Pediococcus acidilactici

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1. Classification

Higher order taxa:

Bacteria (domain); Terrabacteria (clade); Bacillota (phylum); Bacilli (class); Lactobacillales (order); Lactobacillaceae (family); Pediococcus (genus)

Species:

Pediococcus acidilactici

2. Description and significance

The lactic acid bacterium Pediococcus acidilactici belongs to the Gram-positive cocci category, characterized as a facultative anaerobic bacterium, and is a member of the Lactobacillaceae family[1]. It grows well in a range of temperatures and pHs, and can ferment many sugars[2][3]. Due to its capability and metabolism, it is widely used in the fermentation of various food and dairy products[4]. P. acidilactici also holds potential in the fields of probiotics and biotechnology[5]. This is particularly so in the case of digestive and immune health, where it has shown some promise in multiple areas[6]. Specifics of its applications in treating conditions such as heavy metal poisoning and skin-related disorders are still unknown, but are actively being researched[7][8].

3. Genome structure

Like most bacteria, P. acidilactici contains one circular chromosome. In the P. acidilactici ATCC 8042 strain, this chromosome was found to be approximately 2 million base pairs long, with an estimated 1,865 protein-coding DNA sequences[9]. A high amount of genetic diversity has been observed in different strains of P. acidilactici. A comparative genome analysis study concluded that the genome of this species is “open,” meaning that it regularly accepts genes from the environment. As expected for a diverse and open genome, multiple types of mobile genetic elements and the CRISPR locus have been detected in P. acidilactici[4]. Additionally, evidence of site-specific recombination has been found in the P. acidilactici genome[9]. Various gene sequences for unique elements like carbohydrate-active enzymes (CAZymes) and bacteriocins were also identified in the genome[10].

4. Cell structure

P. acidilactici is a Gram-positive, facultative anaerobic, cocci-shaped bacteria. A genomic analysis study found that there are 41 strains of P. acidilactici from diverse ecological niches[4]. Belonging to the Lactobacillaceae family, P. acidilactici is also nonmotile, non-spore-forming, and catalase-negative spherical. Its size is about 1.5–2.0 μm in diameter and grows in pairs and tetrads[11].

5. Metabolic processes

P. acidilactici is a facultatively anaerobic homofermentative lactic acid bacterium (LAB), meaning it principally ferments glucose to produce lactic acid as the end-product. It is metabolically flexible and can survive in a broad range of environments[4]. It grows the best in 35-40 ℃ and a pH of 6-6.5. However, it is able to grow at 50℃ as well, with pH levels dropping as low as 3.6[2]. It is commonly found in the human and animal digestive tracts. It is well-known for its ability to ferment glucose, ribose, xylose, fructose, and galactose to DL-lactate, and certain strains can also ferment lactose, sucrose, and maltose[3]. In a controlled laboratory medium (MRS broth), P. acidilactici experiences optimal growth rate and biomass at 35℃ and pH 6.5, and maximum bacteriocin production at 35℃ and pH 6.1[12]. Notably, P. acidilactici is capable of producing antibacterial compounds, particularly bacteriocins, a class of peptidoglycan hydrolases[9].

6. Ecology

P. acidilactici can be found in many environments as its metabolism allows it to use various carbon sources, some of which enhance the adaptability of P. acidilactici so that it is able to survive in different environments[4]. P. acidilactici is a lactic acid bacteria and can be found in human and animal digestive tracts[4]. It can also be found in fermented products like fermented cabbage or other foods where the bacterium can conduct lactic acid fermentation[12].

7. Pathology

P. acidilactici is not pathogenic. P. acidilactici has been shown to have antibacterial effects, including producing bacteriocins, a class of antibiotics[12]. P. acidilactici is safe for use in multiple different applications, including in the food industry[7].

8. Applications in the Industry

P. acidilactici plays an important role in multiple food and health fields. P. acidilactici can be added to food to help against the infection of the bacterium Vibrio nigripulchritudo in the global shrimp farming industry. Meanwhile, food containing P. acidilactici can help improve the overall immunity and health level of shrimps[13].

In the health industry, P. acidilactici performs antibacterial activity against multiple human pathogens that can contaminate food, including Listeria monocytogenes. Thus, diets containing P. acidilactici can help regulate the intestinal flora and improve the immune system[14].

