Biofilm Production in Borehole Water Sources and their Susceptibility to Antibiotics and Antibiofilm Effect of Noni Foliar Extracts
Authors: O. Amadi Lawrence , Emeka Faith T, , Lekia Grace I, 
Published: February 2023

Background: Bacteria produce biofilm in a variety of systems; water, implant devices in humans and living tissues. They can be persistent and express virulent factors, increased resistance to antimicrobials and human immunity. Plant-based extracts have shown promising outcomes in inhibiting quorum sensing system and modulation of biofilm formation with lesser side effects. Thus, foliar extracts of Noni plant was the subject of such trial as an antibiofilm/antibacterial agent.
Objective: Investigate borehole water sources from three communities in Port Harcourt Local Government Area (PHALGA) for biofilm producers (BPs), antibiogram as well as antibiofilm effect of Noni (Morinda citrifolia) foliar extracts.
Method: Microbiological protocols were adopted to isolate and identify bacteria whereas Congo red agar was used to detect biofilm producers (BPs). Antibiogram of BPs were done (with various antibiotics) as well as antibiofilm/antibacterial effect of Noni foliar extracts.
Results: Bioassays detected the biofilm producers (BPs) as Staphylococcus aureus, Klebsiella pneumoniae, Bacillus and Serratia species. The bioburden were 55.0±2.5CFU/mL and 51.0±0.2CFU/mL for total heterotrophic bacteria and coliform counts from Ọbaziolu and Rumuelechi communities respectively. Rumuelechi borehole water had the highest percentage relative abundance of S. aureus (80%) and Bacillus (66.7%) whereas Ọbaziolu had Serratia (66.7%) and negative/zero for S. aureus and Ọrora had the least of all the isolated BPs. Antibiogram data revealed that all the BPs were 100% resistant to Cloxacillin and Cotrimoxazole but showed high rate of varying susceptibility to other antimicrobials; S. aureus depicted (100%) susceptibility to Gentamicin and Streptomycin; Bacillus to Tetracycline; Serratia to Augmentin and K. pneumoniae to Gentamicin. All the BPs showed multidrug resistance (MDR) with Serratia and K. pneumoniae being resistant to 6 and Bacillus and S. aureus 5-antibiotics respectively. Furthermore, susceptibility test on these BPs indicated that inhibitory activity of Noni foliar extracts were concentration-dependent. At a concentration of 3000mg/mL methanolic extract (MtE) showed the largest inhibition zone of 20.00mm against B. subtilis and aqueous extract (AqE) 15.00mm on Serratia species and such phenomenon is indicative of broad spectrum activity. Chloramphenicol (control) had the overall largest inhibition zones on the BPs except on B. subtilis. The susceptibility of these crude phytocompounds to BPs promises to be a novel and an alternative natural agent to synthetic antibiofilm products.
Conclusion: Biofilm producers were detected in borehole water supply in three communities in Port Harcourt Local Government Area. The predominant BPs were Staphylococcus aureus, Bacillus and Serratia species. The BPs showed multi-antibiotic resistance with the Gram negative bacteria being resistant to more drug-types. Crude phytocompounds of Noni foliar extracts demonstrated broad spectrum activity with promising prospects as likely therapeutic option against biofilm-based infections. Additionally, the degree of multidrug resistance (MDR) depicted by these BPs to conventional antimicrobials is worrisome and demands regular monitoring, environmental sanitation and good hygienic measures to mitigate public health hazards.