## 1 Introduction  
_Saccharomyces degradans_ 2-40 (_Sde_ 2-40; early name _Microbulbifer degradans_ 2-40), a motile gamma proteobacterium of marine origin, uniquely utilises different carbon sources and degrades a variety of complex polysaccharides such as agar, alginic acid, carrageenan, cellulose, chitin, glucan, laminin, pectin, pullulan, starch, and xylans [1; 2; 3; 4; 5; 6]. _Sde_ 2-40 can powerfully degrade polysaccharides from plant and marine sources. Agarose, the main agar constituent, is acquired from marine algae (Rhodophyta) such as _Gelidium_ and _Gracilaria_[7; 8]. Xylan, the principal constituent of plant cell wall hemicellulose, is copiously occurring polysaccharide next to cellulose [9]. _Sde_ 2-40 has the capability of utilizing agarose and xylan for growth [1; 4; 6]. Different microorganisms under stress conditions of growth can natively produce carbon storage polyesters like polyhydroxyalkanoate (PHAs) [10; 11]. Poly(3-hydroxyburrate) (PHB) is the most commonly produced PHA by bacteria. _Sde_ 2-40 can produce PHB homopolymer using glucose and starch as carbon sources in marine sea salt minimal media [12; 13; 14]. Recently, research interest has been growing in the bacterial cumulative process for the production of PHA using complex polysaccharides [15; 16]. _Sde_ 2-40, due to its extraordinary metabolic capacity, is deliberated to be a supremely resourceful bacterium for degradation of polysaccharides. The genome sequence of this bacterium contains open reading frames in excess of 180, which encode for enzymes like agarases, alginases, amylases, cellulases, chitinases, pectinases, and xylanases [5]. The expression and characterization of carbohydrates of _Sde_ 2-40 was studied through its cultivation in minimal media containing complex polysaccharides [17]. The crucial enzymes involved in PHA synthesis, \(\beta\)-ketothiolase, acetoacetyl-CoA reductase, and PHA synthase, were identified in the genome of _Sde_ 2-40 [18]. Reports are available on the growth of _Sde_ 2-40 using 0.2% agarose and xylan [6; 17]. However, the ability of _Sde_ 2-40 to utilize agarose or xylan in higher quantities in growth media and simultaneously produce PHA has not been investigated yet. In nature, the majority of biotransformations happen due to combined metabolic pathways of diverse microbes such as the natural fermentation of saps containing sugars, compost piles, mammalian gut, aerobic and anaerobic water zones, human skin, and forest soils [19; 20]. Utilization of substrates in co-culture occurs via collective metabolic action of the recognized strains of microbes [21]. Co-cultures have been applied in industrial biotechnology for wastewater treatment, remediation of soil, and the production of biogas [22]. In the food industry, co-cultures are used to produce cheese [23], yoghurt [24], and whisky [25]. Co-cultivation of microorganisms can be more beneficial than using a single microorganism in many situations, as it can increase yield, reduce cost of process via inexpensive substrate utilization [26], and control product quality. Co-culture and mixed culture fermentations have great promise for the development of bio-fuels, bio-energy, and bio-based products. Different wild type and recombinant microorganisms have been reported to produce PHAs using algal and plant biomass [27; 28; 29]. However, biomass hydrolysis pre-treatment before fermentation is a prerequisite in these systems for easy assimilation by microorganisms [30]. Low pH and high temperature conditions are generally used for pre-treatment processes. These conditions can prohibit bacterial growth, produce potentially toxic products, and hinder downstream fermentative processes which can lead to lowering yield and increasing cost of production [31; 32; 33]. Therefore, a strategy coupling steps of hydrolysis and fermentation (i.e., consolidated bioprocessing) is a smart approach to produce PHAs using carbon sources derived from algae and plants (Figure 1A).