9. Current Research

One study involving P. acidilactici focuses on its influences on regulating fasting blood glucose and other factors to explore its potential applications in treating Prediabetes (PreD) and Type II Diabetes (T2D). The study compares the body indexes of two groups of male mice feeding on a high fat diet (HFD), one adds placebos and the other adds pA1c strains of the P. acidilactici. HFD can cause dysbiosis, which can induce local inflammation and lead to higher intestine permeability, resulting in high blood glucose levels[15]. After tracing 12 weeks of multiple body indexes and analyzing fixed tissue samples (pancreas and small intestine), pA1c has proven to improve fasting blood glucose levels, promote insulin secretion, and preserve β-pancreatic islets functions. The GLP-1 serum level is an incretin that is vital for insulin secretion and hepatic glucose synthesis increases after treatment with pA1c. pA1c is also able to reduce the expression of glucose-regulating studied enzymes G6P, PEPCK, and GCK, which can be related to decreasing gluconeogenesis. Overall, P. acidilactici helps control blood glucose levels and protect the pancreas by regulating multiple factors in the gut, which signals for it to be a potential protection and treatment for PreD and T2D patients[6].

Another study of P. acidilactici states how the microbe affects gut microbiota and metabolomes that leads to a decrease in heavy metals (HM) that are toxic to the body[7]. The experiment is conducted on two groups of 76 occupational workers in the metal industry who consumed (1) probiotic yogurt with the HM-resistant strain of P. acidilactici GR-1 or (2) conventional yogurt over the course of 12 weeks. Compared to the conventional yogurt, the probiotic yogurt with the HM-resistant strain of P. acidilactici GR-1, shows evidence of lower heavy metal levels and improved serum biochemicals indices. Further research into probiotics would open up options that will be effective and accessible against high heavy metal levels and other forms of toxic metal exposure. The experiment validated the GR-1’s protective effect against metals in the intestines' antioxidative function[7].

Hyperpigmentation is a typically harmless condition where patches of the epidermis (skin) are darker than the rest of the surrounding skin. A clinical trial with P. acidilactici PMC48 was conducted to see if the microbe can combat hyperpigmentation caused by the accumulation of melanin in the skin. Trial participants were artificially tanned via UV-induced rays and had PMC48 directly applied to their skin. The 22 participants were observed for 8 weeks for any visual changes, skin brightness, and melanin index. PMC48 showed significant positive effects in both skin whitening and decreasing the melanin index of artificially induced pigmented skin. There was a 47.647% decrease in tanned skin color intensity, an 8.098% increase in skin brightness, an 11.818% decrease in melanin index, and a 20.943% increase in skin moisture. PMC48 showed no signs of toxicity in both in vitro and in vivo analyses. The results showcase P. acidilactici's promising role in the cosmetic or pharmaceutical industry in combating skin-related disorders or treatments[8].

Most P. acidilactici research focuses on the potential probiotic effects on the human body’s internal system. P. acidilactici FZU106 was isolated from Hongqu rice wine to investigate its effect on hyperlipidemia and lipid metabolism. High-fat diet-induced hyperlipidemic rats were observed in the study to see if FZU106 would intervene in the processes occurring in the liver or lipid metabolizing processes. The strain was found to decrease mRNA levels in CD36, which transports fatty acids to the cells, thus preventing the uptake of fatty acids. Additional liver genes that were observed to be significantly regulated by FZU106 are CD36, CYP7A1, SREBP-1c, BSEP, LDLr, and HMGCR. The findings show that FZU106 was able to go against lipid metabolism and oxidative stress to inhibit processes such as abnormal increases in body weight[16].

