ISOLATION AND IDENTIFICATION OF MICROORGANISMS FROM HERBAL MIXTURES SOLD AT GADAU METROPOLIS

ABSTRACT Herbal medicines remain one of the most accessible and widely used forms of primary health care in developing countries, especially Nigeria, where over 70% of the population depends on them for the treatment of common ailments. These preparations are perceived to be natural, affordable and safe; however, they are often produced under unhygienic conditions and stored without regulatory oversight, creating avenues for microbial contamination. This study was conducted to isolate and identify microorganisms associated with selected liquid herbal mixtures sold within Gadau metropolis, Bauchi State, Nigeria, with a view to assessing their microbiological safety relative to World Health Organization (WHO) standards. Six different liquid herbal mixtures were randomly purchased from major sale points within Gadau (Main Market, Fada Junction and School Main Gate). The samples were kept under refrigeration at 4 °C until analysis and were processed using standard microbiological methods. Each sample was thoroughly homogenized, serially diluted, and plated on Nutrient Agar and MacConkey Agar using pour plate and streak plate techniques. Colonies were incubated at 37 °C for 24–48 hours under aerobic conditions. Distinct colonies were then purified and subjected to Gram staining and biochemical tests (catalase, coagulase and indole) for identification. Total bacterial counts were expressed as colony-forming units per millilitre (CFU/mL) and compared with the permissible WHO limit of 1 × 10³ CFU/mL for herbal products. The results showed heavy microbial contamination in all the herbal mixtures analyzed. Morphological examination revealed colonies with circular or irregular shapes, raised or flat elevation, smooth or pinpoint surfaces and varying pigmentation on Nutrient and MacConkey Agar. Bacterial loads ranged from 2.6 × 10³ to 9.2 × 10³ CFU/mL with a mean of 5.95 × 10³ CFU/mL, exceeding WHO standards by up to ninefold in some cases. Gram staining and biochemical profiles revealed the presence of several potential pathogens: Escherichia coli (indicative of faecal contamination), Staphylococcus aureus (suggesting contamination from human handlers), Bacillus spp. (environmental spore formers), Salmonella spp. (enteric pathogen associated with typhoid and gastroenteritis) and Pseudomonas spp. (opportunistic pathogen and spoilage organism). These findings highlight a significant public health concern, as consumption of herbal mixtures with such high microbial loads can result in acute infections, chronic illnesses or degradation of the active components, reducing therapeutic efficacy. The results also corroborate previous studies across Nigeria and other developing countries showing widespread microbial contamination of non-regulated herbal products. Inadequate heat processing, improper handling of raw materials, poor storage conditions and use of unsafe water during preparation are probable sources of contamination. It is concluded that the liquid herbal mixtures sold in Gadau metropolis are microbiologically unsafe according to WHO standards. The study recommends that herbal practitioners be trained on good manufacturing practices and hygienic processing, and that regulatory agencies such as NAFDAC intensify routine microbiological screening of herbal preparations. Such measures are essential to safeguard public health, ensure product quality and sustain confidence in traditional medicine as a viable component of Nigeria’s healthcare system.