Exploring the Diversity of Some Microorganisms from Lake Al-Asfar, KSA: The Good, the Bad, and the Pathogenic

<b>Background:</b> Lake Al-Asfar in KSA was used as a sink for wastewater for decades and suffered from pollution. The lake is a habitat to different microbial species that play important ecological roles, some of which are good, and some are bad and even pathogenic. In a previous investigation, algal-bacteria consortia have proven to be beneficial in bioremediating heavy metals and hydrocarbons in Lake Al-Asfar. The identity of algae was revealed to be <i>Chlorella</i> sp. and <i>Geitlernema</i> sp. in the consortia. The identity of the heterotrophic bacterial partners, on the other hand, awaits investigation and is addressed in the present research. On the other hand, investigating the diversity of Protozoa and parasites is also tackled as they represent indicators of pollution. Some pose serious health risks, but some of them also contribute to reducing some of the pollution levels. <b>Methods:</b> Bacteria associated with algae were isolated in pure form. The polyphasic approach was used to identify bacterial samples, including staining procedures, the use of Vitek technology, and scanning electron microscopy. This information was integrated with structure information such as capsule presence, endospore formation, and wall characteristics indicated by Gram stain. With regard to protists including Protozoa and parasites, Light microscopy and taxonomic books of identification were used to reveal their identity. <b>Results:</b> three main bacterial strains belonging to the following genera were identified: <i>Sphingomonas</i>, <i>Rhizobium</i>, and <i>Enterbacter</i>. The last is potentially pathogenic and poses health risks to Lake goers. Rhizobium, on the other hand, is most likely found in the lake from agricultural wastewater and is a nitrogen fixer that increases the fertility of crops. The first bacterium is associated with special lipid metabolism and is hardly pathogenic. Several diverse microscopic forms of protists, mainly Protozoa and parasites, were identified, which included <i>Entamoeba histolytica</i>, <i>Balantidium coli</i>, <i>Ascaris lumbricoides</i>, <i>Amoeba</i>, <i>Paramecium</i>, <i>Euglena</i>, and <i>Gymnodinium</i> sp. <b>Discussion:</b> The three types of bacteria identified have metabolic activities that are associated with bioremediation. On the other hand, protists, including Protozoa and parasites, are regular members of wastewater communities and help in scavenging solid wastes, but they cause hazards such as secreting toxins, causing disease, and impacting the bioremediation potential by feeding on beneficial bioremediating algae and bacteria. This is part of the wastewater ecosystem dynamics, but efforts must be exerted to minimize, if not completely eliminate, pathogenic parasites in order to maximize the growth of algal consortia. <b>Conclusions:</b> Vitek technology is an emerging less time- and effort-consuming fast technology for identifying bacteria. Bacteria identified have significant ecological bioremediating roles, together with their algal partners, but some pose pathogenic risks. Identifying co-inhabitants like protists and parasites helps to shed light on their impact on one another and pave the way for restoration efforts that minimize the biological hazards and maximize the use of beneficial local microorganisms.