Abstract
The objective of the current work was to investigate the potential of halophilic bacterial isolates for efficient utilization of crude glycerol from algal biodiesel waste into polyhydroxyalkanoates (PHAs) a green plastic. Screening of the isolates was directly done in algal biodiesel waste residue containing solid agar plates supplemented with Nile red. Crude glycerol is a biodiesel waste whose bioconversion into value-added products provides an alternative for efficient management with dual benefit. For the scale-up studies of PHAs, Halomonas spp. especially H. daqingensis was observed as a potential candidate growing well in 3% Algal biodiesel waste residue (ABWR), 5% NaCl supplementation at 35°C within 48 h of incubation. Maximum Cell dry weight (CDW) of 0.362 ± 0.001 g and 0.236 ± 0.003 g PHA was obtained with H. daqingensis when grown in the fermentor with 0.5 vvm air flow rate and 200 rpm containing 3% ABWR supplemented with 5% NaCl at 35°C incubation temperature for 48 h. ABWR can serve as a sole substrate for PHA production at an industrial scale serving two approaches: getting rid of the biodiesel industrial waste containing high amount of glycerol besides using waste replacing commercial substrate thereby reducing the cost of the product.
Highlights
IntroductionThe major drawback of these synthetic plastics is its non-biodegradability and its toxic nature during incineration with the release of harmful gases into the environment
Petroleum-based plastics are essential for widespread applicability in routine life
Exploitation of waste substrates like crude glycerol from biodiesel for PHA production helps in getting rid of waste management problems and thereby decreasing environmental concerns too (Ibrahim and Steinbüchel, 2009; Zhu et al, 2013)
Summary
The major drawback of these synthetic plastics is its non-biodegradability and its toxic nature during incineration with the release of harmful gases into the environment. This has led to serious damage to the environment. Bioplastic production may increase from 2 Mt/y in 2017 to 2.4 Mt/y in 2022 as per the reports (Bioplastics Market Data, 2017 2017-2022). The present scenario affecting the cost of PHAs in the world market is the use of expensive substrates and downstream processing methodology (Kumar and Kim, 2018). Several substrates are reported in the literature which are exploited for PHA production viz. Several substrates are reported in the literature which are exploited for PHA production viz. sugars, fatty acids, vinasses-molasses mixture, waste sludge, waste water, etc
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