The effect of commercial conjugated linoleic acid products on experimental periodontitis and diabetes mellitus in Wistar rats

Conjugated linoleic acid (CLA) as a functional food: Is it beneficial or not?

Conjugated linoleic acid (CLA) has attracted great attention in recent years as a popular class of functional food that is broadly used. It refers to a group of geometric and positional isomers of linoleic acid (LA) with a conjugated double bond. The main natural sources of CLA are dairy products, beef and lamb, whereas only trace amounts occur naturally in plant lipids. CLA has been shown to improve various health issues, having effects on obesity, inflammatory, anti-carcinogenicity, atherogenicity, immunomodulation, and osteosynthesis. Also, compared to studies on humans, many animal researches reveal more positive benefits on health. CLA represents a nutritional avenue to improve lifestyle diseases and metabolic syndrome. Most of these effects are attributed to the two major CLA isomers [conjugated linoleic acid cis-9,trans-11 isomer (c9,t11), and conjugated linoleic acid trans-10,cis-12 isomer (t10,c12)], and their mixture (CLA mix). In contrast, adverse effects of CLA have been also reported, such as glucose homeostasis, insulin resistance, hepatic steatosis and induction of colon carcinogenesis in humans, as well as milk fat inhibition in ruminants, lowering chicken productivity, influencing egg quality and altering growth performance in fish. This review article aims to discuss the health benefits of CLA as a nutraceutical supplement and highlight the possible mechanisms of action that may contribute to its outcome. It also outlines the feasible adverse effects of CLA besides summarizing the recent peer-reviewed publications on CLA to ensure its efficacy and safety for proper application in humans.

Multiple biological activities and biosynthesis mechanisms of specific conjugated linoleic acid isomers and analytical methods for prospective application

Conjugated linoleic acid (CLA) is a collective term for the octadecadienoic acid isomers containing conjugated double bonds. This article reviewed CLA isomers from biological activities, biosynthesis mechanisms and analytical methods. The biological activities of CLA isomers in anti-obesity, cardiovascular protection, diabetes management and anti-cancer in vitro and in vivo were mainly reviewed. More attention has been paid to the production of the specific CLA isomer due to its biological activity. The biosynthesis methods of CLA isomers, such as dietary modification in ruminants and fermentation by microorganisms & enzymes, were systematically introduced. A rapid, accurate and economic analysis method will promote the research in both biological activities and biosynthesis mechanisms of CLA isomers. The merits of UV spectrometry, GC, HPLC, MS and CE used in the analysis of CLA isomers were also compared in detail. This paper aims to put into perspective the current status and future trends on CLA isomers.

Enhancing the Recovery of Bioactive Compounds of Soybean Fermented with Rhizopus oligosporus Using Supercritical CO2: Antioxidant, Anti-Inflammatory, and Oxidative Proprieties of the Resulting Extract

The aim of the present study was to evaluate the use of supercritical CO₂ combined with cosolvent for the recovery of bioactive compounds of soybean fermented with Rhizopus oligosporus NRRL 2710. Soxhlet extractions using seven different organic solvents (n-hexane, petroleum ether, ethyl acetate, acetone, ethanol, methanol, and water) were initially performed for comparative purposes. The extracts obtained were characterized by physicochemical, antioxidant, total phenolic, and oxidative proprieties. For the Soxhlet extractions, the highest and lowest yields obtained were 45.24% and 15.56%, using methanol and hexane, respectively. The extraction using supercritical CO₂ combined with ethanol as a static modifier (scCO₂ + EtOH) presented, at a high pressure (25 MPa) and temperature (80 °C), a phenolic compound content of 1391.9 μg GAE g⁻¹ and scavenging of 0.17 g, reaching a 42.87% yield. The extracts obtained by sCO₂ + EtOH were characterized by high contents of essential fatty acids (linoleic acid and oleic acid) and bioactive compounds (gallic acid, trans-cinnamic acid, daidzein, and genistein). These extracts also showed a great potential for inhibiting hyaluronidase enzymes (i.e., anti-inflammatory activity). Thermogravimetric analyses of the samples showed similar profiles, with oil degradation values in the range from 145 to 540 °C, indicating progressive oil decomposition with a mass loss ranging from 93 to 98.7%. In summary, this study demonstrated the flexibility of scCO₂ + EtOH as a green technology that can be used to obtain high-value-added products from fermented soybean.

