Effects of nutritional and ambient oxygen condition on biofilm formation in Mycobacterium avium subsp. hominissuis via altered glycolipid expression

Abstract

Mycobacterium avium subsp. hominissuis (MAH) is the major causative agent of nontuberculous mycobacteriosis, the representative case of environment-related infectious diseases the incidence of which is increasing in industrialized countries. MAH is found in biofilm in drinking water distribution system and residential environments. We investigated the effect of gaseous and nutritional conditions, and the role of glycopeptidolipids (GPLs) on biofilm-like pellicle formation in MAH. Pellicle formation was observed under 5% oxygen in Middlebrook 7H9 broth containing 0.2% glycerol and 10% albumin-dextrose-catalase enrichment but not under normoxia or in nutrient-poor media. An analysis of 17 environmental isolates revealed that hypoxia (5% oxygen) preferentially enhanced pellicle formation both in plastic plates and in glass tubes, compared with hypercapnia (5% carbon dioxide). Wild-type strains (WT) developed much thicker pellicles than GPL-deficient rough mutants (RM). WT bacterial cells distributed randomly and individually in contrast to that RM cells positioned linearly in a definite order. Exogenous supplementation of GPLs thickened the pellicles of RM, resulting in a similar morphological pattern to WT. These data suggest a significant implication of eutrophication and hypoxia in biofilm-like pellicle formation, and a functional role of GPLs on development of pellicles in MAH.

Genome-wide identification of essential genes in Mycobacterium intracellulare by transposon sequencing — Implication for metabolic remodeling

“…The common environment under these conditions is hypoxia as suggested by low oxygen concentration in natural water, tuberculous granuloma and inside biofilms in biofilm-forming bacteria 18,19,21 . First, we confirmed that, similar to pellicle formation in MAH as we demonstrated previously 16 , M. intracellulare ATCC13950 formed a pellicle under an atmosphere of 5% oxygen (Fig. S1).…”

“…1). The protocol of planktonic and pellicle bacterial culture was followed from the previous report 16 . To obtain planktonic bacteria, we started 100 ml cultures from OD 0.003 in 7H9/ADC (without Tween 80) and incubated aerobically in static conditions at 37 °C for 1 week.…”

“…We recently discovered that one of the etiological agents of MAC disease, M. avium subsp. hominissuis (MAH) forms a pellicle biofilm suspended at the air-liquid interface when cultured under hypoxia 16,17 , implicating a role of hypoxia in biofilm formation as an ecological adaptation, such as residing in natural water with limited aeration 18 or in hypoxic granuloma in vivo 19 . Biofilm formation is considered to be an important phenomenon for bacteria to achieve long-term survival in harsh environments such as in nature and inside human hosts 20 .…”

Nicotine Enhances Staphylococcus epidermidis Biofilm Formation by Altering the Bacterial Autolysis, Extracellular DNA Releasing, and Polysaccharide Intercellular Adhesin Production

“…Bacterial biofilm formation can be influenced by diverse microenvironmental conditions ( Van Wamel et al, 2007 ; Alves et al, 2010 ; Wang et al, 2015 ; Totani et al, 2017 ). Tobaco smoke, a contributor to various infectious diseases, has been shown to enhance bacterial biofilm formation in multiple species, such as Staphylococcus aureus, Streptococcus pneumoniae , and Streptococcus mutans ( Hutcherson et al, 2015 ).…”

On-Chip Isoniazid Exposure of Mycobacterium smegmatis Penicillin-Binding Protein (PBP) Mutant Using Time-Lapse Fluorescent Microscopy

“…Therefore, these technologies have great potential for observing and quantifying the microenvironmental conditions that shape the survival strategies of bacteria, such as biofilms. Biofilms are strictly regulated by their surrounding microenvironments [ 14 , 15 , 16 ]; these might be able to be tightly controlled using microfluidic devices. Moreover, microfluidic cell culture systems have provided great potential for culturing currently viable but non-culturable bacteria (VBNCs) in laboratories, while discovering the mechanisms behind their phenotype [ 11 ].…”