It is imperative to say that we are immersed in a sea of microorganisms due to their ubiquitous presence on the planet, from soil to water and air. Human bodies harbor a vast array of microorganisms from both the inside and out called the human microbiome. It is composed of single-celled organisms, including archaea, fungi, viruses, and bacteria, including bacteriophages, where bacteria are the biggest players, and this is collectively referred to as the human microbiome. These organisms have a symbiotic relationship with humans and impact human physiology where they colonize various sites on and in the human body, adapting to specific features of each niche. However, dysbiosis, or the deviation from normal microbial composition, is associated with adverse health effects, disrupted ecosystems, and eco-imbalance in nature. In this review, we delve into the comprehensive oversight of bacteria, their cosmopolitan presence, and their additional applications affecting human lives.

Canthaxanthin is an orange-red keto-carotenoid that occurs naturally and is also manufactured by synthetic methods for regular applications. In nature, canthaxanthin mainly exists in microbes such as different bacterial species, fungi, and algae, as well as in animals such as crustaceans, certain fishes, and birds. However, the amount of canthaxanthin produced in these organisms varies significantly. Additionally, the compound can be generated from genetically modified organisms using genetic engineering techniques Canthaxanthin finds extensive application as an additive in animal feed, in the pharmaceutical industry, as a coloring agent for various food products, and in cosmetics. It has powerful antioxidant properties and plays a role in lipid metabolism, neuroprotection, and immunomodulation. This article gives an extensive insight into the structure and methods of synthesis of canthaxanthin along with its various newly discovered sources identified so far. The significant applications of canthaxanthin, particularly its role in pharmaceuticals, are critically evaluated. Furthermore, the article discusses future aspects and challenges associated with canthaxanthin production and regulation.