Impact of High-Altitude Hypoxia on Bone Defect Repair: A Review of Molecular Mechanisms and Therapeutic Implications

Reaching areas at altitudes over 2,500–3,000 m above sea level has become increasingly common due to commerce, military deployment, tourism, and entertainment. The high-altitude environment exerts systemic effects on humans that represent a series of compensatory reactions and affects the activity of bone cells. Cellular structures closely related to oxygen-sensing produce corresponding functional changes, resulting in decreased tissue vascularization, declined repair ability of bone defects, and longer healing time. This review focuses on the impact of high-altitude hypoxia on bone defect repair and discusses the possible mechanisms related to ion channels, reactive oxygen species production, mitochondrial function, autophagy, and epigenetics. Based on the key pathogenic mechanisms, potential therapeutic strategies have also been suggested. This review contributes novel insights into the mechanisms of abnormal bone defect repair in hypoxic environments, along with therapeutic applications. We aim to provide a foundation for future targeted, personalized, and precise bone regeneration therapies according to the adaptation of patients to high altitudes.

Metabolic Disturbance and Th17/Treg Imbalance Are Associated With Progression of Gingivitis

Objective

This study sought to explore the role of metabolic disturbance in immunoregulation of gingivitis targeting T helper 17 cells (Th17)/regulatory T cell (Treg).

Materials and Methods

A total of 20 gingivitis patients and 19 healthy volunteers were recruited. Quantitative real time polymerase chain reaction (qRT-PCR) was used to evaluate expression patterns of Forkhead box protein P3 (Foxp3), transforming growth factor-β (TGF-β), retinoid-related orphan receptor-gammat (RORγt) and interleukin 17A (IL-17A) in the peripheral blood lymphocytes of subjects across the two groups. Moreover, the enzyme-linked immunosorbent assay (ELISA) technique was used to detect levels of TGF-β, IL-4, IL-6,TL-10 and L-17A secreted in the plasma as well as the SIgA secreted in saliva. Flow cytometry was used to detect the percentage of CD4⁺CD25⁺ Foxp3⁺Treg cells and the percentage of CD4⁺IL-17A⁺ Th17 cells in whole blood of subjects in both groups. Gas chromatography-mass spectrometry (GC-MS) was employed to analyze the plasma metabolites in the gingivitis patient group. Statistical analysis was applied to determine whether the plasma metabolites and related metabolic pathways significantly differed between gingivitis patients and healthy controls. Ingenuity pathway analysis (IPA) was employed to identify the potential relation between the metabolites and the Th17 and Treg related pathway.

Results

The percentages of CD4⁺IL17A⁺Th17 cells and IL-17 significantly increased in the peripheral blood in the gingivitis group. Moreover, the upregulation of IL-17A mRNA and RORγt mRNA were also found in the gingivitis group. However, the percentage of CD4⁺CD25⁺ Foxp3⁺Treg cells and Foxp3 mRNA in the whole blood did not significantly change. However, TGF-β mRNA as well as TGF-β, IL-4, IL-6, IL-10 in the periperial blood and SIgA in the saliva were higher in the gingivitis group. Notably, that the ratio of Th17/Treg cells was significantly increased during peripheral circulation. Furthermore, we identified 18 different metabolites which were differentially expressed in plasma between the gingivitis and healthy control groups. Notably, the levels of cholesterol, glycerol 1-octadecanoate, d-glucose, uric acid, cyclohexaneacetic acid, 3-pyridine, tryptophan, and undecane 2,4-dimethyl were significantly up-regulated. whereas the levels of lactic acid, glycine, linoleic acid, monopalmitic acid, glycerol, palmitic acid, pyruvate, 1-(3-methylbutyl)-2,3,4,6-tetramethylbenzene, 1 5-anhydro d-altrol, and boric acid were down-regulated in the gingivitis group, relative to healthy controls. IPA showed that these metabolites are connected to IL17 signaling, TGF-B signaling, and IL10 signaling, which are related closely to Th17 and Treg pathway.

Conclusion

Overall, these results showed that disturbance to glycolysis as well as amino and fatty acid metabolism are associated with Th17/Treg balance in gingivitis. Impaired immunometabolism may influence some periodontally involved systemic diseases, hence it is a promising strategy in targeted development of treatment therapies.

