Isolation of bacteria producing polyhydroxyalkanoates (PHA) from municipal sewage sludge

Abstract

Bacterial isolates from sludge samples collected at a local municipal sewage treatment plant were screened for bacteria producing polyhydroxyalkanoates (PHA). Initially Sudan black B staining was performed to detect lipid cellular inclusions. Lipid-positive isolates were then grown in a nitrogen limitation E2 medium containing 2% (w/v) glucose to promote accumulation of PHA before the subsequent staining with Nile blue A. The positive isolates were quantified initially with a u.v. spectrophotometer, for a very large number of isolates (105) and among them high PHA-producing isolates (15) were selected and were confirmed by gas chromatographic analysis. The GC analysis showed the polymers produced by 13 of the selected isolates to be polyhydroxybutyrate (PHB), and the remaining two isolates produced polyhydroxybutyrate-co-hydroxyvalerate (PHB-co-HV) copolymer. The proportion of the PHA-positive bacterial isolates showed variability in the number of PHA accumulators during various months. The correlation of PHB production with the cell dry weight (CDW) was found to be statistically significant. The metabolism of PHB in these selected 15 isolates was studied using the Nile blue A staining, which showed an initial increase in the fluorescence followed by a decline, on further incubation. All the selected 15 isolates were classified to genus level by studying their morphological and biochemical characteristics. There were

Polyphasic Identification of Amylolytic Bacteria Producing Bioplastic Poly-β-hydroxybutyrate (PHB)

“…Isolate of PSA10 which is the highest PHB-producing bacterial strain, compared to both local amylolytic bacteria producing PHB (Table 1), was closely related to B. megaterium based on the analysis of 16S rRNA gene. This corresponds with the previous studies, which reported that B. megaterium is a bacteria that is known as the PHB producer who first investigated (Lenz & Marchessault 2005;Visnuvardhan et al 2008).…”

“…Species references selected in this study are Bacillus subtilis, Bacillus cereus and Bacillus megaterium. The three species were chosen because the references has been known to hydrolyze starch (Holt et al 1994) and accumulate PHB (Halami 2008;Singh et al 2009;Visnuvardhan et al 2008). In this study, Bacillus pumilus used also as a reference species to represent members of the genus Bacillus which has a different character with the three reference species selected.…”

A novel Bacillus sp. accumulating poly (3-hydroxybutyrate-co-3-hydroxyvalerate) from a single carbon substrate

“…DiVerent samples from the municipal sewage treatment plant at Hyderabad, India, were screened for PHA-producing bacteria and have been described elsewhere [9]. Bacterial strain 88D was isolated on Luria Bertani (LB) medium (Hi media, India).…”

Polyhydroxyalkanoate (PHA) accumulation potential and PHA-accumulating microbial communities in various activated sludge processes of municipal wastewater treatment plants

“…Alcaligenes , which belong to the family Alcaligeneceae , was reported to have a high PHA accumulation potential (Vishnuvardhan Reddy et al . ). However, this study could not find specific PHA‐accumulating organisms that might be related to the PHA accumulation potentials observed in the PHA accumulation experiments (Figs and ).…”

“…Furthermore, only a few studies have investigated the abundance and taxonomic compositions of PHA‐accumulating bacteria in activated sludge using culture‐dependent (Vishnuvardhan Reddy et al . ) and culture‐independent molecular techniques (Oshiki et al . , ).…”