10. References

[1] Klaenhammer, T. R. (1993). Genetics of bacteriocins produced by lactic acid bacteria. FEMS Microbiology Review, 12, 39-85. https://doi.org/10.1111/j.1574-6976.1993.tb00012.x
[2] Anastasiadou, S., Papagianni, M., Filiousis, G., Ambrosiadis, I., & Koidis, P. (2008). Pediocin SA-1, an antimicrobial peptide from Pediococcus acidilactici NRRL B5627: Production conditions, purification and characterization. Biores Technol, 99, 5384–5390. https://doi.org/10.1016/j.biortech.2007.11.015
[3] Papagianni, M., & Sofia, A. (2009). “Pediocins: The bacteriocins of Pediococci. Sources, production, properties and applications.” Microbial Cell Factories, 8(1), 1-16. https://doi.org/10.1186/1475-2859-8-3
[4] Li Z., Song Q., Wang M., Ren J., Liu S., & Zhao S. (2021). Comparative genomics analysis of Pediococcus acidilactici species. Journal of Microbioly, 59(6), 573-583. https://doi.org/10.1007/s12275-021-0618-6
[5] Abbasiliasi, S., Tan, J. S., Bashokouh, F., Ibrahim, T. A. T., Mustafa, S., Vakhshiteh, F., Sivasamboo, S., & Ariff, A. B. (2017). In vitro assessment of Pediococcus acidilactici Kp10 for its potential use in the food industry. BMC Microbiol, 17, 121. https://doi.org/10.1186/s12866-017-1000-z [
6] Cabello-Olmo, M., Oneca, M., Pajares, M. J., Jiménez, M., Ayo, J., Encío, I. J., Barajas, M., & Araña, M. (2022). Antidiabetic effects of Pediococcus acidilactici pA1c on HFD-induced mice. Nutrients, 14(3), 692. https://doi.org/10.3390/nu14030692
[7] Feng, P., Yang, J., Zhao, S., Ling, Z., Han, R., Wu, Y., ... & Li, X. (2022). Human supplementation with Pediococcus acidilactici GR-1 decreases heavy metals levels through modifying the gut microbiota and metabolome. npj Biofilms Microbiomes, 8, 63. https://doi.org/10.1038/s41522-022-00326-8
[8] Park, H., Seo H., Kim S., Haq, A. U., Bae, S. H., Lee, H. J., ... & Song, H. Y. (2023) Clinical effect of Pediococcus acidilactici PMC48 on hyperpigmented skin. Journal of Cosmetic Dermatology, 00, 1-12. https://doi.org/10.1111/jocd.15891
[9] Cho, S.W., Yang, J., Park, S., Kim, B., & Seo, S. W. (2019). Complete Genome Sequence of Lactic Acid Bacterium Pediococcus acidilactici Strain ATCC 8042, an Autolytic Anti-bacterial Peptidoglycan Hydrolase Producer. Biotechnol Bioproc, 24, 483–487. https://doi.org/10.1007/s12257-019-0037-2
[10] Surachat K, Kantachote D, Deachamag P, Wonglapsuwan M. Genomic Insight into Pediococcus acidilactici HN9, a Potential Probiotic Strain Isolated from the Traditional Thai-Style Fermented Beef Nhang. Microorganisms. 2020 Dec 27;9(1):50. doi: 10.3390/microorganisms9010050. PMID: 33375492; PMCID: PMC7823806.
[11] Cobos, M. A., de Coss A. L., Ramirez, N. D., Gonzalez, S. S., & Cerrato, R. F. (2011). Pediococcus acidilactici isolated from the rumen of lambs with rumen acidosis, 16S rRNA identification and sensibility to monensin and lasalocid. Research in veterinary science, 90(1), 26-30. https://doi.org/10.1016/j.rvsc.2010.05.006
[12] Zhang, J., Zhang, Y., Liu, S., Han, Y., & Zhou, Z. (2012). Modeling Growth and Bacteriocin Production by Pediococcus acidilactici PA003 as a Function of Temperature and pH Value. Applied Biochem Biotechnol, 166, 1388–1400. https://doi.org/10.1007/s12010-011-9532-4
[13] Castex, M., Lemaire, P., Wabete, N., & Chim, L. (2010). Effect of probiotic Pediococcus acidilactici on antioxidant defences and oxidative stress of Litopenaeus stylirostris under Vibrio nigripulchritudo challenge. Fish & shellfish immunology, 28(4), 622-631.https://doi.org/10.1016/j.fsi.2009.12.024
[14] Qiao, Y., Qiu, Z., Tian, F., Yu, L., Zhao, J., Zhang, H., Zhai, Q., & Chen, W. (2022). Effect of bacteriocin-producing Pediococcus acidilactici strains on the immune system and intestinal flora of normal mice. Food Science and Human Wellness, 11(2), 238-246. https://doi.org/10.1016/j.fshw.2021.11.008
[15] Rohr, M. W., Narasimhulu, C. A., Rudeski-Rohr, T. A., & Parthasarathy, S. (2020). Negative effects of a high-fat diet on intestinal permeability: a review. Advances in Nutrition, 11(1), 77-91. https://doi.org/10.1093/advances/nmz061
[16] Zhang Q., Guo W. L., Chen G. M., Qian, M., Han, J. Z., Lv, X. C., ... & Ni, L. (2022) Pediococcus acidilactici FZU106 alleviates high-fat diet-induced lipid metabolism disorder in association with the modulation of intestinal microbiota in hyperlipidemic rats. Current Research in Food Science, 5, 775-788. https://doi.org/10.1016/j.crfs.2022.04.009

Edited by [Reshma Subramonian, Eugenia Lim, Aziza Barkuschwabe, Jincheng Liu and Alina Tran], students of [mailto:jmbhat@bu.edu Jennifer Bhatnagar] for BI 311 General Microbiology, 2023, Boston University. [[Category:Pages edited by students of Jennifer Bhatnagar at Boston University]]