3,4,5-Trihydroxybenzoic Acid Attenuates Ligature-Induced Periodontal Disease in Wistar Rats

BACKGROUND

3,4,5-Trihydroxybenzoic acid, which is also known as gallic acid, is an antiinflammatory agent that could provide beneficial effects in preventing periodontal inflammation. The present study aimed to evaluate the anti-inflammatory effects of gallic acid on experimental periodontitis in Wistar rats. Alveolar bone loss, osteoclastic activity, osteoblastic activity, and collagenase activity were also determined.

METHODS

Thirty-two Wistar rats were used in the present study. Study groups were created as following: Healthy control (C,n=8) group; periodontitis (P,n=8) group; periodontitis and 30 mg/kg gallic acid administered group (G30,n=8); periodontitis and 60 mg/kg gallic acid administered group (G60,n=8). Experimental periodontitis was created by placing 4-0 silk sutures around the mandibular right first molar tooth. Morphological changes in alveolar bone were determined by stereomicroscopic evaluation. Mandibles were undergone histological evaluation. Matrix metalloproteinase (MMP)-8, tissue inhibitor of MMPs (TIMP)-1, bone morphogenetic protein (BMP)-2 expressions, tartrateresistant acid phosphatase (TRAP) positive osteoclast cells, osteoblast, and inflammatory cell counts were determined.

RESULTS

The highest alveolar bone loss was observed in the periodontitis group. Both doses of gallic acid decreased alveolar bone loss as compared to the P group. TRAP-positive osteoclast cell counts were higher in the P group, and gallic acid successfully lowered these counts. Osteoblast cells also increased in gallic acid administered groups. Inflammation in the P group was also higher than those of C, G30, and G60 groups supporting the role of gallic acid in preventing inflammation. 30 and 60 mg/kg doses of gallic acid decreased MMP-8 levels and increased TIMP-1 levels. BMP levels increased in gallic acid administered groups, similar to several osteoblasts.

CONCLUSION

Present results revealed an anti-inflammatory effect of gallic acid, which was indicated by decreased alveolar bone loss and collagenase activity and increased osteoblastic activity.

LysR Family Regulator LttR Controls Production of Conjugated Linoleic Acid in Lactobacillus plantarum by Directly Activating the cla Operon

Conjugated linoleic acids (CLAs) have attracted more attention as functional lipids due to their potential physiological activities, including anticancer, anti-inflammatory, anti-cardiovascular disease, and antidiabetes activities. Microbiological synthesis of CLA has become a compelling method due to its high isomer selectivity and convenient separation and purification processes. In Lactobacillus plantarum, the generation of CLA from linoleic acids (LAs) requires the combination of CLA oleate hydratase (CLA-HY), CLA short-chain dehydrogenase (CLA-DH), and CLA acetoacetate decarboxylase (CLA-DC), which are separately encoded by cla-hy, cla-dh, and cla-dc. However, the regulatory mechanisms of CLA synthesis remain unknown. In this study, we found that a LysR family transcriptional regulator, LTTR, directly bound to the promoter region of the cla operon and activated the transcription of cla-dh and cla-dc. The binding motif was also predicted by bioinformatics analysis and verified by electrophoretic mobility shift assays (EMSAs) and DNase I footprinting assays. The lttR overexpression strain showed a 5-fold increase in CLA production. Moreover, we uncovered that the transcription of lttR is activated by LA. These results indicate that LttR senses LA and promotes CLA production by activating the transcription of cla-dh and cla-dc. This study reveals a new regulatory mechanism in CLA biotransformation and provides a new potential metabolic engineering strategy to increase the yield of CLA.IMPORTANCE Our work has identified a novel transcriptional regulator, LTTR, that regulates the production of CLA by activating the transcription of cla-dh and cla-dc, essential genes participating in CLA synthesis in Lactobacillus plantarum This study provides insight into the regulatory mechanism of CLA synthesis and broadens our understanding of the synthesis and regulatory mechanisms of the biosynthesis of CLA.

