversity of rumen bacteria was significantly greater in the pasture group compared to the pen-ration group. The ACE index, Chao1 index, Shannon index, and Simpson index were all notably higher in the pasture group than in the pen-ration group. Utilizing beta diversity analysis to examine the differences in rumen bacteria between the pasture group and pen-ration group, it was observed that the homogeneity of bacteria in the pasture group was lower than that in the pen-ration group. Furthermore, the diversity of rumen bacteria in the pasture group was greater than that in the pen-ration group. Twenty-one phyla were identified in the pasture group, and 14 phyla were identified in the pen-ration group. The dominant phyla in the pasture group were Bacteroidetes and Fibrobacteres; the dominant phyla in the pen-ration group were Proteobacteria and Bacteroidetes. The relative abundance of Proteobacteria was significantly higher in the pen-ration group than in the pasture group (p < 0.01). Diversity at the genus level was also higher in the pasture group, with 176 genera in the pasture group and 113 genera in the pen-ration group. The dominant genera in the pasture group were Prevotella_1, Rikenellaceae_RC9_gut_group, and Bacteroidales_BS11_gut_group_Na; the dominant genera in the pen-ration group were Prevotella_1, Prevotella_7, Succinivibrionaceae_UCG-001, and Succinivibrionaceae_NA.

Discussion

The rumen bacterial community of Tan sheep is significantly influenced by pen-ration and pasture-fed conditions, leading to variations in fatty acid content in the muscle, which in turn affects the flavor and nutritional value of the meat to some extent. Pasture-fed conditions have been shown to enhance the diversity of rumen bacterial community structure in Tan sheep, thereby increasing the nutritional value of their meat.

Complexation of multiple mineral elements by fermentation and its application in laying hens

To overcome the problems with current mineral supplements for laying hens including low absorption, mineral antagonism, and high cost, we developed mineral element fermentation complexes (MEFC) by synergistically fermenting bean dregs and soybean meal with strains and proteases and complexing with mineral elements. The fermentation complexation process was optimized based on the small peptide and organic acid contents and the complexation rate of mineral elements after fermentation. The optimal conditions were as follows: the total inoculum size was 5% (v/w), 15% (w/w) wheat flour middling was added to the medium, and mineral elements (with 4% CaCO3) were added after the completion of aerobic fermentation, fermentation at 34°C and 11 days of fermentation. Under these conditions, the complexation rates of Ca, Fe, Cu, Mn, and Zn were 90.62, 97.24, 73.33, 94.64, and 95.93%, respectively. The small peptide, free amino acid, and organic acid contents were 41.62%, 48.09 and 183.53 mg/g, respectively. After 60 days of fermentation, 82.11% of the Fe in the MEFC was ferrous ions, indicating that fermentation had a good antioxidant effect on ferrous ion, and the antioxidant protection period was at least 60 days. Fourier transform infrared spectroscopy showed that the mineral ions were complexed with amino and carboxyl groups. The added mineral elements promoted microbial growth, protein degradation, and organic acid secretion and significantly improved fermentation efficiency. Animal experiments showed that MEFC had positive effects on several parameters, including production performance (average daily feed intake, P < 0.05; egg production rate, P < 0.05; and average egg weight, P < 0.05), mineral absorption, intestinal morphology (villus height to crypt depth ratio in the jejunum and ileum, P < 0.05), and blood routine and biochemical indexes (red blood cells, P < 0.05; hemoglobin, P < 0.05). This study provides theoretical support for the development of mineral complexes for laying hens via fermentation.

Biosynthesis of c9,t11-conjugated linoleic acid and the effect on characteristics in fermented soy milk

The objective of this work was to investigate the effect of fermentation conditions on c9,t11-conjugated linoleic acid (CLA) synthesized by Lactobacillus casei and the variation of physicochemical characteristics, including pH, viable cell number, syneresis and texture profile, of fermented soy milk (FSM) during storage at 4 °C for 28 days. Fermentation in 7°Brix of soy milk (SM) supplemented with 0.1% linoleic acid and incubated at 37 °C for 72 h was found to be the optimal conditions for c9,t11-CLA biosynthesis. Within the storage of 14 days, viable cell number, total flavonoid content, water-holding capacity, spontaneous syneresis and texture profile in FSM remained stable. During the storage of 28 days, the viable cell number and c9,t11-CLA level were higher than 6.58 log CFU/mL and 816.33 μg/g, respectively.