Effects of the Association of Periodontitis and Type 1 Diabetes Mellitus Induced on Periodontal Tissues and the Duodenal Mucosa of Wistar Rats

Forty Wistar rats were used: (1) control group (CG); (2) group of periodontal disease (PD); (3) type 1 diabetes mellitus group (T1DM); (4) type 1 diabetes mellitus + periodontal disease group (T1DM + PD). In groups T1DM and T1DM + PD, T1DM induction was performed with the administration of streptozotocin (STZ) 80 mg/kg intraperitoneal body weight. The PD and T1DM + PD groups were submitted to PD induction with ligation. After the experimental phase and euthanasia, histological, radiographic, and morphological analyses were performed. For data analysis, was used the one-way ANOVA and post-test Tukey. The T1DM + PD group had a significantly higher level of fasting blood glucose compared to the other groups. In radiographic and histomorphometric analyses, the T1DM + PD group showed greater alveolar bone loss compared to the control group. The T1DM + PD group showed greater osteoclastic activity compared to the control, T1DM, and PD groups and exhibited an intense inflammatory infiltrate, most of which were PMN, being that the amount of this group of cells (PMN) was significantly greater than the PD group. The heights of the intestinal villi were statistically higher in the PD, T1DM, T1DM + PD groups, compared to the control. Regarding the height of the crypt, only the T1DM and T1DM + PD groups were significantly higher compared to the other groups. Association of diabetes and periodontal inflammation increased the deleterious effects on bone tissue and adverse effect on the permeability of the duodenal mucosa.

Hyaluronic acid with antioxidants improve wound healing in rats

Hyaluronic acid (HA) is found in connective tissue and participates in wound healing. We investigated the efficacy of a HA gel (2% hyaluronic acid; 1% antioxidants, coenzyme Q10 and vitamin E; and 5% benzocaine) on healing of palatal wounds in rats. We established two groups of rats: a control group treated with vehicle and an HA group treated with HA gel. The control group was divided into five subgroups and the HA group was divided into four subgroups according to the day on which animals were sacrificed. Wounds were created by elevating 5 mm diameter full thickness flaps. Healed and unhealed wound areas were measured using photographs. Transforming growth factor (TGF)-β, insulin-like growth factor (IGF), and collagen I and III expressions were determined using immunohistochemistry. The number of fibroblasts increased and inflammatory cells decreased from day 0 to 21 in both groups. The HA group exhibited more fibroblasts by day 7 compared to controls; (TGF)-β and IGF levels were similar between HA and control groups. HA groups exhibited fewer inflammatory cells than controls on days 3 and 7. We found significant differences in TGF-β and IGF levels among HA groups between days 3 and 21, and among control groups between days 0 and 21. Collagen I and III levels were greater for the day 3 HA group compared to controls. We observed improved wound healing in HA treated rats within 7 days.

Evaluation of apoptosis and hypoxia-related factors in gingival tissues of smoker and non-smoker periodontitis patients

OBJECTIVE

Smoking causes pathological changes in all tissues, including gingiva and alveolar bone. The aim of present study was to evaluate apoptotic tissue alterations and tissue destruction in smoker and non-smoker periodontitis patients and healthy individuals.

METHODS

Gingival biopsy samples from 15 systemically and orally healthy individuals (Group 1), 15 systemically healthy periodontitis patients (Group 2), 15 systemically and orally healthy smokers (Group 3), and 15 systemically healthy smoker periodontitis patients (Group 4) were enrolled in the present study. Clinical periodontal measurements as plaque index (PI), gingival index (GI), and clinical attachment levels (CAL) were recorded, and gingival biopsies were obtained. Biopsy samples were fixed in formalin solution and embedded in paraffin. Fibroblast and inflammatory cell counts were determined via histomorphometrically. Hypoxia-inducible factor alpha (HIF-1α), vascular endothelial growth factor(VEGF), tissue inhibitor of matrix metalloproteinase-1(TIMP-1), matrix metalloproteinases-8(MMP-8) expressions, Bax, Bcl-2, and caspase-3 expressions were evaluated via immunohistochemistry.

RESULTS

Demographic data of the study groups were similar. Smoking levels of the smokers were also similar. The highest fibroblast cell counts were observed in healthy controls and the counts were similar in other groups. The highest inflammatory cell counts were found in smoker periodontitis group, and the lowest counts were found in healthy control groups. The differences were statistically significant. HIF-1α and Bax expressions were elevated and Bcl-2 decreased in smoker periodontitis patients compared with healthy individuals. However, there were no differences in VEGF, MMP-8, and TIMP-1 expressions.

CONCLUSION

Within limits of present study, it can be suggested that both smoking and periodontitis caused similar decrease in fibroblast counts while causing a dramatic increase in inflammatory cell counts. Increased apoptosis and hypoxia also accompanied to the increased inflammation.

Evaluation of the effect of oleuropein on alveolar bone loss, inflammation, and apoptosis in experimental periodontitis

THE OBJECTIVE

The present study aimed to evaluate the effects of oleuropein on ligature-induced alveolar bone loss. In this respect, osteoblastic activity, osteoclastic activity, inflammatory markers, and apoptosis were evaluated.

BACKGROUND

Oleuropein is a flavonoid, which has potent anti-inflammatory and bone-protective effects.

METHODS

Thirty-two Wistar rats were divided into four experimental groups as following: control (C, n = 8) group; periodontitis (P, n = 8) group; periodontitis and low-dose oleuropein group (12 mg/kg/day oleuropein, LDO group, n = 8); and periodontitis and high-dose oleuropein group (24 mg/kg/day oleuropein, HDO group, n = 8). Periodontitis was induced via ligatures. Study period was 14 days, and animals were sacrificed at end of this period. Mandibles were examined via a stereomicroscope and underwent histological procedures. Osteoblast, tartrate-resistant acid phosphatase (TRAP)-positive osteoclast, and inflammatory cell counts were determined in hematoxylin-eosin stained sections. Inducible nitric oxide synthase (iNOS), bone morphogenetic protein-4, the cluster of differentiation (CD)-68, cysteine-aspartic proteases-3 (Caspase 3), and B-cell lymphoma-2 (Bcl-2) expressions were evaluated via immunohistochemistry.

RESULTS

Periodontitis group had highest alveolar bone loss, and these levels significantly decreased in LDO and HDO groups. Both 12 and 24 mg/kg oleuropein groups significantly increased osteoblast cell counts and decreased TRAP-positive osteoclast and inflammatory cell counts. BMP-4 and bcl-2 expressions were elevated in oleuropein groups while caspase-3 expressions decreased. iNOS and CD68 were higher in periodontitis group compared to control group, but there was no significant difference between other groups.

CONCLUSION

Oleuropein successfully decreased alveolar bone loss as a result of decreased osteoclastic activity, inflammation, and apoptosis and increased osteoblastic activity.

Experimental investigation of effects of platelet-rich plasma on early phases of orthodontic tooth movement

INTRODUCTION

The aim of this study was to evaluate the effects of platelet-rich plasma on orthodontic tooth movement in rats.

METHODS

We divided 48 Wistar male albino rats into 3 groups: control group, platelet-rich plasma group, and platelet-poor plasma group. The rats in all study groups had orthodontic tooth movement of their maxillary right first molars. Either platelet-rich plasma or platelet-poor plasma was injected into the animals in the platelet-rich plasma and platelet-poor plasma groups, respectively; the rats in the control group had no injection. Distances between the maxillary molar and incisor were measured on days 0, 1, 3, 7, and 14. Active osteoblast numbers in tension sites and osteoclast numbers in compression sites were examined histologically. Immunohistochemical evaluations of tartrate-resistant acid phosphatase (TRAP), transforming growth factor-β (TGF-β), and alkaline phosphatase (ALP) expressions were also performed.

RESULTS

The rats in the platelet-rich plasma group showed less tooth movement than those in the control group at day 3. At day 14, maximum tooth movement was observed in all groups. However, there was no statistical significance among the groups at day 14. In terms of osteoclast and osteoblast cells, no significant differences were observed in any group or at any time. Also, there were no significant differences in TRAP, ALP, and TGF-β expressions in the groups.

CONCLUSIONS

The application of platelet-rich plasma was not beneficial as an adjunct to orthodontic treatment.

Enhanced Oxidative Damage and Nrf2 Downregulation Contribute to the Aggravation of Periodontitis by Diabetes Mellitus

Diabetes mellitus is a well-recognized risk factor for periodontitis. The goal of the present study was to elucidate whether oxidative stress and nuclear factor erythroid 2-related factor 2 (Nrf2) participate in the aggravation of periodontitis by diabetes. For this purpose, we assigned Wistar rats to control, periodontitis, diabetes, and diabetic periodontitis groups. Two weeks after induction of diabetes by streptozotocin, periodontitis was induced by ligation. Two weeks later, periodontal tissues and blood were harvested and analyzed by stereomicroscopy, immunohistochemistry, and real-time polymerase chain reaction. We found that ligation induced more severe bone loss and periodontal cell apoptosis in diabetic rats than in normal rats (p < 0.05). Compared with the control group, periodontitis significantly enhanced local oxidative damage (elevated expression of 3-nitrotyrosine, 4-hydroxy-2-nonenal, and 8-hydroxy-deoxyguanosine), whereas diabetes significantly increased systemic oxidative damage and suppressed antioxidant capacity (increased malondialdehyde expression and decreased superoxide dismutase activity) (p < 0.05). Simultaneous periodontitis and diabetes synergistically aggravated both local and systemic oxidative damage (p < 0.05); this finding was strongly correlated with the more severe periodontal destruction in diabetic periodontitis. Furthermore, gene and protein expression of Nrf2 was significantly downregulated in diabetic periodontitis (p < 0.05). Multiple regression analysis indicated that the reduced Nrf2 expression was strongly correlated with the aggravated periodontal destruction and oxidative damage in diabetic periodontitis. We conclude that enhanced local and systemic oxidative damage and Nrf2 downregulation contribute to the development and progression of diabetic periodontitis.