Combined proteomics and transcriptomics analysis of Lactococcus lactis under different culture conditions

During industrial handling, Lactococcus lactis needs to adapt to different culture conditions by regulating its metabolic pathways. Modifying culture conditions may be an important way to control the biomass and functional metabolites of lactic acid bacteria. In this study, we identified the differentially expressed genes and proteins of L. lactis under different culture conditions by integrating transcriptomics and proteomics. We also analyzed the data using a bioinformatic approach to reveal the regulatory mechanisms affected by culture conditions. The transcriptome and proteome studies indicated that different culture conditions (fructose, calcium ion, palmitic acid, low pH) affected gene and protein expressions. The levels of differentially expressed proteins did not significantly correlate with the expression levels of their corresponding genes. Our results highlight the importance of comparative transcriptomics and proteomics analyses. In this study, fructose and pH significantly affected sugar metabolism of L. lactis. When lactose was replaced by fructose, fructokinase expression was promoted, and fructose metabolism was accelerated, whereas starch and sucrose metabolism and galactose metabolism system were inhibited. Low pH may be beneficial to homofermentation of L. lactis, which may also metabolize galactose through the tagatose pathway and the Leloir pathway. Fatty acid metabolism and fatty acid biosynthesis were significantly downregulated under calcium ion and palmitic acid. The purine metabolism was upregulated under fructose treatment and downregulated under palmitic acid treatment.

Utilization of optimized processing conditions for high yield synthesis of conjugated linoleic acid by L. plantarum AB20-961 and L. plantarum DSM2601 in semi-dry fermented sausage

The aim of this study was to utilize optimized processing conditions to obtain the highest conjugated linoleic acid (CLA) contents in semi-dry fermented sausages produced with L. plantarum AB20-961 and L. plantarum DSM 2601. Optimized conditions were 5.7 meat pH, 5% hydrolyzed safflower oil addition, 10⁸ CFU/g added starter culture, fermentation time of 73 h for L. plantarum DSM2601 and 79 h for L. plantarum AB20-961, 24 °C fermentation temperature, 65 °C internal cooking temperature and 90% relative humidity. Results indicated that CLA contents in sausages were increased 21% by L. plantarum AB20-961 and 121% by L. plantarum DSM2601 after fermentation compared to initial CLA level determined on manufacturing day (P < .05). After fermentation, an increased CLA content of sausages remained stable during heat processing and storage. Sausages incorporated with L. plantarum strains and hydrolyzed safflower oil had the highest TBARS and PUFA levels, and the lowest pH and moisture content (P < .05). Differences were not found in sensorial and other physicochemical properties among sausage treatment groups. This study demonstrated that high CLA content can be achieved in sausages by utilizing optimum processing conditions described above and starter cultures (L. plantarum AB20-961 and L. plantarum DSM2601) without any adverse effects on quality of the final product.

Bioconversion enhancement of conjugated linoleic acid by Lactobacillus plantarum using the culture media manipulation and numerical optimization

The ability of different Lactobacillus strains to produce conjugated linoleic acid (CLA) from linoleic acid was evaluated. Preliminary experiments revealed that L. plantarum among the screened strains had the highest CLA-producing potential (95.25 μg/mL). The cell growth of this bacterium was studied in three media of MRS broth, skim milk and skim milk supplemented with yeast extract and glucose. Results showed that the use of yeast extract and glucose could significantly increase the cell growth and CLA production. Response surface methodology (RSM) was applied to investigate the effects of three independent variables; linoleic acid (LA), yeast extract concentrations and inoculum size on the CLA formation. A second-order polynomial model with high R (2) value (0.981) was developed using multiple linear regression analysis. The optimum conditions to achieve the highest CLA production (240.69 μg/mL) was obtained using 3 mg/mL LA, 4 g/L yeast extract and inoculum size of 4 % v/v. CLA concentration of the optimal sample was analyzed by Gas Chromatography (GC). The cis-9, trans-11 CLA was the major CLA isomer of total CLA detected.