A novel pH-responsive quaternary ammonium chitosan-liposome nanoparticles for periodontal treatment

The aim of this study was to evaluate the antibacterial activity and cytocompatibility of novel pH-activated nanoparticles (NPs) in vitro and in vivo. The NPs were synthesized from a quaternary ammonium chitosan, i.e., N,N,N-trimethyl chitosan, a liposome, and doxycycline (TMC-Lip-DOX NPs). The cytocompatibility of the NPs was evaluated. The TMC-Lip-DOX NPs achieved superb inhibition of free mixed bacteria and biofilm formation. They also showed excellent biocompatibility with human periodontal ligament fibroblasts. Animal experiments showed that the NPs strongly inhibited biofilm formation and prevented alveolar bone absorption in vivo. All the results indicate that the TMC-Lip-DOX NPs have good potential for use in the treatment of periodontal and other inflammatory diseases.

Investigation of the effect of astaxanthin on alveolar bone loss in experimental periodontitis

BACKGROUND AND OBJECTIVE

Astaxanthin is a keto-carotenoid that has a strong antioxidant effect. The purpose of this study was to evaluate the effects of astaxanthin on alveolar bone loss and histopathological changes in ligature-induced periodontitis in rats.

MATERIAL AND METHODS

Wistar rats were divided into four experimental groups: non-ligated (C, n = 6); ligature only (L, n = 6); ligature and astaxanthin (1 mg/kg/day astaxanthin, AS1 group, n = 8); ligature and astaxanthin (5 mg/kg/day astaxanthin, AS5 group, n = 8). Silk ligatures were placed at the gingival margin of lower first molars of the mandibular quadrant. The study duration was 11 days and the animals were killed at the end of this period. Changes in alveolar bone levels were clinically measured and tissues were immunohistochemically examined, osteocalcin, bone morphogenic protein-2, inducible nitric oxide synthase, Bax and bcl-2 levels in alveolar bone and tartrate-resistant acid phosphatase-positive osteoclast cells, osteoblast and inflammatory cell counts were determined.

RESULTS

Alveolar bone loss was highest in the L group and the differences among the L, AS1 and AS5 groups were also significant (P < .05). Both doses of astaxanthin decreased tartrate-resistant acid phosphatase-positive+ osteoclast cell and increased osteoblast cell counts (P < .05). The inflammation in the L group was also higher than those of the C and AS1 groups were (P < .05) indicating the anti-inflammatory effect of astaxanthin. Although inducible nitric oxide synthase, osteocalcin, bone morphogenic protein-2 and bax staining percentages were all highest in the AS5 group and bcl-2 staining percentage was highest in the AS1 group, values were close to each other (P > .05).

CONCLUSION

Within the limits of this study, it can be suggested that astaxanthin administration may reduce alveolar bone loss by increasing osteoblastic activity and decrease osteoclastic activity in experimental periodontitis model.

Bacterial conjugated linoleic acid production and their applications

Conjugated linoleic acid (CLA) has been shown to exert various potential physiological properties including anti-carcinogenic, anti-obesity, anti-cardiovascular and anti-diabetic activities, and consequently has been considered as a promising food supplement. Bacterial biosynthesis of CLA is an attractive approach for commercial production due to its high isomer-selectivity and convenient purification process. Many bacterial species have been reported to convert free linoleic acid (LA) to CLA, hitherto only the precise CLA-producing mechanisms in Propionibacterium acnes and Lactobacillus plantarum have been illustrated completely, prompting the development of recombinant technology used in CLA production. The purpose of the article is to review the bacterial CLA producers as well as the recent progress on describing the mechanism of microbial CLA-production. Furthermore, the advances and potential in the heterologous expression of CLA genetic determinants will be presented.